ICU-20119 63rc BRS, merge current unicode-icu master into cldr34a-integration branch

icu4c/source/common/charstr.cpp

@@ -126,15 +126,21 @@ char *CharString::getAppendBuffer(int32_t minCapacity,
 }
 
 CharString &CharString::appendInvariantChars(const UnicodeString &s, UErrorCode &errorCode) {
+    return appendInvariantChars(s.getBuffer(), s.length(), errorCode);
+}
+
+CharString &CharString::appendInvariantChars(const UChar* uchars, int32_t ucharsLen, UErrorCode &errorCode) {
     if(U_FAILURE(errorCode)) {
         return *this;
     }
-    if (!uprv_isInvariantUnicodeString(s)) {
+    if (!uprv_isInvariantUString(uchars, ucharsLen)) {
         errorCode = U_INVARIANT_CONVERSION_ERROR;
         return *this;
     }
-    if(ensureCapacity(len+s.length()+1, 0, errorCode)) {
-        len+=s.extract(0, 0x7fffffff, buffer.getAlias()+len, buffer.getCapacity()-len, US_INV);
+    if(ensureCapacity(len+ucharsLen+1, 0, errorCode)) {
+        u_UCharsToChars(uchars, buffer.getAlias()+len, ucharsLen);
+        len += ucharsLen;
+        buffer[len] = 0;
     }
     return *this;
 }

icu4c/source/common/charstr.h

@@ -123,6 +123,7 @@ public:
                           UErrorCode &errorCode);
 
     CharString &appendInvariantChars(const UnicodeString &s, UErrorCode &errorCode);
+    CharString &appendInvariantChars(const UChar* uchars, int32_t ucharsLen, UErrorCode& errorCode);
 
     /**
      * Appends a filename/path part, e.g., a directory name.

icu4c/source/common/cmemory.h

@@ -279,6 +279,10 @@ inline T *LocalMemory<T>::allocateInsteadAndCopy(int32_t newCapacity, int32_t le
  *
  * Unlike LocalMemory and LocalArray, this class never adopts
  * (takes ownership of) another array.
+ *
+ * WARNING: MaybeStackArray only works with primitive (plain-old data) types.
+ * It does NOT know how to call a destructor! If you work with classes with
+ * destructors, consider LocalArray in localpointer.h.
  */
 template<typename T, int32_t stackCapacity>
 class MaybeStackArray {

icu4c/source/common/locid.cpp

@@ -31,6 +31,7 @@
 ******************************************************************************
 */
 
+#include <utility>
 
 #include "unicode/bytestream.h"
 #include "unicode/locid.h"
@@ -45,9 +46,11 @@
 #include "cstring.h"
 #include "uassert.h"
 #include "uhash.h"
+#include "ulocimp.h"
 #include "ucln_cmn.h"
 #include "ustr_imp.h"
 #include "charstr.h"
+#include "bytesinkutil.h"
 
 U_CDECL_BEGIN
 static UBool U_CALLCONV locale_cleanup(void);
@@ -426,56 +429,70 @@ Locale::Locale(const Locale &other)
     *this = other;
 }
 
-Locale &Locale::operator=(const Locale &other)
-{
+Locale::Locale(Locale&& other) U_NOEXCEPT
+    : UObject(other), fullName(fullNameBuffer), baseName(fullName) {
+  *this = std::move(other);
+}
+
+Locale& Locale::operator=(const Locale& other) {
     if (this == &other) {
         return *this;
     }
 
-    /* Free our current storage */
-    if (baseName != fullName) {
-        uprv_free(baseName);
-    }
-    baseName = NULL;
-    if(fullName != fullNameBuffer) {
-        uprv_free(fullName);
-        fullName = fullNameBuffer;
+    setToBogus();
+
+    if (other.fullName == other.fullNameBuffer) {
+        uprv_strcpy(fullNameBuffer, other.fullNameBuffer);
+    } else if (other.fullName == nullptr) {
+        fullName = nullptr;
+    } else {
+        fullName = uprv_strdup(other.fullName);
+        if (fullName == nullptr) return *this;
     }
 
-    /* Allocate the full name if necessary */
-    if(other.fullName != other.fullNameBuffer) {
-        fullName = (char *)uprv_malloc(sizeof(char)*(uprv_strlen(other.fullName)+1));
-        if (fullName == NULL) {
-            // if memory allocation fails, set this object to bogus.
-            fIsBogus = TRUE;
-            return *this;
-        }
-    }
-    /* Copy the full name */
-    uprv_strcpy(fullName, other.fullName);
-
-    /* Copy the baseName if it differs from fullName. */
     if (other.baseName == other.fullName) {
         baseName = fullName;
-    } else {
-        if (other.baseName) {
-            baseName = uprv_strdup(other.baseName);
-            if (baseName == nullptr) {
-                // if memory allocation fails, set this object to bogus.
-                fIsBogus = TRUE;
-                return *this;
-            }
-        }
+    } else if (other.baseName != nullptr) {
+        baseName = uprv_strdup(other.baseName);
+        if (baseName == nullptr) return *this;
     }
 
-    /* Copy the language and country fields */
     uprv_strcpy(language, other.language);
     uprv_strcpy(script, other.script);
     uprv_strcpy(country, other.country);
 
-    /* The variantBegin is an offset, just copy it */
     variantBegin = other.variantBegin;
     fIsBogus = other.fIsBogus;
+
+    return *this;
+}
+
+Locale& Locale::operator=(Locale&& other) U_NOEXCEPT {
+    if (baseName != fullName) uprv_free(baseName);
+    if (fullName != fullNameBuffer) uprv_free(fullName);
+
+    if (other.fullName == other.fullNameBuffer) {
+        uprv_strcpy(fullNameBuffer, other.fullNameBuffer);
+        fullName = fullNameBuffer;
+    } else {
+        fullName = other.fullName;
+    }
+
+    if (other.baseName == other.fullName) {
+        baseName = fullName;
+    } else {
+        baseName = other.baseName;
+    }
+
+    uprv_strcpy(language, other.language);
+    uprv_strcpy(script, other.script);
+    uprv_strcpy(country, other.country);
+
+    variantBegin = other.variantBegin;
+    fIsBogus = other.fIsBogus;
+
+    other.baseName = other.fullName = other.fullNameBuffer;
+
     return *this;
 }
 
@@ -713,6 +730,126 @@ Locale::setDefault( const   Locale&     newLocale,
     locale_set_default_internal(localeID, status);
 }
 
+void
+Locale::addLikelySubtags(UErrorCode& status) {
+    if (U_FAILURE(status)) {
+        return;
+    }
+
+    // The maximized locale ID string is often longer, but there is no good
+    // heuristic to estimate just how much longer. Leave that to CharString.
+    CharString maximizedLocaleID;
+    int32_t maximizedLocaleIDCapacity = uprv_strlen(fullName);
+
+    char* buffer;
+    int32_t reslen;
+
+    for (;;) {
+        buffer = maximizedLocaleID.getAppendBuffer(
+                /*minCapacity=*/maximizedLocaleIDCapacity,
+                /*desiredCapacityHint=*/maximizedLocaleIDCapacity,
+                maximizedLocaleIDCapacity,
+                status);
+
+        if (U_FAILURE(status)) {
+            return;
+        }
+
+        reslen = uloc_addLikelySubtags(
+                fullName,
+                buffer,
+                maximizedLocaleIDCapacity,
+                &status);
+
+        if (status != U_BUFFER_OVERFLOW_ERROR) {
+            break;
+        }
+
+        maximizedLocaleIDCapacity = reslen;
+        status = U_ZERO_ERROR;
+    }
+
+    if (U_FAILURE(status)) {
+        return;
+    }
+
+    maximizedLocaleID.append(buffer, reslen, status);
+    if (status == U_STRING_NOT_TERMINATED_WARNING) {
+        status = U_ZERO_ERROR;  // Terminators provided by CharString.
+    }
+
+    if (U_FAILURE(status)) {
+        return;
+    }
+
+    init(maximizedLocaleID.data(), /*canonicalize=*/FALSE);
+    if (isBogus()) {
+        status = U_ILLEGAL_ARGUMENT_ERROR;
+    }
+}
+
+void
+Locale::minimizeSubtags(UErrorCode& status) {
+    if (U_FAILURE(status)) {
+        return;
+    }
+
+    // Except for a few edge cases (like the empty string, that is minimized to
+    // "en__POSIX"), minimized locale ID strings will be either the same length
+    // or shorter than their input.
+    CharString minimizedLocaleID;
+    int32_t minimizedLocaleIDCapacity = uprv_strlen(fullName);
+
+    char* buffer;
+    int32_t reslen;
+
+    for (;;) {
+        buffer = minimizedLocaleID.getAppendBuffer(
+                /*minCapacity=*/minimizedLocaleIDCapacity,
+                /*desiredCapacityHint=*/minimizedLocaleIDCapacity,
+                minimizedLocaleIDCapacity,
+                status);
+
+        if (U_FAILURE(status)) {
+            return;
+        }
+
+        reslen = uloc_minimizeSubtags(
+                fullName,
+                buffer,
+                minimizedLocaleIDCapacity,
+                &status);
+
+        if (status != U_BUFFER_OVERFLOW_ERROR) {
+            break;
+        }
+
+        // Because of the internal minimal buffer size of CharString, I can't
+        // think of any input data for which this could possibly ever happen.
+        // Maybe it would be better replaced with an assertion instead?
+        minimizedLocaleIDCapacity = reslen;
+        status = U_ZERO_ERROR;
+    }
+
+    if (U_FAILURE(status)) {
+        return;
+    }
+
+    minimizedLocaleID.append(buffer, reslen, status);
+    if (status == U_STRING_NOT_TERMINATED_WARNING) {
+        status = U_ZERO_ERROR;  // Terminators provided by CharString.
+    }
+
+    if (U_FAILURE(status)) {
+        return;
+    }
+
+    init(minimizedLocaleID.data(), /*canonicalize=*/FALSE);
+    if (isBogus()) {
+        status = U_ILLEGAL_ARGUMENT_ERROR;
+    }
+}
+
 Locale U_EXPORT2
 Locale::forLanguageTag(StringPiece tag, UErrorCode& status)
 {
@@ -722,12 +859,6 @@ Locale::forLanguageTag(StringPiece tag, UErrorCode& status)
         return result;
     }
 
-    // TODO: Remove the need for a const char* to a NUL terminated buffer.
-    const CharString tag_nul(tag, status);
-    if (U_FAILURE(status)) {
-        return result;
-    }
-
     // If a BCP-47 language tag is passed as the language parameter to the
     // normal Locale constructor, it will actually fall back to invoking
     // uloc_forLanguageTag() to parse it if it somehow is able to detect that
@@ -757,8 +888,9 @@ Locale::forLanguageTag(StringPiece tag, UErrorCode& status)
             return result;
         }
 
-        reslen = uloc_forLanguageTag(
-                tag_nul.data(),
+        reslen = ulocimp_forLanguageTag(
+                tag.data(),
+                tag.length(),
                 buffer,
                 resultCapacity,
                 &parsedLength,
@@ -1174,20 +1306,79 @@ KeywordEnumeration::~KeywordEnumeration() {
     uprv_free(keywords);
 }
 
+// A wrapper around KeywordEnumeration that calls uloc_toUnicodeLocaleKey() in
+// the next() method for each keyword before returning it.
+class UnicodeKeywordEnumeration : public KeywordEnumeration {
+public:
+    using KeywordEnumeration::KeywordEnumeration;
+    virtual ~UnicodeKeywordEnumeration() = default;
+
+    virtual const char* next(int32_t* resultLength, UErrorCode& status) {
+        const char* legacy_key = KeywordEnumeration::next(nullptr, status);
+        if (U_SUCCESS(status) && legacy_key != nullptr) {
+            const char* key = uloc_toUnicodeLocaleKey(legacy_key);
+            if (key == nullptr) {
+                status = U_ILLEGAL_ARGUMENT_ERROR;
+            } else {
+                if (resultLength != nullptr) *resultLength = uprv_strlen(key);
+                return key;
+            }
+        }
+        if (resultLength != nullptr) *resultLength = 0;
+        return nullptr;
+    }
+};
+
 StringEnumeration *
 Locale::createKeywords(UErrorCode &status) const
 {
     char keywords[256];
-    int32_t keywordCapacity = 256;
+    int32_t keywordCapacity = sizeof keywords;
     StringEnumeration *result = NULL;
 
+    if (U_FAILURE(status)) {
+        return result;
+    }
+
     const char* variantStart = uprv_strchr(fullName, '@');
     const char* assignment = uprv_strchr(fullName, '=');
     if(variantStart) {
         if(assignment > variantStart) {
             int32_t keyLen = locale_getKeywords(variantStart+1, '@', keywords, keywordCapacity, NULL, 0, NULL, FALSE, &status);
-            if(keyLen) {
+            if(U_SUCCESS(status) && keyLen) {
                 result = new KeywordEnumeration(keywords, keyLen, 0, status);
+                if (!result) {
+                    status = U_MEMORY_ALLOCATION_ERROR;
+                }
+            }
+        } else {
+            status = U_INVALID_FORMAT_ERROR;
+        }
+    }
+    return result;
+}
+
+StringEnumeration *
+Locale::createUnicodeKeywords(UErrorCode &status) const
+{
+    char keywords[256];
+    int32_t keywordCapacity = sizeof keywords;
+    StringEnumeration *result = NULL;
+
+    if (U_FAILURE(status)) {
+        return result;
+    }
+
+    const char* variantStart = uprv_strchr(fullName, '@');
+    const char* assignment = uprv_strchr(fullName, '=');
+    if(variantStart) {
+        if(assignment > variantStart) {
+            int32_t keyLen = locale_getKeywords(variantStart+1, '@', keywords, keywordCapacity, NULL, 0, NULL, FALSE, &status);
+            if(U_SUCCESS(status) && keyLen) {
+                result = new UnicodeKeywordEnumeration(keywords, keyLen, 0, status);
+                if (!result) {
+                    status = U_MEMORY_ALLOCATION_ERROR;
+                }
             }
         } else {
             status = U_INVALID_FORMAT_ERROR;
@@ -1202,6 +1393,105 @@ Locale::getKeywordValue(const char* keywordName, char *buffer, int32_t bufLen, U
     return uloc_getKeywordValue(fullName, keywordName, buffer, bufLen, &status);
 }
 
+void
+Locale::getKeywordValue(StringPiece keywordName, ByteSink& sink, UErrorCode& status) const {
+    if (U_FAILURE(status)) {
+        return;
+    }
+
+    if (fIsBogus) {
+        status = U_ILLEGAL_ARGUMENT_ERROR;
+        return;
+    }
+
+    // TODO: Remove the need for a const char* to a NUL terminated buffer.
+    const CharString keywordName_nul(keywordName, status);
+    if (U_FAILURE(status)) {
+        return;
+    }
+
+    LocalMemory<char> scratch;
+    int32_t scratch_capacity = 16;  // Arbitrarily chosen default size.
+
+    char* buffer;
+    int32_t result_capacity, reslen;
+
+    for (;;) {
+        if (scratch.allocateInsteadAndReset(scratch_capacity) == nullptr) {
+            status = U_MEMORY_ALLOCATION_ERROR;
+            return;
+        }
+
+        buffer = sink.GetAppendBuffer(
+                /*min_capacity=*/scratch_capacity,
+                /*desired_capacity_hint=*/scratch_capacity,
+                scratch.getAlias(),
+                scratch_capacity,
+                &result_capacity);
+
+        reslen = uloc_getKeywordValue(
+                fullName,
+                keywordName_nul.data(),
+                buffer,
+                result_capacity,
+                &status);
+
+        if (status != U_BUFFER_OVERFLOW_ERROR) {
+            break;
+        }
+
+        scratch_capacity = reslen;
+        status = U_ZERO_ERROR;
+    }
+
+    if (U_FAILURE(status)) {
+        return;
+    }
+
+    sink.Append(buffer, reslen);
+    if (status == U_STRING_NOT_TERMINATED_WARNING) {
+        status = U_ZERO_ERROR;  // Terminators not used.
+    }
+}
+
+void
+Locale::getUnicodeKeywordValue(StringPiece keywordName,
+                               ByteSink& sink,
+                               UErrorCode& status) const {
+    // TODO: Remove the need for a const char* to a NUL terminated buffer.
+    const CharString keywordName_nul(keywordName, status);
+    if (U_FAILURE(status)) {
+        return;
+    }
+
+    const char* legacy_key = uloc_toLegacyKey(keywordName_nul.data());
+
+    if (legacy_key == nullptr) {
+        status = U_ILLEGAL_ARGUMENT_ERROR;
+        return;
+    }
+
+    CharString legacy_value;
+    {
+        CharStringByteSink sink(&legacy_value);
+        getKeywordValue(legacy_key, sink, status);
+    }
+
+    if (U_FAILURE(status)) {
+        return;
+    }
+
+    const char* unicode_value = uloc_toUnicodeLocaleType(
+            keywordName_nul.data(), legacy_value.data());
+
+    if (unicode_value == nullptr) {
+        status = U_ILLEGAL_ARGUMENT_ERROR;
+        return;
+    }
+
+    sink.Append(unicode_value, uprv_strlen(unicode_value));
+}
+
 void
 Locale::setKeywordValue(const char* keywordName, const char* keywordValue, UErrorCode &status)
 {
@@ -1212,6 +1502,46 @@ Locale::setKeywordValue(const char* keywordName, const char* keywordValue, UErro
     }
 }
 
+void
+Locale::setKeywordValue(StringPiece keywordName,
+                        StringPiece keywordValue,
+                        UErrorCode& status) {
+    // TODO: Remove the need for a const char* to a NUL terminated buffer.
+    const CharString keywordName_nul(keywordName, status);
+    const CharString keywordValue_nul(keywordValue, status);
+    setKeywordValue(keywordName_nul.data(), keywordValue_nul.data(), status);
+}
+
+void
+Locale::setUnicodeKeywordValue(StringPiece keywordName,
+                               StringPiece keywordValue,
+                               UErrorCode& status) {
+    // TODO: Remove the need for a const char* to a NUL terminated buffer.
+    const CharString keywordName_nul(keywordName, status);
+    const CharString keywordValue_nul(keywordValue, status);
+
+    if (U_FAILURE(status)) {
+        return;
+    }
+
+    const char* legacy_key = uloc_toLegacyKey(keywordName_nul.data());
+
+    if (legacy_key == nullptr) {
+        status = U_ILLEGAL_ARGUMENT_ERROR;
+        return;
+    }
+
+    const char* legacy_value =
+        uloc_toLegacyType(keywordName_nul.data(), keywordValue_nul.data());
+
+    if (legacy_value == nullptr) {
+        status = U_ILLEGAL_ARGUMENT_ERROR;
+        return;
+    }
+
+    setKeywordValue(legacy_key, legacy_value, status);
+}
+
 const char *
 Locale::getBaseName() const {
     return baseName;

icu4c/source/common/putil.cpp

@@ -1668,7 +1668,8 @@ The leftmost codepage (.xxx) wins.
     /* Note that we scan the *uncorrected* ID. */
     if ((p = uprv_strrchr(posixID, '@')) != NULL) {
         if (correctedPOSIXLocale == NULL) {
-            correctedPOSIXLocale = static_cast<char *>(uprv_malloc(uprv_strlen(posixID)+1));
+            /* new locale can be 1 char longer than old one if @ -> __ */
+            correctedPOSIXLocale = static_cast<char *>(uprv_malloc(uprv_strlen(posixID)+2));
             /* Exit on memory allocation error. */
             if (correctedPOSIXLocale == NULL) {
                 return NULL;
@@ -1685,7 +1686,7 @@ The leftmost codepage (.xxx) wins.
         }
 
         if (uprv_strchr(correctedPOSIXLocale,'_') == NULL) {
-            uprv_strcat(correctedPOSIXLocale, "__"); /* aa@b -> aa__b */
+            uprv_strcat(correctedPOSIXLocale, "__"); /* aa@b -> aa__b (note this can make the new locale 1 char longer) */
         }
         else {
             uprv_strcat(correctedPOSIXLocale, "_"); /* aa_CC@b -> aa_CC_b */

icu4c/source/common/putilimp.h

@@ -94,7 +94,7 @@ typedef size_t uintptr_t;
 #   define U_NL_LANGINFO_CODESET CODESET
 #endif
 
-#ifdef U_TZSET
+#if defined(U_TZSET) || defined(U_HAVE_TZSET)
     /* Use the predefined value. */
 #elif U_PLATFORM_USES_ONLY_WIN32_API
     // UWP doesn't support tzset or environment variables for tz
@@ -132,7 +132,7 @@ typedef size_t uintptr_t;
 #   define U_TIMEZONE timezone
 #endif
 
-#ifdef U_TZNAME
+#if defined(U_TZNAME) || defined(U_HAVE_TZNAME)
     /* Use the predefined value. */
 #elif U_PLATFORM_USES_ONLY_WIN32_API
     /* not usable on all windows platforms */

icu4c/source/common/uinvchar.h

@@ -53,22 +53,6 @@ uprv_isInvariantString(const char *s, int32_t length);
 U_INTERNAL UBool U_EXPORT2
 uprv_isInvariantUString(const UChar *s, int32_t length);
 
-#ifdef __cplusplus
-
-/**
- * Check if a UnicodeString only contains invariant characters.
- * See utypes.h for details.
- *
- * @param s Input string.
- * @return TRUE if s contains only invariant characters.
- */
-U_INTERNAL inline UBool U_EXPORT2
-uprv_isInvariantUnicodeString(const icu::UnicodeString &s) {
-    return uprv_isInvariantUString(icu::toUCharPtr(s.getBuffer()), s.length());
-}
-
-#endif  /* __cplusplus */
-
 /**
  * \def U_UPPER_ORDINAL
  * Get the ordinal number of an uppercase invariant character

icu4c/source/common/uloc_tag.cpp

@@ -1460,9 +1460,9 @@ _appendLDMLExtensionAsKeywords(const char* ldmlext, ExtensionListEntry** appendT
                     kwd->value = pType;
 
                     if (!_addExtensionToList(&kwdFirst, kwd, FALSE)) {
-                        *status = U_ILLEGAL_ARGUMENT_ERROR;
+                        // duplicate keyword is allowed, Only the first
+                        // is honored.
                         uprv_free(kwd);
-                        goto cleanup;
                     }
                 }
 
@@ -2416,6 +2416,23 @@ uloc_forLanguageTag(const char* langtag,
                     int32_t localeIDCapacity,
                     int32_t* parsedLength,
                     UErrorCode* status) {
+    return ulocimp_forLanguageTag(
+            langtag,
+            -1,
+            localeID,
+            localeIDCapacity,
+            parsedLength,
+            status);
+}
+
+
+U_CAPI int32_t U_EXPORT2
+ulocimp_forLanguageTag(const char* langtag,
+                       int32_t tagLen,
+                       char* localeID,
+                       int32_t localeIDCapacity,
+                       int32_t* parsedLength,
+                       UErrorCode* status) {
     ULanguageTag *lt;
     int32_t reslen = 0;
     const char *subtag, *p;
@@ -2423,7 +2440,7 @@ uloc_forLanguageTag(const char* langtag,
     int32_t i, n;
     UBool noRegion = TRUE;
 
-    lt = ultag_parse(langtag, -1, parsedLength, status);
+    lt = ultag_parse(langtag, tagLen, parsedLength, status);
     if (U_FAILURE(*status)) {
         return 0;
     }

icu4c/source/common/ulocimp.h

@@ -61,6 +61,38 @@ ulocimp_getCountry(const char *localeID,
                    char *country, int32_t countryCapacity,
                    const char **pEnd);
 
+/**
+ * Returns a locale ID for the specified BCP47 language tag string.
+ * If the specified language tag contains any ill-formed subtags,
+ * the first such subtag and all following subtags are ignored.
+ * <p>
+ * This implements the 'Language-Tag' production of BCP47, and so
+ * supports grandfathered (regular and irregular) as well as private
+ * use language tags.  Private use tags are represented as 'x-whatever',
+ * and grandfathered tags are converted to their canonical replacements
+ * where they exist.  Note that a few grandfathered tags have no modern
+ * replacement, these will be converted using the fallback described in
+ * the first paragraph, so some information might be lost.
+ * @param langtag   the input BCP47 language tag.
+ * @param tagLen    the length of langtag, or -1 to call uprv_strlen().
+ * @param localeID  the output buffer receiving a locale ID for the
+ *                  specified BCP47 language tag.
+ * @param localeIDCapacity  the size of the locale ID output buffer.
+ * @param parsedLength  if not NULL, successfully parsed length
+ *                      for the input language tag is set.
+ * @param err       error information if receiving the locald ID
+ *                  failed.
+ * @return          the length of the locale ID.
+ * @internal ICU 63
+ */
+U_STABLE int32_t U_EXPORT2
+ulocimp_forLanguageTag(const char* langtag,
+                       int32_t tagLen,
+                       char* localeID,
+                       int32_t localeIDCapacity,
+                       int32_t* parsedLength,
+                       UErrorCode* err);
+
 /**
  * Get the region to use for supplemental data lookup. Uses
  * (1) any region specified by locale tag "rg"; if none then

icu4c/source/common/unicode/locid.h

@@ -32,6 +32,8 @@
 #define LOCID_H
 
 #include "unicode/bytestream.h"
+#include "unicode/localpointer.h"
+#include "unicode/strenum.h"
 #include "unicode/stringpiece.h"
 #include "unicode/utypes.h"
 #include "unicode/uobject.h"
@@ -282,6 +284,14 @@ public:
      */
     Locale(const    Locale& other);
 
+    /**
+     * Move constructor; might leave source in bogus state.
+     * This locale will have the same contents that the source locale had.
+     *
+     * @param other The Locale object being moved in.
+     * @draft ICU 63
+     */
+    Locale(Locale&& other) U_NOEXCEPT;
 
     /**
      * Destructor
@@ -298,6 +308,17 @@ public:
      */
     Locale& operator=(const Locale& other);
 
+    /**
+     * Move assignment operator; might leave source in bogus state.
+     * This locale will have the same contents that the source locale had.
+     * The behavior is undefined if *this and the source are the same object.
+     *
+     * @param other The Locale object being moved in.
+     * @return      *this
+     * @draft ICU 63
+     */
+    Locale& operator=(Locale&& other) U_NOEXCEPT;
+
     /**
      * Checks if two locale keys are the same.
      *
@@ -483,6 +504,69 @@ public:
      */
     const char * getBaseName() const;
 
+#ifndef U_HIDE_DRAFT_API
+    /**
+     * Add the likely subtags for this Locale, per the algorithm described
+     * in the following CLDR technical report:
+     *
+     *   http://www.unicode.org/reports/tr35/#Likely_Subtags
+     *
+     * If this Locale is already in the maximal form, or not valid, or there is
+     * no data available for maximization, the Locale will be unchanged.
+     *
+     * For example, "und-Zzzz" cannot be maximized, since there is no
+     * reasonable maximization.
+     *
+     * Examples:
+     *
+     * "en" maximizes to "en_Latn_US"
+     *
+     * "de" maximizes to "de_Latn_US"
+     *
+     * "sr" maximizes to "sr_Cyrl_RS"
+     *
+     * "sh" maximizes to "sr_Latn_RS" (Note this will not reverse.)
+     *
+     * "zh_Hani" maximizes to "zh_Hans_CN" (Note this will not reverse.)
+     *
+     * @param status  error information if maximizing this Locale failed.
+     *                If this Locale is not well-formed, the error code is
+     *                U_ILLEGAL_ARGUMENT_ERROR.
+     * @draft ICU 63
+     */
+    void addLikelySubtags(UErrorCode& status);
+
+    /**
+     * Minimize the subtags for this Locale, per the algorithm described
+     * in the following CLDR technical report:
+     *
+     *   http://www.unicode.org/reports/tr35/#Likely_Subtags
+     *
+     * If this Locale is already in the minimal form, or not valid, or there is
+     * no data available for minimization, the Locale will be unchanged.
+     *
+     * Since the minimization algorithm relies on proper maximization, see the
+     * comments for addLikelySubtags for reasons why there might not be any
+     * data.
+     *
+     * Examples:
+     *
+     * "en_Latn_US" minimizes to "en"
+     *
+     * "de_Latn_US" minimizes to "de"
+     *
+     * "sr_Cyrl_RS" minimizes to "sr"
+     *
+     * "zh_Hant_TW" minimizes to "zh_TW" (The region is preferred to the
+     * script, and minimizing to "zh" would imply "zh_Hans_CN".)
+     *
+     * @param status  error information if maximizing this Locale failed.
+     *                If this Locale is not well-formed, the error code is
+     *                U_ILLEGAL_ARGUMENT_ERROR.
+     * @draft ICU 63
+     */
+    void minimizeSubtags(UErrorCode& status);
+#endif  // U_HIDE_DRAFT_API
 
     /**
      * Gets the list of keywords for the specified locale.
@@ -490,13 +574,64 @@ public:
      * @param status the status code
      * @return pointer to StringEnumeration class, or NULL if there are no keywords. 
      * Client must dispose of it by calling delete.
+     * @see getKeywords
      * @stable ICU 2.8
      */
     StringEnumeration * createKeywords(UErrorCode &status) const;
 
+#ifndef U_HIDE_DRAFT_API
+
+    /**
+     * Gets the list of Unicode keywords for the specified locale.
+     *
+     * @param status the status code
+     * @return pointer to StringEnumeration class, or NULL if there are no keywords.
+     * Client must dispose of it by calling delete.
+     * @see getUnicodeKeywords
+     * @draft ICU 63
+     */
+    StringEnumeration * createUnicodeKeywords(UErrorCode &status) const;
+
+    /**
+     * Gets the set of keywords for this Locale.
+     *
+     * A wrapper to call createKeywords() and write the resulting
+     * keywords as standard strings (or compatible objects) into any kind of
+     * container that can be written to by an STL style output iterator.
+     *
+     * @param iterator  an STL style output iterator to write the keywords to.
+     * @param status    error information if creating set of keywords failed.
+     * @return          a set of strings with all keywords.
+     * @draft ICU 63
+     */
+    template<typename StringClass, typename OutputIterator>
+    inline void getKeywords(OutputIterator iterator, UErrorCode& status) const;
+
+    /**
+     * Gets the set of Unicode keywords for this Locale.
+     *
+     * A wrapper to call createUnicodeKeywords() and write the resulting
+     * keywords as standard strings (or compatible objects) into any kind of
+     * container that can be written to by an STL style output iterator.
+     *
+     * @param iterator  an STL style output iterator to write the keywords to.
+     * @param status    error information if creating set of keywords failed.
+     * @return          a set of strings with all keywords.
+     * @draft ICU 63
+     */
+    template<typename StringClass, typename OutputIterator>
+    inline void getUnicodeKeywords(OutputIterator iterator, UErrorCode& status) const;
+
+#endif  // U_HIDE_DRAFT_API
+
     /**
      * Gets the value for a keyword.
      *
+     * This uses legacy keyword=value pairs, like "collation=phonebook".
+     *
+     * ICU4C doesn't do automatic conversion between legacy and Unicode
+     * keywords and values in getters and setters (as opposed to ICU4J).
+     *
      * @param keywordName name of the keyword for which we want the value. Case insensitive.
      * @param buffer The buffer to receive the keyword value.
      * @param bufferCapacity The capacity of receiving buffer
@@ -507,12 +642,81 @@ public:
      */
     int32_t getKeywordValue(const char* keywordName, char *buffer, int32_t bufferCapacity, UErrorCode &status) const;
 
+#ifndef U_HIDE_DRAFT_API
+    /**
+     * Gets the value for a keyword.
+     *
+     * This uses legacy keyword=value pairs, like "collation=phonebook".
+     *
+     * ICU4C doesn't do automatic conversion between legacy and Unicode
+     * keywords and values in getters and setters (as opposed to ICU4J).
+     *
+     * @param keywordName  name of the keyword for which we want the value.
+     * @param sink         the sink to receive the keyword value.
+     * @param status       error information if getting the value failed.
+     * @draft ICU 63
+     */
+    void getKeywordValue(StringPiece keywordName, ByteSink& sink, UErrorCode& status) const;
+
+    /**
+     * Gets the value for a keyword.
+     *
+     * This uses legacy keyword=value pairs, like "collation=phonebook".
+     *
+     * ICU4C doesn't do automatic conversion between legacy and Unicode
+     * keywords and values in getters and setters (as opposed to ICU4J).
+     *
+     * @param keywordName  name of the keyword for which we want the value.
+     * @param status       error information if getting the value failed.
+     * @return             the keyword value.
+     * @draft ICU 63
+     */
+    template<typename StringClass>
+    inline StringClass getKeywordValue(StringPiece keywordName, UErrorCode& status) const;
+
+    /**
+     * Gets the Unicode value for a Unicode keyword.
+     *
+     * This uses Unicode key-value pairs, like "co-phonebk".
+     *
+     * ICU4C doesn't do automatic conversion between legacy and Unicode
+     * keywords and values in getters and setters (as opposed to ICU4J).
+     *
+     * @param keywordName  name of the keyword for which we want the value.
+     * @param sink         the sink to receive the keyword value.
+     * @param status       error information if getting the value failed.
+     * @draft ICU 63
+     */
+    void getUnicodeKeywordValue(StringPiece keywordName, ByteSink& sink, UErrorCode& status) const;
+
+    /**
+     * Gets the Unicode value for a Unicode keyword.
+     *
+     * This uses Unicode key-value pairs, like "co-phonebk".
+     *
+     * ICU4C doesn't do automatic conversion between legacy and Unicode
+     * keywords and values in getters and setters (as opposed to ICU4J).
+     *
+     * @param keywordName  name of the keyword for which we want the value.
+     * @param status       error information if getting the value failed.
+     * @return             the keyword value.
+     * @draft ICU 63
+     */
+    template<typename StringClass>
+    inline StringClass getUnicodeKeywordValue(StringPiece keywordName, UErrorCode& status) const;
+#endif  // U_HIDE_DRAFT_API
+
     /**
      * Sets or removes the value for a keyword.
      *
      * For removing all keywords, use getBaseName(),
      * and construct a new Locale if it differs from getName().
      *
+     * This uses legacy keyword=value pairs, like "collation=phonebook".
+     *
+     * ICU4C doesn't do automatic conversion between legacy and Unicode
+     * keywords and values in getters and setters (as opposed to ICU4J).
+     *
      * @param keywordName name of the keyword to be set. Case insensitive.
      * @param keywordValue value of the keyword to be set. If 0-length or
      *  NULL, will result in the keyword being removed. No error is given if
@@ -523,6 +727,48 @@ public:
      */
     void setKeywordValue(const char* keywordName, const char* keywordValue, UErrorCode &status);
 
+#ifndef U_HIDE_DRAFT_API
+    /**
+     * Sets or removes the value for a keyword.
+     *
+     * For removing all keywords, use getBaseName(),
+     * and construct a new Locale if it differs from getName().
+     *
+     * This uses legacy keyword=value pairs, like "collation=phonebook".
+     *
+     * ICU4C doesn't do automatic conversion between legacy and Unicode
+     * keywords and values in getters and setters (as opposed to ICU4J).
+     *
+     * @param keywordName name of the keyword to be set.
+     * @param keywordValue value of the keyword to be set. If 0-length or
+     *  NULL, will result in the keyword being removed. No error is given if
+     *  that keyword does not exist.
+     * @param status Returns any error information while performing this operation.
+     * @draft ICU 63
+     */
+    void setKeywordValue(StringPiece keywordName, StringPiece keywordValue, UErrorCode& status);
+
+    /**
+     * Sets or removes the Unicode value for a Unicode keyword.
+     *
+     * For removing all keywords, use getBaseName(),
+     * and construct a new Locale if it differs from getName().
+     *
+     * This uses Unicode key-value pairs, like "co-phonebk".
+     *
+     * ICU4C doesn't do automatic conversion between legacy and Unicode
+     * keywords and values in getters and setters (as opposed to ICU4J).
+     *
+     * @param keywordName name of the keyword to be set.
+     * @param keywordValue value of the keyword to be set. If 0-length or
+     *  NULL, will result in the keyword being removed. No error is given if
+     *  that keyword does not exist.
+     * @param status Returns any error information while performing this operation.
+     * @draft ICU 63
+     */
+    void setUnicodeKeywordValue(StringPiece keywordName, StringPiece keywordValue, UErrorCode& status);
+#endif  // U_HIDE_DRAFT_API
+
     /**
      * returns the locale's three-letter language code, as specified
      * in ISO draft standard ISO-639-2.
@@ -867,6 +1113,62 @@ Locale::getName() const
     return fullName;
 }
 
+#ifndef U_HIDE_DRAFT_API
+
+template<typename StringClass, typename OutputIterator> inline void
+Locale::getKeywords(OutputIterator iterator, UErrorCode& status) const
+{
+    LocalPointer<StringEnumeration> keys(createKeywords(status));
+    if (U_FAILURE(status)) {
+        return;
+    }
+    for (;;) {
+        int32_t resultLength;
+        const char* buffer = keys->next(&resultLength, status);
+        if (U_FAILURE(status) || buffer == nullptr) {
+            return;
+        }
+        *iterator++ = StringClass(buffer, resultLength);
+    }
+}
+
+template<typename StringClass, typename OutputIterator> inline void
+Locale::getUnicodeKeywords(OutputIterator iterator, UErrorCode& status) const
+{
+    LocalPointer<StringEnumeration> keys(createUnicodeKeywords(status));
+    if (U_FAILURE(status)) {
+        return;
+    }
+    for (;;) {
+        int32_t resultLength;
+        const char* buffer = keys->next(&resultLength, status);
+        if (U_FAILURE(status) || buffer == nullptr) {
+            return;
+        }
+        *iterator++ = StringClass(buffer, resultLength);
+    }
+}
+
+template<typename StringClass> inline StringClass
+Locale::getKeywordValue(StringPiece keywordName, UErrorCode& status) const
+{
+    StringClass result;
+    StringByteSink<StringClass> sink(&result);
+    getKeywordValue(keywordName, sink, status);
+    return result;
+}
+
+template<typename StringClass> inline StringClass
+Locale::getUnicodeKeywordValue(StringPiece keywordName, UErrorCode& status) const
+{
+    StringClass result;
+    StringByteSink<StringClass> sink(&result);
+    getUnicodeKeywordValue(keywordName, sink, status);
+    return result;
+}
+
+#endif  // U_HIDE_DRAFT_API
+
 inline UBool
 Locale::isBogus(void) const {
     return fIsBogus;

icu4c/source/common/unicode/platform.h

@@ -420,6 +420,9 @@
 #ifndef __has_cpp_attribute
 #    define __has_cpp_attribute(x) 0
 #endif
+#ifndef __has_declspec_attribute
+#    define __has_declspec_attribute(x) 0
+#endif
 #ifndef __has_builtin
 #    define __has_builtin(x) 0
 #endif
@@ -783,6 +786,8 @@ namespace std {
     /* Use the predefined value. */
 #elif defined(U_STATIC_IMPLEMENTATION)
 #   define U_EXPORT
+#elif defined(_MSC_VER) || (__has_declspec_attribute(dllexport) && __has_declspec_attribute(dllimport))
+#   define U_EXPORT __declspec(dllexport)
 #elif defined(__GNUC__)
 #   define U_EXPORT __attribute__((visibility("default")))
 #elif (defined(__SUNPRO_CC) && __SUNPRO_CC >= 0x550) \
@@ -790,8 +795,6 @@ namespace std {
 #   define U_EXPORT __global
 /*#elif defined(__HP_aCC) || defined(__HP_cc)
 #   define U_EXPORT __declspec(dllexport)*/
-#elif defined(_MSC_VER)
-#   define U_EXPORT __declspec(dllexport)
 #else
 #   define U_EXPORT
 #endif
@@ -807,7 +810,7 @@ namespace std {
 
 #ifdef U_IMPORT
     /* Use the predefined value. */
-#elif defined(_MSC_VER)
+#elif defined(_MSC_VER) || (__has_declspec_attribute(dllexport) && __has_declspec_attribute(dllimport))
     /* Windows needs to export/import data. */
 #   define U_IMPORT __declspec(dllimport)
 #else

icu4c/source/data/build.xml

@@ -59,7 +59,7 @@
         </taskdef>
     </target>
     <!-- target for generating ICU data -->
-    <target name="all" depends="locales, collation, rbnf, supplementalData, metadata, metaZones, windowsZones, likelySubtags, plurals, numberingSystems, translit, brkitr, keyTypeData, genderList, dayPeriods" />
+    <target name="all" depends="locales, collation, rbnf, supplementalData, metadata, metaZones, windowsZones, likelySubtags, plurals, pluralRanges, numberingSystems, translit, brkitr, keyTypeData, genderList, dayPeriods" />
     <!-- parallel target -->
     <target name="pall" depends="init">
         <parallel threadsPerProcessor ="1">
@@ -258,6 +258,18 @@
             </run>
         </cldr-build>
     </target>
+    <target name="pluralRanges" depends="init,setup" description="builds pluralRanges.txt from pluralRanges.xml">
+        <cldr-build toolName="org.unicode.cldr.icu.NewLdml2IcuConverter" destFile="pluralRanges.txt" noArgs="true">
+            <!-- launch the tool and generate the data after reading the config file -->
+            <run>
+                <args>
+                    <arg name="-s" value="${env.CLDR_DIR}/common/supplemental" />
+                    <arg name="-d" value="${env.ICU4C_DIR}/source/data/misc"/>
+                    <arg name="-t" value="pluralRanges"/>
+                </args>
+            </run>
+        </cldr-build>
+    </target>
     <target name="numberingSystems" depends="init,setup" description="builds numberingSystems.txt from numberingSystems.xml">
         <cldr-build toolName="org.unicode.cldr.icu.NewLdml2IcuConverter" destFile="numberingSystems.txt" noArgs="true">
             <!-- launch the tool and generate the data after reading the config file -->
@@ -414,6 +426,9 @@
             <fileset id="plurals" dir="${env.ICU4C_DIR}/source/data/misc">
                 <include name="plurals.txt" />
             </fileset>
+            <fileset id="pluralRanges" dir="${env.ICU4C_DIR}/source/data/misc">
+                <include name="pluralRanges.txt" />
+            </fileset>
             <fileset id="numberingSystems" dir="${env.ICU4C_DIR}/source/data/misc">
                 <include name="numberingSystems.txt" />
             </fileset>

icu4c/source/data/misc/currencyNumericCodes.txt

@@ -6,7 +6,7 @@
 // Corporation and others.  All Rights Reserved.
 //---------------------------------------------------------
 // Build tool: com.ibm.icu.dev.tool.currency.NumericCodeData
-// Build date: 2018-06-06T22:39:58Z
+// Build date: 2018-09-17T17:52:05Z
 //---------------------------------------------------------
 // >> !!! >>   THIS IS A MACHINE-GENERATED FILE   << !!! <<
 // >> !!! >>>            DO NOT EDIT             <<< !!! <<
@@ -270,9 +270,11 @@ currencyNumericCodes:table(nofallback){
         UYN:int{858}
         UYP:int{858}
         UYU:int{858}
+        UYW:int{927}
         UZS:int{860}
         VEB:int{862}
         VEF:int{937}
+        VES:int{928}
         VNC:int{704}
         VND:int{704}
         VUV:int{548}

icu4c/source/data/misc/miscfiles.mk

@@ -28,4 +28,4 @@ MISC_SOURCE = \
 zoneinfo64.txt supplementalData.txt likelySubtags.txt plurals.txt \
 numberingSystems.txt icuver.txt icustd.txt metadata.txt metaZones.txt \
 windowsZones.txt keyTypeData.txt timezoneTypes.txt currencyNumericCodes.txt \
-genderList.txt dayPeriods.txt
+genderList.txt dayPeriods.txt pluralRanges.txt

icu4c/source/data/misc/pluralRanges.txt

@@ -0,0 +1,981 @@
+// © 2016 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html#License
+pluralRanges:table(nofallback){
+    locales{
+        af{"set05"}
+        ak{"set02"}
+        am{"set01"}
+        ar{"set18"}
+        as{"set01"}
+        az{"set04"}
+        be{"set15"}
+        bg{"set05"}
+        bn{"set01"}
+        bs{"set11"}
+        ca{"set05"}
+        cs{"set14"}
+        cy{"set17"}
+        da{"set06"}
+        de{"set04"}
+        el{"set04"}
+        en{"set05"}
+        es{"set05"}
+        et{"set05"}
+        eu{"set05"}
+        fa{"set02"}
+        fi{"set05"}
+        fil{"set06"}
+        fr{"set01"}
+        ga{"set16"}
+        gl{"set04"}
+        gsw{"set04"}
+        gu{"set01"}
+        he{"set13"}
+        hi{"set01"}
+        hr{"set11"}
+        hu{"set04"}
+        hy{"set01"}
+        id{"set00"}
+        io{"set05"}
+        is{"set06"}
+        it{"set04"}
+        ja{"set00"}
+        ka{"set03"}
+        kk{"set04"}
+        km{"set00"}
+        kn{"set01"}
+        ko{"set00"}
+        ky{"set04"}
+        lo{"set00"}
+        lt{"set15"}
+        lv{"set09"}
+        mk{"set08"}
+        ml{"set04"}
+        mn{"set04"}
+        mr{"set01"}
+        ms{"set00"}
+        my{"set00"}
+        nb{"set05"}
+        ne{"set04"}
+        nl{"set04"}
+        or{"set02"}
+        pa{"set06"}
+        pl{"set14"}
+        ps{"set01"}
+        pt{"set01"}
+        ro{"set10"}
+        ru{"set15"}
+        scn{"set04"}
+        sd{"set02"}
+        si{"set07"}
+        sk{"set14"}
+        sl{"set12"}
+        sq{"set04"}
+        sr{"set11"}
+        sv{"set05"}
+        sw{"set04"}
+        ta{"set04"}
+        te{"set04"}
+        th{"set00"}
+        tk{"set04"}
+        tr{"set04"}
+        ug{"set04"}
+        uk{"set15"}
+        ur{"set05"}
+        uz{"set04"}
+        vi{"set00"}
+        yue{"set00"}
+        zh{"set00"}
+        zu{"set01"}
+    }
+    rules{
+        set00{
+            {
+                "other",
+                "other",
+                "other",
+            }
+        }
+        set01{
+            {
+                "one",
+                "one",
+                "one",
+            }
+            {
+                "one",
+                "other",
+                "other",
+            }
+            {
+                "other",
+                "other",
+                "other",
+            }
+        }
+        set02{
+            {
+                "one",
+                "one",
+                "other",
+            }
+            {
+                "one",
+                "other",
+                "other",
+            }
+            {
+                "other",
+                "other",
+                "other",
+            }
+        }
+        set03{
+            {
+                "one",
+                "other",
+                "one",
+            }
+            {
+                "other",
+                "one",
+                "other",
+            }
+            {
+                "other",
+                "other",
+                "other",
+            }
+        }
+        set04{
+            {
+                "one",
+                "other",
+                "other",
+            }
+            {
+                "other",
+                "one",
+                "one",
+            }
+            {
+                "other",
+                "other",
+                "other",
+            }
+        }
+        set05{
+            {
+                "one",
+                "other",
+                "other",
+            }
+            {
+                "other",
+                "one",
+                "other",
+            }
+            {
+                "other",
+                "other",
+                "other",
+            }
+        }
+        set06{
+            {
+                "one",
+                "one",
+                "one",
+            }
+            {
+                "one",
+                "other",
+                "other",
+            }
+            {
+                "other",
+                "one",
+                "one",
+            }
+            {
+                "other",
+                "other",
+                "other",
+            }
+        }
+        set07{
+            {
+                "one",
+                "one",
+                "one",
+            }
+            {
+                "one",
+                "other",
+                "other",
+            }
+            {
+                "other",
+                "one",
+                "other",
+            }
+            {
+                "other",
+                "other",
+                "other",
+            }
+        }
+        set08{
+            {
+                "one",
+                "one",
+                "other",
+            }
+            {
+                "one",
+                "other",
+                "other",
+            }
+            {
+                "other",
+                "one",
+                "other",
+            }
+            {
+                "other",
+                "other",
+                "other",
+            }
+        }
+        set09{
+            {
+                "zero",
+                "zero",
+                "other",
+            }
+            {
+                "zero",
+                "one",
+                "one",
+            }
+            {
+                "zero",
+                "other",
+                "other",
+            }
+            {
+                "one",
+                "zero",
+                "other",
+            }
+            {
+                "one",
+                "one",
+                "one",
+            }
+            {
+                "one",
+                "other",
+                "other",
+            }
+            {
+                "other",
+                "zero",
+                "other",
+            }
+            {
+                "other",
+                "one",
+                "one",
+            }
+            {
+                "other",
+                "other",
+                "other",
+            }
+        }
+        set10{
+            {
+                "one",
+                "few",
+                "few",
+            }
+            {
+                "one",
+                "other",
+                "other",
+            }
+            {
+                "few",
+                "one",
+                "few",
+            }
+            {
+                "few",
+                "few",
+                "few",
+            }
+            {
+                "few",
+                "other",
+                "other",
+            }
+            {
+                "other",
+                "few",
+                "few",
+            }
+            {
+                "other",
+                "other",
+                "other",
+            }
+        }
+        set11{
+            {
+                "one",
+                "one",
+                "one",
+            }
+            {
+                "one",
+                "few",
+                "few",
+            }
+            {
+                "one",
+                "other",
+                "other",
+            }
+            {
+                "few",
+                "one",
+                "one",
+            }
+            {
+                "few",
+                "few",
+                "few",
+            }
+            {
+                "few",
+                "other",
+                "other",
+            }
+            {
+                "other",
+                "one",
+                "one",
+            }
+            {
+                "other",
+                "few",
+                "few",
+            }
+            {
+                "other",
+                "other",
+                "other",
+            }
+        }
+        set12{
+            {
+                "one",
+                "one",
+                "few",
+            }
+            {
+                "one",
+                "two",
+                "two",
+            }
+            {
+                "one",
+                "few",
+                "few",
+            }
+            {
+                "one",
+                "other",
+                "other",
+            }
+            {
+                "two",
+                "one",
+                "few",
+            }
+            {
+                "two",
+                "two",
+                "two",
+            }
+            {
+                "two",
+                "few",
+                "few",
+            }
+            {
+                "two",
+                "other",
+                "other",
+            }
+            {
+                "few",
+                "one",
+                "few",
+            }
+            {
+                "few",
+                "two",
+                "two",
+            }
+            {
+                "few",
+                "few",
+                "few",
+            }
+            {
+                "few",
+                "other",
+                "other",
+            }
+            {
+                "other",
+                "one",
+                "few",
+            }
+            {
+                "other",
+                "two",
+                "two",
+            }
+            {
+                "other",
+                "few",
+                "few",
+            }
+            {
+                "other",
+                "other",
+                "other",
+            }
+        }
+        set13{
+            {
+                "one",
+                "two",
+                "other",
+            }
+            {
+                "one",
+                "many",
+                "many",
+            }
+            {
+                "one",
+                "other",
+                "other",
+            }
+            {
+                "two",
+                "many",
+                "other",
+            }
+            {
+                "two",
+                "other",
+                "other",
+            }
+            {
+                "many",
+                "many",
+                "many",
+            }
+            {
+                "many",
+                "other",
+                "many",
+            }
+            {
+                "other",
+                "one",
+                "other",
+            }
+            {
+                "other",
+                "two",
+                "other",
+            }
+            {
+                "other",
+                "many",
+                "many",
+            }
+            {
+                "other",
+                "other",
+                "other",
+            }
+        }
+        set14{
+            {
+                "one",
+                "few",
+                "few",
+            }
+            {
+                "one",
+                "many",
+                "many",
+            }
+            {
+                "one",
+                "other",
+                "other",
+            }
+            {
+                "few",
+                "few",
+                "few",
+            }
+            {
+                "few",
+                "many",
+                "many",
+            }
+            {
+                "few",
+                "other",
+                "other",
+            }
+            {
+                "many",
+                "one",
+                "one",
+            }
+            {
+                "many",
+                "few",
+                "few",
+            }
+            {
+                "many",
+                "many",
+                "many",
+            }
+            {
+                "many",
+                "other",
+                "other",
+            }
+            {
+                "other",
+                "one",
+                "one",
+            }
+            {
+                "other",
+                "few",
+                "few",
+            }
+            {
+                "other",
+                "many",
+                "many",
+            }
+            {
+                "other",
+                "other",
+                "other",
+            }
+        }
+        set15{
+            {
+                "one",
+                "one",
+                "one",
+            }
+            {
+                "one",
+                "few",
+                "few",
+            }
+            {
+                "one",
+                "many",
+                "many",
+            }
+            {
+                "one",
+                "other",
+                "other",
+            }
+            {
+                "few",
+                "one",
+                "one",
+            }
+            {
+                "few",
+                "few",
+                "few",
+            }
+            {
+                "few",
+                "many",
+                "many",
+            }
+            {
+                "few",
+                "other",
+                "other",
+            }
+            {
+                "many",
+                "one",
+                "one",
+            }
+            {
+                "many",
+                "few",
+                "few",
+            }
+            {
+                "many",
+                "many",
+                "many",
+            }
+            {
+                "many",
+                "other",
+                "other",
+            }
+            {
+                "other",
+                "one",
+                "one",
+            }
+            {
+                "other",
+                "few",
+                "few",
+            }
+            {
+                "other",
+                "many",
+                "many",
+            }
+            {
+                "other",
+                "other",
+                "other",
+            }
+        }
+        set16{
+            {
+                "one",
+                "two",
+                "two",
+            }
+            {
+                "one",
+                "few",
+                "few",
+            }
+            {
+                "one",
+                "many",
+                "many",
+            }
+            {
+                "one",
+                "other",
+                "other",
+            }
+            {
+                "two",
+                "few",
+                "few",
+            }
+            {
+                "two",
+                "many",
+                "many",
+            }
+            {
+                "two",
+                "other",
+                "other",
+            }
+            {
+                "few",
+                "few",
+                "few",
+            }
+            {
+                "few",
+                "many",
+                "many",
+            }
+            {
+                "few",
+                "other",
+                "other",
+            }
+            {
+                "many",
+                "many",
+                "many",
+            }
+            {
+                "many",
+                "other",
+                "other",
+            }
+            {
+                "other",
+                "one",
+                "one",
+            }
+            {
+                "other",
+                "two",
+                "two",
+            }
+            {
+                "other",
+                "few",
+                "few",
+            }
+            {
+                "other",
+                "many",
+                "many",
+            }
+            {
+                "other",
+                "other",
+                "other",
+            }
+        }
+        set17{
+            {
+                "zero",
+                "one",
+                "one",
+            }
+            {
+                "zero",
+                "two",
+                "two",
+            }
+            {
+                "zero",
+                "few",
+                "few",
+            }
+            {
+                "zero",
+                "many",
+                "many",
+            }
+            {
+                "zero",
+                "other",
+                "other",
+            }
+            {
+                "one",
+                "two",
+                "two",
+            }
+            {
+                "one",
+                "few",
+                "few",
+            }
+            {
+                "one",
+                "many",
+                "many",
+            }
+            {
+                "one",
+                "other",
+                "other",
+            }
+            {
+                "two",
+                "few",
+                "few",
+            }
+            {
+                "two",
+                "many",
+                "many",
+            }
+            {
+                "two",
+                "other",
+                "other",
+            }
+            {
+                "few",
+                "many",
+                "many",
+            }
+            {
+                "few",
+                "other",
+                "other",
+            }
+            {
+                "many",
+                "other",
+                "other",
+            }
+            {
+                "other",
+                "one",
+                "one",
+            }
+            {
+                "other",
+                "two",
+                "two",
+            }
+            {
+                "other",
+                "few",
+                "few",
+            }
+            {
+                "other",
+                "many",
+                "many",
+            }
+            {
+                "other",
+                "other",
+                "other",
+            }
+        }
+        set18{
+            {
+                "zero",
+                "one",
+                "zero",
+            }
+            {
+                "zero",
+                "two",
+                "zero",
+            }
+            {
+                "zero",
+                "few",
+                "few",
+            }
+            {
+                "zero",
+                "many",
+                "many",
+            }
+            {
+                "zero",
+                "other",
+                "other",
+            }
+            {
+                "one",
+                "two",
+                "other",
+            }
+            {
+                "one",
+                "few",
+                "few",
+            }
+            {
+                "one",
+                "many",
+                "many",
+            }
+            {
+                "one",
+                "other",
+                "other",
+            }
+            {
+                "two",
+                "few",
+                "few",
+            }
+            {
+                "two",
+                "many",
+                "many",
+            }
+            {
+                "two",
+                "other",
+                "other",
+            }
+            {
+                "few",
+                "few",
+                "few",
+            }
+            {
+                "few",
+                "many",
+                "many",
+            }
+            {
+                "few",
+                "other",
+                "other",
+            }
+            {
+                "many",
+                "few",
+                "few",
+            }
+            {
+                "many",
+                "many",
+                "many",
+            }
+            {
+                "many",
+                "other",
+                "other",
+            }
+            {
+                "other",
+                "one",
+                "other",
+            }
+            {
+                "other",
+                "two",
+                "other",
+            }
+            {
+                "other",
+                "few",
+                "few",
+            }
+            {
+                "other",
+                "many",
+                "many",
+            }
+            {
+                "other",
+                "other",
+                "other",
+            }
+        }
+    }
+}

icu4c/source/i18n/Makefile.in

@@ -111,9 +111,9 @@ double-conversion-fast-dtoa.o double-conversion-strtod.o \
 numparse_stringsegment.o numparse_parsednumber.o numparse_impl.o \
 numparse_symbols.o numparse_decimal.o numparse_scientific.o numparse_currency.o \
 numparse_affixes.o numparse_compositions.o numparse_validators.o \
+numrange_fluent.o numrange_impl.o \
 erarules.o
 
-
 ## Header files to install
 HEADERS = $(srcdir)/unicode/*.h
 

icu4c/source/i18n/calendar.cpp

@@ -3797,7 +3797,7 @@ Calendar::setWeekData(const Locale& desiredLocale, const char *type, UErrorCode&
         Locale max = Locale::createFromName(maxLocaleID);
         useLocale = Locale(max.getLanguage(),max.getCountry());
     } else {
-        useLocale = Locale(desiredLocale);
+        useLocale = desiredLocale;
     }
 
     /* The code here is somewhat of a hack, since week data and weekend data aren't really tied to

icu4c/source/i18n/decimfmt.cpp

@@ -1057,12 +1057,19 @@ UBool DecimalFormat::areSignificantDigitsUsed() const {
 
 void DecimalFormat::setSignificantDigitsUsed(UBool useSignificantDigits) {
     // These are the default values from the old implementation.
+    if (useSignificantDigits) {
+        if (fields->properties->minimumSignificantDigits != -1 ||
+            fields->properties->maximumSignificantDigits != -1) {
+            return;
+        }
+    } else {
+        if (fields->properties->minimumSignificantDigits == -1 &&
+            fields->properties->maximumSignificantDigits == -1) {
+            return;
+        }
+    }
     int32_t minSig = useSignificantDigits ? 1 : -1;
     int32_t maxSig = useSignificantDigits ? 6 : -1;
-    if (fields->properties->minimumSignificantDigits == minSig &&
-        fields->properties->maximumSignificantDigits == maxSig) {
-        return;
-    }
     fields->properties->minimumSignificantDigits = minSig;
     fields->properties->maximumSignificantDigits = maxSig;
     touchNoError();

icu4c/source/i18n/erarules.cpp

@@ -99,13 +99,13 @@ static int32_t compareEncodedDateWithYMD(int encoded, int year, int month, int d
     }
 }
 
-EraRules::EraRules(int32_t *startDates, int32_t numEras)
-    : startDates(startDates), numEras(numEras) {
+EraRules::EraRules(LocalArray<int32_t>& eraStartDates, int32_t numEras)
+    : numEras(numEras) {
+    startDates.moveFrom(eraStartDates);
     initCurrentEra();
 }
 
 EraRules::~EraRules() {
-    uprv_free(startDates);
 }
 
 EraRules* EraRules::createInstance(const char *calType, UBool includeTentativeEra, UErrorCode& status) {
@@ -116,7 +116,7 @@ EraRules* EraRules::createInstance(const char *calType, UBool includeTentativeEr
     ures_getByKey(rb.getAlias(), "calendarData", rb.getAlias(), &status);
     ures_getByKey(rb.getAlias(), calType, rb.getAlias(), &status);
     ures_getByKey(rb.getAlias(), "eras", rb.getAlias(), &status);
-
+        
     if (U_FAILURE(status)) {
         return nullptr;
     }
@@ -124,33 +124,32 @@ EraRules* EraRules::createInstance(const char *calType, UBool includeTentativeEr
     int32_t numEras = ures_getSize(rb.getAlias());
     int32_t firstTentativeIdx = MAX_INT32;
 
-    int32_t *startDates = (int32_t*)uprv_malloc(numEras * sizeof(int32_t));
-    if (startDates == nullptr) {
-        status = U_MEMORY_ALLOCATION_ERROR;
+    LocalArray<int32_t> startDates(new int32_t[numEras], status);
+    if (U_FAILURE(status)) {
         return nullptr;
     }
-    uprv_memset(startDates, 0, numEras * sizeof(int32_t));
+    uprv_memset(startDates.getAlias(), 0 , numEras * sizeof(int32_t));
 
     while (ures_hasNext(rb.getAlias())) {
         LocalUResourceBundlePointer eraRuleRes(ures_getNextResource(rb.getAlias(), nullptr, &status));
         if (U_FAILURE(status)) {
-            goto error;
+            return nullptr;
         }
         const char *eraIdxStr = ures_getKey(eraRuleRes.getAlias());
         char *endp;
         int32_t eraIdx = (int32_t)strtol(eraIdxStr, &endp, 10);
         if ((size_t)(endp - eraIdxStr) != uprv_strlen(eraIdxStr)) {
             status = U_INVALID_FORMAT_ERROR;
-            goto error;
+            return nullptr;
         }
         if (eraIdx < 0 || eraIdx >= numEras) {
             status = U_INVALID_FORMAT_ERROR;
-            goto error;
+            return nullptr;
         }
         if (isSet(startDates[eraIdx])) {
             // start date of the index was already set
             status = U_INVALID_FORMAT_ERROR;
-            goto error;
+            return nullptr;
         }
 
         UBool hasName = TRUE;
@@ -159,17 +158,17 @@ EraRules* EraRules::createInstance(const char *calType, UBool includeTentativeEr
         while (ures_hasNext(eraRuleRes.getAlias())) {
             LocalUResourceBundlePointer res(ures_getNextResource(eraRuleRes.getAlias(), nullptr, &status));
             if (U_FAILURE(status)) {
-                goto error;
+                return nullptr;
             }
             const char *key = ures_getKey(res.getAlias());
             if (uprv_strcmp(key, "start") == 0) {
                 const int32_t *fields = ures_getIntVector(res.getAlias(), &len, &status);
                 if (U_FAILURE(status)) {
-                    goto error;
+                    return nullptr;
                 }
                 if (len != 3 || !isValidRuleStartDate(fields[0], fields[1], fields[2])) {
                     status = U_INVALID_FORMAT_ERROR;
-                    goto error;
+                    return nullptr;
                 }
                 startDates[eraIdx] = encodeDate(fields[0], fields[1], fields[2]);
             } else if (uprv_strcmp(key, "named") == 0) {
@@ -193,20 +192,20 @@ EraRules* EraRules::createInstance(const char *calType, UBool includeTentativeEr
                     // This implementation does not support end only rule for eras other than
                     // the first one.
                     status = U_INVALID_FORMAT_ERROR;
-                    goto error;
+                    return nullptr;
                 }
                 U_ASSERT(eraIdx == 0);
                 startDates[eraIdx] = MIN_ENCODED_START;
             } else {
                 status = U_INVALID_FORMAT_ERROR;
-                goto error;
+                return nullptr;
             }
         }
 
         if (hasName) {
             if (eraIdx >= firstTentativeIdx) {
                 status = U_INVALID_FORMAT_ERROR;
-                goto error;
+                return nullptr;
             }
         } else {
             if (eraIdx < firstTentativeIdx) {
@@ -226,10 +225,6 @@ EraRules* EraRules::createInstance(const char *calType, UBool includeTentativeEr
         status = U_MEMORY_ALLOCATION_ERROR;
     }
     return result;
-
-error:
-    uprv_free(startDates);
-    return nullptr;
 }
 
 void EraRules::getStartDate(int32_t eraIdx, int32_t (&fields)[3], UErrorCode& status) const {

icu4c/source/i18n/erarules.h

@@ -12,6 +12,16 @@
 
 U_NAMESPACE_BEGIN
 
+// Export an explicit template instantiation of LocalArray used as a data member of EraRules.
+// When building DLLs for Windows this is required even though no direct access leaks out of the i18n library.
+// See digitlst.h, pluralaffix.h, datefmt.h, and others for similar examples.
+#if U_PF_WINDOWS <= U_PLATFORM && U_PLATFORM <= U_PF_CYGWIN
+// Ignore warning 4661 as LocalPointerBase does not use operator== or operator!=
+#pragma warning(suppress: 4661)
+template class U_I18N_API LocalPointerBase<int32_t>;
+template class U_I18N_API LocalArray<int32_t>;
+#endif
+
 class U_I18N_API EraRules : public UMemory {
 public:
     ~EraRules();
@@ -66,11 +76,11 @@ public:
     }
 
 private:
-    EraRules(int32_t *startDates, int32_t numEra);
+    EraRules(LocalArray<int32_t>& eraStartDates, int32_t numEra);
 
     void initCurrentEra();
 
-    int32_t *startDates;
+    LocalArray<int32_t> startDates;
     int32_t numEras;
     int32_t currentEra;
 };

icu4c/source/i18n/i18n.vcxproj

@@ -289,6 +289,8 @@
     <ClCompile Include="numparse_affixes.cpp" />
     <ClCompile Include="numparse_compositions.cpp" />
     <ClCompile Include="numparse_validators.cpp" />
+    <ClCompile Include="numrange_fluent.cpp" />
+    <ClCompile Include="numrange_impl.cpp" />
     <ClCompile Include="numfmt.cpp" />
     <ClCompile Include="numsys.cpp" />
     <ClCompile Include="olsontz.cpp" />
@@ -552,6 +554,7 @@
     <ClInclude Include="numparse_validators.h" />
     <ClInclude Include="numparse_types.h" />
     <ClInclude Include="numparse_utils.h" />
+    <ClInclude Include="numrange_impl.h" />
   </ItemGroup>
   <ItemGroup>
     <ResourceCompile Include="i18n.rc" />

icu4c/source/i18n/i18n.vcxproj.filters

@@ -624,6 +624,12 @@
     <ClCompile Include="numparse_validators.cpp">
       <Filter>formatting</Filter>
     </ClCompile>
+    <ClCompile Include="numrange_fluent.cpp">
+      <Filter>formatting</Filter>
+    </ClCompile>
+    <ClCompile Include="numrange_impl.cpp">
+      <Filter>formatting</Filter>
+    </ClCompile>
     <ClCompile Include="dayperiodrules.cpp">
       <Filter>formatting</Filter>
     </ClCompile>
@@ -914,6 +920,9 @@
     <ClInclude Include="numparse_utils.h">
       <Filter>formatting</Filter>
     </ClInclude>
+    <ClInclude Include="numrange_impl.h">
+      <Filter>formatting</Filter>
+    </ClInclude>
     <ClInclude Include="olsontz.h">
       <Filter>formatting</Filter>
     </ClInclude>

icu4c/source/i18n/i18n_uwp.vcxproj

@@ -396,6 +396,8 @@
     <ClCompile Include="numparse_affixes.cpp" />
     <ClCompile Include="numparse_compositions.cpp" />
     <ClCompile Include="numparse_validators.cpp" />
+    <ClCompile Include="numrange_fluent.cpp" />
+    <ClCompile Include="numrange_impl.cpp" />
     <ClCompile Include="numfmt.cpp" />
     <ClCompile Include="numsys.cpp" />
     <ClCompile Include="olsontz.cpp" />
@@ -657,6 +659,7 @@
     <ClInclude Include="numparse_validators.h" />
     <ClInclude Include="numparse_types.h" />
     <ClInclude Include="numparse_utils.h" />
+    <ClInclude Include="numrange_impl.h" />
   </ItemGroup>
   <ItemGroup>
     <ResourceCompile Include="i18n.rc" />

icu4c/source/i18n/indiancal.cpp

@@ -347,12 +347,15 @@ IndianCalendar::inDaylightTime(UErrorCode& status) const
     return (UBool)(U_SUCCESS(status) ? (internalGet(UCAL_DST_OFFSET) != 0) : FALSE);
 }
 
-// default century
-const UDate     IndianCalendar::fgSystemDefaultCentury          = DBL_MIN;
-const int32_t   IndianCalendar::fgSystemDefaultCenturyYear      = -1;
 
-UDate           IndianCalendar::fgSystemDefaultCenturyStart     = DBL_MIN;
-int32_t         IndianCalendar::fgSystemDefaultCenturyStartYear = -1;
+/**
+ * The system maintains a static default century start date and Year.  They are
+ * initialized the first time they are used.  Once the system default century date
+ * and year are set, they do not change.
+ */
+static UDate           gSystemDefaultCenturyStart       = DBL_MIN;
+static int32_t         gSystemDefaultCenturyStartYear   = -1;
+static icu::UInitOnce  gSystemDefaultCenturyInit        = U_INITONCE_INITIALIZER;
 
 
 UBool IndianCalendar::haveDefaultCentury() const
@@ -360,88 +363,46 @@ UBool IndianCalendar::haveDefaultCentury() const
     return TRUE;
 }
 
-UDate IndianCalendar::defaultCenturyStart() const
-{
-    return internalGetDefaultCenturyStart();
-}
-
-int32_t IndianCalendar::defaultCenturyStartYear() const
-{
-    return internalGetDefaultCenturyStartYear();
-}
-
-UDate
-IndianCalendar::internalGetDefaultCenturyStart() const
-{
-    // lazy-evaluate systemDefaultCenturyStart
-    UBool needsUpdate;
-    { 
-        Mutex m;
-        needsUpdate = (fgSystemDefaultCenturyStart == fgSystemDefaultCentury);
-    }
-
-    if (needsUpdate) {
-        initializeSystemDefaultCentury();
-    }
-
-    // use defaultCenturyStart unless it's the flag value;
-    // then use systemDefaultCenturyStart
-
-    return fgSystemDefaultCenturyStart;
-}
-
-int32_t
-IndianCalendar::internalGetDefaultCenturyStartYear() const
-{
-    // lazy-evaluate systemDefaultCenturyStartYear
-    UBool needsUpdate;
-    { 
-        Mutex m;
-
-        needsUpdate = (fgSystemDefaultCenturyStart == fgSystemDefaultCentury);
-    }
-
-    if (needsUpdate) {
-        initializeSystemDefaultCentury();
-    }
-
-    // use defaultCenturyStart unless it's the flag value;
-    // then use systemDefaultCenturyStartYear
-
-    return    fgSystemDefaultCenturyStartYear;
-}
-
-void
-IndianCalendar::initializeSystemDefaultCentury()
+static void U_CALLCONV
+initializeSystemDefaultCentury()
 {
     // initialize systemDefaultCentury and systemDefaultCenturyYear based
     // on the current time.  They'll be set to 80 years before
     // the current time.
-    // No point in locking as it should be idempotent.
-    if (fgSystemDefaultCenturyStart == fgSystemDefaultCentury) {
-        UErrorCode status = U_ZERO_ERROR;
+    UErrorCode status = U_ZERO_ERROR;
 
-        IndianCalendar calendar(Locale("@calendar=Indian"),status);
-        if (U_SUCCESS(status)) {
-            calendar.setTime(Calendar::getNow(), status);
-            calendar.add(UCAL_YEAR, -80, status);
+    IndianCalendar calendar ( Locale ( "@calendar=Indian" ), status);
+    if ( U_SUCCESS ( status ) ) {
+        calendar.setTime ( Calendar::getNow(), status );
+        calendar.add ( UCAL_YEAR, -80, status );
 
-            UDate    newStart = calendar.getTime(status);
-            int32_t  newYear  = calendar.get(UCAL_YEAR, status);
+        UDate    newStart = calendar.getTime ( status );
+        int32_t  newYear  = calendar.get ( UCAL_YEAR, status );
 
-            {
-                Mutex m;
-
-                fgSystemDefaultCenturyStart = newStart;
-                fgSystemDefaultCenturyStartYear = newYear;
-            }
-        }
-
-        // We have no recourse upon failure unless we want to propagate the failure
-        // out.
+        gSystemDefaultCenturyStart = newStart;
+        gSystemDefaultCenturyStartYear = newYear;
     }
+    // We have no recourse upon failure.
 }
 
+
+UDate
+IndianCalendar::defaultCenturyStart() const
+{
+    // lazy-evaluate systemDefaultCenturyStart
+    umtx_initOnce(gSystemDefaultCenturyInit, &initializeSystemDefaultCentury);
+    return gSystemDefaultCenturyStart;
+}
+
+int32_t
+IndianCalendar::defaultCenturyStartYear() const
+{
+    // lazy-evaluate systemDefaultCenturyStartYear
+    umtx_initOnce(gSystemDefaultCenturyInit, &initializeSystemDefaultCentury);
+    return    gSystemDefaultCenturyStartYear;
+}
+
+
 UOBJECT_DEFINE_RTTI_IMPLEMENTATION(IndianCalendar)
 
 U_NAMESPACE_END

icu4c/source/i18n/indiancal.h

@@ -68,7 +68,7 @@ U_NAMESPACE_BEGIN
  */
 
 
-class IndianCalendar : public Calendar {
+class U_I18N_API IndianCalendar : public Calendar {
 public:
   /**
    * Useful constants for IndianCalendar.
@@ -274,10 +274,10 @@ public:
    * @return   The class ID for all objects of this class.
    * @internal
    */
-  U_I18N_API static UClassID U_EXPORT2 getStaticClassID(void);
+  static UClassID U_EXPORT2 getStaticClassID(void);
 
   /**
-   * return the calendar type, "buddhist".
+   * return the calendar type, "indian".
    *
    * @return calendar type
    * @internal
@@ -320,49 +320,6 @@ protected:
    * @internal
    */
   virtual int32_t defaultCenturyStartYear() const;
-
- private: // default century stuff.
-  /**
-   * The system maintains a static default century start date.  This is initialized
-   * the first time it is used.  Before then, it is set to SYSTEM_DEFAULT_CENTURY to
-   * indicate an uninitialized state.  Once the system default century date and year
-   * are set, they do not change.
-   */
-  static UDate         fgSystemDefaultCenturyStart;
-
-  /**
-   * See documentation for systemDefaultCenturyStart.
-   */
-  static int32_t          fgSystemDefaultCenturyStartYear;
-
-  /**
-   * Default value that indicates the defaultCenturyStartYear is unitialized
-   */
-  static const int32_t    fgSystemDefaultCenturyYear;
-
-  /**
-   * start of default century, as a date
-   */
-  static const UDate        fgSystemDefaultCentury;
-
-  /**
-   * Returns the beginning date of the 100-year window that dates 
-   * with 2-digit years are considered to fall within.
-   */
-  UDate         internalGetDefaultCenturyStart(void) const;
-
-  /**
-   * Returns the first year of the 100-year window that dates with 
-   * 2-digit years are considered to fall within.
-   */
-  int32_t          internalGetDefaultCenturyStartYear(void) const;
-
-  /**
-   * Initializes the 100-year window that dates with 2-digit years
-   * are considered to fall within so that its start date is 80 years
-   * before the current time.
-   */
-  static void  initializeSystemDefaultCentury(void);
 };
 
 U_NAMESPACE_END

icu4c/source/i18n/japancal.cpp

@@ -59,11 +59,19 @@ static void U_CALLCONV initializeEras(UErrorCode &status) {
     // By default, such tentative era is disabled.
 
     // 1. Environment variable ICU_ENABLE_TENTATIVE_ERA=true or false
-    // 2. Windows registry (TBD)
 
     UBool includeTentativeEra = FALSE;
 
-#if U_PLATFORM_HAS_WINUWP_API == 0
+#if U_PLATFORM_HAS_WINUWP_API == 1
+    // UWP doesn't allow access to getenv(), but we can call GetEnvironmentVariableW to do the same thing.
+    UChar varName[26] = {};
+    u_charsToUChars(TENTATIVE_ERA_VAR_NAME, varName, static_cast<int32_t>(uprv_strlen(TENTATIVE_ERA_VAR_NAME)));
+    WCHAR varValue[5] = {};
+    DWORD ret = GetEnvironmentVariableW(reinterpret_cast<WCHAR*>(varName), varValue, UPRV_LENGTHOF(varValue));
+    if ((ret == 4) && (_wcsicmp(varValue, L"true") == 0)) {
+        includeTentativeEra = TRUE;
+    }
+#else
     char *envVarVal = getenv(TENTATIVE_ERA_VAR_NAME);
     if (envVarVal != NULL && uprv_stricmp(envVarVal, "true") == 0) {
         includeTentativeEra = TRUE;

icu4c/source/i18n/listformatter.cpp

@@ -288,8 +288,7 @@ ListFormatter* ListFormatter::createInstance(const Locale& locale, UErrorCode& e
 }
 
 ListFormatter* ListFormatter::createInstance(const Locale& locale, const char *style, UErrorCode& errorCode) {
-    Locale tempLocale = locale;
-    const ListFormatInternal* listFormatInternal = getListFormatInternal(tempLocale, style, errorCode);
+    const ListFormatInternal* listFormatInternal = getListFormatInternal(locale, style, errorCode);
     if (U_FAILURE(errorCode)) {
         return nullptr;
     }

icu4c/source/i18n/number_compact.cpp

@@ -273,13 +273,13 @@ void CompactHandler::processQuantity(DecimalQuantity &quantity, MicroProps &micr
     if (U_FAILURE(status)) { return; }
 
     // Treat zero as if it had magnitude 0
-    int magnitude;
+    int32_t magnitude;
     if (quantity.isZero()) {
         magnitude = 0;
         micros.rounder.apply(quantity, status);
     } else {
         // TODO: Revisit chooseMultiplierAndApply
-        int multiplier = micros.rounder.chooseMultiplierAndApply(quantity, data, status);
+        int32_t multiplier = micros.rounder.chooseMultiplierAndApply(quantity, data, status);
         magnitude = quantity.isZero() ? 0 : quantity.getMagnitude();
         magnitude -= multiplier;
     }

icu4c/source/i18n/number_decimalquantity.cpp

@@ -1154,8 +1154,31 @@ const char16_t* DecimalQuantity::checkHealth() const {
 }
 
 bool DecimalQuantity::operator==(const DecimalQuantity& other) const {
-    // FIXME: Make a faster implementation.
-    return toString() == other.toString();
+    bool basicEquals =
+            scale == other.scale
+            && precision == other.precision
+            && flags == other.flags
+            && lOptPos == other.lOptPos
+            && lReqPos == other.lReqPos
+            && rReqPos == other.rReqPos
+            && rOptPos == other.rOptPos
+            && isApproximate == other.isApproximate;
+    if (!basicEquals) {
+        return false;
+    }
+
+    if (precision == 0) {
+        return true;
+    } else if (isApproximate) {
+        return origDouble == other.origDouble && origDelta == other.origDelta;
+    } else {
+        for (int m = getUpperDisplayMagnitude(); m >= getLowerDisplayMagnitude(); m--) {
+            if (getDigit(m) != other.getDigit(m)) {
+                return false;
+            }
+        }
+        return true;
+    }
 }
 
 UnicodeString DecimalQuantity::toString() const {

icu4c/source/i18n/number_fluent.cpp

@@ -363,6 +363,7 @@ UnlocalizedNumberFormatter::UnlocalizedNumberFormatter(const NFS<UNF>& other)
     // No additional fields to assign
 }
 
+// Make default copy constructor call the NumberFormatterSettings copy constructor.
 UnlocalizedNumberFormatter::UnlocalizedNumberFormatter(UNF&& src) U_NOEXCEPT
         : UNF(static_cast<NFS<UNF>&&>(src)) {}
 
@@ -383,6 +384,7 @@ UnlocalizedNumberFormatter& UnlocalizedNumberFormatter::operator=(UNF&& src) U_N
     return *this;
 }
 
+// Make default copy constructor call the NumberFormatterSettings copy constructor.
 LocalizedNumberFormatter::LocalizedNumberFormatter(const LNF& other)
         : LNF(static_cast<const NFS<LNF>&>(other)) {}
 
@@ -405,7 +407,8 @@ LocalizedNumberFormatter::LocalizedNumberFormatter(NFS<LNF>&& src) U_NOEXCEPT
 
 LocalizedNumberFormatter& LocalizedNumberFormatter::operator=(const LNF& other) {
     NFS<LNF>::operator=(static_cast<const NFS<LNF>&>(other));
-    // No additional fields to assign (let call count and compiled formatter reset to defaults)
+    // Reset to default values.
+    clear();
     return *this;
 }
 
@@ -417,20 +420,26 @@ LocalizedNumberFormatter& LocalizedNumberFormatter::operator=(LNF&& src) U_NOEXC
         // Formatter is compiled
         lnfMoveHelper(static_cast<LNF&&>(src));
     } else {
-        // Reset to default values.
-        auto* callCount = reinterpret_cast<u_atomic_int32_t*>(fUnsafeCallCount);
-        umtx_storeRelease(*callCount, 0);
-        fCompiled = nullptr;
+        clear();
     }
     return *this;
 }
 
+void LocalizedNumberFormatter::clear() {
+    // Reset to default values.
+    auto* callCount = reinterpret_cast<u_atomic_int32_t*>(fUnsafeCallCount);
+    umtx_storeRelease(*callCount, 0);
+    delete fCompiled;
+    fCompiled = nullptr;
+}
+
 void LocalizedNumberFormatter::lnfMoveHelper(LNF&& src) {
     // Copy over the compiled formatter and set call count to INT32_MIN as in computeCompiled().
     // Don't copy the call count directly because doing so requires a loadAcquire/storeRelease.
     // The bits themselves appear to be platform-dependent, so copying them might not be safe.
     auto* callCount = reinterpret_cast<u_atomic_int32_t*>(fUnsafeCallCount);
     umtx_storeRelease(*callCount, INT32_MIN);
+    delete fCompiled;
     fCompiled = src.fCompiled;
     // Reset the source object to leave it in a safe state.
     auto* srcCallCount = reinterpret_cast<u_atomic_int32_t*>(src.fUnsafeCallCount);
@@ -657,9 +666,9 @@ LocalizedNumberFormatter::formatDecimalQuantity(const DecimalQuantity& dq, UErro
 
 void LocalizedNumberFormatter::formatImpl(impl::UFormattedNumberData* results, UErrorCode& status) const {
     if (computeCompiled(status)) {
-        fCompiled->apply(results->quantity, results->string, status);
+        fCompiled->format(results->quantity, results->string, status);
     } else {
-        NumberFormatterImpl::applyStatic(fMacros, results->quantity, results->string, status);
+        NumberFormatterImpl::formatStatic(fMacros, results->quantity, results->string, status);
     }
 }
 
@@ -706,7 +715,11 @@ bool LocalizedNumberFormatter::computeCompiled(UErrorCode& status) const {
 
     if (currentCount == fMacros.threshold && fMacros.threshold > 0) {
         // Build the data structure and then use it (slow to fast path).
-        const NumberFormatterImpl* compiled = NumberFormatterImpl::fromMacros(fMacros, status);
+        const NumberFormatterImpl* compiled = new NumberFormatterImpl(fMacros, status);
+        if (compiled == nullptr) {
+            status = U_MEMORY_ALLOCATION_ERROR;
+            return false;
+        }
         U_ASSERT(fCompiled == nullptr);
         const_cast<LocalizedNumberFormatter*>(this)->fCompiled = compiled;
         umtx_storeRelease(*callCount, INT32_MIN);

icu4c/source/i18n/number_formatimpl.cpp

@@ -67,14 +67,18 @@ getCurrencyFormatInfo(const Locale& locale, const char* isoCode, UErrorCode& sta
 MicroPropsGenerator::~MicroPropsGenerator() = default;
 
 
-NumberFormatterImpl* NumberFormatterImpl::fromMacros(const MacroProps& macros, UErrorCode& status) {
-    return new NumberFormatterImpl(macros, true, status);
+NumberFormatterImpl::NumberFormatterImpl(const MacroProps& macros, UErrorCode& status)
+    : NumberFormatterImpl(macros, true, status) {
 }
 
-void NumberFormatterImpl::applyStatic(const MacroProps& macros, DecimalQuantity& inValue,
-                                      NumberStringBuilder& outString, UErrorCode& status) {
+int32_t NumberFormatterImpl::formatStatic(const MacroProps& macros, DecimalQuantity& inValue,
+                                       NumberStringBuilder& outString, UErrorCode& status) {
     NumberFormatterImpl impl(macros, false, status);
-    impl.applyUnsafe(inValue, outString, status);
+    MicroProps& micros = impl.preProcessUnsafe(inValue, status);
+    if (U_FAILURE(status)) { return 0; }
+    int32_t length = writeNumber(micros, inValue, outString, 0, status);
+    length += writeAffixes(micros, outString, 0, length, status);
+    return length;
 }
 
 int32_t NumberFormatterImpl::getPrefixSuffixStatic(const MacroProps& macros, int8_t signum,
@@ -89,22 +93,40 @@ int32_t NumberFormatterImpl::getPrefixSuffixStatic(const MacroProps& macros, int
 // The "unsafe" method simply re-uses fMicros, eliminating the extra copy operation.
 // See MicroProps::processQuantity() for details.
 
-void NumberFormatterImpl::apply(DecimalQuantity& inValue, NumberStringBuilder& outString,
+int32_t NumberFormatterImpl::format(DecimalQuantity& inValue, NumberStringBuilder& outString,
                                 UErrorCode& status) const {
-    if (U_FAILURE(status)) { return; }
     MicroProps micros;
-    if (!fMicroPropsGenerator) { return; }
-    fMicroPropsGenerator->processQuantity(inValue, micros, status);
-    if (U_FAILURE(status)) { return; }
-    microsToString(micros, inValue, outString, status);
+    preProcess(inValue, micros, status);
+    if (U_FAILURE(status)) { return 0; }
+    int32_t length = writeNumber(micros, inValue, outString, 0, status);
+    length += writeAffixes(micros, outString, 0, length, status);
+    return length;
 }
 
-void NumberFormatterImpl::applyUnsafe(DecimalQuantity& inValue, NumberStringBuilder& outString,
-                                      UErrorCode& status) {
+void NumberFormatterImpl::preProcess(DecimalQuantity& inValue, MicroProps& microsOut,
+                                     UErrorCode& status) const {
     if (U_FAILURE(status)) { return; }
+    if (fMicroPropsGenerator == nullptr) {
+        status = U_INTERNAL_PROGRAM_ERROR;
+        return;
+    }
+    fMicroPropsGenerator->processQuantity(inValue, microsOut, status);
+    microsOut.rounder.apply(inValue, status);
+    microsOut.integerWidth.apply(inValue, status);
+}
+
+MicroProps& NumberFormatterImpl::preProcessUnsafe(DecimalQuantity& inValue, UErrorCode& status) {
+    if (U_FAILURE(status)) {
+        return fMicros; // must always return a value
+    }
+    if (fMicroPropsGenerator == nullptr) {
+        status = U_INTERNAL_PROGRAM_ERROR;
+        return fMicros; // must always return a value
+    }
     fMicroPropsGenerator->processQuantity(inValue, fMicros, status);
-    if (U_FAILURE(status)) { return; }
-    microsToString(fMicros, inValue, outString, status);
+    fMicros.rounder.apply(inValue, status);
+    fMicros.integerWidth.apply(inValue, status);
+    return fMicros;
 }
 
 int32_t NumberFormatterImpl::getPrefixSuffix(int8_t signum, StandardPlural::Form plural,
@@ -115,7 +137,7 @@ int32_t NumberFormatterImpl::getPrefixSuffix(int8_t signum, StandardPlural::Form
     const Modifier* modifier = fImmutablePatternModifier->getModifier(signum, plural);
     modifier->apply(outString, 0, 0, status);
     if (U_FAILURE(status)) { return 0; }
-    return modifier->getPrefixLength(status);
+    return modifier->getPrefixLength();
 }
 
 int32_t NumberFormatterImpl::getPrefixSuffixUnsafe(int8_t signum, StandardPlural::Form plural,
@@ -126,7 +148,7 @@ int32_t NumberFormatterImpl::getPrefixSuffixUnsafe(int8_t signum, StandardPlural
     fPatternModifier->setNumberProperties(signum, plural);
     fPatternModifier->apply(outString, 0, 0, status);
     if (U_FAILURE(status)) { return 0; }
-    return fPatternModifier->getPrefixLength(status);
+    return fPatternModifier->getPrefixLength();
 }
 
 NumberFormatterImpl::NumberFormatterImpl(const MacroProps& macros, bool safe, UErrorCode& status) {
@@ -344,25 +366,23 @@ NumberFormatterImpl::macrosToMicroGenerator(const MacroProps& macros, bool safe,
     // Outer modifier (CLDR units and currency long names)
     if (isCldrUnit) {
         fLongNameHandler.adoptInstead(
-                new LongNameHandler(
-                        LongNameHandler::forMeasureUnit(
-                                macros.locale,
-                                macros.unit,
-                                macros.perUnit,
-                                unitWidth,
-                                resolvePluralRules(macros.rules, macros.locale, status),
-                                chain,
-                                status)));
+                LongNameHandler::forMeasureUnit(
+                        macros.locale,
+                        macros.unit,
+                        macros.perUnit,
+                        unitWidth,
+                        resolvePluralRules(macros.rules, macros.locale, status),
+                        chain,
+                        status));
         chain = fLongNameHandler.getAlias();
     } else if (isCurrency && unitWidth == UNUM_UNIT_WIDTH_FULL_NAME) {
         fLongNameHandler.adoptInstead(
-                new LongNameHandler(
-                        LongNameHandler::forCurrencyLongNames(
-                                macros.locale,
-                                currency,
-                                resolvePluralRules(macros.rules, macros.locale, status),
-                                chain,
-                                status)));
+                LongNameHandler::forCurrencyLongNames(
+                        macros.locale,
+                        currency,
+                        resolvePluralRules(macros.rules, macros.locale, status),
+                        chain,
+                        status));
         chain = fLongNameHandler.getAlias();
     } else {
         // No outer modifier required
@@ -404,50 +424,46 @@ NumberFormatterImpl::resolvePluralRules(const PluralRules* rulesPtr, const Local
     return fRules.getAlias();
 }
 
-int32_t NumberFormatterImpl::microsToString(const MicroProps& micros, DecimalQuantity& quantity,
-                                            NumberStringBuilder& string, UErrorCode& status) {
-    micros.rounder.apply(quantity, status);
-    micros.integerWidth.apply(quantity, status);
-    int32_t length = writeNumber(micros, quantity, string, status);
-    // NOTE: When range formatting is added, these modifiers can bubble up.
-    // For now, apply them all here at once.
+int32_t NumberFormatterImpl::writeAffixes(const MicroProps& micros, NumberStringBuilder& string,
+                                          int32_t start, int32_t end, UErrorCode& status) {
     // Always apply the inner modifier (which is "strong").
-    length += micros.modInner->apply(string, 0, length, status);
+    int32_t length = micros.modInner->apply(string, start, end, status);
     if (micros.padding.isValid()) {
         length += micros.padding
-                .padAndApply(*micros.modMiddle, *micros.modOuter, string, 0, length, status);
+                .padAndApply(*micros.modMiddle, *micros.modOuter, string, start, length + end, status);
     } else {
-        length += micros.modMiddle->apply(string, 0, length, status);
-        length += micros.modOuter->apply(string, 0, length, status);
+        length += micros.modMiddle->apply(string, start, length + end, status);
+        length += micros.modOuter->apply(string, start, length + end, status);
     }
     return length;
 }
 
 int32_t NumberFormatterImpl::writeNumber(const MicroProps& micros, DecimalQuantity& quantity,
-                                         NumberStringBuilder& string, UErrorCode& status) {
+                                         NumberStringBuilder& string, int32_t index,
+                                         UErrorCode& status) {
     int32_t length = 0;
     if (quantity.isInfinite()) {
         length += string.insert(
-                length,
+                length + index,
                 micros.symbols->getSymbol(DecimalFormatSymbols::ENumberFormatSymbol::kInfinitySymbol),
                 UNUM_INTEGER_FIELD,
                 status);
 
     } else if (quantity.isNaN()) {
         length += string.insert(
-                length,
+                length + index,
                 micros.symbols->getSymbol(DecimalFormatSymbols::ENumberFormatSymbol::kNaNSymbol),
                 UNUM_INTEGER_FIELD,
                 status);
 
     } else {
         // Add the integer digits
-        length += writeIntegerDigits(micros, quantity, string, status);
+        length += writeIntegerDigits(micros, quantity, string, length + index, status);
 
         // Add the decimal point
         if (quantity.getLowerDisplayMagnitude() < 0 || micros.decimal == UNUM_DECIMAL_SEPARATOR_ALWAYS) {
             length += string.insert(
-                    length,
+                    length + index,
                     micros.useCurrency ? micros.symbols->getSymbol(
                             DecimalFormatSymbols::ENumberFormatSymbol::kMonetarySeparatorSymbol) : micros
                             .symbols
@@ -458,21 +474,22 @@ int32_t NumberFormatterImpl::writeNumber(const MicroProps& micros, DecimalQuanti
         }
 
         // Add the fraction digits
-        length += writeFractionDigits(micros, quantity, string, status);
+        length += writeFractionDigits(micros, quantity, string, length + index, status);
     }
 
     return length;
 }
 
 int32_t NumberFormatterImpl::writeIntegerDigits(const MicroProps& micros, DecimalQuantity& quantity,
-                                                NumberStringBuilder& string, UErrorCode& status) {
+                                                NumberStringBuilder& string, int32_t index,
+                                                UErrorCode& status) {
     int length = 0;
     int integerCount = quantity.getUpperDisplayMagnitude() + 1;
     for (int i = 0; i < integerCount; i++) {
         // Add grouping separator
         if (micros.grouping.groupAtPosition(i, quantity)) {
             length += string.insert(
-                    0,
+                    index,
                     micros.useCurrency ? micros.symbols->getSymbol(
                             DecimalFormatSymbols::ENumberFormatSymbol::kMonetaryGroupingSeparatorSymbol)
                                        : micros.symbols->getSymbol(
@@ -484,20 +501,21 @@ int32_t NumberFormatterImpl::writeIntegerDigits(const MicroProps& micros, Decima
         // Get and append the next digit value
         int8_t nextDigit = quantity.getDigit(i);
         length += utils::insertDigitFromSymbols(
-                string, 0, nextDigit, *micros.symbols, UNUM_INTEGER_FIELD, status);
+                string, index, nextDigit, *micros.symbols, UNUM_INTEGER_FIELD, status);
     }
     return length;
 }
 
 int32_t NumberFormatterImpl::writeFractionDigits(const MicroProps& micros, DecimalQuantity& quantity,
-                                                 NumberStringBuilder& string, UErrorCode& status) {
+                                                 NumberStringBuilder& string, int32_t index,
+                                                 UErrorCode& status) {
     int length = 0;
     int fractionCount = -quantity.getLowerDisplayMagnitude();
     for (int i = 0; i < fractionCount; i++) {
         // Get and append the next digit value
         int8_t nextDigit = quantity.getDigit(-i - 1);
         length += utils::insertDigitFromSymbols(
-                string, string.length(), nextDigit, *micros.symbols, UNUM_FRACTION_FIELD, status);
+                string, length + index, nextDigit, *micros.symbols, UNUM_FRACTION_FIELD, status);
     }
     return length;
 }

icu4c/source/i18n/number_formatimpl.h

@@ -29,14 +29,14 @@ class NumberFormatterImpl : public UMemory {
      * Builds a "safe" MicroPropsGenerator, which is thread-safe and can be used repeatedly.
      * The caller owns the returned NumberFormatterImpl.
      */
-    static NumberFormatterImpl *fromMacros(const MacroProps &macros, UErrorCode &status);
+    NumberFormatterImpl(const MacroProps &macros, UErrorCode &status);
 
     /**
      * Builds and evaluates an "unsafe" MicroPropsGenerator, which is cheaper but can be used only once.
      */
-    static void
-    applyStatic(const MacroProps &macros, DecimalQuantity &inValue, NumberStringBuilder &outString,
-                UErrorCode &status);
+    static int32_t
+    formatStatic(const MacroProps &macros, DecimalQuantity &inValue, NumberStringBuilder &outString,
+                 UErrorCode &status);
 
     /**
      * Prints only the prefix and suffix; used for DecimalFormat getters.
@@ -51,7 +51,12 @@ class NumberFormatterImpl : public UMemory {
     /**
      * Evaluates the "safe" MicroPropsGenerator created by "fromMacros".
      */
-    void apply(DecimalQuantity& inValue, NumberStringBuilder& outString, UErrorCode& status) const;
+    int32_t format(DecimalQuantity& inValue, NumberStringBuilder& outString, UErrorCode& status) const;
+
+    /**
+     * Like format(), but saves the result into an output MicroProps without additional processing.
+     */
+    void preProcess(DecimalQuantity& inValue, MicroProps& microsOut, UErrorCode& status) const;
 
     /**
      * Like getPrefixSuffixStatic() but uses the safe compiled object.
@@ -59,6 +64,19 @@ class NumberFormatterImpl : public UMemory {
     int32_t getPrefixSuffix(int8_t signum, StandardPlural::Form plural, NumberStringBuilder& outString,
                             UErrorCode& status) const;
 
+    /**
+     * Synthesizes the output string from a MicroProps and DecimalQuantity.
+     * This method formats only the main number, not affixes.
+     */
+    static int32_t writeNumber(const MicroProps& micros, DecimalQuantity& quantity,
+                               NumberStringBuilder& string, int32_t index, UErrorCode& status);
+
+    /**
+     * Adds the affixes.  Intended to be called immediately after formatNumber.
+     */
+    static int32_t writeAffixes(const MicroProps& micros, NumberStringBuilder& string, int32_t start,
+                                int32_t end, UErrorCode& status);
+
   private:
     // Head of the MicroPropsGenerator linked list:
     const MicroPropsGenerator *fMicroPropsGenerator = nullptr;
@@ -85,7 +103,7 @@ class NumberFormatterImpl : public UMemory {
 
     NumberFormatterImpl(const MacroProps &macros, bool safe, UErrorCode &status);
 
-    void applyUnsafe(DecimalQuantity &inValue, NumberStringBuilder &outString, UErrorCode &status);
+    MicroProps& preProcessUnsafe(DecimalQuantity &inValue, UErrorCode &status);
 
     int32_t getPrefixSuffixUnsafe(int8_t signum, StandardPlural::Form plural,
                                   NumberStringBuilder& outString, UErrorCode& status);
@@ -113,31 +131,13 @@ class NumberFormatterImpl : public UMemory {
     const MicroPropsGenerator *
     macrosToMicroGenerator(const MacroProps &macros, bool safe, UErrorCode &status);
 
-    /**
-     * Synthesizes the output string from a MicroProps and DecimalQuantity.
-     *
-     * @param micros
-     *            The MicroProps after the quantity has been consumed. Will not be mutated.
-     * @param quantity
-     *            The DecimalQuantity to be rendered. May be mutated.
-     * @param string
-     *            The output string. Will be mutated.
-     */
-    static int32_t
-    microsToString(const MicroProps &micros, DecimalQuantity &quantity, NumberStringBuilder &string,
-                   UErrorCode &status);
-
-    static int32_t
-    writeNumber(const MicroProps &micros, DecimalQuantity &quantity, NumberStringBuilder &string,
-                UErrorCode &status);
-
     static int32_t
     writeIntegerDigits(const MicroProps &micros, DecimalQuantity &quantity, NumberStringBuilder &string,
-                       UErrorCode &status);
+                       int32_t index, UErrorCode &status);
 
     static int32_t
     writeFractionDigits(const MicroProps &micros, DecimalQuantity &quantity, NumberStringBuilder &string,
-                        UErrorCode &status);
+                        int32_t index, UErrorCode &status);
 };
 
 }  // namespace impl

icu4c/source/i18n/number_longnames.cpp

@@ -39,7 +39,7 @@ static int32_t getIndex(const char* pluralKeyword, UErrorCode& status) {
 
 static UnicodeString getWithPlural(
         const UnicodeString* strings,
-        int32_t plural,
+        StandardPlural::Form plural,
         UErrorCode& status) {
     UnicodeString result = strings[plural];
     if (result.isBogus()) {
@@ -156,7 +156,7 @@ UnicodeString getPerUnitFormat(const Locale& locale, const UNumberUnitWidth &wid
 
 } // namespace
 
-LongNameHandler
+LongNameHandler*
 LongNameHandler::forMeasureUnit(const Locale &loc, const MeasureUnit &unitRef, const MeasureUnit &perUnit,
                                 const UNumberUnitWidth &width, const PluralRules *rules,
                                 const MicroPropsGenerator *parent, UErrorCode &status) {
@@ -173,20 +173,28 @@ LongNameHandler::forMeasureUnit(const Locale &loc, const MeasureUnit &unitRef, c
         }
     }
 
-    LongNameHandler result(rules, parent);
+    auto* result = new LongNameHandler(rules, parent);
+    if (result == nullptr) {
+        status = U_MEMORY_ALLOCATION_ERROR;
+        return nullptr;
+    }
     UnicodeString simpleFormats[ARRAY_LENGTH];
     getMeasureData(loc, unit, width, simpleFormats, status);
     if (U_FAILURE(status)) { return result; }
     // TODO: What field to use for units?
-    simpleFormatsToModifiers(simpleFormats, UNUM_FIELD_COUNT, result.fModifiers, status);
+    result->simpleFormatsToModifiers(simpleFormats, UNUM_FIELD_COUNT, status);
     return result;
 }
 
-LongNameHandler
+LongNameHandler*
 LongNameHandler::forCompoundUnit(const Locale &loc, const MeasureUnit &unit, const MeasureUnit &perUnit,
                                  const UNumberUnitWidth &width, const PluralRules *rules,
                                  const MicroPropsGenerator *parent, UErrorCode &status) {
-    LongNameHandler result(rules, parent);
+    auto* result = new LongNameHandler(rules, parent);
+    if (result == nullptr) {
+        status = U_MEMORY_ALLOCATION_ERROR;
+        return nullptr;
+    }
     UnicodeString primaryData[ARRAY_LENGTH];
     getMeasureData(loc, unit, width, primaryData, status);
     if (U_FAILURE(status)) { return result; }
@@ -213,46 +221,52 @@ LongNameHandler::forCompoundUnit(const Locale &loc, const MeasureUnit &unit, con
         if (U_FAILURE(status)) { return result; }
     }
     // TODO: What field to use for units?
-    multiSimpleFormatsToModifiers(primaryData, perUnitFormat, UNUM_FIELD_COUNT, result.fModifiers, status);
+    result->multiSimpleFormatsToModifiers(primaryData, perUnitFormat, UNUM_FIELD_COUNT, status);
     return result;
 }
 
-LongNameHandler LongNameHandler::forCurrencyLongNames(const Locale &loc, const CurrencyUnit &currency,
+LongNameHandler* LongNameHandler::forCurrencyLongNames(const Locale &loc, const CurrencyUnit &currency,
                                                       const PluralRules *rules,
                                                       const MicroPropsGenerator *parent,
                                                       UErrorCode &status) {
-    LongNameHandler result(rules, parent);
+    auto* result = new LongNameHandler(rules, parent);
+    if (result == nullptr) {
+        status = U_MEMORY_ALLOCATION_ERROR;
+        return nullptr;
+    }
     UnicodeString simpleFormats[ARRAY_LENGTH];
     getCurrencyLongNameData(loc, currency, simpleFormats, status);
-    if (U_FAILURE(status)) { return result; }
-    simpleFormatsToModifiers(simpleFormats, UNUM_CURRENCY_FIELD, result.fModifiers, status);
+    if (U_FAILURE(status)) { return nullptr; }
+    result->simpleFormatsToModifiers(simpleFormats, UNUM_CURRENCY_FIELD, status);
     return result;
 }
 
 void LongNameHandler::simpleFormatsToModifiers(const UnicodeString *simpleFormats, Field field,
-                                               SimpleModifier *output, UErrorCode &status) {
+                                               UErrorCode &status) {
     for (int32_t i = 0; i < StandardPlural::Form::COUNT; i++) {
-        UnicodeString simpleFormat = getWithPlural(simpleFormats, i, status);
+        StandardPlural::Form plural = static_cast<StandardPlural::Form>(i);
+        UnicodeString simpleFormat = getWithPlural(simpleFormats, plural, status);
         if (U_FAILURE(status)) { return; }
         SimpleFormatter compiledFormatter(simpleFormat, 0, 1, status);
         if (U_FAILURE(status)) { return; }
-        output[i] = SimpleModifier(compiledFormatter, field, false);
+        fModifiers[i] = SimpleModifier(compiledFormatter, field, false, {this, 0, plural});
     }
 }
 
 void LongNameHandler::multiSimpleFormatsToModifiers(const UnicodeString *leadFormats, UnicodeString trailFormat,
-                                                    Field field, SimpleModifier *output, UErrorCode &status) {
+                                                    Field field, UErrorCode &status) {
     SimpleFormatter trailCompiled(trailFormat, 1, 1, status);
     if (U_FAILURE(status)) { return; }
     for (int32_t i = 0; i < StandardPlural::Form::COUNT; i++) {
-        UnicodeString leadFormat = getWithPlural(leadFormats, i, status);
+        StandardPlural::Form plural = static_cast<StandardPlural::Form>(i);
+        UnicodeString leadFormat = getWithPlural(leadFormats, plural, status);
         if (U_FAILURE(status)) { return; }
         UnicodeString compoundFormat;
         trailCompiled.format(leadFormat, compoundFormat, status);
         if (U_FAILURE(status)) { return; }
         SimpleFormatter compoundCompiled(compoundFormat, 0, 1, status);
         if (U_FAILURE(status)) { return; }
-        output[i] = SimpleModifier(compoundCompiled, field, false);
+        fModifiers[i] = SimpleModifier(compoundCompiled, field, false, {this, 0, plural});
     }
 }
 
@@ -265,4 +279,8 @@ void LongNameHandler::processQuantity(DecimalQuantity &quantity, MicroProps &mic
     micros.modOuter = &fModifiers[utils::getStandardPlural(rules, copy)];
 }
 
+const Modifier* LongNameHandler::getModifier(int8_t /*signum*/, StandardPlural::Form plural) const {
+    return &fModifiers[plural];
+}
+
 #endif /* #if !UCONFIG_NO_FORMATTING */

icu4c/source/i18n/number_longnames.h

@@ -14,13 +14,13 @@
 U_NAMESPACE_BEGIN namespace number {
 namespace impl {
 
-class LongNameHandler : public MicroPropsGenerator, public UMemory {
+class LongNameHandler : public MicroPropsGenerator, public ModifierStore, public UMemory {
   public:
-    static LongNameHandler
+    static LongNameHandler*
     forCurrencyLongNames(const Locale &loc, const CurrencyUnit &currency, const PluralRules *rules,
                          const MicroPropsGenerator *parent, UErrorCode &status);
 
-    static LongNameHandler
+    static LongNameHandler*
     forMeasureUnit(const Locale &loc, const MeasureUnit &unit, const MeasureUnit &perUnit,
                    const UNumberUnitWidth &width, const PluralRules *rules,
                    const MicroPropsGenerator *parent, UErrorCode &status);
@@ -28,6 +28,8 @@ class LongNameHandler : public MicroPropsGenerator, public UMemory {
     void
     processQuantity(DecimalQuantity &quantity, MicroProps &micros, UErrorCode &status) const U_OVERRIDE;
 
+    const Modifier* getModifier(int8_t signum, StandardPlural::Form plural) const U_OVERRIDE;
+
   private:
     SimpleModifier fModifiers[StandardPlural::Form::COUNT];
     const PluralRules *rules;
@@ -36,15 +38,14 @@ class LongNameHandler : public MicroPropsGenerator, public UMemory {
     LongNameHandler(const PluralRules *rules, const MicroPropsGenerator *parent)
             : rules(rules), parent(parent) {}
 
-    static LongNameHandler
+    static LongNameHandler*
     forCompoundUnit(const Locale &loc, const MeasureUnit &unit, const MeasureUnit &perUnit,
                     const UNumberUnitWidth &width, const PluralRules *rules,
                     const MicroPropsGenerator *parent, UErrorCode &status);
 
-    static void simpleFormatsToModifiers(const UnicodeString *simpleFormats, Field field,
-                                         SimpleModifier *output, UErrorCode &status);
-    static void multiSimpleFormatsToModifiers(const UnicodeString *leadFormats, UnicodeString trailFormat,
-                                         Field field, SimpleModifier *output, UErrorCode &status);
+    void simpleFormatsToModifiers(const UnicodeString *simpleFormats, Field field, UErrorCode &status);
+    void multiSimpleFormatsToModifiers(const UnicodeString *leadFormats, UnicodeString trailFormat,
+                                       Field field, UErrorCode &status);
 };
 
 }  // namespace impl

icu4c/source/i18n/number_mapper.cpp

@@ -225,8 +225,8 @@ MacroProps NumberPropertyMapper::oldToNew(const DecimalFormatProperties& propert
         // TODO: Overriding here is a bit of a hack. Should this logic go earlier?
         if (macros.precision.fType == Precision::PrecisionType::RND_FRACTION) {
             // For the purposes of rounding, get the original min/max int/frac, since the local
-            // variables
-            // have been manipulated for display purposes.
+            // variables have been manipulated for display purposes.
+            int maxInt_ = properties.maximumIntegerDigits;
             int minInt_ = properties.minimumIntegerDigits;
             int minFrac_ = properties.minimumFractionDigits;
             int maxFrac_ = properties.maximumFractionDigits;
@@ -237,9 +237,15 @@ MacroProps NumberPropertyMapper::oldToNew(const DecimalFormatProperties& propert
                 // Patterns like "#.##E0" (no zeros in the mantissa), which mean round to maxFrac+1
                 macros.precision = Precision::constructSignificant(1, maxFrac_ + 1).withMode(roundingMode);
             } else {
-                // All other scientific patterns, which mean round to minInt+maxFrac
-                macros.precision = Precision::constructSignificant(
-                        minInt_ + minFrac_, minInt_ + maxFrac_).withMode(roundingMode);
+                int maxSig_ = minInt_ + maxFrac_;
+                // Bug #20058: if maxInt_ > minInt_ > 1, then minInt_ should be 1.
+                if (maxInt_ > minInt_ && minInt_ > 1) {
+                    minInt_ = 1;
+                }
+                int minSig_ = minInt_ + minFrac_;
+                // To avoid regression, maxSig is not reset when minInt_ set to 1.
+                // TODO: Reset maxSig_ = 1 + minFrac_ to follow the spec.
+                macros.precision = Precision::constructSignificant(minSig_, maxSig_).withMode(roundingMode);
             }
         }
     }

icu4c/source/i18n/number_modifiers.cpp

@@ -53,6 +53,21 @@ void U_CALLCONV initDefaultCurrencySpacing(UErrorCode &status) {
 
 Modifier::~Modifier() = default;
 
+Modifier::Parameters::Parameters()
+        : obj(nullptr) {}
+
+Modifier::Parameters::Parameters(
+    const ModifierStore* _obj, int8_t _signum, StandardPlural::Form _plural)
+        : obj(_obj), signum(_signum), plural(_plural) {}
+
+ModifierStore::~ModifierStore() = default;
+
+AdoptingModifierStore::~AdoptingModifierStore()  {
+    for (const Modifier *mod : mods) {
+        delete mod;
+    }
+}
+
 
 int32_t ConstantAffixModifier::apply(NumberStringBuilder &output, int leftIndex, int rightIndex,
                                      UErrorCode &status) const {
@@ -62,13 +77,11 @@ int32_t ConstantAffixModifier::apply(NumberStringBuilder &output, int leftIndex,
     return length;
 }
 
-int32_t ConstantAffixModifier::getPrefixLength(UErrorCode &status) const {
-    (void)status;
+int32_t ConstantAffixModifier::getPrefixLength() const {
     return fPrefix.length();
 }
 
-int32_t ConstantAffixModifier::getCodePointCount(UErrorCode &status) const {
-    (void)status;
+int32_t ConstantAffixModifier::getCodePointCount() const {
     return fPrefix.countChar32() + fSuffix.countChar32();
 }
 
@@ -76,8 +89,38 @@ bool ConstantAffixModifier::isStrong() const {
     return fStrong;
 }
 
+bool ConstantAffixModifier::containsField(UNumberFormatFields field) const {
+    (void)field;
+    // This method is not currently used.
+    U_ASSERT(false);
+    return false;
+}
+
+void ConstantAffixModifier::getParameters(Parameters& output) const {
+    (void)output;
+    // This method is not currently used.
+    U_ASSERT(false);
+}
+
+bool ConstantAffixModifier::semanticallyEquivalent(const Modifier& other) const {
+    auto* _other = dynamic_cast<const ConstantAffixModifier*>(&other);
+    if (_other == nullptr) {
+        return false;
+    }
+    return fPrefix == _other->fPrefix
+        && fSuffix == _other->fSuffix
+        && fField == _other->fField
+        && fStrong == _other->fStrong;
+}
+
+
 SimpleModifier::SimpleModifier(const SimpleFormatter &simpleFormatter, Field field, bool strong)
-        : fCompiledPattern(simpleFormatter.compiledPattern), fField(field), fStrong(strong) {
+        : SimpleModifier(simpleFormatter, field, strong, {}) {}
+
+SimpleModifier::SimpleModifier(const SimpleFormatter &simpleFormatter, Field field, bool strong,
+                               const Modifier::Parameters parameters)
+        : fCompiledPattern(simpleFormatter.compiledPattern), fField(field), fStrong(strong),
+          fParameters(parameters) {
     int32_t argLimit = SimpleFormatter::getArgumentLimit(
             fCompiledPattern.getBuffer(), fCompiledPattern.length());
     if (argLimit == 0) {
@@ -90,15 +133,19 @@ SimpleModifier::SimpleModifier(const SimpleFormatter &simpleFormatter, Field fie
     } else {
         U_ASSERT(argLimit == 1);
         if (fCompiledPattern.charAt(1) != 0) {
+            // Found prefix
             fPrefixLength = fCompiledPattern.charAt(1) - ARG_NUM_LIMIT;
             fSuffixOffset = 3 + fPrefixLength;
         } else {
+            // No prefix
             fPrefixLength = 0;
             fSuffixOffset = 2;
         }
         if (3 + fPrefixLength < fCompiledPattern.length()) {
+            // Found suffix
             fSuffixLength = fCompiledPattern.charAt(fSuffixOffset) - ARG_NUM_LIMIT;
         } else {
+            // No suffix
             fSuffixLength = 0;
         }
     }
@@ -113,13 +160,11 @@ int32_t SimpleModifier::apply(NumberStringBuilder &output, int leftIndex, int ri
     return formatAsPrefixSuffix(output, leftIndex, rightIndex, fField, status);
 }
 
-int32_t SimpleModifier::getPrefixLength(UErrorCode &status) const {
-    (void)status;
+int32_t SimpleModifier::getPrefixLength() const {
     return fPrefixLength;
 }
 
-int32_t SimpleModifier::getCodePointCount(UErrorCode &status) const {
-    (void)status;
+int32_t SimpleModifier::getCodePointCount() const {
     int32_t count = 0;
     if (fPrefixLength > 0) {
         count += fCompiledPattern.countChar32(2, fPrefixLength);
@@ -134,10 +179,35 @@ bool SimpleModifier::isStrong() const {
     return fStrong;
 }
 
+bool SimpleModifier::containsField(UNumberFormatFields field) const {
+    (void)field;
+    // This method is not currently used.
+    U_ASSERT(false);
+    return false;
+}
+
+void SimpleModifier::getParameters(Parameters& output) const {
+    output = fParameters;
+}
+
+bool SimpleModifier::semanticallyEquivalent(const Modifier& other) const {
+    auto* _other = dynamic_cast<const SimpleModifier*>(&other);
+    if (_other == nullptr) {
+        return false;
+    }
+    if (fParameters.obj != nullptr) {
+        return fParameters.obj == _other->fParameters.obj;
+    }
+    return fCompiledPattern == _other->fCompiledPattern
+        && fField == _other->fField
+        && fStrong == _other->fStrong;
+}
+
+
 int32_t
 SimpleModifier::formatAsPrefixSuffix(NumberStringBuilder &result, int32_t startIndex, int32_t endIndex,
                                      Field field, UErrorCode &status) const {
-    if (fSuffixOffset == -1) {
+    if (fSuffixOffset == -1 && fPrefixLength + fSuffixLength > 0) {
         // There is no argument for the inner number; overwrite the entire segment with our string.
         return result.splice(startIndex, endIndex, fCompiledPattern, 2, 2 + fPrefixLength, field, status);
     } else {
@@ -157,6 +227,65 @@ SimpleModifier::formatAsPrefixSuffix(NumberStringBuilder &result, int32_t startI
     }
 }
 
+
+int32_t
+SimpleModifier::formatTwoArgPattern(const SimpleFormatter& compiled, NumberStringBuilder& result,
+                                    int32_t index, int32_t* outPrefixLength, int32_t* outSuffixLength,
+                                    Field field, UErrorCode& status) {
+    const UnicodeString& compiledPattern = compiled.compiledPattern;
+    int32_t argLimit = SimpleFormatter::getArgumentLimit(
+            compiledPattern.getBuffer(), compiledPattern.length());
+    if (argLimit != 2) {
+        status = U_INTERNAL_PROGRAM_ERROR;
+        return 0;
+    }
+    int32_t offset = 1; // offset into compiledPattern
+    int32_t length = 0; // chars added to result
+
+    int32_t prefixLength = compiledPattern.charAt(offset);
+    offset++;
+    if (prefixLength < ARG_NUM_LIMIT) {
+        // No prefix
+        prefixLength = 0;
+    } else {
+        prefixLength -= ARG_NUM_LIMIT;
+        result.insert(index + length, compiledPattern, offset, offset + prefixLength, field, status);
+        offset += prefixLength;
+        length += prefixLength;
+        offset++;
+    }
+
+    int32_t infixLength = compiledPattern.charAt(offset);
+    offset++;
+    if (infixLength < ARG_NUM_LIMIT) {
+        // No infix
+        infixLength = 0;
+    } else {
+        infixLength -= ARG_NUM_LIMIT;
+        result.insert(index + length, compiledPattern, offset, offset + infixLength, field, status);
+        offset += infixLength;
+        length += infixLength;
+        offset++;
+    }
+
+    int32_t suffixLength;
+    if (offset == compiledPattern.length()) {
+        // No suffix
+        suffixLength = 0;
+    } else {
+        suffixLength = compiledPattern.charAt(offset) -  ARG_NUM_LIMIT;
+        offset++;
+        result.insert(index + length, compiledPattern, offset, offset + suffixLength, field, status);
+        length += suffixLength;
+    }
+
+    *outPrefixLength = prefixLength;
+    *outSuffixLength = suffixLength;
+
+    return length;
+}
+
+
 int32_t ConstantMultiFieldModifier::apply(NumberStringBuilder &output, int leftIndex, int rightIndex,
                                           UErrorCode &status) const {
     int32_t length = output.insert(leftIndex, fPrefix, status);
@@ -171,13 +300,11 @@ int32_t ConstantMultiFieldModifier::apply(NumberStringBuilder &output, int leftI
     return length;
 }
 
-int32_t ConstantMultiFieldModifier::getPrefixLength(UErrorCode &status) const {
-    (void)status;
+int32_t ConstantMultiFieldModifier::getPrefixLength() const {
     return fPrefix.length();
 }
 
-int32_t ConstantMultiFieldModifier::getCodePointCount(UErrorCode &status) const {
-    (void)status;
+int32_t ConstantMultiFieldModifier::getCodePointCount() const {
     return fPrefix.codePointCount() + fSuffix.codePointCount();
 }
 
@@ -185,6 +312,29 @@ bool ConstantMultiFieldModifier::isStrong() const {
     return fStrong;
 }
 
+bool ConstantMultiFieldModifier::containsField(UNumberFormatFields field) const {
+    return fPrefix.containsField(field) || fSuffix.containsField(field);
+}
+
+void ConstantMultiFieldModifier::getParameters(Parameters& output) const {
+    output = fParameters;
+}
+
+bool ConstantMultiFieldModifier::semanticallyEquivalent(const Modifier& other) const {
+    auto* _other = dynamic_cast<const ConstantMultiFieldModifier*>(&other);
+    if (_other == nullptr) {
+        return false;
+    }
+    if (fParameters.obj != nullptr) {
+        return fParameters.obj == _other->fParameters.obj;
+    }
+    return fPrefix.contentEquals(_other->fPrefix)
+        && fSuffix.contentEquals(_other->fSuffix)
+        && fOverwrite == _other->fOverwrite
+        && fStrong == _other->fStrong;
+}
+
+
 CurrencySpacingEnabledModifier::CurrencySpacingEnabledModifier(const NumberStringBuilder &prefix,
                                                                const NumberStringBuilder &suffix,
                                                                bool overwrite,

icu4c/source/i18n/number_modifiers.h

@@ -31,12 +31,18 @@ class U_I18N_API ConstantAffixModifier : public Modifier, public UObject {
     int32_t apply(NumberStringBuilder &output, int32_t leftIndex, int32_t rightIndex,
                   UErrorCode &status) const U_OVERRIDE;
 
-    int32_t getPrefixLength(UErrorCode &status) const U_OVERRIDE;
+    int32_t getPrefixLength() const U_OVERRIDE;
 
-    int32_t getCodePointCount(UErrorCode &status) const U_OVERRIDE;
+    int32_t getCodePointCount() const U_OVERRIDE;
 
     bool isStrong() const U_OVERRIDE;
 
+    bool containsField(UNumberFormatFields field) const U_OVERRIDE;
+
+    void getParameters(Parameters& output) const U_OVERRIDE;
+
+    bool semanticallyEquivalent(const Modifier& other) const U_OVERRIDE;
+
   private:
     UnicodeString fPrefix;
     UnicodeString fSuffix;
@@ -52,21 +58,30 @@ class U_I18N_API SimpleModifier : public Modifier, public UMemory {
   public:
     SimpleModifier(const SimpleFormatter &simpleFormatter, Field field, bool strong);
 
+    SimpleModifier(const SimpleFormatter &simpleFormatter, Field field, bool strong,
+                   const Modifier::Parameters parameters);
+
     // Default constructor for LongNameHandler.h
     SimpleModifier();
 
     int32_t apply(NumberStringBuilder &output, int32_t leftIndex, int32_t rightIndex,
                   UErrorCode &status) const U_OVERRIDE;
 
-    int32_t getPrefixLength(UErrorCode &status) const U_OVERRIDE;
+    int32_t getPrefixLength() const U_OVERRIDE;
 
-    int32_t getCodePointCount(UErrorCode &status) const U_OVERRIDE;
+    int32_t getCodePointCount() const U_OVERRIDE;
 
     bool isStrong() const U_OVERRIDE;
 
+    bool containsField(UNumberFormatFields field) const U_OVERRIDE;
+
+    void getParameters(Parameters& output) const U_OVERRIDE;
+
+    bool semanticallyEquivalent(const Modifier& other) const U_OVERRIDE;
+
     /**
      * TODO: This belongs in SimpleFormatterImpl. The only reason I haven't moved it there yet is because
-     * DoubleSidedStringBuilder is an internal class and SimpleFormatterImpl feels like it should not depend on it.
+     * NumberStringBuilder is an internal class and SimpleFormatterImpl feels like it should not depend on it.
      *
      * <p>
      * Formats a value that is already stored inside the StringBuilder <code>result</code> between the indices
@@ -85,16 +100,33 @@ class U_I18N_API SimpleModifier : public Modifier, public UMemory {
      * @return The number of characters (UTF-16 code points) that were added to the StringBuilder.
      */
     int32_t
-    formatAsPrefixSuffix(NumberStringBuilder &result, int32_t startIndex, int32_t endIndex, Field field,
-                         UErrorCode &status) const;
+    formatAsPrefixSuffix(NumberStringBuilder& result, int32_t startIndex, int32_t endIndex, Field field,
+                         UErrorCode& status) const;
+
+    /**
+     * TODO: Like above, this belongs with the rest of the SimpleFormatterImpl code.
+     * I put it here so that the SimpleFormatter uses in NumberStringBuilder are near each other.
+     *
+     * <p>
+     * Applies the compiled two-argument pattern to the NumberStringBuilder.
+     *
+     * <p>
+     * This method is optimized for the case where the prefix and suffix are often empty, such as
+     * in the range pattern like "{0}-{1}".
+     */
+    static int32_t
+    formatTwoArgPattern(const SimpleFormatter& compiled, NumberStringBuilder& result,
+                        int32_t index, int32_t* outPrefixLength, int32_t* outSuffixLength,
+                        Field field, UErrorCode& status);
 
   private:
     UnicodeString fCompiledPattern;
     Field fField;
-    bool fStrong;
-    int32_t fPrefixLength;
-    int32_t fSuffixOffset;
-    int32_t fSuffixLength;
+    bool fStrong = false;
+    int32_t fPrefixLength = 0;
+    int32_t fSuffixOffset = -1;
+    int32_t fSuffixLength = 0;
+    Modifier::Parameters fParameters;
 };
 
 /**
@@ -103,6 +135,18 @@ class U_I18N_API SimpleModifier : public Modifier, public UMemory {
  */
 class U_I18N_API ConstantMultiFieldModifier : public Modifier, public UMemory {
   public:
+    ConstantMultiFieldModifier(
+            const NumberStringBuilder &prefix,
+            const NumberStringBuilder &suffix,
+            bool overwrite,
+            bool strong,
+            const Modifier::Parameters parameters)
+      : fPrefix(prefix),
+        fSuffix(suffix),
+        fOverwrite(overwrite),
+        fStrong(strong),
+        fParameters(parameters) {}
+
     ConstantMultiFieldModifier(
             const NumberStringBuilder &prefix,
             const NumberStringBuilder &suffix,
@@ -116,12 +160,18 @@ class U_I18N_API ConstantMultiFieldModifier : public Modifier, public UMemory {
     int32_t apply(NumberStringBuilder &output, int32_t leftIndex, int32_t rightIndex,
                   UErrorCode &status) const U_OVERRIDE;
 
-    int32_t getPrefixLength(UErrorCode &status) const U_OVERRIDE;
+    int32_t getPrefixLength() const U_OVERRIDE;
 
-    int32_t getCodePointCount(UErrorCode &status) const U_OVERRIDE;
+    int32_t getCodePointCount() const U_OVERRIDE;
 
     bool isStrong() const U_OVERRIDE;
 
+    bool containsField(UNumberFormatFields field) const U_OVERRIDE;
+
+    void getParameters(Parameters& output) const U_OVERRIDE;
+
+    bool semanticallyEquivalent(const Modifier& other) const U_OVERRIDE;
+
   protected:
     // NOTE: In Java, these are stored as array pointers. In C++, the NumberStringBuilder is stored by
     // value and is treated internally as immutable.
@@ -129,6 +179,7 @@ class U_I18N_API ConstantMultiFieldModifier : public Modifier, public UMemory {
     NumberStringBuilder fSuffix;
     bool fOverwrite;
     bool fStrong;
+    Modifier::Parameters fParameters;
 };
 
 /** Identical to {@link ConstantMultiFieldModifier}, but supports currency spacing. */
@@ -192,13 +243,11 @@ class U_I18N_API EmptyModifier : public Modifier, public UMemory {
         return 0;
     }
 
-    int32_t getPrefixLength(UErrorCode &status) const U_OVERRIDE {
-        (void)status;
+    int32_t getPrefixLength() const U_OVERRIDE {
         return 0;
     }
 
-    int32_t getCodePointCount(UErrorCode &status) const U_OVERRIDE {
-        (void)status;
+    int32_t getCodePointCount() const U_OVERRIDE {
         return 0;
     }
 
@@ -206,55 +255,75 @@ class U_I18N_API EmptyModifier : public Modifier, public UMemory {
         return fStrong;
     }
 
+    bool containsField(UNumberFormatFields field) const U_OVERRIDE {
+        (void)field;
+        return false;
+    }
+
+    void getParameters(Parameters& output) const U_OVERRIDE {
+        output.obj = nullptr;
+    }
+
+    bool semanticallyEquivalent(const Modifier& other) const U_OVERRIDE {
+        return other.getCodePointCount() == 0;
+    }
+
   private:
     bool fStrong;
 };
 
 /**
- * A ParameterizedModifier by itself is NOT a Modifier. Rather, it wraps a data structure containing two or more
- * Modifiers and returns the modifier appropriate for the current situation.
+ * This implementation of ModifierStore adopts Modifer pointers.
  */
-class U_I18N_API ParameterizedModifier : public UMemory {
+class U_I18N_API AdoptingModifierStore : public ModifierStore, public UMemory {
   public:
-    // NOTE: mods is zero-initialized (to nullptr)
-    ParameterizedModifier() : mods() {
-    }
+    virtual ~AdoptingModifierStore();
+
+    static constexpr StandardPlural::Form DEFAULT_STANDARD_PLURAL = StandardPlural::OTHER;
+
+    AdoptingModifierStore() = default;
 
     // No copying!
-    ParameterizedModifier(const ParameterizedModifier &other) = delete;
+    AdoptingModifierStore(const AdoptingModifierStore &other) = delete;
 
-    ~ParameterizedModifier() {
-        for (const Modifier *mod : mods) {
-            delete mod;
-        }
-    }
-
-    void adoptPositiveNegativeModifiers(
-            const Modifier *positive, const Modifier *zero, const Modifier *negative) {
-        mods[2] = positive;
-        mods[1] = zero;
-        mods[0] = negative;
-    }
-
-    /** The modifier is ADOPTED. */
-    void adoptSignPluralModifier(int8_t signum, StandardPlural::Form plural, const Modifier *mod) {
+    /**
+     * Sets the Modifier with the specified signum and plural form.
+     */
+    void adoptModifier(int8_t signum, StandardPlural::Form plural, const Modifier *mod) {
+        U_ASSERT(mods[getModIndex(signum, plural)] == nullptr);
         mods[getModIndex(signum, plural)] = mod;
     }
 
-    /** Returns a reference to the modifier; no ownership change. */
-    const Modifier *getModifier(int8_t signum) const {
-        return mods[signum + 1];
+    /**
+     * Sets the Modifier with the specified signum.
+     * The modifier will apply to all plural forms.
+     */
+    void adoptModifierWithoutPlural(int8_t signum, const Modifier *mod) {
+        U_ASSERT(mods[getModIndex(signum, DEFAULT_STANDARD_PLURAL)] == nullptr);
+        mods[getModIndex(signum, DEFAULT_STANDARD_PLURAL)] = mod;
     }
 
     /** Returns a reference to the modifier; no ownership change. */
-    const Modifier *getModifier(int8_t signum, StandardPlural::Form plural) const {
-        return mods[getModIndex(signum, plural)];
+    const Modifier *getModifier(int8_t signum, StandardPlural::Form plural) const U_OVERRIDE {
+        const Modifier* modifier = mods[getModIndex(signum, plural)];
+        if (modifier == nullptr && plural != DEFAULT_STANDARD_PLURAL) {
+            modifier = mods[getModIndex(signum, DEFAULT_STANDARD_PLURAL)];
+        }
+        return modifier;
+    }
+
+    /** Returns a reference to the modifier; no ownership change. */
+    const Modifier *getModifierWithoutPlural(int8_t signum) const {
+        return mods[getModIndex(signum, DEFAULT_STANDARD_PLURAL)];
     }
 
   private:
-    const Modifier *mods[3 * StandardPlural::COUNT];
+    // NOTE: mods is zero-initialized (to nullptr)
+    const Modifier *mods[3 * StandardPlural::COUNT] = {};
 
     inline static int32_t getModIndex(int8_t signum, StandardPlural::Form plural) {
+        U_ASSERT(signum >= -1 && signum <= 1);
+        U_ASSERT(plural >= 0 && plural < StandardPlural::COUNT);
         return static_cast<int32_t>(plural) * 3 + (signum + 1);
     }
 };

icu4c/source/i18n/number_padding.cpp

@@ -62,7 +62,7 @@ Padder Padder::forProperties(const DecimalFormatProperties& properties) {
 int32_t Padder::padAndApply(const Modifier &mod1, const Modifier &mod2,
                             NumberStringBuilder &string, int32_t leftIndex, int32_t rightIndex,
                             UErrorCode &status) const {
-    int32_t modLength = mod1.getCodePointCount(status) + mod2.getCodePointCount(status);
+    int32_t modLength = mod1.getCodePointCount() + mod2.getCodePointCount();
     int32_t requiredPadding = fWidth - modLength - string.codePointCount();
     U_ASSERT(leftIndex == 0 &&
              rightIndex == string.length()); // fix the previous line to remove this assertion

icu4c/source/i18n/number_patternmodifier.cpp

@@ -69,7 +69,7 @@ MutablePatternModifier::createImmutableAndChain(const MicroPropsGenerator* paren
             StandardPlural::Form::MANY,
             StandardPlural::Form::OTHER};
 
-    auto pm = new ParameterizedModifier();
+    auto pm = new AdoptingModifierStore();
     if (pm == nullptr) {
         status = U_MEMORY_ALLOCATION_ERROR;
         return nullptr;
@@ -79,11 +79,11 @@ MutablePatternModifier::createImmutableAndChain(const MicroPropsGenerator* paren
         // Slower path when we require the plural keyword.
         for (StandardPlural::Form plural : STANDARD_PLURAL_VALUES) {
             setNumberProperties(1, plural);
-            pm->adoptSignPluralModifier(1, plural, createConstantModifier(status));
+            pm->adoptModifier(1, plural, createConstantModifier(status));
             setNumberProperties(0, plural);
-            pm->adoptSignPluralModifier(0, plural, createConstantModifier(status));
+            pm->adoptModifier(0, plural, createConstantModifier(status));
             setNumberProperties(-1, plural);
-            pm->adoptSignPluralModifier(-1, plural, createConstantModifier(status));
+            pm->adoptModifier(-1, plural, createConstantModifier(status));
         }
         if (U_FAILURE(status)) {
             delete pm;
@@ -93,12 +93,11 @@ MutablePatternModifier::createImmutableAndChain(const MicroPropsGenerator* paren
     } else {
         // Faster path when plural keyword is not needed.
         setNumberProperties(1, StandardPlural::Form::COUNT);
-        Modifier* positive = createConstantModifier(status);
+        pm->adoptModifierWithoutPlural(1, createConstantModifier(status));
         setNumberProperties(0, StandardPlural::Form::COUNT);
-        Modifier* zero = createConstantModifier(status);
+        pm->adoptModifierWithoutPlural(0, createConstantModifier(status));
         setNumberProperties(-1, StandardPlural::Form::COUNT);
-        Modifier* negative = createConstantModifier(status);
-        pm->adoptPositiveNegativeModifiers(positive, zero, negative);
+        pm->adoptModifierWithoutPlural(-1, createConstantModifier(status));
         if (U_FAILURE(status)) {
             delete pm;
             return nullptr;
@@ -120,7 +119,7 @@ ConstantMultiFieldModifier* MutablePatternModifier::createConstantModifier(UErro
     }
 }
 
-ImmutablePatternModifier::ImmutablePatternModifier(ParameterizedModifier* pm, const PluralRules* rules,
+ImmutablePatternModifier::ImmutablePatternModifier(AdoptingModifierStore* pm, const PluralRules* rules,
                                                    const MicroPropsGenerator* parent)
         : pm(pm), rules(rules), parent(parent) {}
 
@@ -132,7 +131,7 @@ void ImmutablePatternModifier::processQuantity(DecimalQuantity& quantity, MicroP
 
 void ImmutablePatternModifier::applyToMicros(MicroProps& micros, DecimalQuantity& quantity) const {
     if (rules == nullptr) {
-        micros.modMiddle = pm->getModifier(quantity.signum());
+        micros.modMiddle = pm->getModifierWithoutPlural(quantity.signum());
     } else {
         // TODO: Fix this. Avoid the copy.
         DecimalQuantity copy(quantity);
@@ -144,7 +143,7 @@ void ImmutablePatternModifier::applyToMicros(MicroProps& micros, DecimalQuantity
 
 const Modifier* ImmutablePatternModifier::getModifier(int8_t signum, StandardPlural::Form plural) const {
     if (rules == nullptr) {
-        return pm->getModifier(signum);
+        return pm->getModifierWithoutPlural(signum);
     } else {
         return pm->getModifier(signum, plural);
     }
@@ -204,23 +203,25 @@ int32_t MutablePatternModifier::apply(NumberStringBuilder& output, int32_t leftI
     return prefixLen + overwriteLen + suffixLen;
 }
 
-int32_t MutablePatternModifier::getPrefixLength(UErrorCode& status) const {
+int32_t MutablePatternModifier::getPrefixLength() const {
     // The unsafe code path performs self-mutation, so we need a const_cast.
     // This method needs to be const because it overrides a const method in the parent class.
     auto nonConstThis = const_cast<MutablePatternModifier*>(this);
 
     // Enter and exit CharSequence Mode to get the length.
+    UErrorCode status = U_ZERO_ERROR; // status fails only with an iilegal argument exception
     nonConstThis->prepareAffix(true);
     int result = AffixUtils::unescapedCodePointCount(currentAffix, *this, status);  // prefix length
     return result;
 }
 
-int32_t MutablePatternModifier::getCodePointCount(UErrorCode& status) const {
+int32_t MutablePatternModifier::getCodePointCount() const {
     // The unsafe code path performs self-mutation, so we need a const_cast.
     // This method needs to be const because it overrides a const method in the parent class.
     auto nonConstThis = const_cast<MutablePatternModifier*>(this);
 
     // Render the affixes to get the length
+    UErrorCode status = U_ZERO_ERROR; // status fails only with an iilegal argument exception
     nonConstThis->prepareAffix(true);
     int result = AffixUtils::unescapedCodePointCount(currentAffix, *this, status);  // prefix length
     nonConstThis->prepareAffix(false);
@@ -232,6 +233,26 @@ bool MutablePatternModifier::isStrong() const {
     return fStrong;
 }
 
+bool MutablePatternModifier::containsField(UNumberFormatFields field) const {
+    (void)field;
+    // This method is not currently used.
+    U_ASSERT(false);
+    return false;
+}
+
+void MutablePatternModifier::getParameters(Parameters& output) const {
+    (void)output;
+    // This method is not currently used.
+    U_ASSERT(false);
+}
+
+bool MutablePatternModifier::semanticallyEquivalent(const Modifier& other) const {
+    (void)other;
+    // This method is not currently used.
+    U_ASSERT(false);
+    return false;
+}
+
 int32_t MutablePatternModifier::insertPrefix(NumberStringBuilder& sb, int position, UErrorCode& status) {
     prepareAffix(true);
     int length = AffixUtils::unescape(currentAffix, sb, position, *this, status);

icu4c/source/i18n/number_patternmodifier.h

@@ -18,13 +18,13 @@
 U_NAMESPACE_BEGIN
 
 // Export an explicit template instantiation of the LocalPointer that is used as a
-// data member of ParameterizedModifier.
+// data member of AdoptingModifierStore.
 // (When building DLLs for Windows this is required.)
 #if U_PF_WINDOWS <= U_PLATFORM && U_PLATFORM <= U_PF_CYGWIN
 // Ignore warning 4661 as LocalPointerBase does not use operator== or operator!=
 #pragma warning(suppress: 4661)
-template class U_I18N_API LocalPointerBase<number::impl::ParameterizedModifier>;
-template class U_I18N_API LocalPointer<number::impl::ParameterizedModifier>;
+template class U_I18N_API LocalPointerBase<number::impl::AdoptingModifierStore>;
+template class U_I18N_API LocalPointer<number::impl::AdoptingModifierStore>;
 #endif
 
 namespace number {
@@ -45,10 +45,10 @@ class U_I18N_API ImmutablePatternModifier : public MicroPropsGenerator, public U
     const Modifier* getModifier(int8_t signum, StandardPlural::Form plural) const;
 
   private:
-    ImmutablePatternModifier(ParameterizedModifier* pm, const PluralRules* rules,
+    ImmutablePatternModifier(AdoptingModifierStore* pm, const PluralRules* rules,
                              const MicroPropsGenerator* parent);
 
-    const LocalPointer<ParameterizedModifier> pm;
+    const LocalPointer<AdoptingModifierStore> pm;
     const PluralRules* rules;
     const MicroPropsGenerator* parent;
 
@@ -178,12 +178,18 @@ class U_I18N_API MutablePatternModifier
     int32_t apply(NumberStringBuilder &output, int32_t leftIndex, int32_t rightIndex,
                   UErrorCode &status) const U_OVERRIDE;
 
-    int32_t getPrefixLength(UErrorCode &status) const U_OVERRIDE;
+    int32_t getPrefixLength() const U_OVERRIDE;
 
-    int32_t getCodePointCount(UErrorCode &status) const U_OVERRIDE;
+    int32_t getCodePointCount() const U_OVERRIDE;
 
     bool isStrong() const U_OVERRIDE;
 
+    bool containsField(UNumberFormatFields field) const U_OVERRIDE;
+
+    void getParameters(Parameters& output) const U_OVERRIDE;
+
+    bool semanticallyEquivalent(const Modifier& other) const U_OVERRIDE;
+
     /**
      * Returns the string that substitutes a given symbol type in a pattern.
      */

icu4c/source/i18n/number_scientific.cpp

@@ -76,17 +76,16 @@ int32_t ScientificModifier::apply(NumberStringBuilder &output, int32_t /*leftInd
     return i - rightIndex;
 }
 
-int32_t ScientificModifier::getPrefixLength(UErrorCode &status) const {
-    (void)status;
+int32_t ScientificModifier::getPrefixLength() const {
     // TODO: Localized exponent separator location.
     return 0;
 }
 
-int32_t ScientificModifier::getCodePointCount(UErrorCode &status) const {
-    (void)status;
-    // This method is not used for strong modifiers.
-    U_ASSERT(false);
-    return 0;
+int32_t ScientificModifier::getCodePointCount() const {
+    // NOTE: This method is only called one place, NumberRangeFormatterImpl.
+    // The call site only cares about != 0 and != 1.
+    // Return a very large value so that if this method is used elsewhere, we should notice.
+    return 999;
 }
 
 bool ScientificModifier::isStrong() const {
@@ -94,6 +93,27 @@ bool ScientificModifier::isStrong() const {
     return true;
 }
 
+bool ScientificModifier::containsField(UNumberFormatFields field) const {
+    (void)field;
+    // This method is not used for inner modifiers.
+    U_ASSERT(false);
+    return false;
+}
+
+void ScientificModifier::getParameters(Parameters& output) const {
+    // Not part of any plural sets
+    output.obj = nullptr;
+}
+
+bool ScientificModifier::semanticallyEquivalent(const Modifier& other) const {
+    auto* _other = dynamic_cast<const ScientificModifier*>(&other);
+    if (_other == nullptr) {
+        return false;
+    }
+    // TODO: Check for locale symbols and settings as well? Could be less efficient.
+    return fExponent == _other->fExponent;
+}
+
 // Note: Visual Studio does not compile this function without full name space. Why?
 icu::number::impl::ScientificHandler::ScientificHandler(const Notation *notation, const DecimalFormatSymbols *symbols,
 	const MicroPropsGenerator *parent) : 

icu4c/source/i18n/number_scientific.h

@@ -24,12 +24,18 @@ class U_I18N_API ScientificModifier : public UMemory, public Modifier {
     int32_t apply(NumberStringBuilder &output, int32_t leftIndex, int32_t rightIndex,
                   UErrorCode &status) const U_OVERRIDE;
 
-    int32_t getPrefixLength(UErrorCode &status) const U_OVERRIDE;
+    int32_t getPrefixLength() const U_OVERRIDE;
 
-    int32_t getCodePointCount(UErrorCode &status) const U_OVERRIDE;
+    int32_t getCodePointCount() const U_OVERRIDE;
 
     bool isStrong() const U_OVERRIDE;
 
+    bool containsField(UNumberFormatFields field) const U_OVERRIDE;
+
+    void getParameters(Parameters& output) const U_OVERRIDE;
+
+    bool semanticallyEquivalent(const Modifier& other) const U_OVERRIDE;
+
   private:
     int32_t fExponent;
     const ScientificHandler *fHandler;

icu4c/source/i18n/number_stringbuilder.cpp

@@ -241,6 +241,9 @@ NumberStringBuilder::insert(int32_t index, const NumberStringBuilder &other, UEr
 }
 
 int32_t NumberStringBuilder::prepareForInsert(int32_t index, int32_t count, UErrorCode &status) {
+    U_ASSERT(index >= 0);
+    U_ASSERT(index <= fLength);
+    U_ASSERT(count >= 0);
     if (index == 0 && fZero - count >= 0) {
         // Append to start
         fZero -= count;
@@ -485,4 +488,13 @@ void NumberStringBuilder::getAllFieldPositions(FieldPositionIteratorHandler& fpi
     }
 }
 
+bool NumberStringBuilder::containsField(Field field) const {
+    for (int32_t i = 0; i < fLength; i++) {
+        if (field == fieldAt(i)) {
+            return true;
+        }
+    }
+    return false;
+}
+
 #endif /* #if !UCONFIG_NO_FORMATTING */

icu4c/source/i18n/number_stringbuilder.h

@@ -106,6 +106,8 @@ class U_I18N_API NumberStringBuilder : public UMemory {
 
     void getAllFieldPositions(FieldPositionIteratorHandler& fpih, UErrorCode& status) const;
 
+    bool containsField(Field field) const;
+
   private:
     bool fUsingHeap = false;
     ValueOrHeapArray<char16_t> fChars;

icu4c/source/i18n/number_types.h

@@ -16,6 +16,7 @@
 #include "uassert.h"
 #include "unicode/platform.h"
 #include "unicode/uniset.h"
+#include "standardplural.h"
 
 U_NAMESPACE_BEGIN namespace number {
 namespace impl {
@@ -45,6 +46,7 @@ class Modifier;
 class MutablePatternModifier;
 class DecimalQuantity;
 class NumberStringBuilder;
+class ModifierStore;
 struct MicroProps;
 
 
@@ -127,12 +129,13 @@ class U_I18N_API AffixPatternProvider {
     virtual bool hasBody() const = 0;
 };
 
+
 /**
  * A Modifier is an object that can be passed through the formatting pipeline until it is finally applied to the string
  * builder. A Modifier usually contains a prefix and a suffix that are applied, but it could contain something else,
  * like a {@link com.ibm.icu.text.SimpleFormatter} pattern.
  *
- * A Modifier is usually immutable, except in cases such as {@link MurkyModifier}, which are mutable for performance
+ * A Modifier is usually immutable, except in cases such as {@link MutablePatternModifier}, which are mutable for performance
  * reasons.
  *
  * Exported as U_I18N_API because it is a base class for other exported types
@@ -162,12 +165,12 @@ class U_I18N_API Modifier {
      *
      * @return The number of characters (UTF-16 code units) in the prefix.
      */
-    virtual int32_t getPrefixLength(UErrorCode& status) const = 0;
+    virtual int32_t getPrefixLength() const = 0;
 
     /**
      * Returns the number of code points in the modifier, prefix plus suffix.
      */
-    virtual int32_t getCodePointCount(UErrorCode& status) const = 0;
+    virtual int32_t getCodePointCount() const = 0;
 
     /**
      * Whether this modifier is strong. If a modifier is strong, it should always be applied immediately and not allowed
@@ -177,8 +180,57 @@ class U_I18N_API Modifier {
      * @return Whether the modifier is strong.
      */
     virtual bool isStrong() const = 0;
+
+    /**
+     * Whether the modifier contains at least one occurrence of the given field.
+     */
+    virtual bool containsField(UNumberFormatFields field) const = 0;
+
+    /**
+     * A fill-in for getParameters(). obj will always be set; if non-null, the other
+     * two fields are also safe to read.
+     */
+    struct Parameters {
+        const ModifierStore* obj = nullptr;
+        int8_t signum;
+        StandardPlural::Form plural;
+
+        Parameters();
+        Parameters(const ModifierStore* _obj, int8_t _signum, StandardPlural::Form _plural);
+    };
+
+    /**
+     * Gets a set of "parameters" for this Modifier.
+     *
+     * TODO: Make this return a `const Parameters*` more like Java?
+     */
+    virtual void getParameters(Parameters& output) const = 0;
+
+    /**
+     * Returns whether this Modifier is *semantically equivalent* to the other Modifier;
+     * in many cases, this is the same as equal, but parameters should be ignored.
+     */
+    virtual bool semanticallyEquivalent(const Modifier& other) const = 0;
 };
 
+
+/**
+ * This is *not* a modifier; rather, it is an object that can return modifiers
+ * based on given parameters.
+ *
+ * Exported as U_I18N_API because it is a base class for other exported types.
+ */
+class U_I18N_API ModifierStore {
+  public:
+    virtual ~ModifierStore();
+
+    /**
+     * Returns a Modifier with the given parameters (best-effort).
+     */
+    virtual const Modifier* getModifier(int8_t signum, StandardPlural::Form plural) const = 0;
+};
+
+
 /**
  * This interface is used when all number formatting settings, including the locale, are known, except for the quantity
  * itself. The {@link #processQuantity} method performs the final step in the number processing pipeline: it uses the

icu4c/source/i18n/numparse_scientific.cpp

@@ -56,6 +56,11 @@ bool ScientificMatcher::match(StringSegment& segment, ParsedNumber& result, UErr
         return false;
     }
 
+    // Only accept one exponent per string.
+    if (0 != (result.flags & FLAG_HAS_EXPONENT)) {
+        return false;
+    }
+
     // First match the scientific separator, and then match another number after it.
     // NOTE: This is guarded by the smoke test; no need to check fExponentSeparatorString length again.
     int overlap1 = segment.getCommonPrefixLength(fExponentSeparatorString);

icu4c/source/i18n/numrange_fluent.cpp

@@ -0,0 +1,438 @@
+// © 2018 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
+
+#include "unicode/utypes.h"
+
+#if !UCONFIG_NO_FORMATTING
+
+// Allow implicit conversion from char16_t* to UnicodeString for this file:
+// Helpful in toString methods and elsewhere.
+#define UNISTR_FROM_STRING_EXPLICIT
+
+#include "numrange_impl.h"
+#include "util.h"
+#include "number_utypes.h"
+
+using namespace icu;
+using namespace icu::number;
+using namespace icu::number::impl;
+
+
+// This function needs to be declared in this namespace so it can be friended.
+// NOTE: In Java, this logic is handled in the resolve() function.
+void icu::number::impl::touchRangeLocales(RangeMacroProps& macros) {
+    macros.formatter1.fMacros.locale = macros.locale;
+    macros.formatter2.fMacros.locale = macros.locale;
+}
+
+
+template<typename Derived>
+Derived NumberRangeFormatterSettings<Derived>::numberFormatterBoth(const UnlocalizedNumberFormatter& formatter) const& {
+    Derived copy(*this);
+    copy.fMacros.formatter1 = formatter;
+    copy.fMacros.singleFormatter = true;
+    touchRangeLocales(copy.fMacros);
+    return copy;
+}
+
+template<typename Derived>
+Derived NumberRangeFormatterSettings<Derived>::numberFormatterBoth(const UnlocalizedNumberFormatter& formatter) && {
+    Derived move(std::move(*this));
+    move.fMacros.formatter1 = formatter;
+    move.fMacros.singleFormatter = true;
+    touchRangeLocales(move.fMacros);
+    return move;
+}
+
+template<typename Derived>
+Derived NumberRangeFormatterSettings<Derived>::numberFormatterBoth(UnlocalizedNumberFormatter&& formatter) const& {
+    Derived copy(*this);
+    copy.fMacros.formatter1 = std::move(formatter);
+    copy.fMacros.singleFormatter = true;
+    touchRangeLocales(copy.fMacros);
+    return copy;
+}
+
+template<typename Derived>
+Derived NumberRangeFormatterSettings<Derived>::numberFormatterBoth(UnlocalizedNumberFormatter&& formatter) && {
+    Derived move(std::move(*this));
+    move.fMacros.formatter1 = std::move(formatter);
+    move.fMacros.singleFormatter = true;
+    touchRangeLocales(move.fMacros);
+    return move;
+}
+
+template<typename Derived>
+Derived NumberRangeFormatterSettings<Derived>::numberFormatterFirst(const UnlocalizedNumberFormatter& formatter) const& {
+    Derived copy(*this);
+    copy.fMacros.formatter1 = formatter;
+    copy.fMacros.singleFormatter = false;
+    touchRangeLocales(copy.fMacros);
+    return copy;
+}
+
+template<typename Derived>
+Derived NumberRangeFormatterSettings<Derived>::numberFormatterFirst(const UnlocalizedNumberFormatter& formatter) && {
+    Derived move(std::move(*this));
+    move.fMacros.formatter1 = formatter;
+    move.fMacros.singleFormatter = false;
+    touchRangeLocales(move.fMacros);
+    return move;
+}
+
+template<typename Derived>
+Derived NumberRangeFormatterSettings<Derived>::numberFormatterFirst(UnlocalizedNumberFormatter&& formatter) const& {
+    Derived copy(*this);
+    copy.fMacros.formatter1 = std::move(formatter);
+    copy.fMacros.singleFormatter = false;
+    touchRangeLocales(copy.fMacros);
+    return copy;
+}
+
+template<typename Derived>
+Derived NumberRangeFormatterSettings<Derived>::numberFormatterFirst(UnlocalizedNumberFormatter&& formatter) && {
+    Derived move(std::move(*this));
+    move.fMacros.formatter1 = std::move(formatter);
+    move.fMacros.singleFormatter = false;
+    touchRangeLocales(move.fMacros);
+    return move;
+}
+
+template<typename Derived>
+Derived NumberRangeFormatterSettings<Derived>::numberFormatterSecond(const UnlocalizedNumberFormatter& formatter) const& {
+    Derived copy(*this);
+    copy.fMacros.formatter2 = formatter;
+    copy.fMacros.singleFormatter = false;
+    touchRangeLocales(copy.fMacros);
+    return copy;
+}
+
+template<typename Derived>
+Derived NumberRangeFormatterSettings<Derived>::numberFormatterSecond(const UnlocalizedNumberFormatter& formatter) && {
+    Derived move(std::move(*this));
+    move.fMacros.formatter2 = formatter;
+    move.fMacros.singleFormatter = false;
+    touchRangeLocales(move.fMacros);
+    return move;
+}
+
+template<typename Derived>
+Derived NumberRangeFormatterSettings<Derived>::numberFormatterSecond(UnlocalizedNumberFormatter&& formatter) const& {
+    Derived copy(*this);
+    copy.fMacros.formatter2 = std::move(formatter);
+    copy.fMacros.singleFormatter = false;
+    touchRangeLocales(copy.fMacros);
+    return copy;
+}
+
+template<typename Derived>
+Derived NumberRangeFormatterSettings<Derived>::numberFormatterSecond(UnlocalizedNumberFormatter&& formatter) && {
+    Derived move(std::move(*this));
+    move.fMacros.formatter2 = std::move(formatter);
+    move.fMacros.singleFormatter = false;
+    touchRangeLocales(move.fMacros);
+    return move;
+}
+
+template<typename Derived>
+Derived NumberRangeFormatterSettings<Derived>::collapse(UNumberRangeCollapse collapse) const& {
+    Derived copy(*this);
+    copy.fMacros.collapse = collapse;
+    return copy;
+}
+
+template<typename Derived>
+Derived NumberRangeFormatterSettings<Derived>::collapse(UNumberRangeCollapse collapse) && {
+    Derived move(std::move(*this));
+    move.fMacros.collapse = collapse;
+    return move;
+}
+
+template<typename Derived>
+Derived NumberRangeFormatterSettings<Derived>::identityFallback(UNumberRangeIdentityFallback identityFallback) const& {
+    Derived copy(*this);
+    copy.fMacros.identityFallback = identityFallback;
+    return copy;
+}
+
+template<typename Derived>
+Derived NumberRangeFormatterSettings<Derived>::identityFallback(UNumberRangeIdentityFallback identityFallback) && {
+    Derived move(std::move(*this));
+    move.fMacros.identityFallback = identityFallback;
+    return move;
+}
+
+// Declare all classes that implement NumberRangeFormatterSettings
+// See https://stackoverflow.com/a/495056/1407170
+template
+class icu::number::NumberRangeFormatterSettings<icu::number::UnlocalizedNumberRangeFormatter>;
+template
+class icu::number::NumberRangeFormatterSettings<icu::number::LocalizedNumberRangeFormatter>;
+
+
+UnlocalizedNumberRangeFormatter NumberRangeFormatter::with() {
+    UnlocalizedNumberRangeFormatter result;
+    return result;
+}
+
+LocalizedNumberRangeFormatter NumberRangeFormatter::withLocale(const Locale& locale) {
+    return with().locale(locale);
+}
+
+
+template<typename T> using NFS = NumberRangeFormatterSettings<T>;
+using LNF = LocalizedNumberRangeFormatter;
+using UNF = UnlocalizedNumberRangeFormatter;
+
+UnlocalizedNumberRangeFormatter::UnlocalizedNumberRangeFormatter(const UNF& other)
+        : UNF(static_cast<const NFS<UNF>&>(other)) {}
+
+UnlocalizedNumberRangeFormatter::UnlocalizedNumberRangeFormatter(const NFS<UNF>& other)
+        : NFS<UNF>(other) {
+    // No additional fields to assign
+}
+
+// Make default copy constructor call the NumberRangeFormatterSettings copy constructor.
+UnlocalizedNumberRangeFormatter::UnlocalizedNumberRangeFormatter(UNF&& src) U_NOEXCEPT
+        : UNF(static_cast<NFS<UNF>&&>(src)) {}
+
+UnlocalizedNumberRangeFormatter::UnlocalizedNumberRangeFormatter(NFS<UNF>&& src) U_NOEXCEPT
+        : NFS<UNF>(std::move(src)) {
+    // No additional fields to assign
+}
+
+UnlocalizedNumberRangeFormatter& UnlocalizedNumberRangeFormatter::operator=(const UNF& other) {
+    NFS<UNF>::operator=(static_cast<const NFS<UNF>&>(other));
+    // No additional fields to assign
+    return *this;
+}
+
+UnlocalizedNumberRangeFormatter& UnlocalizedNumberRangeFormatter::operator=(UNF&& src) U_NOEXCEPT {
+    NFS<UNF>::operator=(static_cast<NFS<UNF>&&>(src));
+    // No additional fields to assign
+    return *this;
+}
+
+// Make default copy constructor call the NumberRangeFormatterSettings copy constructor.
+LocalizedNumberRangeFormatter::LocalizedNumberRangeFormatter(const LNF& other)
+        : LNF(static_cast<const NFS<LNF>&>(other)) {}
+
+LocalizedNumberRangeFormatter::LocalizedNumberRangeFormatter(const NFS<LNF>& other)
+        : NFS<LNF>(other) {
+    // No additional fields to assign
+}
+
+LocalizedNumberRangeFormatter::LocalizedNumberRangeFormatter(LocalizedNumberRangeFormatter&& src) U_NOEXCEPT
+        : LNF(static_cast<NFS<LNF>&&>(src)) {}
+
+LocalizedNumberRangeFormatter::LocalizedNumberRangeFormatter(NFS<LNF>&& src) U_NOEXCEPT
+        : NFS<LNF>(std::move(src)) {
+    // Steal the compiled formatter
+    LNF&& _src = static_cast<LNF&&>(src);
+    fImpl = _src.fImpl;
+    _src.fImpl = nullptr;
+}
+
+LocalizedNumberRangeFormatter& LocalizedNumberRangeFormatter::operator=(const LNF& other) {
+    NFS<LNF>::operator=(static_cast<const NFS<LNF>&>(other));
+    // Do not steal; just clear
+    delete fImpl;
+    fImpl = nullptr;
+    return *this;
+}
+
+LocalizedNumberRangeFormatter& LocalizedNumberRangeFormatter::operator=(LNF&& src) U_NOEXCEPT {
+    NFS<LNF>::operator=(static_cast<NFS<LNF>&&>(src));
+    // Steal the compiled formatter
+    delete fImpl;
+    fImpl = src.fImpl;
+    src.fImpl = nullptr;
+    return *this;
+}
+
+
+LocalizedNumberRangeFormatter::~LocalizedNumberRangeFormatter() {
+    delete fImpl;
+}
+
+LocalizedNumberRangeFormatter::LocalizedNumberRangeFormatter(const RangeMacroProps& macros, const Locale& locale) {
+    fMacros = macros;
+    fMacros.locale = locale;
+    touchRangeLocales(fMacros);
+}
+
+LocalizedNumberRangeFormatter::LocalizedNumberRangeFormatter(RangeMacroProps&& macros, const Locale& locale) {
+    fMacros = std::move(macros);
+    fMacros.locale = locale;
+    touchRangeLocales(fMacros);
+}
+
+LocalizedNumberRangeFormatter UnlocalizedNumberRangeFormatter::locale(const Locale& locale) const& {
+    return LocalizedNumberRangeFormatter(fMacros, locale);
+}
+
+LocalizedNumberRangeFormatter UnlocalizedNumberRangeFormatter::locale(const Locale& locale)&& {
+    return LocalizedNumberRangeFormatter(std::move(fMacros), locale);
+}
+
+
+FormattedNumberRange LocalizedNumberRangeFormatter::formatFormattableRange(
+        const Formattable& first, const Formattable& second, UErrorCode& status) const {
+    if (U_FAILURE(status)) {
+        return FormattedNumberRange(U_ILLEGAL_ARGUMENT_ERROR);
+    }
+
+    auto results = new UFormattedNumberRangeData();
+    if (results == nullptr) {
+        status = U_MEMORY_ALLOCATION_ERROR;
+        return FormattedNumberRange(status);
+    }
+
+    first.populateDecimalQuantity(results->quantity1, status);
+    if (U_FAILURE(status)) {
+        return FormattedNumberRange(status);
+    }
+
+    second.populateDecimalQuantity(results->quantity2, status);
+    if (U_FAILURE(status)) {
+        return FormattedNumberRange(status);
+    }
+
+    formatImpl(*results, first == second, status);
+
+    // Do not save the results object if we encountered a failure.
+    if (U_SUCCESS(status)) {
+        return FormattedNumberRange(results);
+    } else {
+        delete results;
+        return FormattedNumberRange(status);
+    }
+}
+
+void LocalizedNumberRangeFormatter::formatImpl(
+        UFormattedNumberRangeData& results, bool equalBeforeRounding, UErrorCode& status) const {
+    if (fImpl == nullptr) {
+        // TODO: Fix this once the atomic is ready!
+        auto* nonConstThis = const_cast<LocalizedNumberRangeFormatter*>(this);
+        nonConstThis->fImpl = new NumberRangeFormatterImpl(fMacros, status);
+        if (U_FAILURE(status)) {
+            return;
+        }
+        if (fImpl == nullptr) {
+            status = U_MEMORY_ALLOCATION_ERROR;
+            return;
+        }
+    }
+    fImpl->format(results, equalBeforeRounding, status);
+}
+
+
+FormattedNumberRange::FormattedNumberRange(FormattedNumberRange&& src) U_NOEXCEPT
+        : fResults(src.fResults), fErrorCode(src.fErrorCode) {
+    // Disown src.fResults to prevent double-deletion
+    src.fResults = nullptr;
+    src.fErrorCode = U_INVALID_STATE_ERROR;
+}
+
+FormattedNumberRange& FormattedNumberRange::operator=(FormattedNumberRange&& src) U_NOEXCEPT {
+    delete fResults;
+    fResults = src.fResults;
+    fErrorCode = src.fErrorCode;
+    // Disown src.fResults to prevent double-deletion
+    src.fResults = nullptr;
+    src.fErrorCode = U_INVALID_STATE_ERROR;
+    return *this;
+}
+
+UnicodeString FormattedNumberRange::toString(UErrorCode& status) const {
+    if (U_FAILURE(status)) {
+        return ICU_Utility::makeBogusString();
+    }
+    if (fResults == nullptr) {
+        status = fErrorCode;
+        return ICU_Utility::makeBogusString();
+    }
+    return fResults->string.toUnicodeString();
+}
+
+Appendable& FormattedNumberRange::appendTo(Appendable& appendable, UErrorCode& status) const {
+    if (U_FAILURE(status)) {
+        return appendable;
+    }
+    if (fResults == nullptr) {
+        status = fErrorCode;
+        return appendable;
+    }
+    appendable.appendString(fResults->string.chars(), fResults->string.length());
+    return appendable;
+}
+
+UBool FormattedNumberRange::nextFieldPosition(FieldPosition& fieldPosition, UErrorCode& status) const {
+    if (U_FAILURE(status)) {
+        return FALSE;
+    }
+    if (fResults == nullptr) {
+        status = fErrorCode;
+        return FALSE;
+    }
+    // NOTE: MSVC sometimes complains when implicitly converting between bool and UBool
+    return fResults->string.nextFieldPosition(fieldPosition, status) ? TRUE : FALSE;
+}
+
+void FormattedNumberRange::getAllFieldPositions(FieldPositionIterator& iterator, UErrorCode& status) const {
+    FieldPositionIteratorHandler fpih(&iterator, status);
+    getAllFieldPositionsImpl(fpih, status);
+}
+
+void FormattedNumberRange::getAllFieldPositionsImpl(
+        FieldPositionIteratorHandler& fpih, UErrorCode& status) const {
+    if (U_FAILURE(status)) {
+        return;
+    }
+    if (fResults == nullptr) {
+        status = fErrorCode;
+        return;
+    }
+    fResults->string.getAllFieldPositions(fpih, status);
+}
+
+UnicodeString FormattedNumberRange::getFirstDecimal(UErrorCode& status) const {
+    if (U_FAILURE(status)) {
+        return ICU_Utility::makeBogusString();
+    }
+    if (fResults == nullptr) {
+        status = fErrorCode;
+        return ICU_Utility::makeBogusString();
+    }
+    return fResults->quantity1.toScientificString();
+}
+
+UnicodeString FormattedNumberRange::getSecondDecimal(UErrorCode& status) const {
+    if (U_FAILURE(status)) {
+        return ICU_Utility::makeBogusString();
+    }
+    if (fResults == nullptr) {
+        status = fErrorCode;
+        return ICU_Utility::makeBogusString();
+    }
+    return fResults->quantity2.toScientificString();
+}
+
+UNumberRangeIdentityResult FormattedNumberRange::getIdentityResult(UErrorCode& status) const {
+    if (U_FAILURE(status)) {
+        return UNUM_IDENTITY_RESULT_NOT_EQUAL;
+    }
+    if (fResults == nullptr) {
+        status = fErrorCode;
+        return UNUM_IDENTITY_RESULT_NOT_EQUAL;
+    }
+    return fResults->identityResult;
+}
+
+FormattedNumberRange::~FormattedNumberRange() {
+    delete fResults;
+}
+
+
+
+#endif /* #if !UCONFIG_NO_FORMATTING */

icu4c/source/i18n/numrange_impl.cpp

@@ -0,0 +1,483 @@
+// © 2018 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
+
+#include "unicode/utypes.h"
+
+#if !UCONFIG_NO_FORMATTING
+
+// Allow implicit conversion from char16_t* to UnicodeString for this file:
+// Helpful in toString methods and elsewhere.
+#define UNISTR_FROM_STRING_EXPLICIT
+
+#include "unicode/numberrangeformatter.h"
+#include "numrange_impl.h"
+#include "patternprops.h"
+#include "uresimp.h"
+#include "util.h"
+
+using namespace icu;
+using namespace icu::number;
+using namespace icu::number::impl;
+
+namespace {
+
+// Helper function for 2-dimensional switch statement
+constexpr int8_t identity2d(UNumberRangeIdentityFallback a, UNumberRangeIdentityResult b) {
+    return static_cast<int8_t>(a) | (static_cast<int8_t>(b) << 4);
+}
+
+
+struct NumberRangeData {
+    SimpleFormatter rangePattern;
+    SimpleFormatter approximatelyPattern;
+};
+
+class NumberRangeDataSink : public ResourceSink {
+  public:
+    NumberRangeDataSink(NumberRangeData& data) : fData(data) {}
+
+    void put(const char* key, ResourceValue& value, UBool /*noFallback*/, UErrorCode& status) U_OVERRIDE {
+        ResourceTable miscTable = value.getTable(status);
+        if (U_FAILURE(status)) { return; }
+        for (int i = 0; miscTable.getKeyAndValue(i, key, value); i++) {
+            if (uprv_strcmp(key, "range") == 0) {
+                if (fData.rangePattern.getArgumentLimit() != 0) {
+                    continue; // have already seen this pattern
+                }
+                fData.rangePattern = {value.getUnicodeString(status), status};
+            } else if (uprv_strcmp(key, "approximately") == 0) {
+                if (fData.approximatelyPattern.getArgumentLimit() != 0) {
+                    continue; // have already seen this pattern
+                }
+                fData.approximatelyPattern = {value.getUnicodeString(status), status};
+            }
+        }
+    }
+
+  private:
+    NumberRangeData& fData;
+};
+
+void getNumberRangeData(const char* localeName, const char* nsName, NumberRangeData& data, UErrorCode& status) {
+    if (U_FAILURE(status)) { return; }
+    LocalUResourceBundlePointer rb(ures_open(NULL, localeName, &status));
+    if (U_FAILURE(status)) { return; }
+    NumberRangeDataSink sink(data);
+
+    CharString dataPath;
+    dataPath.append("NumberElements/", -1, status);
+    dataPath.append(nsName, -1, status);
+    dataPath.append("/miscPatterns", -1, status);
+    ures_getAllItemsWithFallback(rb.getAlias(), dataPath.data(), sink, status);
+    if (U_FAILURE(status)) { return; }
+
+    // TODO: Is it necessary to manually fall back to latn, or does the data sink take care of that?
+
+    if (data.rangePattern.getArgumentLimit() == 0) {
+        // No data!
+        data.rangePattern = {u"{0}–{1}", status};
+    }
+    if (data.approximatelyPattern.getArgumentLimit() == 0) {
+        // No data!
+        data.approximatelyPattern = {u"~{0}", status};
+    }
+}
+
+class PluralRangesDataSink : public ResourceSink {
+  public:
+    PluralRangesDataSink(StandardPluralRanges& output) : fOutput(output) {}
+
+    void put(const char* /*key*/, ResourceValue& value, UBool /*noFallback*/, UErrorCode& status) U_OVERRIDE {
+        ResourceArray entriesArray = value.getArray(status);
+        if (U_FAILURE(status)) { return; }
+        fOutput.setCapacity(entriesArray.getSize());
+        for (int i = 0; entriesArray.getValue(i, value); i++) {
+            ResourceArray pluralFormsArray = value.getArray(status);
+            if (U_FAILURE(status)) { return; }
+            pluralFormsArray.getValue(0, value);
+            StandardPlural::Form first = StandardPlural::fromString(value.getUnicodeString(status), status);
+            if (U_FAILURE(status)) { return; }
+            pluralFormsArray.getValue(1, value);
+            StandardPlural::Form second = StandardPlural::fromString(value.getUnicodeString(status), status);
+            if (U_FAILURE(status)) { return; }
+            pluralFormsArray.getValue(2, value);
+            StandardPlural::Form result = StandardPlural::fromString(value.getUnicodeString(status), status);
+            if (U_FAILURE(status)) { return; }
+            fOutput.addPluralRange(first, second, result);
+        }
+    }
+
+  private:
+    StandardPluralRanges& fOutput;
+};
+
+void getPluralRangesData(const Locale& locale, StandardPluralRanges& output, UErrorCode& status) {
+    if (U_FAILURE(status)) { return; }
+    LocalUResourceBundlePointer rb(ures_openDirect(nullptr, "pluralRanges", &status));
+    if (U_FAILURE(status)) { return; }
+
+    CharString dataPath;
+    dataPath.append("locales/", -1, status);
+    dataPath.append(locale.getLanguage(), -1, status);
+    if (U_FAILURE(status)) { return; }
+    int32_t setLen;
+    // Not all languages are covered: fail gracefully
+    UErrorCode internalStatus = U_ZERO_ERROR;
+    const UChar* set = ures_getStringByKeyWithFallback(rb.getAlias(), dataPath.data(), &setLen, &internalStatus);
+    if (U_FAILURE(internalStatus)) { return; }
+
+    dataPath.clear();
+    dataPath.append("rules/", -1, status);
+    dataPath.appendInvariantChars(set, setLen, status);
+    if (U_FAILURE(status)) { return; }
+    PluralRangesDataSink sink(output);
+    ures_getAllItemsWithFallback(rb.getAlias(), dataPath.data(), sink, status);
+    if (U_FAILURE(status)) { return; }
+}
+
+} // namespace
+
+
+void StandardPluralRanges::initialize(const Locale& locale, UErrorCode& status) {
+    getPluralRangesData(locale, *this, status);
+}
+
+void StandardPluralRanges::addPluralRange(
+        StandardPlural::Form first,
+        StandardPlural::Form second,
+        StandardPlural::Form result) {
+    U_ASSERT(fTriplesLen < fTriples.getCapacity());
+    fTriples[fTriplesLen] = {first, second, result};
+    fTriplesLen++;
+}
+
+void StandardPluralRanges::setCapacity(int32_t length) {
+    if (length > fTriples.getCapacity()) {
+        fTriples.resize(length, 0);
+    }
+}
+
+StandardPlural::Form
+StandardPluralRanges::resolve(StandardPlural::Form first, StandardPlural::Form second) const {
+    for (int32_t i=0; i<fTriplesLen; i++) {
+        const auto& triple = fTriples[i];
+        if (triple.first == first && triple.second == second) {
+            return triple.result;
+        }
+    }
+    // Default fallback
+    return StandardPlural::OTHER;
+}
+
+
+NumberRangeFormatterImpl::NumberRangeFormatterImpl(const RangeMacroProps& macros, UErrorCode& status)
+    : formatterImpl1(macros.formatter1.fMacros, status),
+      formatterImpl2(macros.formatter2.fMacros, status),
+      fSameFormatters(macros.singleFormatter),
+      fCollapse(macros.collapse),
+      fIdentityFallback(macros.identityFallback) {
+
+    // TODO: As of this writing (ICU 63), there is no locale that has different number miscPatterns
+    // based on numbering system.  Therefore, data is loaded only from latn.  If this changes,
+    // this part of the code should be updated to load from the local numbering system.
+    // The numbering system could come from the one specified in the NumberFormatter passed to
+    // numberFormatterBoth() or similar.
+    // See ICU-20144
+
+    NumberRangeData data;
+    getNumberRangeData(macros.locale.getName(), "latn", data, status);
+    if (U_FAILURE(status)) { return; }
+    fRangeFormatter = data.rangePattern;
+    fApproximatelyModifier = {data.approximatelyPattern, UNUM_FIELD_COUNT, false};
+
+    // TODO: Get locale from PluralRules instead?
+    fPluralRanges.initialize(macros.locale, status);
+    if (U_FAILURE(status)) { return; }
+}
+
+void NumberRangeFormatterImpl::format(UFormattedNumberRangeData& data, bool equalBeforeRounding, UErrorCode& status) const {
+    if (U_FAILURE(status)) {
+        return;
+    }
+
+    MicroProps micros1;
+    MicroProps micros2;
+    formatterImpl1.preProcess(data.quantity1, micros1, status);
+    if (fSameFormatters) {
+        formatterImpl1.preProcess(data.quantity2, micros2, status);
+    } else {
+        formatterImpl2.preProcess(data.quantity2, micros2, status);
+    }
+    if (U_FAILURE(status)) {
+        return;
+    }
+
+    // If any of the affixes are different, an identity is not possible
+    // and we must use formatRange().
+    // TODO: Write this as MicroProps operator==() ?
+    // TODO: Avoid the redundancy of these equality operations with the
+    // ones in formatRange?
+    if (!micros1.modInner->semanticallyEquivalent(*micros2.modInner)
+            || !micros1.modMiddle->semanticallyEquivalent(*micros2.modMiddle)
+            || !micros1.modOuter->semanticallyEquivalent(*micros2.modOuter)) {
+        formatRange(data, micros1, micros2, status);
+        data.identityResult = UNUM_IDENTITY_RESULT_NOT_EQUAL;
+        return;
+    }
+
+    // Check for identity
+    if (equalBeforeRounding) {
+        data.identityResult = UNUM_IDENTITY_RESULT_EQUAL_BEFORE_ROUNDING;
+    } else if (data.quantity1 == data.quantity2) {
+        data.identityResult = UNUM_IDENTITY_RESULT_EQUAL_AFTER_ROUNDING;
+    } else {
+        data.identityResult = UNUM_IDENTITY_RESULT_NOT_EQUAL;
+    }
+
+    switch (identity2d(fIdentityFallback, data.identityResult)) {
+        case identity2d(UNUM_IDENTITY_FALLBACK_RANGE,
+                        UNUM_IDENTITY_RESULT_NOT_EQUAL):
+        case identity2d(UNUM_IDENTITY_FALLBACK_RANGE,
+                        UNUM_IDENTITY_RESULT_EQUAL_AFTER_ROUNDING):
+        case identity2d(UNUM_IDENTITY_FALLBACK_RANGE,
+                        UNUM_IDENTITY_RESULT_EQUAL_BEFORE_ROUNDING):
+        case identity2d(UNUM_IDENTITY_FALLBACK_APPROXIMATELY,
+                        UNUM_IDENTITY_RESULT_NOT_EQUAL):
+        case identity2d(UNUM_IDENTITY_FALLBACK_APPROXIMATELY_OR_SINGLE_VALUE,
+                        UNUM_IDENTITY_RESULT_NOT_EQUAL):
+        case identity2d(UNUM_IDENTITY_FALLBACK_SINGLE_VALUE,
+                        UNUM_IDENTITY_RESULT_NOT_EQUAL):
+            formatRange(data, micros1, micros2, status);
+            break;
+
+        case identity2d(UNUM_IDENTITY_FALLBACK_APPROXIMATELY,
+                        UNUM_IDENTITY_RESULT_EQUAL_AFTER_ROUNDING):
+        case identity2d(UNUM_IDENTITY_FALLBACK_APPROXIMATELY,
+                        UNUM_IDENTITY_RESULT_EQUAL_BEFORE_ROUNDING):
+        case identity2d(UNUM_IDENTITY_FALLBACK_APPROXIMATELY_OR_SINGLE_VALUE,
+                        UNUM_IDENTITY_RESULT_EQUAL_AFTER_ROUNDING):
+            formatApproximately(data, micros1, micros2, status);
+            break;
+
+        case identity2d(UNUM_IDENTITY_FALLBACK_APPROXIMATELY_OR_SINGLE_VALUE,
+                        UNUM_IDENTITY_RESULT_EQUAL_BEFORE_ROUNDING):
+        case identity2d(UNUM_IDENTITY_FALLBACK_SINGLE_VALUE,
+                        UNUM_IDENTITY_RESULT_EQUAL_AFTER_ROUNDING):
+        case identity2d(UNUM_IDENTITY_FALLBACK_SINGLE_VALUE,
+                        UNUM_IDENTITY_RESULT_EQUAL_BEFORE_ROUNDING):
+            formatSingleValue(data, micros1, micros2, status);
+            break;
+
+        default:
+            U_ASSERT(false);
+            break;
+    }
+}
+
+
+void NumberRangeFormatterImpl::formatSingleValue(UFormattedNumberRangeData& data,
+                                                 MicroProps& micros1, MicroProps& micros2,
+                                                 UErrorCode& status) const {
+    if (U_FAILURE(status)) { return; }
+    if (fSameFormatters) {
+        int32_t length = NumberFormatterImpl::writeNumber(micros1, data.quantity1, data.string, 0, status);
+        NumberFormatterImpl::writeAffixes(micros1, data.string, 0, length, status);
+    } else {
+        formatRange(data, micros1, micros2, status);
+    }
+}
+
+
+void NumberRangeFormatterImpl::formatApproximately (UFormattedNumberRangeData& data,
+                                                    MicroProps& micros1, MicroProps& micros2,
+                                                    UErrorCode& status) const {
+    if (U_FAILURE(status)) { return; }
+    if (fSameFormatters) {
+        int32_t length = NumberFormatterImpl::writeNumber(micros1, data.quantity1, data.string, 0, status);
+        length += NumberFormatterImpl::writeAffixes(micros1, data.string, 0, length, status);
+        fApproximatelyModifier.apply(data.string, 0, length, status);
+    } else {
+        formatRange(data, micros1, micros2, status);
+    }
+}
+
+
+void NumberRangeFormatterImpl::formatRange(UFormattedNumberRangeData& data,
+                                           MicroProps& micros1, MicroProps& micros2,
+                                           UErrorCode& status) const {
+    if (U_FAILURE(status)) { return; }
+
+    // modInner is always notation (scientific); collapsable in ALL.
+    // modOuter is always units; collapsable in ALL, AUTO, and UNIT.
+    // modMiddle could be either; collapsable in ALL and sometimes AUTO and UNIT.
+    // Never collapse an outer mod but not an inner mod.
+    bool collapseOuter, collapseMiddle, collapseInner;
+    switch (fCollapse) {
+        case UNUM_RANGE_COLLAPSE_ALL:
+        case UNUM_RANGE_COLLAPSE_AUTO:
+        case UNUM_RANGE_COLLAPSE_UNIT:
+        {
+            // OUTER MODIFIER
+            collapseOuter = micros1.modOuter->semanticallyEquivalent(*micros2.modOuter);
+
+            if (!collapseOuter) {
+                // Never collapse inner mods if outer mods are not collapsable
+                collapseMiddle = false;
+                collapseInner = false;
+                break;
+            }
+
+            // MIDDLE MODIFIER
+            collapseMiddle = micros1.modMiddle->semanticallyEquivalent(*micros2.modMiddle);
+
+            if (!collapseMiddle) {
+                // Never collapse inner mods if outer mods are not collapsable
+                collapseInner = false;
+                break;
+            }
+
+            // MIDDLE MODIFIER HEURISTICS
+            // (could disable collapsing of the middle modifier)
+            // The modifiers are equal by this point, so we can look at just one of them.
+            const Modifier* mm = micros1.modMiddle;
+            if (fCollapse == UNUM_RANGE_COLLAPSE_UNIT) {
+                // Only collapse if the modifier is a unit.
+                // TODO: Make a better way to check for a unit?
+                // TODO: Handle case where the modifier has both notation and unit (compact currency)?
+                if (!mm->containsField(UNUM_CURRENCY_FIELD) && !mm->containsField(UNUM_PERCENT_FIELD)) {
+                    collapseMiddle = false;
+                }
+            } else if (fCollapse == UNUM_RANGE_COLLAPSE_AUTO) {
+                // Heuristic as of ICU 63: collapse only if the modifier is more than one code point.
+                if (mm->getCodePointCount() <= 1) {
+                    collapseMiddle = false;
+                }
+            }
+
+            if (!collapseMiddle || fCollapse != UNUM_RANGE_COLLAPSE_ALL) {
+                collapseInner = false;
+                break;
+            }
+
+            // INNER MODIFIER
+            collapseInner = micros1.modInner->semanticallyEquivalent(*micros2.modInner);
+
+            // All done checking for collapsability.
+            break;
+        }
+
+        default:
+            collapseOuter = false;
+            collapseMiddle = false;
+            collapseInner = false;
+            break;
+    }
+
+    NumberStringBuilder& string = data.string;
+    int32_t lengthPrefix = 0;
+    int32_t length1 = 0;
+    int32_t lengthInfix = 0;
+    int32_t length2 = 0;
+    int32_t lengthSuffix = 0;
+
+    // Use #define so that these are evaluated at the call site.
+    #define UPRV_INDEX_0 (lengthPrefix)
+    #define UPRV_INDEX_1 (lengthPrefix + length1)
+    #define UPRV_INDEX_2 (lengthPrefix + length1 + lengthInfix)
+    #define UPRV_INDEX_3 (lengthPrefix + length1 + lengthInfix + length2)
+
+    int32_t lengthRange = SimpleModifier::formatTwoArgPattern(
+        fRangeFormatter,
+        string,
+        0,
+        &lengthPrefix,
+        &lengthSuffix,
+        UNUM_FIELD_COUNT,
+        status);
+    if (U_FAILURE(status)) { return; }
+    lengthInfix = lengthRange - lengthPrefix - lengthSuffix;
+    U_ASSERT(lengthInfix > 0);
+
+    // SPACING HEURISTIC
+    // Add spacing unless all modifiers are collapsed.
+    // TODO: add API to control this?
+    // TODO: Use a data-driven heuristic like currency spacing?
+    // TODO: Use Unicode [:whitespace:] instead of PatternProps whitespace? (consider speed implications)
+    {
+        bool repeatInner = !collapseInner && micros1.modInner->getCodePointCount() > 0;
+        bool repeatMiddle = !collapseMiddle && micros1.modMiddle->getCodePointCount() > 0;
+        bool repeatOuter = !collapseOuter && micros1.modOuter->getCodePointCount() > 0;
+        if (repeatInner || repeatMiddle || repeatOuter) {
+            // Add spacing if there is not already spacing
+            if (!PatternProps::isWhiteSpace(string.charAt(UPRV_INDEX_1))) {
+                lengthInfix += string.insertCodePoint(UPRV_INDEX_1, u'\u0020', UNUM_FIELD_COUNT, status);
+            }
+            if (!PatternProps::isWhiteSpace(string.charAt(UPRV_INDEX_2 - 1))) {
+                lengthInfix += string.insertCodePoint(UPRV_INDEX_2, u'\u0020', UNUM_FIELD_COUNT, status);
+            }
+        }
+    }
+
+    length1 += NumberFormatterImpl::writeNumber(micros1, data.quantity1, string, UPRV_INDEX_0, status);
+    length2 += NumberFormatterImpl::writeNumber(micros2, data.quantity2, string, UPRV_INDEX_2, status);
+
+    // TODO: Support padding?
+
+    if (collapseInner) {
+        // Note: this is actually a mix of prefix and suffix, but adding to infix length works
+        const Modifier& mod = resolveModifierPlurals(*micros1.modInner, *micros2.modInner);
+        lengthInfix += mod.apply(string, UPRV_INDEX_0, UPRV_INDEX_3, status);
+    } else {
+        length1 += micros1.modInner->apply(string, UPRV_INDEX_0, UPRV_INDEX_1, status);
+        length2 += micros2.modInner->apply(string, UPRV_INDEX_2, UPRV_INDEX_3, status);
+    }
+
+    if (collapseMiddle) {
+        // Note: this is actually a mix of prefix and suffix, but adding to infix length works
+        const Modifier& mod = resolveModifierPlurals(*micros1.modMiddle, *micros2.modMiddle);
+        lengthInfix += mod.apply(string, UPRV_INDEX_0, UPRV_INDEX_3, status);
+    } else {
+        length1 += micros1.modMiddle->apply(string, UPRV_INDEX_0, UPRV_INDEX_1, status);
+        length2 += micros2.modMiddle->apply(string, UPRV_INDEX_2, UPRV_INDEX_3, status);
+    }
+
+    if (collapseOuter) {
+        // Note: this is actually a mix of prefix and suffix, but adding to infix length works
+        const Modifier& mod = resolveModifierPlurals(*micros1.modOuter, *micros2.modOuter);
+        lengthInfix += mod.apply(string, UPRV_INDEX_0, UPRV_INDEX_3, status);
+    } else {
+        length1 += micros1.modOuter->apply(string, UPRV_INDEX_0, UPRV_INDEX_1, status);
+        length2 += micros2.modOuter->apply(string, UPRV_INDEX_2, UPRV_INDEX_3, status);
+    }
+}
+
+
+const Modifier&
+NumberRangeFormatterImpl::resolveModifierPlurals(const Modifier& first, const Modifier& second) const {
+    Modifier::Parameters parameters;
+    first.getParameters(parameters);
+    if (parameters.obj == nullptr) {
+        // No plural form; return a fallback (e.g., the first)
+        return first;
+    }
+    StandardPlural::Form firstPlural = parameters.plural;
+
+    second.getParameters(parameters);
+    if (parameters.obj == nullptr) {
+        // No plural form; return a fallback (e.g., the first)
+        return first;
+    }
+    StandardPlural::Form secondPlural = parameters.plural;
+
+    // Get the required plural form from data
+    StandardPlural::Form resultPlural = fPluralRanges.resolve(firstPlural, secondPlural);
+
+    // Get and return the new Modifier
+    const Modifier* mod = parameters.obj->getModifier(parameters.signum, resultPlural);
+    U_ASSERT(mod != nullptr);
+    return *mod;
+}
+
+
+
+#endif /* #if !UCONFIG_NO_FORMATTING */

icu4c/source/i18n/numrange_impl.h

@@ -0,0 +1,114 @@
+// © 2018 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
+
+#include "unicode/utypes.h"
+
+#if !UCONFIG_NO_FORMATTING
+#ifndef __SOURCE_NUMRANGE_TYPES_H__
+#define __SOURCE_NUMRANGE_TYPES_H__
+
+#include "unicode/numberformatter.h"
+#include "unicode/numberrangeformatter.h"
+#include "unicode/simpleformatter.h"
+#include "number_types.h"
+#include "number_decimalquantity.h"
+#include "number_formatimpl.h"
+#include "number_stringbuilder.h"
+
+U_NAMESPACE_BEGIN namespace number {
+namespace impl {
+
+
+/**
+ * Class similar to UFormattedNumberData.
+ *
+ * Has incomplete magic number logic that will need to be finished
+ * if this is to be exposed as C API in the future.
+ */
+struct UFormattedNumberRangeData : public UMemory {
+    // The magic number to identify incoming objects.
+    // Reads in ASCII as "FDR" (FormatteDnumberRange with room at the end)
+    static constexpr int32_t kMagic = 0x46445200;
+
+    // Data members:
+    int32_t fMagic = kMagic;
+    DecimalQuantity quantity1;
+    DecimalQuantity quantity2;
+    NumberStringBuilder string;
+    UNumberRangeIdentityResult identityResult = UNUM_IDENTITY_RESULT_COUNT;
+
+    // No C conversion methods (no C API yet)
+};
+
+
+class StandardPluralRanges : public UMemory {
+  public:
+    void initialize(const Locale& locale, UErrorCode& status);
+    StandardPlural::Form resolve(StandardPlural::Form first, StandardPlural::Form second) const;
+
+    /** Used for data loading. */
+    void addPluralRange(
+        StandardPlural::Form first,
+        StandardPlural::Form second,
+        StandardPlural::Form result);
+
+    /** Used for data loading. */
+    void setCapacity(int32_t length);
+
+  private:
+    struct StandardPluralRangeTriple {
+        StandardPlural::Form first;
+        StandardPlural::Form second;
+        StandardPlural::Form result;
+    };
+
+    // TODO: An array is simple here, but it results in linear lookup time.
+    // Certain locales have 20-30 entries in this list.
+    // Consider changing to a smarter data structure.
+    typedef MaybeStackArray<StandardPluralRangeTriple, 3> PluralRangeTriples;
+    PluralRangeTriples fTriples;
+    int32_t fTriplesLen = 0;
+};
+
+
+class NumberRangeFormatterImpl : public UMemory {
+  public:
+    NumberRangeFormatterImpl(const RangeMacroProps& macros, UErrorCode& status);
+
+    void format(UFormattedNumberRangeData& data, bool equalBeforeRounding, UErrorCode& status) const;
+
+  private:
+    NumberFormatterImpl formatterImpl1;
+    NumberFormatterImpl formatterImpl2;
+    bool fSameFormatters;
+
+    UNumberRangeCollapse fCollapse;
+    UNumberRangeIdentityFallback fIdentityFallback;
+
+    SimpleFormatter fRangeFormatter;
+    SimpleModifier fApproximatelyModifier;
+
+    StandardPluralRanges fPluralRanges;
+
+    void formatSingleValue(UFormattedNumberRangeData& data,
+                           MicroProps& micros1, MicroProps& micros2,
+                           UErrorCode& status) const;
+
+    void formatApproximately(UFormattedNumberRangeData& data,
+                             MicroProps& micros1, MicroProps& micros2,
+                             UErrorCode& status) const;
+
+    void formatRange(UFormattedNumberRangeData& data,
+                     MicroProps& micros1, MicroProps& micros2,
+                     UErrorCode& status) const;
+
+    const Modifier& resolveModifierPlurals(const Modifier& first, const Modifier& second) const;
+};
+
+
+} // namespace impl
+} // namespace number
+U_NAMESPACE_END
+
+#endif //__SOURCE_NUMRANGE_TYPES_H__
+#endif /* #if !UCONFIG_NO_FORMATTING */

icu4c/source/i18n/unicode/calendar.h

@@ -130,7 +130,7 @@ class BasicTimeZone;
  *
  * **Note:** for some non-Gregorian calendars, different
  * fields may be necessary for complete disambiguation. For example, a full
- * specification of the historial Arabic astronomical calendar requires year,
+ * specification of the historical Arabic astronomical calendar requires year,
  * month, day-of-month *and* day-of-week in some cases.
  *
  * **Note:** There are certain possible ambiguities in
@@ -886,7 +886,7 @@ public:
     /**
      * Sets the behavior for handling wall time repeating multiple times
      * at negative time zone offset transitions. For example, 1:30 AM on
-     * November 6, 2011 in US Eastern time (Ameirca/New_York) occurs twice;
+     * November 6, 2011 in US Eastern time (America/New_York) occurs twice;
      * 1:30 AM EDT, then 1:30 AM EST one hour later. When <code>UCAL_WALLTIME_FIRST</code>
      * is used, the wall time 1:30AM in this example will be interpreted as 1:30 AM EDT
      * (first occurrence). When <code>UCAL_WALLTIME_LAST</code> is used, it will be
@@ -2152,7 +2152,7 @@ private:
     TimeZone*   fZone;
 
     /**
-     * Option for rpeated wall time
+     * Option for repeated wall time
      * @see #setRepeatedWallTimeOption
      */
     UCalendarWallTimeOption fRepeatedWallTime;
@@ -2437,7 +2437,7 @@ private:
     BasicTimeZone* getBasicTimeZone() const;
 
     /**
-     * Find the previous zone transtion near the given time.
+     * Find the previous zone transition near the given time.
      * @param base The base time, inclusive
      * @param transitionTime Receives the result time
      * @param status The error status

icu4c/source/i18n/unicode/numberformatter.h

@@ -144,6 +144,9 @@ class MultiplierFormatHandler;
 class CurrencySymbols;
 class GeneratorHelpers;
 class DecNum;
+class NumberRangeFormatterImpl;
+struct RangeMacroProps;
+void touchRangeLocales(impl::RangeMacroProps& macros);
 
 } // namespace impl
 
@@ -1423,7 +1426,8 @@ struct U_I18N_API MacroProps : public UMemory {
 
 /**
  * An abstract base class for specifying settings related to number formatting. This class is implemented by
- * {@link UnlocalizedNumberFormatter} and {@link LocalizedNumberFormatter}.
+ * {@link UnlocalizedNumberFormatter} and {@link LocalizedNumberFormatter}. This class is not intended for
+ * public subclassing.
  */
 template<typename Derived>
 class U_I18N_API NumberFormatterSettings {
@@ -2108,6 +2112,10 @@ class U_I18N_API NumberFormatterSettings {
 
     friend class LocalizedNumberFormatter;
     friend class UnlocalizedNumberFormatter;
+
+    // Give NumberRangeFormatter access to the MacroProps
+    friend void impl::touchRangeLocales(impl::RangeMacroProps& macros);
+    friend class impl::NumberRangeFormatterImpl;
 };
 
 /**
@@ -2124,13 +2132,6 @@ class U_I18N_API UnlocalizedNumberFormatter
      * Associate the given locale with the number formatter. The locale is used for picking the appropriate symbols,
      * formats, and other data for number display.
      *
-     * <p>
-     * To use the Java default locale, call Locale::getDefault():
-     *
-     * <pre>
-     * NumberFormatter::with(). ... .locale(Locale::getDefault())
-     * </pre>
-     *
      * @param locale
      *            The locale to use when loading data for number formatting.
      * @return The fluent chain.
@@ -2156,7 +2157,6 @@ class U_I18N_API UnlocalizedNumberFormatter
      */
     UnlocalizedNumberFormatter() = default;
 
-    // Make default copy constructor call the NumberFormatterSettings copy constructor.
     /**
      * Returns a copy of this UnlocalizedNumberFormatter.
      * @draft ICU 60
@@ -2295,7 +2295,6 @@ class U_I18N_API LocalizedNumberFormatter
      */
     LocalizedNumberFormatter() = default;
 
-    // Make default copy constructor call the NumberFormatterSettings copy constructor.
     /**
      * Returns a copy of this LocalizedNumberFormatter.
      * @draft ICU 60
@@ -2359,6 +2358,8 @@ class U_I18N_API LocalizedNumberFormatter
 
     LocalizedNumberFormatter(impl::MacroProps &&macros, const Locale &locale);
 
+    void clear();
+
     void lnfMoveHelper(LocalizedNumberFormatter&& src);
 
     /**
@@ -2457,9 +2458,9 @@ class U_I18N_API FormattedNumber : public UMemory {
 #endif  /* U_HIDE_DEPRECATED_API */
 
     /**
-     * Determines the start and end indices of the next occurrence of the given <em>field</em> in the
-     * output string. This allows you to determine the locations of, for example, the integer part,
-     * fraction part, or symbols.
+     * Determines the start (inclusive) and end (exclusive) indices of the next occurrence of the given
+     * <em>field</em> in the output string. This allows you to determine the locations of, for example,
+     * the integer part, fraction part, or symbols.
      *
      * If a field occurs just once, calling this method will find that occurrence and return it. If a
      * field occurs multiple times, this method may be called repeatedly with the following pattern:
@@ -2478,7 +2479,7 @@ class U_I18N_API FormattedNumber : public UMemory {
      *            Input+output variable. On input, the "field" property determines which field to look
      *            up, and the "beginIndex" and "endIndex" properties determine where to begin the search.
      *            On output, the "beginIndex" is set to the beginning of the first occurrence of the
-     *            field with either begin or end indices after the input indices, "endIndex" is set to
+     *            field with either begin or end indices after the input indices; "endIndex" is set to
      *            the end of that occurrence of the field (exclusive index). If a field position is not
      *            found, the method returns FALSE and the FieldPosition may or may not be changed.
      * @param status

icu4c/source/i18n/unicode/numberrangeformatter.h

@@ -0,0 +1,851 @@
+// © 2018 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
+
+#if !UCONFIG_NO_FORMATTING
+#ifndef __NUMBERRANGEFORMATTER_H__
+#define __NUMBERRANGEFORMATTER_H__
+
+#include "unicode/appendable.h"
+#include "unicode/fieldpos.h"
+#include "unicode/fpositer.h"
+#include "unicode/numberformatter.h"
+
+#ifndef U_HIDE_DRAFT_API
+
+/**
+ * \file
+ * \brief C++ API: Library for localized formatting of number, currency, and unit ranges.
+ *
+ * The main entrypoint to the formatting of ranges of numbers, including currencies and other units of measurement.
+ * <p>
+ * Usage example:
+ * <p>
+ * <pre>
+ * NumberRangeFormatter::with()
+ *     .identityFallback(UNUM_IDENTITY_FALLBACK_APPROXIMATELY_OR_SINGLE_VALUE)
+ *     .numberFormatterFirst(NumberFormatter::with().adoptUnit(MeasureUnit::createMeter()))
+ *     .numberFormatterSecond(NumberFormatter::with().adoptUnit(MeasureUnit::createKilometer()))
+ *     .locale("en-GB")
+ *     .formatRange(750, 1.2, status)
+ *     .toString(status);
+ * // => "750 m - 1.2 km"
+ * </pre>
+ * <p>
+ * Like NumberFormatter, NumberRangeFormatter instances are immutable and thread-safe. This API is based on the
+ * <em>fluent</em> design pattern popularized by libraries such as Google's Guava.
+ *
+ * @author Shane Carr
+ */
+
+
+/**
+ * Defines how to merge fields that are identical across the range sign.
+ *
+ * @draft ICU 63
+ */
+typedef enum UNumberRangeCollapse {
+    /**
+     * Use locale data and heuristics to determine how much of the string to collapse. Could end up collapsing none,
+     * some, or all repeated pieces in a locale-sensitive way.
+     *
+     * The heuristics used for this option are subject to change over time.
+     *
+     * @draft ICU 63
+     */
+    UNUM_RANGE_COLLAPSE_AUTO,
+
+    /**
+     * Do not collapse any part of the number. Example: "3.2 thousand kilograms – 5.3 thousand kilograms"
+     *
+     * @draft ICU 63
+     */
+    UNUM_RANGE_COLLAPSE_NONE,
+
+    /**
+     * Collapse the unit part of the number, but not the notation, if present. Example: "3.2 thousand – 5.3 thousand
+     * kilograms"
+     *
+     * @draft ICU 63
+     */
+    UNUM_RANGE_COLLAPSE_UNIT,
+
+    /**
+     * Collapse any field that is equal across the range sign. May introduce ambiguity on the magnitude of the
+     * number. Example: "3.2 – 5.3 thousand kilograms"
+     *
+     * @draft ICU 63
+     */
+    UNUM_RANGE_COLLAPSE_ALL
+} UNumberRangeCollapse;
+
+/**
+ * Defines the behavior when the two numbers in the range are identical after rounding. To programmatically detect
+ * when the identity fallback is used, compare the lower and upper BigDecimals via FormattedNumber.
+ *
+ * @draft ICU 63
+ * @see NumberRangeFormatter
+ */
+typedef enum UNumberRangeIdentityFallback {
+    /**
+     * Show the number as a single value rather than a range. Example: "$5"
+     *
+     * @draft ICU 63
+     */
+    UNUM_IDENTITY_FALLBACK_SINGLE_VALUE,
+
+    /**
+     * Show the number using a locale-sensitive approximation pattern. If the numbers were the same before rounding,
+     * show the single value. Example: "~$5" or "$5"
+     *
+     * @draft ICU 63
+     */
+    UNUM_IDENTITY_FALLBACK_APPROXIMATELY_OR_SINGLE_VALUE,
+
+    /**
+     * Show the number using a locale-sensitive approximation pattern. Use the range pattern always, even if the
+     * inputs are the same. Example: "~$5"
+     *
+     * @draft ICU 63
+     */
+    UNUM_IDENTITY_FALLBACK_APPROXIMATELY,
+
+    /**
+     * Show the number as the range of two equal values. Use the range pattern always, even if the inputs are the
+     * same. Example (with RangeCollapse.NONE): "$5 – $5"
+     *
+     * @draft ICU 63
+     */
+    UNUM_IDENTITY_FALLBACK_RANGE
+} UNumberRangeIdentityFallback;
+
+/**
+ * Used in the result class FormattedNumberRange to indicate to the user whether the numbers formatted in the range
+ * were equal or not, and whether or not the identity fallback was applied.
+ *
+ * @draft ICU 63
+ * @see NumberRangeFormatter
+ */
+typedef enum UNumberRangeIdentityResult {
+    /**
+     * Used to indicate that the two numbers in the range were equal, even before any rounding rules were applied.
+     *
+     * @draft ICU 63
+     * @see NumberRangeFormatter
+     */
+    UNUM_IDENTITY_RESULT_EQUAL_BEFORE_ROUNDING,
+
+    /**
+     * Used to indicate that the two numbers in the range were equal, but only after rounding rules were applied.
+     *
+     * @draft ICU 63
+     * @see NumberRangeFormatter
+     */
+    UNUM_IDENTITY_RESULT_EQUAL_AFTER_ROUNDING,
+
+    /**
+     * Used to indicate that the two numbers in the range were not equal, even after rounding rules were applied.
+     *
+     * @draft ICU 63
+     * @see NumberRangeFormatter
+     */
+    UNUM_IDENTITY_RESULT_NOT_EQUAL,
+
+#ifndef U_HIDE_INTERNAL_API
+    /**
+     * The number of entries in this enum.
+     * @internal
+     */
+    UNUM_IDENTITY_RESULT_COUNT
+#endif
+
+} UNumberRangeIdentityResult;
+
+U_NAMESPACE_BEGIN
+
+namespace number {  // icu::number
+
+// Forward declarations:
+class UnlocalizedNumberRangeFormatter;
+class LocalizedNumberRangeFormatter;
+class FormattedNumberRange;
+
+namespace impl {
+
+// Forward declarations:
+struct RangeMacroProps;
+class DecimalQuantity;
+struct UFormattedNumberRangeData;
+class NumberRangeFormatterImpl;
+
+} // namespace impl
+
+// Other helper classes would go here, but there are none.
+
+namespace impl {  // icu::number::impl
+
+// Do not enclose entire MacroProps with #ifndef U_HIDE_INTERNAL_API, needed for a protected field
+/** @internal */
+struct U_I18N_API RangeMacroProps : public UMemory {
+    /** @internal */
+    UnlocalizedNumberFormatter formatter1; // = NumberFormatter::with();
+
+    /** @internal */
+    UnlocalizedNumberFormatter formatter2; // = NumberFormatter::with();
+
+    /** @internal */
+    bool singleFormatter = true;
+
+    /** @internal */
+    UNumberRangeCollapse collapse = UNUM_RANGE_COLLAPSE_AUTO;
+
+    /** @internal */
+    UNumberRangeIdentityFallback identityFallback = UNUM_IDENTITY_FALLBACK_APPROXIMATELY;
+
+    /** @internal */
+    Locale locale;
+
+    // NOTE: Uses default copy and move constructors.
+
+    /**
+     * Check all members for errors.
+     * @internal
+     */
+    bool copyErrorTo(UErrorCode &status) const {
+        return formatter1.copyErrorTo(status) || formatter2.copyErrorTo(status);
+    }
+};
+
+} // namespace impl
+
+/**
+ * An abstract base class for specifying settings related to number formatting. This class is implemented by
+ * {@link UnlocalizedNumberRangeFormatter} and {@link LocalizedNumberRangeFormatter}. This class is not intended for
+ * public subclassing.
+ */
+template<typename Derived>
+class U_I18N_API NumberRangeFormatterSettings {
+  public:
+    /**
+     * Sets the NumberFormatter instance to use for the numbers in the range. The same formatter is applied to both
+     * sides of the range.
+     * <p>
+     * The NumberFormatter instances must not have a locale applied yet; the locale specified on the
+     * NumberRangeFormatter will be used.
+     *
+     * @param formatter
+     *            The formatter to use for both numbers in the range.
+     * @return The fluent chain.
+     * @draft ICU 63
+     */
+    Derived numberFormatterBoth(const UnlocalizedNumberFormatter &formatter) const &;
+
+    /**
+     * Overload of numberFormatterBoth() for use on an rvalue reference.
+     *
+     * @param formatter
+     *            The formatter to use for both numbers in the range.
+     * @return The fluent chain.
+     * @see #numberFormatterBoth
+     * @draft ICU 63
+     */
+    Derived numberFormatterBoth(const UnlocalizedNumberFormatter &formatter) &&;
+
+    /**
+     * Overload of numberFormatterBoth() for use on an rvalue reference.
+     *
+     * @param formatter
+     *            The formatter to use for both numbers in the range.
+     * @return The fluent chain.
+     * @see #numberFormatterBoth
+     * @draft ICU 63
+     */
+    Derived numberFormatterBoth(UnlocalizedNumberFormatter &&formatter) const &;
+
+    /**
+     * Overload of numberFormatterBoth() for use on an rvalue reference.
+     *
+     * @param formatter
+     *            The formatter to use for both numbers in the range.
+     * @return The fluent chain.
+     * @see #numberFormatterBoth
+     * @draft ICU 63
+     */
+    Derived numberFormatterBoth(UnlocalizedNumberFormatter &&formatter) &&;
+
+    /**
+     * Sets the NumberFormatter instance to use for the first number in the range.
+     * <p>
+     * The NumberFormatter instances must not have a locale applied yet; the locale specified on the
+     * NumberRangeFormatter will be used.
+     *
+     * @param formatterFirst
+     *            The formatter to use for the first number in the range.
+     * @return The fluent chain.
+     * @draft ICU 63
+     */
+    Derived numberFormatterFirst(const UnlocalizedNumberFormatter &formatterFirst) const &;
+
+    /**
+     * Overload of numberFormatterFirst() for use on an rvalue reference.
+     *
+     * @param formatterFirst
+     *            The formatter to use for the first number in the range.
+     * @return The fluent chain.
+     * @see #numberFormatterFirst
+     * @draft ICU 63
+     */
+    Derived numberFormatterFirst(const UnlocalizedNumberFormatter &formatterFirst) &&;
+
+    /**
+     * Overload of numberFormatterFirst() for use on an rvalue reference.
+     *
+     * @param formatterFirst
+     *            The formatter to use for the first number in the range.
+     * @return The fluent chain.
+     * @see #numberFormatterFirst
+     * @draft ICU 63
+     */
+    Derived numberFormatterFirst(UnlocalizedNumberFormatter &&formatterFirst) const &;
+
+    /**
+     * Overload of numberFormatterFirst() for use on an rvalue reference.
+     *
+     * @param formatterFirst
+     *            The formatter to use for the first number in the range.
+     * @return The fluent chain.
+     * @see #numberFormatterFirst
+     * @draft ICU 63
+     */
+    Derived numberFormatterFirst(UnlocalizedNumberFormatter &&formatterFirst) &&;
+
+    /**
+     * Sets the NumberFormatter instance to use for the second number in the range.
+     * <p>
+     * The NumberFormatter instances must not have a locale applied yet; the locale specified on the
+     * NumberRangeFormatter will be used.
+     *
+     * @param formatterSecond
+     *            The formatter to use for the second number in the range.
+     * @return The fluent chain.
+     * @draft ICU 63
+     */
+    Derived numberFormatterSecond(const UnlocalizedNumberFormatter &formatterSecond) const &;
+
+    /**
+     * Overload of numberFormatterSecond() for use on an rvalue reference.
+     *
+     * @param formatterSecond
+     *            The formatter to use for the second number in the range.
+     * @return The fluent chain.
+     * @see #numberFormatterSecond
+     * @draft ICU 63
+     */
+    Derived numberFormatterSecond(const UnlocalizedNumberFormatter &formatterSecond) &&;
+
+    /**
+     * Overload of numberFormatterSecond() for use on an rvalue reference.
+     *
+     * @param formatterSecond
+     *            The formatter to use for the second number in the range.
+     * @return The fluent chain.
+     * @see #numberFormatterSecond
+     * @draft ICU 63
+     */
+    Derived numberFormatterSecond(UnlocalizedNumberFormatter &&formatterSecond) const &;
+
+    /**
+     * Overload of numberFormatterSecond() for use on an rvalue reference.
+     *
+     * @param formatterSecond
+     *            The formatter to use for the second number in the range.
+     * @return The fluent chain.
+     * @see #numberFormatterSecond
+     * @draft ICU 63
+     */
+    Derived numberFormatterSecond(UnlocalizedNumberFormatter &&formatterSecond) &&;
+
+    /**
+     * Sets the aggressiveness of "collapsing" fields across the range separator. Possible values:
+     * <p>
+     * <ul>
+     * <li>ALL: "3-5K miles"</li>
+     * <li>UNIT: "3K - 5K miles"</li>
+     * <li>NONE: "3K miles - 5K miles"</li>
+     * <li>AUTO: usually UNIT or NONE, depending on the locale and formatter settings</li>
+     * </ul>
+     * <p>
+     * The default value is AUTO.
+     *
+     * @param collapse
+     *            The collapsing strategy to use for this range.
+     * @return The fluent chain.
+     * @draft ICU 63
+     */
+    Derived collapse(UNumberRangeCollapse collapse) const &;
+
+    /**
+     * Overload of collapse() for use on an rvalue reference.
+     *
+     * @param collapse
+     *            The collapsing strategy to use for this range.
+     * @return The fluent chain.
+     * @see #collapse
+     * @draft ICU 63
+     */
+    Derived collapse(UNumberRangeCollapse collapse) &&;
+
+    /**
+     * Sets the behavior when the two sides of the range are the same. This could happen if the same two numbers are
+     * passed to the formatRange function, or if different numbers are passed to the function but they become the same
+     * after rounding rules are applied. Possible values:
+     * <p>
+     * <ul>
+     * <li>SINGLE_VALUE: "5 miles"</li>
+     * <li>APPROXIMATELY_OR_SINGLE_VALUE: "~5 miles" or "5 miles", depending on whether the number was the same before
+     * rounding was applied</li>
+     * <li>APPROXIMATELY: "~5 miles"</li>
+     * <li>RANGE: "5-5 miles" (with collapse=UNIT)</li>
+     * </ul>
+     * <p>
+     * The default value is APPROXIMATELY.
+     *
+     * @param identityFallback
+     *            The strategy to use when formatting two numbers that end up being the same.
+     * @return The fluent chain.
+     * @draft ICU 63
+     */
+    Derived identityFallback(UNumberRangeIdentityFallback identityFallback) const &;
+
+    /**
+     * Overload of identityFallback() for use on an rvalue reference.
+     *
+     * @param identityFallback
+     *            The strategy to use when formatting two numbers that end up being the same.
+     * @return The fluent chain.
+     * @see #identityFallback
+     * @draft ICU 63
+     */
+    Derived identityFallback(UNumberRangeIdentityFallback identityFallback) &&;
+
+    /**
+     * Sets the UErrorCode if an error occurred in the fluent chain.
+     * Preserves older error codes in the outErrorCode.
+     * @return TRUE if U_FAILURE(outErrorCode)
+     * @draft ICU 63
+     */
+    UBool copyErrorTo(UErrorCode &outErrorCode) const {
+        if (U_FAILURE(outErrorCode)) {
+            // Do not overwrite the older error code
+            return TRUE;
+        }
+        fMacros.copyErrorTo(outErrorCode);
+        return U_FAILURE(outErrorCode);
+    };
+
+    // NOTE: Uses default copy and move constructors.
+
+  private:
+    impl::RangeMacroProps fMacros;
+
+    // Don't construct me directly!  Use (Un)LocalizedNumberFormatter.
+    NumberRangeFormatterSettings() = default;
+
+    friend class LocalizedNumberRangeFormatter;
+    friend class UnlocalizedNumberRangeFormatter;
+};
+
+/**
+ * A NumberRangeFormatter that does not yet have a locale. In order to format, a locale must be specified.
+ *
+ * @see NumberRangeFormatter
+ * @draft ICU 63
+ */
+class U_I18N_API UnlocalizedNumberRangeFormatter
+        : public NumberRangeFormatterSettings<UnlocalizedNumberRangeFormatter>, public UMemory {
+
+  public:
+    /**
+     * Associate the given locale with the number range formatter. The locale is used for picking the
+     * appropriate symbols, formats, and other data for number display.
+     *
+     * @param locale
+     *            The locale to use when loading data for number formatting.
+     * @return The fluent chain.
+     * @draft ICU 63
+     */
+    LocalizedNumberRangeFormatter locale(const icu::Locale &locale) const &;
+
+    /**
+     * Overload of locale() for use on an rvalue reference.
+     *
+     * @param locale
+     *            The locale to use when loading data for number formatting.
+     * @return The fluent chain.
+     * @see #locale
+     * @draft ICU 63
+     */
+    LocalizedNumberRangeFormatter locale(const icu::Locale &locale) &&;
+
+    /**
+     * Default constructor: puts the formatter into a valid but undefined state.
+     *
+     * @draft ICU 63
+     */
+    UnlocalizedNumberRangeFormatter() = default;
+
+    /**
+     * Returns a copy of this UnlocalizedNumberRangeFormatter.
+     * @draft ICU 63
+     */
+    UnlocalizedNumberRangeFormatter(const UnlocalizedNumberRangeFormatter &other);
+
+    /**
+     * Move constructor:
+     * The source UnlocalizedNumberRangeFormatter will be left in a valid but undefined state.
+     * @draft ICU 63
+     */
+    UnlocalizedNumberRangeFormatter(UnlocalizedNumberRangeFormatter&& src) U_NOEXCEPT;
+
+    /**
+     * Copy assignment operator.
+     * @draft ICU 63
+     */
+    UnlocalizedNumberRangeFormatter& operator=(const UnlocalizedNumberRangeFormatter& other);
+
+    /**
+     * Move assignment operator:
+     * The source UnlocalizedNumberRangeFormatter will be left in a valid but undefined state.
+     * @draft ICU 63
+     */
+    UnlocalizedNumberRangeFormatter& operator=(UnlocalizedNumberRangeFormatter&& src) U_NOEXCEPT;
+
+  private:
+    explicit UnlocalizedNumberRangeFormatter(
+            const NumberRangeFormatterSettings<UnlocalizedNumberRangeFormatter>& other);
+
+    explicit UnlocalizedNumberRangeFormatter(
+            NumberRangeFormatterSettings<UnlocalizedNumberRangeFormatter>&& src) U_NOEXCEPT;
+
+    // To give the fluent setters access to this class's constructor:
+    friend class NumberRangeFormatterSettings<UnlocalizedNumberRangeFormatter>;
+
+    // To give NumberRangeFormatter::with() access to this class's constructor:
+    friend class NumberRangeFormatter;
+};
+
+/**
+ * A NumberRangeFormatter that has a locale associated with it; this means .formatRange() methods are available.
+ *
+ * @see NumberFormatter
+ * @draft ICU 63
+ */
+class U_I18N_API LocalizedNumberRangeFormatter
+        : public NumberRangeFormatterSettings<LocalizedNumberRangeFormatter>, public UMemory {
+  public:
+    /**
+     * Format the given Formattables to a string using the settings specified in the NumberRangeFormatter fluent setting
+     * chain.
+     *
+     * @param first
+     *            The first number in the range, usually to the left in LTR locales.
+     * @param second
+     *            The second number in the range, usually to the right in LTR locales.
+     * @param status
+     *            Set if an error occurs while formatting.
+     * @return A FormattedNumberRange object; call .toString() to get the string.
+     * @draft ICU 63
+     */
+    FormattedNumberRange formatFormattableRange(
+        const Formattable& first, const Formattable& second, UErrorCode& status) const;
+
+    /**
+     * Default constructor: puts the formatter into a valid but undefined state.
+     *
+     * @draft ICU 63
+     */
+    LocalizedNumberRangeFormatter() = default;
+
+    /**
+     * Returns a copy of this LocalizedNumberRangeFormatter.
+     * @draft ICU 63
+     */
+    LocalizedNumberRangeFormatter(const LocalizedNumberRangeFormatter &other);
+
+    /**
+     * Move constructor:
+     * The source LocalizedNumberRangeFormatter will be left in a valid but undefined state.
+     * @draft ICU 63
+     */
+    LocalizedNumberRangeFormatter(LocalizedNumberRangeFormatter&& src) U_NOEXCEPT;
+
+    /**
+     * Copy assignment operator.
+     * @draft ICU 63
+     */
+    LocalizedNumberRangeFormatter& operator=(const LocalizedNumberRangeFormatter& other);
+
+    /**
+     * Move assignment operator:
+     * The source LocalizedNumberRangeFormatter will be left in a valid but undefined state.
+     * @draft ICU 63
+     */
+    LocalizedNumberRangeFormatter& operator=(LocalizedNumberRangeFormatter&& src) U_NOEXCEPT;
+
+#ifndef U_HIDE_INTERNAL_API
+
+    /**
+     * @param results
+     *            The results object. This method will mutate it to save the results.
+     * @param status
+     *            Set if an error occurs while formatting.
+     * @internal
+     */
+    void formatImpl(impl::UFormattedNumberRangeData& results, bool equalBeforeRounding,
+                    UErrorCode& status) const;
+
+#endif
+
+    /**
+     * Destruct this LocalizedNumberRangeFormatter, cleaning up any memory it might own.
+     * @draft ICU 63
+     */
+    ~LocalizedNumberRangeFormatter();
+
+  private:
+    // TODO: This is not thread-safe! Do NOT check this in without an atomic here.
+    impl::NumberRangeFormatterImpl* fImpl = nullptr;
+
+    explicit LocalizedNumberRangeFormatter(
+        const NumberRangeFormatterSettings<LocalizedNumberRangeFormatter>& other);
+
+    explicit LocalizedNumberRangeFormatter(
+        NumberRangeFormatterSettings<LocalizedNumberRangeFormatter>&& src) U_NOEXCEPT;
+
+    LocalizedNumberRangeFormatter(const impl::RangeMacroProps &macros, const Locale &locale);
+
+    LocalizedNumberRangeFormatter(impl::RangeMacroProps &&macros, const Locale &locale);
+
+    void clear();
+
+    // To give the fluent setters access to this class's constructor:
+    friend class NumberRangeFormatterSettings<UnlocalizedNumberRangeFormatter>;
+    friend class NumberRangeFormatterSettings<LocalizedNumberRangeFormatter>;
+
+    // To give UnlocalizedNumberRangeFormatter::locale() access to this class's constructor:
+    friend class UnlocalizedNumberRangeFormatter;
+};
+
+/**
+ * The result of a number range formatting operation. This class allows the result to be exported in several data types,
+ * including a UnicodeString and a FieldPositionIterator.
+ *
+ * @draft ICU 63
+ */
+class U_I18N_API FormattedNumberRange : public UMemory {
+  public:
+    /**
+     * Returns a UnicodeString representation of the formatted number range.
+     *
+     * @param status
+     *            Set if an error occurs while formatting the number to the UnicodeString.
+     * @return a UnicodeString containing the localized number range.
+     * @draft ICU 63
+     */
+    UnicodeString toString(UErrorCode& status) const;
+
+    /**
+     * Appends the formatted number range to an Appendable.
+     *
+     * @param appendable
+     *            The Appendable to which to append the formatted number range string.
+     * @param status
+     *            Set if an error occurs while formatting the number range to the Appendable.
+     * @return The same Appendable, for chaining.
+     * @draft ICU 63
+     * @see Appendable
+     */
+    Appendable &appendTo(Appendable &appendable, UErrorCode& status) const;
+
+    /**
+     * Determines the start (inclusive) and end (exclusive) indices of the next occurrence of the given
+     * <em>field</em> in the output string. This allows you to determine the locations of, for example,
+     * the integer part, fraction part, or symbols.
+     *
+     * If both sides of the range have the same field, the field will occur twice, once before the
+     * range separator and once after the range separator, if applicable.
+     *
+     * If a field occurs just once, calling this method will find that occurrence and return it. If a
+     * field occurs multiple times, this method may be called repeatedly with the following pattern:
+     *
+     * <pre>
+     * FieldPosition fpos(UNUM_INTEGER_FIELD);
+     * while (formattedNumberRange.nextFieldPosition(fpos, status)) {
+     *   // do something with fpos.
+     * }
+     * </pre>
+     *
+     * This method is useful if you know which field to query. If you want all available field position
+     * information, use #getAllFieldPositions().
+     *
+     * @param fieldPosition
+     *            Input+output variable. See {@link FormattedNumber#nextFieldPosition}.
+     * @param status
+     *            Set if an error occurs while populating the FieldPosition.
+     * @return TRUE if a new occurrence of the field was found; FALSE otherwise.
+     * @draft ICU 63
+     * @see UNumberFormatFields
+     */
+    UBool nextFieldPosition(FieldPosition& fieldPosition, UErrorCode& status) const;
+
+    /**
+     * Export the formatted number range to a FieldPositionIterator. This allows you to determine which characters in
+     * the output string correspond to which <em>fields</em>, such as the integer part, fraction part, and sign.
+     *
+     * If information on only one field is needed, use #nextFieldPosition() instead.
+     *
+     * @param iterator
+     *            The FieldPositionIterator to populate with all of the fields present in the formatted number.
+     * @param status
+     *            Set if an error occurs while populating the FieldPositionIterator.
+     * @draft ICU 63
+     * @see UNumberFormatFields
+     */
+    void getAllFieldPositions(FieldPositionIterator &iterator, UErrorCode &status) const;
+
+    /**
+     * Export the first formatted number as a decimal number. This endpoint
+     * is useful for obtaining the exact number being printed after scaling
+     * and rounding have been applied by the number range formatting pipeline.
+     * 
+     * The syntax of the unformatted number is a "numeric string"
+     * as defined in the Decimal Arithmetic Specification, available at
+     * http://speleotrove.com/decimal
+     *
+     * @return A decimal representation of the first formatted number.
+     * @draft ICU 63
+     * @see NumberRangeFormatter
+     * @see #getSecondDecimal
+     */
+    UnicodeString getFirstDecimal(UErrorCode& status) const;
+
+    /**
+     * Export the second formatted number as a decimal number. This endpoint
+     * is useful for obtaining the exact number being printed after scaling
+     * and rounding have been applied by the number range formatting pipeline.
+     * 
+     * The syntax of the unformatted number is a "numeric string"
+     * as defined in the Decimal Arithmetic Specification, available at
+     * http://speleotrove.com/decimal
+     *
+     * @return A decimal representation of the second formatted number.
+     * @draft ICU 63
+     * @see NumberRangeFormatter
+     * @see #getFirstDecimal
+     */
+    UnicodeString getSecondDecimal(UErrorCode& status) const;
+
+    /**
+     * Returns whether the pair of numbers was successfully formatted as a range or whether an identity fallback was
+     * used. For example, if the first and second number were the same either before or after rounding occurred, an
+     * identity fallback was used.
+     *
+     * @return An indication the resulting identity situation in the formatted number range.
+     * @draft ICU 63
+     * @see UNumberRangeIdentityFallback
+     */
+    UNumberRangeIdentityResult getIdentityResult(UErrorCode& status) const;
+
+    /**
+     * Copying not supported; use move constructor instead.
+     */
+    FormattedNumberRange(const FormattedNumberRange&) = delete;
+
+    /**
+     * Copying not supported; use move assignment instead.
+     */
+    FormattedNumberRange& operator=(const FormattedNumberRange&) = delete;
+
+    /**
+     * Move constructor:
+     * Leaves the source FormattedNumberRange in an undefined state.
+     * @draft ICU 63
+     */
+    FormattedNumberRange(FormattedNumberRange&& src) U_NOEXCEPT;
+
+    /**
+     * Move assignment:
+     * Leaves the source FormattedNumberRange in an undefined state.
+     * @draft ICU 63
+     */
+    FormattedNumberRange& operator=(FormattedNumberRange&& src) U_NOEXCEPT;
+
+    /**
+     * Destruct an instance of FormattedNumberRange, cleaning up any memory it might own.
+     * @draft ICU 63
+     */
+    ~FormattedNumberRange();
+
+  private:
+    // Can't use LocalPointer because UFormattedNumberRangeData is forward-declared
+    const impl::UFormattedNumberRangeData *fResults;
+
+    // Error code for the terminal methods
+    UErrorCode fErrorCode;
+
+    /**
+     * Internal constructor from data type. Adopts the data pointer.
+     * @internal
+     */
+    explicit FormattedNumberRange(impl::UFormattedNumberRangeData *results)
+        : fResults(results), fErrorCode(U_ZERO_ERROR) {};
+
+    explicit FormattedNumberRange(UErrorCode errorCode)
+        : fResults(nullptr), fErrorCode(errorCode) {};
+
+    void getAllFieldPositionsImpl(FieldPositionIteratorHandler& fpih, UErrorCode& status) const;
+
+    // To give LocalizedNumberRangeFormatter format methods access to this class's constructor:
+    friend class LocalizedNumberRangeFormatter;
+};
+
+/**
+ * See the main description in numberrangeformatter.h for documentation and examples.
+ *
+ * @draft ICU 63
+ */
+class U_I18N_API NumberRangeFormatter final {
+  public:
+    /**
+     * Call this method at the beginning of a NumberRangeFormatter fluent chain in which the locale is not currently
+     * known at the call site.
+     *
+     * @return An {@link UnlocalizedNumberRangeFormatter}, to be used for chaining.
+     * @draft ICU 63
+     */
+    static UnlocalizedNumberRangeFormatter with();
+
+    /**
+     * Call this method at the beginning of a NumberRangeFormatter fluent chain in which the locale is known at the call
+     * site.
+     *
+     * @param locale
+     *            The locale from which to load formats and symbols for number range formatting.
+     * @return A {@link LocalizedNumberRangeFormatter}, to be used for chaining.
+     * @draft ICU 63
+     */
+    static LocalizedNumberRangeFormatter withLocale(const Locale &locale);
+
+    /**
+     * Use factory methods instead of the constructor to create a NumberFormatter.
+     */
+    NumberRangeFormatter() = delete;
+};
+
+}  // namespace number
+U_NAMESPACE_END
+
+#endif  // U_HIDE_DRAFT_API
+
+#endif // __NUMBERRANGEFORMATTER_H__
+
+#endif /* #if !UCONFIG_NO_FORMATTING */

icu4c/source/samples/date/date.c

@@ -48,8 +48,8 @@ int main(int argc, char **argv)
 /* Protos */
 static void usage(void);
 static void version(void);
-static void date(UDate when, const UChar *tz, UDateFormatStyle style, const char *format, UErrorCode *status);
-static UDate getWhen(const char *millis, const char *seconds, const char *format, UDateFormatStyle style, const char *parse, const UChar *tz, UErrorCode *status);
+static void date(UDate when, const UChar *tz, UDateFormatStyle style, const char *format, const char *locale, UErrorCode *status);
+static UDate getWhen(const char *millis, const char *seconds, const char *format, const char *locale, UDateFormatStyle style, const char *parse, const UChar *tz, UErrorCode *status);
 
 UConverter *cnv = NULL;
 
@@ -74,6 +74,7 @@ main(int argc,
   UDateFormatStyle style = UDAT_DEFAULT;
   UErrorCode status = U_ZERO_ERROR;
   const char *format = NULL;
+  const char *locale = NULL;
   char *parse = NULL;
   char *seconds = NULL;
   char *millis = NULL;
@@ -132,6 +133,12 @@ main(int argc,
          parse = argv[optInd];
       }
     }
+    else if (strcmp(arg, "-L") == 0) {
+      if (optInd + 1 < argc) {
+         optInd++;
+         locale = argv[optInd];
+      }
+    }
     /* POSIX.1 says all arguments after -- are not options */
     else if(strcmp(arg, "--") == 0) {
       /* skip the -- */
@@ -162,13 +169,13 @@ main(int argc,
   }
 
   /* get the 'when' (or now) */
-  when = getWhen(millis, seconds, format, style, parse, tz, &status);
+  when = getWhen(millis, seconds, format, locale, style, parse, tz, &status);
   if(parse != NULL) {
     format = FORMAT_MILLIS; /* output in millis */
   }
 
   /* print the date */
-  date(when, tz, style, format, &status);
+  date(when, tz, style, format, locale, &status);
 
   ucnv_close(cnv);
 
@@ -194,6 +201,7 @@ usage()
   puts("  -r <seconds>      Use <seconds> as the time (Epoch 1970) rather than now.");
   puts("  -R <millis>       Use <millis> as the time (Epoch 1970) rather than now.");
   puts("  -P <string>       Parse <string> as the time, output in millis format.");
+  puts("  -L <string>       Use the locale <string> instead of the default ICU locale.");
 }
 
 /* Version information */
@@ -245,6 +253,7 @@ date(UDate when,
      const UChar *tz,
      UDateFormatStyle style,
      const char *format,
+     const char *locale,
      UErrorCode *status )
 {
   UChar *s = 0;
@@ -264,7 +273,7 @@ date(UDate when,
     }
   }
 
-  fmt = udat_open(style, style, 0, tz, -1,NULL,0, status);
+  fmt = udat_open(style, style, locale, tz, -1,NULL,0, status);
   if ( format != NULL ) {
     charsToUCharsDefault(uFormat,sizeof(uFormat)/sizeof(uFormat[0]),format,-1,status);
     udat_applyPattern(fmt,FALSE,uFormat,-1);
@@ -292,7 +301,7 @@ date(UDate when,
   free(s);
 }
 
-static UDate getWhen(const char *millis, const char *seconds, const char *format, 
+static UDate getWhen(const char *millis, const char *seconds, const char *format, const char *locale,
                      UDateFormatStyle style, const char *parse, const UChar *tz, UErrorCode *status) {
   UDateFormat *fmt = NULL; 
   UChar uFormat[100];
@@ -319,7 +328,7 @@ static UDate getWhen(const char *millis, const char *seconds, const char *format
       }
     }
 
-    fmt = udat_open(style, style, 0, tz, -1,NULL,0, status);
+    fmt = udat_open(style, style, locale, tz, -1,NULL,0, status);
     if ( format != NULL ) {
       charsToUCharsDefault(uFormat,sizeof(uFormat)/sizeof(uFormat[0]), format,-1,status);
       udat_applyPattern(fmt,FALSE,uFormat,-1);

icu4c/source/test/cintltst/cloctst.c

@@ -251,6 +251,7 @@ void addLocaleTest(TestNode** root)
     TESTCASE(TestLikelySubtags);
     TESTCASE(TestToLanguageTag);
     TESTCASE(TestForLanguageTag);
+    TESTCASE(TestInvalidLanguageTag);
     TESTCASE(TestTrailingNull);
     TESTCASE(TestUnicodeDefines);
     TESTCASE(TestEnglishExemplarCharacters);
@@ -6030,6 +6031,9 @@ static const struct {
     {"ja-u-ijkl-efgh-abcd-ca-japanese-xx-yyy-zzz-kn",   "ja@attribute=abcd-efgh-ijkl;calendar=japanese;colnumeric=yes;xx=yyy-zzz",  FULL_LENGTH},
     {"de-u-xc-xphonebk-co-phonebk-ca-buddhist-mo-very-lo-extensi-xd-that-de-should-vc-probably-xz-killthebuffer",
      "de@calendar=buddhist;collation=phonebook;de=should;lo=extensi;mo=very;vc=probably;xc=xphonebk;xd=that;xz=yes", 91},
+    {"de-1901-1901", "de__1901", 7},
+    {"de-DE-1901-1901", "de_DE_1901", 10},
+    {"en-a-bbb-a-ccc", "en@a=bbb", 8},
     /* #12761 */
     {"en-a-bar-u-baz",      "en@a=bar;attribute=baz",   FULL_LENGTH},
     {"en-a-bar-u-baz-x-u-foo",  "en@a=bar;attribute=baz;x=u-foo",   FULL_LENGTH},
@@ -6047,6 +6051,11 @@ static const struct {
     {"zh-cmn-TW", "cmn_TW", FULL_LENGTH},
     {"zh-x_t-ab", "zh", 2},
     {"zh-hans-cn-u-ca-x_t-u", "zh_Hans_CN@calendar=yes",  15},
+    /* #20140 dupe keys in U-extension */
+    {"zh-u-ca-chinese-ca-gregory", "zh@calendar=chinese", FULL_LENGTH},
+    {"zh-u-ca-gregory-co-pinyin-ca-chinese", "zh@calendar=gregorian;collation=pinyin", FULL_LENGTH},
+    {"de-latn-DE-1901-u-co-phonebk-co-pinyin-ca-gregory", "de_Latn_DE_1901@calendar=gregorian;collation=phonebook", FULL_LENGTH},
+    {"th-u-kf-nu-thai-kf-false", "th@colcasefirst=yes;numbers=thai", FULL_LENGTH},
     {NULL,          NULL,           0}
 };
 
@@ -6081,6 +6090,35 @@ static void TestForLanguageTag(void) {
     }
 }
 
+/* See https://unicode-org.atlassian.net/browse/ICU-20149 .
+ * Depending on the resolution of that bug, this test may have
+ * to be revised.
+ */
+static void TestInvalidLanguageTag(void) {
+    static const char* invalid_lang_tags[] = {
+        "zh-u-foo-foo-co-pinyin", /* duplicate attribute in U extension */
+        "zh-cmn-hans-u-foo-foo-co-pinyin", /* duplicate attribute in U extension */
+#if 0
+        /*
+         * These do not lead to an error. Instead, parsing stops at the 1st
+         * invalid subtag.
+         */
+        "de-DE-1901-1901", /* duplicate variant */
+        "en-a-bbb-a-ccc", /* duplicate extension */
+#endif
+        NULL
+    };
+    char locale[256];
+    for (const char** tag = invalid_lang_tags; *tag != NULL; tag++) {
+        UErrorCode status = U_ZERO_ERROR;
+        uloc_forLanguageTag(*tag, locale, sizeof(locale), NULL, &status);
+        if (status != U_ILLEGAL_ARGUMENT_ERROR) {
+            log_err("Error returned by uloc_forLanguageTag for input language tag [%s] : %s - expected error:  %s\n",
+                    *tag, u_errorName(status), u_errorName(U_ILLEGAL_ARGUMENT_ERROR));
+        }
+    }
+}
+
 static void TestToUnicodeLocaleKey(void)
 {
     /* $IN specifies the result should be the input pointer itself */

icu4c/source/test/cintltst/cloctst.h

@@ -123,6 +123,7 @@ static void TestLikelySubtags(void);
  * lanuage tag
  */
 static void TestForLanguageTag(void);
+static void TestInvalidLanguageTag(void);
 static void TestToLanguageTag(void);
 
 static void TestToUnicodeLocaleKey(void);

icu4c/source/test/depstest/dependencies.txt

@@ -164,7 +164,6 @@ library: common
     ubidi ushape ubiditransform
     listformatter
     resourcebundle service_registration resbund_cnv ures_cnv icudataver ucat
-    loclikely
     currency
     locale_display_names2
     conversion converter_selector ucnv_set ucnvdisp
@@ -383,7 +382,7 @@ group: cstr
 group: uscript
     uscript.o  # uscript_getCode() accepts a locale ID and loads its script code data
   deps
-    propname loclikely
+    propname resourcebundle
 
 group: uscript_props  # script metadata properties
     uscript_props.o
@@ -583,7 +582,7 @@ group: locale_display_names2
 group: currency
     ucurr.o
   deps
-    loclikely resourcebundle ulist ustring_case_locale
+    resourcebundle ulist ustring_case_locale
     stdlib_qsort  # for ucurr.o (which does not use ICU's uarrsort.o)
     static_unicode_sets usetiter
 
@@ -592,11 +591,6 @@ group: icudataver  # u_getDataVersion()
   deps
     resourcebundle
 
-group: loclikely
-    loclikely.o
-  deps
-    resourcebundle uscript_props propname
-
 group: locresdata
     # This was intended to collect locale functions that load resource bundle data.
     # See the resourcebundle group about what else loads data.
@@ -631,9 +625,12 @@ group: resourcebundle
     locid.o locmap.o wintz.o
     # Do we need class LocaleBased? http://bugs.icu-project.org/trac/ticket/8608
     locbased.o
+    loclikely.o
   deps
     udata ucol_swp
     sort stringenumeration uhash uvector
+    uscript_props propname
+    bytesinkutil
 
 group: udata
     udata.o ucmndata.o udatamem.o
@@ -832,7 +829,6 @@ group: localedata
   deps
     uniset_props resourcebundle
     uset_props  # TODO: change to using C++ UnicodeSet, remove this dependency
-    loclikely
 
 group: genderinfo
     gender.o

icu4c/source/test/intltest/Makefile.in

@@ -66,7 +66,7 @@ numbertest_affixutils.o numbertest_api.o numbertest_decimalquantity.o \
 numbertest_modifiers.o numbertest_patternmodifier.o numbertest_patternstring.o \
 numbertest_stringbuilder.o numbertest_stringsegment.o \
 numbertest_parse.o numbertest_doubleconversion.o numbertest_skeletons.o \
-static_unisets_test.o numfmtdatadriventest.o erarulestest.o
+static_unisets_test.o numfmtdatadriventest.o numbertest_range.o erarulestest.o
 
 DEPS = $(OBJECTS:.o=.d)
 

icu4c/source/test/intltest/intltest.vcxproj

@@ -256,6 +256,7 @@
     <ClCompile Include="numbertest_parse.cpp" />
     <ClCompile Include="numbertest_doubleconversion.cpp" />
     <ClCompile Include="numbertest_skeletons.cpp" />
+    <ClCompile Include="numbertest_range.cpp" />
     <ClCompile Include="numfmtst.cpp" />
     <ClCompile Include="numfmtdatadriventest.cpp" />
     <ClCompile Include="numrgts.cpp" />

icu4c/source/test/intltest/intltest.vcxproj.filters

@@ -289,6 +289,9 @@
     <ClCompile Include="numbertest_skeletons.cpp">
       <Filter>formatting</Filter>
     </ClCompile>
+    <ClCompile Include="numbertest_range.cpp">
+      <Filter>formatting</Filter>
+    </ClCompile>
     <ClCompile Include="numfmtst.cpp">
       <Filter>formatting</Filter>
     </ClCompile>

icu4c/source/test/intltest/loctest.cpp

@@ -6,7 +6,12 @@
  * others. All Rights Reserved.
  ********************************************************************/
 
+#include <iterator>
+#include <set>
+#include <utility>
+
 #include "loctest.h"
+#include "unicode/localpointer.h"
 #include "unicode/decimfmt.h"
 #include "unicode/ucurr.h"
 #include "unicode/smpdtfmt.h"
@@ -220,9 +225,18 @@ void LocaleTest::runIndexedTest( int32_t index, UBool exec, const char* &name, c
 #endif
     TESTCASE_AUTO(TestSetIsBogus);
     TESTCASE_AUTO(TestParallelAPIValues);
+    TESTCASE_AUTO(TestAddLikelySubtags);
+    TESTCASE_AUTO(TestMinimizeSubtags);
     TESTCASE_AUTO(TestKeywordVariants);
+    TESTCASE_AUTO(TestCreateUnicodeKeywords);
     TESTCASE_AUTO(TestKeywordVariantParsing);
+    TESTCASE_AUTO(TestCreateKeywordSet);
+    TESTCASE_AUTO(TestCreateUnicodeKeywordSet);
+    TESTCASE_AUTO(TestGetKeywordValueStdString);
+    TESTCASE_AUTO(TestGetUnicodeKeywordValueStdString);
     TESTCASE_AUTO(TestSetKeywordValue);
+    TESTCASE_AUTO(TestSetKeywordValueStringPiece);
+    TESTCASE_AUTO(TestSetUnicodeKeywordValueStringPiece);
     TESTCASE_AUTO(TestGetBaseName);
 #if !UCONFIG_NO_FILE_IO
     TESTCASE_AUTO(TestGetLocale);
@@ -236,6 +250,8 @@ void LocaleTest::runIndexedTest( int32_t index, UBool exec, const char* &name, c
     TESTCASE_AUTO(TestBug13554);
     TESTCASE_AUTO(TestForLanguageTag);
     TESTCASE_AUTO(TestToLanguageTag);
+    TESTCASE_AUTO(TestMoveAssign);
+    TESTCASE_AUTO(TestMoveCtor);
     TESTCASE_AUTO_END;
 }
 
@@ -1601,6 +1617,34 @@ LocaleTest::TestSetIsBogus() {
 }
 
 
+void
+LocaleTest::TestAddLikelySubtags() {
+    IcuTestErrorCode status(*this, "TestAddLikelySubtags()");
+
+    static const Locale min("sv");
+    static const Locale max("sv_Latn_SE");
+
+    Locale result(min);
+    result.addLikelySubtags(status);
+    status.errIfFailureAndReset("\"%s\"", min.getName());
+    assertEquals("addLikelySubtags", max.getName(), result.getName());
+}
+
+
+void
+LocaleTest::TestMinimizeSubtags() {
+    IcuTestErrorCode status(*this, "TestMinimizeSubtags()");
+
+    static const Locale max("zh_Hant_TW");
+    static const Locale min("zh_TW");
+
+    Locale result(max);
+    result.minimizeSubtags(status);
+    status.errIfFailureAndReset("\"%s\"", max.getName());
+    assertEquals("minimizeSubtags", min.getName(), result.getName());
+}
+
+
 void
 LocaleTest::TestKeywordVariants(void) {
     static const struct {
@@ -1708,6 +1752,55 @@ LocaleTest::TestKeywordVariants(void) {
 
 }
 
+
+void
+LocaleTest::TestCreateUnicodeKeywords(void) {
+    IcuTestErrorCode status(*this, "TestCreateUnicodeKeywords()");
+
+    static const Locale l("de@calendar=buddhist;collation=phonebook");
+
+    LocalPointer<StringEnumeration> keys(l.createUnicodeKeywords(status));
+    status.errIfFailureAndReset("\"%s\"", l.getName());
+
+    const char* key;
+    int32_t resultLength;
+
+    key = keys->next(&resultLength, status);
+    status.errIfFailureAndReset("key #1");
+    assertEquals("resultLength", 2, resultLength);
+    assertTrue("key != nullptr", key != nullptr);
+    assertEquals("calendar", "ca", key);
+
+    key = keys->next(&resultLength, status);
+    status.errIfFailureAndReset("key #2");
+    assertEquals("resultLength", 2, resultLength);
+    assertTrue("key != nullptr", key != nullptr);
+    assertEquals("collation", "co", key);
+
+    key = keys->next(&resultLength, status);
+    status.errIfFailureAndReset("end of keys");
+    assertEquals("resultLength", 0, resultLength);
+    assertTrue("key == nullptr", key == nullptr);
+
+    const UnicodeString* skey;
+    keys->reset(status);  // KeywordEnumeration::reset() never touches status.
+
+    skey = keys->snext(status);
+    status.errIfFailureAndReset("skey #1");
+    assertTrue("skey != nullptr", skey != nullptr);
+    assertEquals("calendar", "ca", *skey);
+
+    skey = keys->snext(status);
+    status.errIfFailureAndReset("skey #2");
+    assertTrue("skey != nullptr", skey != nullptr);
+    assertEquals("collation", "co", *skey);
+
+    skey = keys->snext(status);
+    status.errIfFailureAndReset("end of keys");
+    assertTrue("skey == nullptr", skey == nullptr);
+}
+
+
 void
 LocaleTest::TestKeywordVariantParsing(void) {
     static const struct {
@@ -1739,6 +1832,74 @@ LocaleTest::TestKeywordVariantParsing(void) {
     }
 }
 
+void
+LocaleTest::TestCreateKeywordSet(void) {
+    IcuTestErrorCode status(*this, "TestCreateKeywordSet()");
+
+    static const Locale l("de@calendar=buddhist;collation=phonebook");
+
+    std::set<std::string> result;
+    l.getKeywords<std::string>(
+            std::insert_iterator<decltype(result)>(result, result.begin()),
+            status);
+    status.errIfFailureAndReset("\"%s\"", l.getName());
+
+    assertEquals("set::size()", 2, result.size());
+    assertTrue("set::find(\"calendar\")",
+               result.find("calendar") != result.end());
+    assertTrue("set::find(\"collation\")",
+               result.find("collation") != result.end());
+}
+
+void
+LocaleTest::TestCreateUnicodeKeywordSet(void) {
+    IcuTestErrorCode status(*this, "TestCreateUnicodeKeywordSet()");
+
+    static const Locale l("de@calendar=buddhist;collation=phonebook");
+
+    std::set<std::string> result;
+    l.getUnicodeKeywords<std::string>(
+            std::insert_iterator<decltype(result)>(result, result.begin()),
+            status);
+    status.errIfFailureAndReset("\"%s\"", l.getName());
+
+    assertEquals("set::size()", 2, result.size());
+    assertTrue("set::find(\"ca\")",
+               result.find("ca") != result.end());
+    assertTrue("set::find(\"co\")",
+               result.find("co") != result.end());
+}
+
+void
+LocaleTest::TestGetKeywordValueStdString(void) {
+    IcuTestErrorCode status(*this, "TestGetKeywordValueStdString()");
+
+    static const char tag[] = "fa-u-nu-latn";
+    static const char keyword[] = "numbers";
+    static const char expected[] = "latn";
+
+    Locale l = Locale::forLanguageTag(tag, status);
+    status.errIfFailureAndReset("\"%s\"", tag);
+
+    std::string result = l.getKeywordValue<std::string>(keyword, status);
+    status.errIfFailureAndReset("\"%s\"", keyword);
+    assertEquals(keyword, expected, result.c_str());
+}
+
+void
+LocaleTest::TestGetUnicodeKeywordValueStdString(void) {
+    IcuTestErrorCode status(*this, "TestGetUnicodeKeywordValueStdString()");
+
+    static const char keyword[] = "co";
+    static const char expected[] = "phonebk";
+
+    static const Locale l("de@calendar=buddhist;collation=phonebook");
+
+    std::string result = l.getUnicodeKeywordValue<std::string>(keyword, status);
+    status.errIfFailureAndReset("\"%s\"", keyword);
+    assertEquals(keyword, expected, result.c_str());
+}
+
 void
 LocaleTest::TestSetKeywordValue(void) {
     static const struct {
@@ -1774,6 +1935,33 @@ LocaleTest::TestSetKeywordValue(void) {
     }
 }
 
+void
+LocaleTest::TestSetKeywordValueStringPiece(void) {
+    IcuTestErrorCode status(*this, "TestSetKeywordValueStringPiece()");
+    Locale l(Locale::getGerman());
+
+    l.setKeywordValue(StringPiece("collation"), StringPiece("phonebook"), status);
+    l.setKeywordValue(StringPiece("calendarxxx", 8), StringPiece("buddhistxxx", 8), status);
+
+    static const char expected[] = "de@calendar=buddhist;collation=phonebook";
+    assertEquals("", expected, l.getName());
+}
+
+void
+LocaleTest::TestSetUnicodeKeywordValueStringPiece(void) {
+    IcuTestErrorCode status(*this, "TestSetUnicodeKeywordValueStringPiece()");
+    Locale l(Locale::getGerman());
+
+    l.setUnicodeKeywordValue(StringPiece("co"), StringPiece("phonebk"), status);
+    status.errIfFailureAndReset();
+
+    l.setUnicodeKeywordValue(StringPiece("caxxx", 2), StringPiece("buddhistxxx", 8), status);
+    status.errIfFailureAndReset();
+
+    static const char expected[] = "de@calendar=buddhist;collation=phonebook";
+    assertEquals("", expected, l.getName());
+}
+
 void
 LocaleTest::TestGetBaseName(void) {
     static const struct {
@@ -2845,3 +3033,95 @@ void LocaleTest::TestToLanguageTag() {
     assertEquals("bogus", U_ILLEGAL_ARGUMENT_ERROR, status.reset());
     assertTrue(result_bogus.c_str(), result_bogus.empty());
 }
+
+void LocaleTest::TestMoveAssign() {
+    // ULOC_FULLNAME_CAPACITY == 157 (uloc.h)
+    Locale l1("de@collation=phonebook;x="
+              "aaaaabbbbbcccccdddddeeeeefffffggggghhhhh"
+              "aaaaabbbbbcccccdddddeeeeefffffggggghhhhh"
+              "aaaaabbbbbcccccdddddeeeeefffffggggghhhhh"
+              "aaaaabbbbbzz");
+
+    Locale l2;
+    {
+        Locale l3(l1);
+        assertTrue("l1 == l3", l1 == l3);
+        l2 = std::move(l3);
+        assertTrue("l1 == l2", l1 == l2);
+        assertTrue("l2 != l3", l2.getName() != l3.getName());
+    }
+
+    // This should remain true also after l3 has been destructed.
+    assertTrue("l1 == l2, again", l1 == l2);
+
+    Locale l4("de@collation=phonebook");
+
+    Locale l5;
+    {
+        Locale l6(l4);
+        assertTrue("l4 == l6", l4 == l6);
+        l5 = std::move(l6);
+        assertTrue("l4 == l5", l4 == l5);
+        assertTrue("l5 != l6", l5.getName() != l6.getName());
+    }
+
+    // This should remain true also after l6 has been destructed.
+    assertTrue("l4 == l5, again", l4 == l5);
+
+    Locale l7("vo_Cyrl_AQ_EURO");
+
+    Locale l8;
+    {
+        Locale l9(l7);
+        assertTrue("l7 == l9", l7 == l9);
+        l8 = std::move(l9);
+        assertTrue("l7 == l8", l7 == l8);
+        assertTrue("l8 != l9", l8.getName() != l9.getName());
+    }
+
+    // This should remain true also after l9 has been destructed.
+    assertTrue("l7 == l8, again", l7 == l8);
+
+    assertEquals("language", l7.getLanguage(), l8.getLanguage());
+    assertEquals("script", l7.getScript(), l8.getScript());
+    assertEquals("country", l7.getCountry(), l8.getCountry());
+    assertEquals("variant", l7.getVariant(), l8.getVariant());
+    assertEquals("bogus", l7.isBogus(), l8.isBogus());
+}
+
+void LocaleTest::TestMoveCtor() {
+    // ULOC_FULLNAME_CAPACITY == 157 (uloc.h)
+    Locale l1("de@collation=phonebook;x="
+              "aaaaabbbbbcccccdddddeeeeefffffggggghhhhh"
+              "aaaaabbbbbcccccdddddeeeeefffffggggghhhhh"
+              "aaaaabbbbbcccccdddddeeeeefffffggggghhhhh"
+              "aaaaabbbbbzz");
+
+    Locale l3(l1);
+    assertTrue("l1 == l3", l1 == l3);
+    Locale l2(std::move(l3));
+    assertTrue("l1 == l2", l1 == l2);
+    assertTrue("l2 != l3", l2.getName() != l3.getName());
+
+    Locale l4("de@collation=phonebook");
+
+    Locale l6(l4);
+    assertTrue("l4 == l6", l4 == l6);
+    Locale l5(std::move(l6));
+    assertTrue("l4 == l5", l4 == l5);
+    assertTrue("l5 != l6", l5.getName() != l6.getName());
+
+    Locale l7("vo_Cyrl_AQ_EURO");
+
+    Locale l9(l7);
+    assertTrue("l7 == l9", l7 == l9);
+    Locale l8(std::move(l9));
+    assertTrue("l7 == l8", l7 == l8);
+    assertTrue("l8 != l9", l8.getName() != l9.getName());
+
+    assertEquals("language", l7.getLanguage(), l8.getLanguage());
+    assertEquals("script", l7.getScript(), l8.getScript());
+    assertEquals("country", l7.getCountry(), l8.getCountry());
+    assertEquals("variant", l7.getVariant(), l8.getVariant());
+    assertEquals("bogus", l7.isBogus(), l8.isBogus());
+}

icu4c/source/test/intltest/loctest.h

@@ -72,14 +72,21 @@ public:
     
     void TestVariantParsing(void);
 
-   /* Test getting keyword enumeratin */
+   /* Test getting keyword enumeration */
    void TestKeywordVariants(void);
+   void TestCreateUnicodeKeywords(void);
 
    /* Test getting keyword values */
    void TestKeywordVariantParsing(void);
+   void TestCreateKeywordSet(void);
+   void TestCreateUnicodeKeywordSet(void);
+   void TestGetKeywordValueStdString(void);
+   void TestGetUnicodeKeywordValueStdString(void);
 
    /* Test setting keyword values */
    void TestSetKeywordValue(void);
+   void TestSetKeywordValueStringPiece(void);
+   void TestSetUnicodeKeywordValueStringPiece(void);
 
    /* Test getting the locale base name */
    void TestGetBaseName(void);
@@ -108,9 +115,15 @@ public:
     void TestBug13277();
     void TestBug13554();
 
+    void TestAddLikelySubtags();
+    void TestMinimizeSubtags();
+
     void TestForLanguageTag();
     void TestToLanguageTag();
 
+    void TestMoveAssign();
+    void TestMoveCtor();
+
 private:
     void _checklocs(const char* label,
                     const char* req,

icu4c/source/test/intltest/numbertest.h

@@ -11,6 +11,8 @@
 #include "number_affixutils.h"
 #include "numparse_stringsegment.h"
 #include "unicode/locid.h"
+#include "unicode/numberformatter.h"
+#include "unicode/numberrangeformatter.h"
 
 using namespace icu::number;
 using namespace icu::number::impl;
@@ -244,6 +246,54 @@ class NumberSkeletonTest : public IntlTest {
     void expectedErrorSkeleton(const char16_t** cases, int32_t casesLen);
 };
 
+class NumberRangeFormatterTest : public IntlTest {
+  public:
+    NumberRangeFormatterTest();
+    NumberRangeFormatterTest(UErrorCode &status);
+
+    void testSanity();
+    void testBasic();
+    void testCollapse();
+    void testIdentity();
+    void testDifferentFormatters();
+    void testPlurals();
+    void testCopyMove();
+
+    void runIndexedTest(int32_t index, UBool exec, const char *&name, char *par = 0);
+
+  private:
+    CurrencyUnit USD;
+    CurrencyUnit GBP;
+    CurrencyUnit PTE;
+
+    MeasureUnit METER;
+    MeasureUnit KILOMETER;
+    MeasureUnit FAHRENHEIT;
+    MeasureUnit KELVIN;
+
+    void assertFormatRange(
+      const char16_t* message,
+      const UnlocalizedNumberRangeFormatter& f,
+      Locale locale,
+      const char16_t* expected_10_50,
+      const char16_t* expected_49_51,
+      const char16_t* expected_50_50,
+      const char16_t* expected_00_30,
+      const char16_t* expected_00_00,
+      const char16_t* expected_30_3K,
+      const char16_t* expected_30K_50K,
+      const char16_t* expected_49K_51K,
+      const char16_t* expected_50K_50K,
+      const char16_t* expected_50K_50M);
+    
+    void assertFormattedRangeEquals(
+      const char16_t* message,
+      const LocalizedNumberRangeFormatter& l,
+      double first,
+      double second,
+      const char16_t* expected);
+};
+
 
 // NOTE: This macro is identical to the one in itformat.cpp
 #define TESTCLASS(id, TestClass)          \
@@ -276,6 +326,7 @@ class NumberTest : public IntlTest {
         TESTCLASS(8, StringSegmentTest);
         TESTCLASS(9, NumberParserTest);
         TESTCLASS(10, NumberSkeletonTest);
+        TESTCLASS(11, NumberRangeFormatterTest);
         default: name = ""; break; // needed to end loop
         }
     }

icu4c/source/test/intltest/numbertest_api.cpp

@@ -17,6 +17,7 @@
 #include "unicode/utypes.h"
 
 // Horrible workaround for the lack of a status code in the constructor...
+// (Also affects numbertest_range.cpp)
 UErrorCode globalNumberFormatterApiTestStatus = U_ZERO_ERROR;
 
 NumberFormatterApiTest::NumberFormatterApiTest()
@@ -2371,8 +2372,15 @@ void NumberFormatterApiTest::copyMove() {
     assertTrue("[constructor] Source should be reset after move", l1.getCompiled() == nullptr);
 
     // Reset l1 and l2 to check for macro-props copying for behavior testing
+    // Make the test more interesting: also warm them up with a compiled formatter.
     l1 = NumberFormatter::withLocale("en");
+    l1.formatInt(1, status);
+    l1.formatInt(1, status);
+    l1.formatInt(1, status);
     l2 = NumberFormatter::withLocale("en");
+    l2.formatInt(1, status);
+    l2.formatInt(1, status);
+    l2.formatInt(1, status);
 
     // Copy assignment
     l1 = l3;

icu4c/source/test/intltest/numbertest_modifiers.cpp

@@ -162,12 +162,12 @@ void ModifiersTest::assertModifierEquals(const Modifier &mod, NumberStringBuilde
                                          UErrorCode &status) {
     int32_t oldCount = sb.codePointCount();
     mod.apply(sb, 0, sb.length(), status);
-    assertEquals("Prefix length", expectedPrefixLength, mod.getPrefixLength(status));
+    assertEquals("Prefix length", expectedPrefixLength, mod.getPrefixLength());
     assertEquals("Strong", expectedStrong, mod.isStrong());
     if (dynamic_cast<const CurrencySpacingEnabledModifier*>(&mod) == nullptr) {
         // i.e., if mod is not a CurrencySpacingEnabledModifier
         assertEquals("Code point count equals actual code point count",
-                sb.codePointCount() - oldCount, mod.getCodePointCount(status));
+                sb.codePointCount() - oldCount, mod.getCodePointCount());
     }
 
     UnicodeString debugString;

icu4c/source/test/intltest/numbertest_patternmodifier.cpp

@@ -170,14 +170,14 @@ void PatternModifierTest::testMutableEqualsImmutable() {
 UnicodeString PatternModifierTest::getPrefix(const MutablePatternModifier &mod, UErrorCode &status) {
     NumberStringBuilder nsb;
     mod.apply(nsb, 0, 0, status);
-    int32_t prefixLength = mod.getPrefixLength(status);
+    int32_t prefixLength = mod.getPrefixLength();
     return UnicodeString(nsb.toUnicodeString(), 0, prefixLength);
 }
 
 UnicodeString PatternModifierTest::getSuffix(const MutablePatternModifier &mod, UErrorCode &status) {
     NumberStringBuilder nsb;
     mod.apply(nsb, 0, 0, status);
-    int32_t prefixLength = mod.getPrefixLength(status);
+    int32_t prefixLength = mod.getPrefixLength();
     return UnicodeString(nsb.toUnicodeString(), prefixLength, nsb.length() - prefixLength);
 }
 

icu4c/source/test/intltest/numbertest_range.cpp

@@ -0,0 +1,793 @@
+// © 2018 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
+
+#include "unicode/utypes.h"
+
+#if !UCONFIG_NO_FORMATTING
+
+#include "numbertest.h"
+#include "unicode/numberrangeformatter.h"
+
+#include <cmath>
+#include <numparse_affixes.h>
+
+// Horrible workaround for the lack of a status code in the constructor...
+// (Also affects numbertest_api.cpp)
+UErrorCode globalNumberRangeFormatterTestStatus = U_ZERO_ERROR;
+
+NumberRangeFormatterTest::NumberRangeFormatterTest()
+        : NumberRangeFormatterTest(globalNumberRangeFormatterTestStatus) {
+}
+
+NumberRangeFormatterTest::NumberRangeFormatterTest(UErrorCode& status)
+        : USD(u"USD", status),
+          GBP(u"GBP", status),
+          PTE(u"PTE", status) {
+
+    // Check for error on the first MeasureUnit in case there is no data
+    LocalPointer<MeasureUnit> unit(MeasureUnit::createMeter(status));
+    if (U_FAILURE(status)) {
+        dataerrln("%s %d status = %s", __FILE__, __LINE__, u_errorName(status));
+        return;
+    }
+    METER = *unit;
+
+    KILOMETER = *LocalPointer<MeasureUnit>(MeasureUnit::createKilometer(status));
+    FAHRENHEIT = *LocalPointer<MeasureUnit>(MeasureUnit::createFahrenheit(status));
+    KELVIN = *LocalPointer<MeasureUnit>(MeasureUnit::createKelvin(status));
+}
+
+void NumberRangeFormatterTest::runIndexedTest(int32_t index, UBool exec, const char*& name, char*) {
+    if (exec) {
+        logln("TestSuite NumberRangeFormatterTest: ");
+    }
+    TESTCASE_AUTO_BEGIN;
+        TESTCASE_AUTO(testSanity);
+        TESTCASE_AUTO(testBasic);
+        TESTCASE_AUTO(testCollapse);
+        TESTCASE_AUTO(testIdentity);
+        TESTCASE_AUTO(testDifferentFormatters);
+        TESTCASE_AUTO(testPlurals);
+        TESTCASE_AUTO(testCopyMove);
+    TESTCASE_AUTO_END;
+}
+
+void NumberRangeFormatterTest::testSanity() {
+    IcuTestErrorCode status(*this, "testSanity");
+    LocalizedNumberRangeFormatter lnrf1 = NumberRangeFormatter::withLocale("en-us");
+    LocalizedNumberRangeFormatter lnrf2 = NumberRangeFormatter::with().locale("en-us");
+    assertEquals("Formatters should have same behavior 1",
+        lnrf1.formatFormattableRange(4, 6, status).toString(status),
+        lnrf2.formatFormattableRange(4, 6, status).toString(status));
+}
+
+void NumberRangeFormatterTest::testBasic() {
+    assertFormatRange(
+        u"Basic",
+        NumberRangeFormatter::with(),
+        Locale("en-us"),
+        u"1–5",
+        u"~5",
+        u"~5",
+        u"0–3",
+        u"~0",
+        u"3–3,000",
+        u"3,000–5,000",
+        u"4,999–5,001",
+        u"~5,000",
+        u"5,000–5,000,000");
+
+    assertFormatRange(
+        u"Basic with units",
+        NumberRangeFormatter::with()
+            .numberFormatterBoth(NumberFormatter::with().unit(METER)),
+        Locale("en-us"),
+        u"1–5 m",
+        u"~5 m",
+        u"~5 m",
+        u"0–3 m",
+        u"~0 m",
+        u"3–3,000 m",
+        u"3,000–5,000 m",
+        u"4,999–5,001 m",
+        u"~5,000 m",
+        u"5,000–5,000,000 m");
+
+    assertFormatRange(
+        u"Basic with different units",
+        NumberRangeFormatter::with()
+            .numberFormatterFirst(NumberFormatter::with().unit(METER))
+            .numberFormatterSecond(NumberFormatter::with().unit(KILOMETER)),
+        Locale("en-us"),
+        u"1 m – 5 km",
+        u"5 m – 5 km",
+        u"5 m – 5 km",
+        u"0 m – 3 km",
+        u"0 m – 0 km",
+        u"3 m – 3,000 km",
+        u"3,000 m – 5,000 km",
+        u"4,999 m – 5,001 km",
+        u"5,000 m – 5,000 km",
+        u"5,000 m – 5,000,000 km");
+
+    assertFormatRange(
+        u"Basic long unit",
+        NumberRangeFormatter::with()
+            .numberFormatterBoth(NumberFormatter::with().unit(METER).unitWidth(UNUM_UNIT_WIDTH_FULL_NAME)),
+        Locale("en-us"),
+        u"1–5 meters",
+        u"~5 meters",
+        u"~5 meters",
+        u"0–3 meters",
+        u"~0 meters",
+        u"3–3,000 meters",
+        u"3,000–5,000 meters",
+        u"4,999–5,001 meters",
+        u"~5,000 meters",
+        u"5,000–5,000,000 meters");
+
+    assertFormatRange(
+        u"Non-English locale and unit",
+        NumberRangeFormatter::with()
+            .numberFormatterBoth(NumberFormatter::with().unit(FAHRENHEIT).unitWidth(UNUM_UNIT_WIDTH_FULL_NAME)),
+        Locale("fr-FR"),
+        u"1–5 degrés Fahrenheit",
+        u"~5 degrés Fahrenheit",
+        u"~5 degrés Fahrenheit",
+        u"0–3 degrés Fahrenheit",
+        u"~0 degré Fahrenheit",
+        u"3–3 000 degrés Fahrenheit",
+        u"3 000–5 000 degrés Fahrenheit",
+        u"4 999–5 001 degrés Fahrenheit",
+        u"~5 000 degrés Fahrenheit",
+        u"5 000–5 000 000 degrés Fahrenheit");
+
+    assertFormatRange(
+        u"Locale with custom range separator",
+        NumberRangeFormatter::with(),
+        Locale("ja"),
+        u"1～5",
+        u"~5",
+        u"~5",
+        u"0～3",
+        u"~0",
+        u"3～3,000",
+        u"3,000～5,000",
+        u"4,999～5,001",
+        u"~5,000",
+        u"5,000～5,000,000");
+
+    assertFormatRange(
+        u"Locale that already has spaces around range separator",
+        NumberRangeFormatter::with()
+            .collapse(UNUM_RANGE_COLLAPSE_NONE)
+            .numberFormatterBoth(NumberFormatter::with().unit(KELVIN)),
+        Locale("hr"),
+        u"1 K – 5 K",
+        u"~5 K",
+        u"~5 K",
+        u"0 K – 3 K",
+        u"~0 K",
+        u"3 K – 3.000 K",
+        u"3.000 K – 5.000 K",
+        u"4.999 K – 5.001 K",
+        u"~5.000 K",
+        u"5.000 K – 5.000.000 K");
+
+    assertFormatRange(
+        u"Locale with custom numbering system and no plural ranges data",
+        NumberRangeFormatter::with(),
+        Locale("shn@numbers=beng"),
+        // 012459 = ০১৩৪৫৯
+        u"১–৫",
+        u"~৫",
+        u"~৫",
+        u"০–৩",
+        u"~০",
+        u"৩–৩,০০০",
+        u"৩,০০০–৫,০০০",
+        u"৪,৯৯৯–৫,০০১",
+        u"~৫,০০০",
+        u"৫,০০০–৫,০০০,০০০");
+
+    assertFormatRange(
+        u"Portuguese currency",
+        NumberRangeFormatter::with()
+            .numberFormatterBoth(NumberFormatter::with().unit(PTE)),
+        Locale("pt-PT"),
+        u"1$00 - 5$00 \u200B",
+        u"~5$00 \u200B",
+        u"~5$00 \u200B",
+        u"0$00 - 3$00 \u200B",
+        u"~0$00 \u200B",
+        u"3$00 - 3000$00 \u200B",
+        u"3000$00 - 5000$00 \u200B",
+        u"4999$00 - 5001$00 \u200B",
+        u"~5000$00 \u200B",
+        u"5000$00 - 5,000,000$00 \u200B");
+}
+
+void NumberRangeFormatterTest::testCollapse() {
+    assertFormatRange(
+        u"Default collapse on currency (default rounding)",
+        NumberRangeFormatter::with()
+            .numberFormatterBoth(NumberFormatter::with().unit(USD)),
+        Locale("en-us"),
+        u"$1.00 – $5.00",
+        u"~$5.00",
+        u"~$5.00",
+        u"$0.00 – $3.00",
+        u"~$0.00",
+        u"$3.00 – $3,000.00",
+        u"$3,000.00 – $5,000.00",
+        u"$4,999.00 – $5,001.00",
+        u"~$5,000.00",
+        u"$5,000.00 – $5,000,000.00");
+
+    assertFormatRange(
+        u"Default collapse on currency",
+        NumberRangeFormatter::with()
+            .numberFormatterBoth(NumberFormatter::with().unit(USD).precision(Precision::integer())),
+        Locale("en-us"),
+        u"$1 – $5",
+        u"~$5",
+        u"~$5",
+        u"$0 – $3",
+        u"~$0",
+        u"$3 – $3,000",
+        u"$3,000 – $5,000",
+        u"$4,999 – $5,001",
+        u"~$5,000",
+        u"$5,000 – $5,000,000");
+
+    assertFormatRange(
+        u"No collapse on currency",
+        NumberRangeFormatter::with()
+            .collapse(UNUM_RANGE_COLLAPSE_NONE)
+            .numberFormatterBoth(NumberFormatter::with().unit(USD).precision(Precision::integer())),
+        Locale("en-us"),
+        u"$1 – $5",
+        u"~$5",
+        u"~$5",
+        u"$0 – $3",
+        u"~$0",
+        u"$3 – $3,000",
+        u"$3,000 – $5,000",
+        u"$4,999 – $5,001",
+        u"~$5,000",
+        u"$5,000 – $5,000,000");
+
+    assertFormatRange(
+        u"Unit collapse on currency",
+        NumberRangeFormatter::with()
+            .collapse(UNUM_RANGE_COLLAPSE_UNIT)
+            .numberFormatterBoth(NumberFormatter::with().unit(USD).precision(Precision::integer())),
+        Locale("en-us"),
+        u"$1–5",
+        u"~$5",
+        u"~$5",
+        u"$0–3",
+        u"~$0",
+        u"$3–3,000",
+        u"$3,000–5,000",
+        u"$4,999–5,001",
+        u"~$5,000",
+        u"$5,000–5,000,000");
+
+    assertFormatRange(
+        u"All collapse on currency",
+        NumberRangeFormatter::with()
+            .collapse(UNUM_RANGE_COLLAPSE_ALL)
+            .numberFormatterBoth(NumberFormatter::with().unit(USD).precision(Precision::integer())),
+        Locale("en-us"),
+        u"$1–5",
+        u"~$5",
+        u"~$5",
+        u"$0–3",
+        u"~$0",
+        u"$3–3,000",
+        u"$3,000–5,000",
+        u"$4,999–5,001",
+        u"~$5,000",
+        u"$5,000–5,000,000");
+
+    assertFormatRange(
+        u"Default collapse on currency ISO code",
+        NumberRangeFormatter::with()
+            .numberFormatterBoth(NumberFormatter::with()
+                .unit(GBP)
+                .unitWidth(UNUM_UNIT_WIDTH_ISO_CODE)
+                .precision(Precision::integer())),
+        Locale("en-us"),
+        u"GBP 1–5",
+        u"~GBP 5",  // TODO: Fix this at some point
+        u"~GBP 5",
+        u"GBP 0–3",
+        u"~GBP 0",
+        u"GBP 3–3,000",
+        u"GBP 3,000–5,000",
+        u"GBP 4,999–5,001",
+        u"~GBP 5,000",
+        u"GBP 5,000–5,000,000");
+
+    assertFormatRange(
+        u"No collapse on currency ISO code",
+        NumberRangeFormatter::with()
+            .collapse(UNUM_RANGE_COLLAPSE_NONE)
+            .numberFormatterBoth(NumberFormatter::with()
+                .unit(GBP)
+                .unitWidth(UNUM_UNIT_WIDTH_ISO_CODE)
+                .precision(Precision::integer())),
+        Locale("en-us"),
+        u"GBP 1 – GBP 5",
+        u"~GBP 5",  // TODO: Fix this at some point
+        u"~GBP 5",
+        u"GBP 0 – GBP 3",
+        u"~GBP 0",
+        u"GBP 3 – GBP 3,000",
+        u"GBP 3,000 – GBP 5,000",
+        u"GBP 4,999 – GBP 5,001",
+        u"~GBP 5,000",
+        u"GBP 5,000 – GBP 5,000,000");
+
+    assertFormatRange(
+        u"Unit collapse on currency ISO code",
+        NumberRangeFormatter::with()
+            .collapse(UNUM_RANGE_COLLAPSE_UNIT)
+            .numberFormatterBoth(NumberFormatter::with()
+                .unit(GBP)
+                .unitWidth(UNUM_UNIT_WIDTH_ISO_CODE)
+                .precision(Precision::integer())),
+        Locale("en-us"),
+        u"GBP 1–5",
+        u"~GBP 5",  // TODO: Fix this at some point
+        u"~GBP 5",
+        u"GBP 0–3",
+        u"~GBP 0",
+        u"GBP 3–3,000",
+        u"GBP 3,000–5,000",
+        u"GBP 4,999–5,001",
+        u"~GBP 5,000",
+        u"GBP 5,000–5,000,000");
+
+    assertFormatRange(
+        u"All collapse on currency ISO code",
+        NumberRangeFormatter::with()
+            .collapse(UNUM_RANGE_COLLAPSE_ALL)
+            .numberFormatterBoth(NumberFormatter::with()
+                .unit(GBP)
+                .unitWidth(UNUM_UNIT_WIDTH_ISO_CODE)
+                .precision(Precision::integer())),
+        Locale("en-us"),
+        u"GBP 1–5",
+        u"~GBP 5",  // TODO: Fix this at some point
+        u"~GBP 5",
+        u"GBP 0–3",
+        u"~GBP 0",
+        u"GBP 3–3,000",
+        u"GBP 3,000–5,000",
+        u"GBP 4,999–5,001",
+        u"~GBP 5,000",
+        u"GBP 5,000–5,000,000");
+
+    // Default collapse on measurement unit is in testBasic()
+
+    assertFormatRange(
+        u"No collapse on measurement unit",
+        NumberRangeFormatter::with()
+            .collapse(UNUM_RANGE_COLLAPSE_NONE)
+            .numberFormatterBoth(NumberFormatter::with().unit(METER)),
+        Locale("en-us"),
+        u"1 m – 5 m",
+        u"~5 m",
+        u"~5 m",
+        u"0 m – 3 m",
+        u"~0 m",
+        u"3 m – 3,000 m",
+        u"3,000 m – 5,000 m",
+        u"4,999 m – 5,001 m",
+        u"~5,000 m",
+        u"5,000 m – 5,000,000 m");
+
+    assertFormatRange(
+        u"Unit collapse on measurement unit",
+        NumberRangeFormatter::with()
+            .collapse(UNUM_RANGE_COLLAPSE_UNIT)
+            .numberFormatterBoth(NumberFormatter::with().unit(METER)),
+        Locale("en-us"),
+        u"1–5 m",
+        u"~5 m",
+        u"~5 m",
+        u"0–3 m",
+        u"~0 m",
+        u"3–3,000 m",
+        u"3,000–5,000 m",
+        u"4,999–5,001 m",
+        u"~5,000 m",
+        u"5,000–5,000,000 m");
+
+    assertFormatRange(
+        u"All collapse on measurement unit",
+        NumberRangeFormatter::with()
+            .collapse(UNUM_RANGE_COLLAPSE_ALL)
+            .numberFormatterBoth(NumberFormatter::with().unit(METER)),
+        Locale("en-us"),
+        u"1–5 m",
+        u"~5 m",
+        u"~5 m",
+        u"0–3 m",
+        u"~0 m",
+        u"3–3,000 m",
+        u"3,000–5,000 m",
+        u"4,999–5,001 m",
+        u"~5,000 m",
+        u"5,000–5,000,000 m");
+
+    assertFormatRange(
+        u"Default collapse, long-form compact notation",
+        NumberRangeFormatter::with()
+            .numberFormatterBoth(NumberFormatter::with().notation(Notation::compactLong())),
+        Locale("de-CH"),
+        u"1–5",
+        u"~5",
+        u"~5",
+        u"0–3",
+        u"~0",
+        u"3–3 Tausend",
+        u"3–5 Tausend",
+        u"~5 Tausend",
+        u"~5 Tausend",
+        u"5 Tausend – 5 Millionen");
+
+    assertFormatRange(
+        u"Unit collapse, long-form compact notation",
+        NumberRangeFormatter::with()
+            .collapse(UNUM_RANGE_COLLAPSE_UNIT)
+            .numberFormatterBoth(NumberFormatter::with().notation(Notation::compactLong())),
+        Locale("de-CH"),
+        u"1–5",
+        u"~5",
+        u"~5",
+        u"0–3",
+        u"~0",
+        u"3–3 Tausend",
+        u"3 Tausend – 5 Tausend",
+        u"~5 Tausend",
+        u"~5 Tausend",
+        u"5 Tausend – 5 Millionen");
+
+    assertFormatRange(
+        u"Default collapse on measurement unit with compact-short notation",
+        NumberRangeFormatter::with()
+            .numberFormatterBoth(NumberFormatter::with().notation(Notation::compactShort()).unit(METER)),
+        Locale("en-us"),
+        u"1–5 m",
+        u"~5 m",
+        u"~5 m",
+        u"0–3 m",
+        u"~0 m",
+        u"3–3K m",
+        u"3K – 5K m",
+        u"~5K m",
+        u"~5K m",
+        u"5K – 5M m");
+
+    assertFormatRange(
+        u"No collapse on measurement unit with compact-short notation",
+        NumberRangeFormatter::with()
+            .collapse(UNUM_RANGE_COLLAPSE_NONE)
+            .numberFormatterBoth(NumberFormatter::with().notation(Notation::compactShort()).unit(METER)),
+        Locale("en-us"),
+        u"1 m – 5 m",
+        u"~5 m",
+        u"~5 m",
+        u"0 m – 3 m",
+        u"~0 m",
+        u"3 m – 3K m",
+        u"3K m – 5K m",
+        u"~5K m",
+        u"~5K m",
+        u"5K m – 5M m");
+
+    assertFormatRange(
+        u"Unit collapse on measurement unit with compact-short notation",
+        NumberRangeFormatter::with()
+            .collapse(UNUM_RANGE_COLLAPSE_UNIT)
+            .numberFormatterBoth(NumberFormatter::with().notation(Notation::compactShort()).unit(METER)),
+        Locale("en-us"),
+        u"1–5 m",
+        u"~5 m",
+        u"~5 m",
+        u"0–3 m",
+        u"~0 m",
+        u"3–3K m",
+        u"3K – 5K m",
+        u"~5K m",
+        u"~5K m",
+        u"5K – 5M m");
+
+    assertFormatRange(
+        u"All collapse on measurement unit with compact-short notation",
+        NumberRangeFormatter::with()
+            .collapse(UNUM_RANGE_COLLAPSE_ALL)
+            .numberFormatterBoth(NumberFormatter::with().notation(Notation::compactShort()).unit(METER)),
+        Locale("en-us"),
+        u"1–5 m",
+        u"~5 m",
+        u"~5 m",
+        u"0–3 m",
+        u"~0 m",
+        u"3–3K m",
+        u"3–5K m",  // this one is the key use case for ALL
+        u"~5K m",
+        u"~5K m",
+        u"5K – 5M m");
+
+    assertFormatRange(
+        u"No collapse on scientific notation",
+        NumberRangeFormatter::with()
+            .collapse(UNUM_RANGE_COLLAPSE_NONE)
+            .numberFormatterBoth(NumberFormatter::with().notation(Notation::scientific())),
+        Locale("en-us"),
+        u"1E0 – 5E0",
+        u"~5E0",
+        u"~5E0",
+        u"0E0 – 3E0",
+        u"~0E0",
+        u"3E0 – 3E3",
+        u"3E3 – 5E3",
+        u"4.999E3 – 5.001E3",
+        u"~5E3",
+        u"5E3 – 5E6");
+
+    assertFormatRange(
+        u"All collapse on scientific notation",
+        NumberRangeFormatter::with()
+            .collapse(UNUM_RANGE_COLLAPSE_ALL)
+            .numberFormatterBoth(NumberFormatter::with().notation(Notation::scientific())),
+        Locale("en-us"),
+        u"1–5E0",
+        u"~5E0",
+        u"~5E0",
+        u"0–3E0",
+        u"~0E0",
+        u"3E0 – 3E3",
+        u"3–5E3",
+        u"4.999–5.001E3",
+        u"~5E3",
+        u"5E3 – 5E6");
+
+    // TODO: Test compact currency?
+    // The code is not smart enough to differentiate the notation from the unit.
+}
+
+void NumberRangeFormatterTest::testIdentity() {
+    assertFormatRange(
+        u"Identity fallback Range",
+        NumberRangeFormatter::with().identityFallback(UNUM_IDENTITY_FALLBACK_RANGE),
+        Locale("en-us"),
+        u"1–5",
+        u"5–5",
+        u"5–5",
+        u"0–3",
+        u"0–0",
+        u"3–3,000",
+        u"3,000–5,000",
+        u"4,999–5,001",
+        u"5,000–5,000",
+        u"5,000–5,000,000");
+
+    assertFormatRange(
+        u"Identity fallback Approximately or Single Value",
+        NumberRangeFormatter::with().identityFallback(UNUM_IDENTITY_FALLBACK_APPROXIMATELY_OR_SINGLE_VALUE),
+        Locale("en-us"),
+        u"1–5",
+        u"~5",
+        u"5",
+        u"0–3",
+        u"0",
+        u"3–3,000",
+        u"3,000–5,000",
+        u"4,999–5,001",
+        u"5,000",
+        u"5,000–5,000,000");
+
+    assertFormatRange(
+        u"Identity fallback  Single Value",
+        NumberRangeFormatter::with().identityFallback(UNUM_IDENTITY_FALLBACK_SINGLE_VALUE),
+        Locale("en-us"),
+        u"1–5",
+        u"5",
+        u"5",
+        u"0–3",
+        u"0",
+        u"3–3,000",
+        u"3,000–5,000",
+        u"4,999–5,001",
+        u"5,000",
+        u"5,000–5,000,000");
+
+    assertFormatRange(
+        u"Identity fallback Approximately or Single Value with compact notation",
+        NumberRangeFormatter::with()
+            .identityFallback(UNUM_IDENTITY_FALLBACK_APPROXIMATELY_OR_SINGLE_VALUE)
+            .numberFormatterBoth(NumberFormatter::with().notation(Notation::compactShort())),
+        Locale("en-us"),
+        u"1–5",
+        u"~5",
+        u"5",
+        u"0–3",
+        u"0",
+        u"3–3K",
+        u"3K – 5K",
+        u"~5K",
+        u"5K",
+        u"5K – 5M");
+}
+
+void NumberRangeFormatterTest::testDifferentFormatters() {
+    assertFormatRange(
+        u"Different rounding rules",
+        NumberRangeFormatter::with()
+            .numberFormatterFirst(NumberFormatter::with().precision(Precision::integer()))
+            .numberFormatterSecond(NumberFormatter::with().precision(Precision::fixedDigits(2))),
+        Locale("en-us"),
+        u"1–5.0",
+        u"5–5.0",
+        u"5–5.0",
+        u"0–3.0",
+        u"0–0.0",
+        u"3–3,000",
+        u"3,000–5,000",
+        u"4,999–5,000",
+        u"5,000–5,000",  // TODO: Should this one be ~5,000?
+        u"5,000–5,000,000");
+}
+
+void NumberRangeFormatterTest::testPlurals() {
+    IcuTestErrorCode status(*this, "testPlurals");
+
+    // Locale sl has interesting plural forms:
+    // GBP{
+    //     one{"britanski funt"}
+    //     two{"britanska funta"}
+    //     few{"britanski funti"}
+    //     other{"britanskih funtov"}
+    // }
+    Locale locale("sl");
+
+    UnlocalizedNumberFormatter unf = NumberFormatter::with()
+        .unit(GBP)
+        .unitWidth(UNUM_UNIT_WIDTH_FULL_NAME)
+        .precision(Precision::integer());
+    LocalizedNumberFormatter lnf = unf.locale(locale);
+
+    // For comparison, run the non-range version of the formatter
+    assertEquals(Int64ToUnicodeString(1), u"1 britanski funt", lnf.formatDouble(1, status).toString(status));
+    assertEquals(Int64ToUnicodeString(2), u"2 britanska funta", lnf.formatDouble(2, status).toString(status));
+    assertEquals(Int64ToUnicodeString(3), u"3 britanski funti", lnf.formatDouble(3, status).toString(status));
+    assertEquals(Int64ToUnicodeString(5), u"5 britanskih funtov", lnf.formatDouble(5, status).toString(status));
+    if (status.errIfFailureAndReset()) { return; }
+
+    LocalizedNumberRangeFormatter lnrf = NumberRangeFormatter::with()
+        .numberFormatterBoth(unf)
+        .identityFallback(UNUM_IDENTITY_FALLBACK_RANGE)
+        .locale(locale);
+
+    struct TestCase {
+        double first;
+        double second;
+        const char16_t* expected;
+    } cases[] = {
+        {1, 1, u"1–1 britanski funti"}, // one + one -> few
+        {1, 2, u"1–2 britanska funta"}, // one + two -> two
+        {1, 3, u"1–3 britanski funti"}, // one + few -> few
+        {1, 5, u"1–5 britanskih funtov"}, // one + other -> other
+        {2, 1, u"2–1 britanski funti"}, // two + one -> few
+        {2, 2, u"2–2 britanska funta"}, // two + two -> two
+        {2, 3, u"2–3 britanski funti"}, // two + few -> few
+        {2, 5, u"2–5 britanskih funtov"}, // two + other -> other
+        {3, 1, u"3–1 britanski funti"}, // few + one -> few
+        {3, 2, u"3–2 britanska funta"}, // few + two -> two
+        {3, 3, u"3–3 britanski funti"}, // few + few -> few
+        {3, 5, u"3–5 britanskih funtov"}, // few + other -> other
+        {5, 1, u"5–1 britanski funti"}, // other + one -> few
+        {5, 2, u"5–2 britanska funta"}, // other + two -> two
+        {5, 3, u"5–3 britanski funti"}, // other + few -> few
+        {5, 5, u"5–5 britanskih funtov"}, // other + other -> other
+    };
+    for (auto& cas : cases) {
+        UnicodeString message = Int64ToUnicodeString(cas.first);
+        message += u" ";
+        message += Int64ToUnicodeString(cas.second);
+        status.setScope(message);
+        UnicodeString actual = lnrf.formatFormattableRange(cas.first, cas.second, status).toString(status);
+        assertEquals(message, cas.expected, actual);
+        status.errIfFailureAndReset();
+    }
+}
+
+void NumberRangeFormatterTest::testCopyMove() {
+    IcuTestErrorCode status(*this, "testCopyMove");
+
+    // Default constructors
+    LocalizedNumberRangeFormatter l1;
+    assertEquals("Initial behavior", u"1–5", l1.formatFormattableRange(1, 5, status).toString(status));
+    if (status.errDataIfFailureAndReset()) { return; }
+
+    // Setup
+    l1 = NumberRangeFormatter::withLocale("fr-FR")
+        .numberFormatterBoth(NumberFormatter::with().unit(USD));
+    assertEquals("Currency behavior", u"1,00–5,00 $US", l1.formatFormattableRange(1, 5, status).toString(status));
+
+    // Copy constructor
+    LocalizedNumberRangeFormatter l2 = l1;
+    assertEquals("Copy constructor", u"1,00–5,00 $US", l2.formatFormattableRange(1, 5, status).toString(status));
+
+    // Move constructor
+    LocalizedNumberRangeFormatter l3 = std::move(l1);
+    assertEquals("Move constructor", u"1,00–5,00 $US", l3.formatFormattableRange(1, 5, status).toString(status));
+
+    // Reset objects for assignment tests
+    l1 = NumberRangeFormatter::withLocale("en-us");
+    l2 = NumberRangeFormatter::withLocale("en-us");
+    assertEquals("Rest behavior, l1", u"1–5", l1.formatFormattableRange(1, 5, status).toString(status));
+    assertEquals("Rest behavior, l2", u"1–5", l2.formatFormattableRange(1, 5, status).toString(status));
+
+    // Copy assignment
+    l1 = l3;
+    assertEquals("Copy constructor", u"1,00–5,00 $US", l1.formatFormattableRange(1, 5, status).toString(status));
+
+    // Move assignment
+    l2 = std::move(l3);
+    assertEquals("Copy constructor", u"1,00–5,00 $US", l2.formatFormattableRange(1, 5, status).toString(status));
+
+    // FormattedNumberRange
+    FormattedNumberRange result = l1.formatFormattableRange(1, 5, status);
+    assertEquals("FormattedNumberRange move constructor", u"1,00–5,00 $US", result.toString(status));
+    result = l1.formatFormattableRange(3, 6, status);
+    assertEquals("FormattedNumberRange move assignment", u"3,00–6,00 $US", result.toString(status));
+}
+
+void  NumberRangeFormatterTest::assertFormatRange(
+      const char16_t* message,
+      const UnlocalizedNumberRangeFormatter& f,
+      Locale locale,
+      const char16_t* expected_10_50,
+      const char16_t* expected_49_51,
+      const char16_t* expected_50_50,
+      const char16_t* expected_00_30,
+      const char16_t* expected_00_00,
+      const char16_t* expected_30_3K,
+      const char16_t* expected_30K_50K,
+      const char16_t* expected_49K_51K,
+      const char16_t* expected_50K_50K,
+      const char16_t* expected_50K_50M) {
+    LocalizedNumberRangeFormatter l = f.locale(locale);
+    assertFormattedRangeEquals(message, l, 1, 5, expected_10_50);
+    assertFormattedRangeEquals(message, l, 4.9999999, 5.0000001, expected_49_51);
+    assertFormattedRangeEquals(message, l, 5, 5, expected_50_50);
+    assertFormattedRangeEquals(message, l, 0, 3, expected_00_30);
+    assertFormattedRangeEquals(message, l, 0, 0, expected_00_00);
+    assertFormattedRangeEquals(message, l, 3, 3000, expected_30_3K);
+    assertFormattedRangeEquals(message, l, 3000, 5000, expected_30K_50K);
+    assertFormattedRangeEquals(message, l, 4999, 5001, expected_49K_51K);
+    assertFormattedRangeEquals(message, l, 5000, 5000, expected_50K_50K);
+    assertFormattedRangeEquals(message, l, 5e3, 5e6, expected_50K_50M);
+}
+
+void NumberRangeFormatterTest::assertFormattedRangeEquals(
+      const char16_t* message,
+      const LocalizedNumberRangeFormatter& l,
+      double first,
+      double second,
+      const char16_t* expected) {
+    IcuTestErrorCode status(*this, "assertFormattedRangeEquals");
+    UnicodeString fullMessage = UnicodeString(message) + u": " + DoubleToUnicodeString(first) + u", " + DoubleToUnicodeString(second);
+    status.setScope(fullMessage);
+    UnicodeString actual = l.formatFormattableRange(first, second, status).toString(status);
+    assertEquals(fullMessage, expected, actual);
+}
+
+
+#endif

icu4c/source/test/intltest/numfmtst.cpp

@@ -215,6 +215,7 @@ void NumberFormatTest::runIndexedTest( int32_t index, UBool exec, const char* &n
   TESTCASE_AUTO(Test13763_FieldPositionIteratorOffset);
   TESTCASE_AUTO(Test13777_ParseLongNameNonCurrencyMode);
   TESTCASE_AUTO(Test13804_EmptyStringsWhenParsing);
+  TESTCASE_AUTO(Test20037_ScientificIntegerOverflow);
   TESTCASE_AUTO(Test13840_ParseLongStringCrash);
   TESTCASE_AUTO(Test13850_EmptyStringCurrency);
   TESTCASE_AUTO_END;
@@ -7367,6 +7368,35 @@ void NumberFormatTest::TestSignificantDigits(void) {
         }
         result.remove();
     }
+
+    // Test for ICU-20063
+    {
+        DecimalFormat df({"en-us", status}, status);
+        df.setSignificantDigitsUsed(TRUE);
+        expect(df, 9.87654321, u"9.87654");
+        df.setMaximumSignificantDigits(3);
+        expect(df, 9.87654321, u"9.88");
+        // setSignificantDigitsUsed with maxSig only
+        df.setSignificantDigitsUsed(TRUE);
+        expect(df, 9.87654321, u"9.88");
+        df.setMinimumSignificantDigits(2);
+        expect(df, 9, u"9.0");
+        // setSignificantDigitsUsed with both minSig and maxSig
+        df.setSignificantDigitsUsed(TRUE);
+        expect(df, 9, u"9.0");
+        // setSignificantDigitsUsed to false: should revert to fraction rounding
+        df.setSignificantDigitsUsed(FALSE);
+        expect(df, 9.87654321, u"9.876543");
+        expect(df, 9, u"9");
+        df.setSignificantDigitsUsed(TRUE);
+        df.setMinimumSignificantDigits(2);
+        expect(df, 9.87654321, u"9.87654");
+        expect(df, 9, u"9.0");
+        // setSignificantDigitsUsed with minSig only
+        df.setSignificantDigitsUsed(TRUE);
+        expect(df, 9.87654321, u"9.87654");
+        expect(df, 9, u"9.0");
+    }
 }
 
 void NumberFormatTest::TestShowZero() {
@@ -9156,6 +9186,28 @@ void NumberFormatTest::Test13804_EmptyStringsWhenParsing() {
     }
 }
 
+void NumberFormatTest::Test20037_ScientificIntegerOverflow() {
+    IcuTestErrorCode status(*this, "Test20037_ScientificIntegerOverflow");
+
+    LocalPointer<NumberFormat> nf(NumberFormat::createInstance(status));
+    Formattable result;
+
+    // Test overflow of exponent
+    nf->parse(u"1E-2147483648", result, status);
+    StringPiece sp = result.getDecimalNumber(status);
+    assertEquals(u"Should snap to zero",
+        u"0",
+        {sp.data(), sp.length(), US_INV});
+
+    // Test edge case overflow of exponent
+    result = Formattable();
+    nf->parse(u"1E-2147483647E-1", result, status);
+    sp = result.getDecimalNumber(status);
+    assertEquals(u"Should not overflow and should parse only the first exponent",
+        u"1E-2147483647",
+        {sp.data(), sp.length(), US_INV});
+}
+
 void NumberFormatTest::Test13840_ParseLongStringCrash() {
     IcuTestErrorCode status(*this, "Test13840_ParseLongStringCrash");
 

icu4c/source/test/intltest/numfmtst.h

@@ -279,6 +279,7 @@ class NumberFormatTest: public CalendarTimeZoneTest {
     void Test13763_FieldPositionIteratorOffset();
     void Test13777_ParseLongNameNonCurrencyMode();
     void Test13804_EmptyStringsWhenParsing();
+    void Test20037_ScientificIntegerOverflow();
     void Test13840_ParseLongStringCrash();
     void Test13850_EmptyStringCurrency();
 

icu4c/source/test/intltest/tsmthred.cpp

@@ -13,6 +13,7 @@
 #include "umutex.h"
 #include "cmemory.h"
 #include "cstring.h"
+#include "indiancal.h"
 #include "uparse.h"
 #include "unicode/localpointer.h"
 #include "unicode/resbund.h"
@@ -82,6 +83,7 @@ void MultithreadTest::runIndexedTest( int32_t index, UBool exec,
     TESTCASE_AUTO(TestBreakTranslit);
     TESTCASE_AUTO(TestIncDec);
 #endif /* #if !UCONFIG_NO_TRANSLITERATION */
+    TESTCASE_AUTO(Test20104);
     TESTCASE_AUTO_END
 }
 
@@ -1549,4 +1551,35 @@ void MultithreadTest::TestIncDec()
 }
 
 
+static Calendar  *gSharedCalendar = {};
+
+class Test20104Thread : public SimpleThread {
+public:
+    Test20104Thread() { };
+    virtual void run();
+};
+
+void Test20104Thread::run() {
+    gSharedCalendar->defaultCenturyStartYear();
+}
+
+void MultithreadTest::Test20104() {
+    UErrorCode status = U_ZERO_ERROR;
+    Locale loc("hi_IN");
+    gSharedCalendar = new IndianCalendar(loc, status);
+    assertSuccess("Test20104", status);
+
+    static constexpr int NUM_THREADS = 4;
+    Test20104Thread threads[NUM_THREADS];
+    for (auto &thread:threads) {
+        thread.start();
+    }
+    for (auto &thread:threads) {
+        thread.join();
+    }
+    delete gSharedCalendar;
+    // Note: failure is reported by Thread Sanitizer. Test itself succeeds.
+}
+
+
 #endif /* !UCONFIG_NO_TRANSLITERATION */

icu4c/source/test/intltest/tsmthred.h

@@ -53,6 +53,7 @@ public:
     void TestUnifiedCache();
     void TestBreakTranslit();
     void TestIncDec();
+    void Test20104();
 };
 
 #endif

icu4c/source/test/testdata/numberformattestspecification.txt

@@ -353,6 +353,15 @@ minIntegerDigits	maxIntegerDigits	minFractionDigits	maxFractionDigits	output	bre
 // JDK fails here because it tries to use 9 + 6 = 15 sig digits.
 2	9	1	6	29.979246E7	K
 
+test ticket 20058
+set locale en
+begin
+pattern	format	output	breaks
+#00.0##E0	0	0.0E0	K
+#00.0##E0	1.2	1.2E0	K
+#00.0E0	0	0.0E0	K
+#00.0E0	1.2	1.2E0	K
+
 test significant digits scientific
 set locale en
 set pattern #E0

icu4c/source/tools/icu-file-utf8-check.py

@@ -0,0 +1,104 @@
+#! /usr/bin/python -B
+
+# Copyright (C) 2016 and later: Unicode, Inc. and others.
+# License & terms of use: http://www.unicode.org/copyright.html
+
+# Copyright (C) 2009-2011, International Business Machines Corporation, Google and Others.
+# All rights reserved.
+
+#
+#  Script to check that ICU source files contain only valid UTF-8 encoded text,
+#  and that all files except '.txt' files do not contain a Byte Order Mark (BOM).
+#
+#  THIS SCRIPT DOES NOT WORK ON WINDOWS
+#     It only works correctly on platforms where the native line ending is a plain \n
+#
+#  usage:
+#     icu-file-utf8-check.py  [options]
+#
+#  options:
+#     -h | --help    Print a usage line and exit.
+#
+#  The tool operates recursively on the directory from which it is run.
+#  Only files from the ICU github repository are checked.
+#  No changes are made to the repository; only the working copy will be altered.
+
+import sys
+import os
+import os.path
+import re
+import getopt
+
+
+def runCommand(cmd):
+    output_file = os.popen(cmd);
+    output_text = output_file.read();
+    exit_status = output_file.close();
+    if exit_status:
+        print >>sys.stderr, '"', cmd, '" failed.  Exiting.'
+        sys.exit(exit_status)
+    return output_text
+
+
+def usage():
+    print "usage: " + sys.argv[0] + " [-h | --help]"
+
+    
+#
+#  File check.         Check source code files for UTF-8 and all except text files for not containing a BOM
+#    file_name:        name of a text file.
+#    is_source:        Flag, set to True if file is a source code file (.c, .cpp, .h, .java).
+#
+def check_file(file_name, is_source):
+    f = open(file_name, 'r')
+    bytes = f.read()
+    f.close()
+
+    if is_source:
+        try:
+            bytes.decode("UTF-8")
+        except UnicodeDecodeError:
+            print "Error: %s is a source code file but contains non-utf-8 bytes." % file_name
+    
+    if ord(bytes[0]) == 0xef:
+        if not (file_name.endswith(".txt") or file_name.endswith(".sln")
+                    or file_name.endswith(".targets")
+                    or ".vcxproj" in file_name):
+            print "Warning: file %s contains a UTF-8 BOM: " % file_name
+
+    return
+
+def main(argv):
+    try:
+        opts, args = getopt.getopt(argv, "h", ("help"))
+    except getopt.GetoptError:
+        print "unrecognized option: " + argv[0]
+        usage()
+        sys.exit(2)
+    for opt, arg in opts:
+        if opt in ("-h", "--help"):
+            usage()
+            sys.exit()
+    if args:
+        print "unexpected command line argument"
+        usage()
+        sys.exit()
+
+    output = runCommand("git ls-files ");
+    file_list = output.splitlines()
+
+    source_file_re = re.compile(".*((?:\\.c$)|(?:\\.cpp$)|(?:\\.h$)|(?:\\.java$))")
+    
+    for f in file_list:
+        if os.path.isdir(f):
+            print "Skipping dir " + f
+            continue
+        if not os.path.isfile(f):
+            print "Repository file not in working copy: " + f
+            continue;
+
+        source_file = source_file_re.match(f)
+        check_file(f, source_file)
+
+if __name__ == "__main__":
+    main(sys.argv[1:])

icu4c/source/tools/icu-svnprops-check.py

@@ -1,189 +0,0 @@
-#! /usr/bin/python -B
-
-# Copyright (C) 2016 and later: Unicode, Inc. and others.
-# License & terms of use: http://www.unicode.org/copyright.html
-
-# Copyright (C) 2009-2011, International Business Machines Corporation, Google and Others.
-# All rights reserved.
-
-#
-#  Script to check and fix svn property settings for ICU source files.
-#  Also check for the correct line endings on files with svn:eol-style = native
-#
-#  THIS SCRIPT DOES NOT WORK ON WINDOWS
-#     It only works correctly on platforms where the native line ending is a plain \n
-#
-#  usage:
-#     icu-svnprops-check.py  [options]
-#
-#  options:
-#     -f | --fix     Fix any problems that are found
-#     -h | --help    Print a usage line and exit.
-#
-#  The tool operates recursively on the directory from which it is run.
-#  Only files from the svn repository are checked.
-#  No changes are made to the repository; only the working copy will be altered.
-
-import sys
-import os
-import os.path
-import re
-import getopt
-
-
-# file_types:  The parsed form of the svn auto-props specification.
-#              A list of file types - .cc, .cpp, .txt, etc.
-#              each element is a [type, proplist]
-#              "type" is a regular expression string that will match a file name
-#              prop list is another list, one element per property.
-#              Each property item is a two element list, [prop name, prop value]
-file_types = list()
-
-def parse_auto_props():
-    aprops = svn_auto_props.splitlines()
-    for propline in aprops:
-        if re.match("\s*(#.*)?$", propline):         # Match comment and blank lines
-            continue
-        if re.match("\s*\[auto-props\]", propline):  # Match the [auto-props] line.
-            continue
-        if not re.match("\s*[^\s]+\s*=", propline):  # minimal syntax check for <file-type> =
-            print "Bad line from autoprops definitions: " + propline
-            continue
-        file_type, string_proplist = propline.split("=", 1)
-
-        #transform the file type expression from autoprops into a normal regular expression.
-        #  e.g.  "*.cpp"  ==>  ".*\.cpp$"
-        file_type = file_type.strip()
-        file_type = file_type.replace(".", "\.")
-        file_type = file_type.replace("*", ".*")
-        file_type = file_type + "$"
-
-        # example string_proplist at this point: " svn:eol-style=native;svn:executable"
-        # split on ';' into a list of properties.  The negative lookahead and lookbehind
-        # in the split regexp are to prevent matching on ';;', which is an escaped ';'
-        # within a property value.
-        string_proplist = re.split("(?<!;);(?!;)", string_proplist)
-        proplist = list()
-        for prop in string_proplist:
-            if prop.find("=") >= 0:
-                prop_name, prop_val = prop.split("=", 1)
-            else:
-                # properties with no explicit value, e.g. svn:executable
-                prop_name, prop_val = prop, ""
-            prop_name = prop_name.strip()
-            prop_val = prop_val.strip()
-            # unescape any ";;" in a property value, e.g. the mime-type from
-            #    *.java = svn:eol-style=native;svn:mime-type=text/plain;;charset=utf-8
-            prop_val = prop_val.replace(";;", ";");
-            # If the prop value "is quoted", remove the quotes.
-            # See svn:keywords for an example of a quoted prop value.
-            match = re.match('^"(.+)"$', prop_val)
-            if match:
-                prop_val = match.group(1)
-            proplist.append((prop_name, prop_val))
-
-        file_types.append((file_type, proplist))
-    # print file_types
-
-        
-def runCommand(cmd):
-    output_file = os.popen(cmd);
-    output_text = output_file.read();
-    exit_status = output_file.close();
-    if exit_status:
-        print >>sys.stderr, '"', cmd, '" failed.  Exiting.'
-        sys.exit(exit_status)
-    return output_text
-
-svn_auto_props = runCommand("svn propget svn:auto-props http://source.icu-project.org/repos/icu")
-
-def usage():
-    print "usage: " + sys.argv[0] + " [-f | --fix] [-h | --help]"
-
-    
-#
-#  UTF-8 file check.   For text files with svn:mime-type=text/anything, check the specified charset
-#    file_name:        name of a text file.
-#    base_mime_type:   svn:mime-type property from the auto-props settings for this file type.
-#    actual_mime_type: existing svn:mime-type property value for the file.
-#    return:           The correct svn:mime-type property value,
-#                         either the original, if it looks OK, otherwise the value from auto-props
-#
-def check_utf8(file_name, base_mime_type, actual_mime_type):
-
-    f = open(file_name, 'r')
-    bytes = f.read()
-    f.close()
-    file_is_utf8 = True
-    try:
-        bytes.decode("UTF-8")
-    except UnicodeDecodeError:
-        file_is_utf8 = False
-
-    if not file_is_utf8 and actual_mime_type.find("utf-8") >= 0:
-        print "Error: %s is not valid utf-8, but has a utf-8 mime type." % file_name
-        return actual_mime_type
-
-    if file_is_utf8 and actual_mime_type.find("charset") >=0 and actual_mime_type.find("utf-8") < 0:
-        print "Warning: %s is valid utf-8, but has a mime-type of %s." % (file_name, actual_mime_type)
-
-    if ord(bytes[0]) == 0xef:
-        if not file_name.endswith(".txt"):
-            print "Warning: file %s contains a UTF-8 BOM: " % file_name
-
-    # If the file already has a charset in its mime-type, don't make any change.
-
-    if actual_mime_type.find("charset=") >= 0:
-        return actual_mime_type;
-
-    return base_mime_type
-
-
-def main(argv):
-    fix_problems = False;
-    try:
-        opts, args = getopt.getopt(argv, "fh", ("fix", "help"))
-    except getopt.GetoptError:
-        print "unrecognized option: " + argv[0]
-        usage()
-        sys.exit(2)
-    for opt, arg in opts:
-        if opt in ("-h", "--help"):
-            usage()
-            sys.exit()
-        if opt in ("-f", "--fix"):
-            fix_problems = True
-    if args:
-        print "unexpected command line argument"
-        usage()
-        sys.exit()
-
-    parse_auto_props()
-    output = runCommand("svn ls -R ");
-    file_list = output.splitlines()
-
-    for f in file_list:
-        if os.path.isdir(f):
-            # print "Skipping dir " + f
-            continue
-        if not os.path.isfile(f):
-            print "Repository file not in working copy: " + f
-            continue;
-
-        for file_pattern, props in file_types:
-            if re.match(file_pattern, f):
-                # print "doing " + f
-                for propname, propval in props:
-                    actual_propval = runCommand("svn propget --strict " + propname + " " + f)
-                    #print propname + ": " + actual_propval
-                    if propname == "svn:mime-type" and propval.find("text/") == 0:
-                        # check for UTF-8 text files, should have svn:mime-type=text/something; charset=utf8
-                        propval = check_utf8(f, propval, actual_propval)
-                    if not (propval == actual_propval or (propval == "" and actual_propval == "*")):
-                        print "svn propset %s '%s' %s" % (propname, propval, f)
-                        if fix_problems:
-                            os.system("svn propset %s '%s' %s" % (propname, propval, f))
-
-
-if __name__ == "__main__":
-    main(sys.argv[1:])

icu4j/main/classes/core/.settings/org.eclipse.jdt.core.prefs

@@ -2,8 +2,11 @@ eclipse.preferences.version=1
 org.eclipse.jdt.core.compiler.annotation.inheritNullAnnotations=disabled
 org.eclipse.jdt.core.compiler.annotation.missingNonNullByDefaultAnnotation=ignore
 org.eclipse.jdt.core.compiler.annotation.nonnull=org.eclipse.jdt.annotation.NonNull
+org.eclipse.jdt.core.compiler.annotation.nonnull.secondary=
 org.eclipse.jdt.core.compiler.annotation.nonnullbydefault=org.eclipse.jdt.annotation.NonNullByDefault
+org.eclipse.jdt.core.compiler.annotation.nonnullbydefault.secondary=
 org.eclipse.jdt.core.compiler.annotation.nullable=org.eclipse.jdt.annotation.Nullable
+org.eclipse.jdt.core.compiler.annotation.nullable.secondary=
 org.eclipse.jdt.core.compiler.annotation.nullanalysis=disabled
 org.eclipse.jdt.core.compiler.codegen.inlineJsrBytecode=enabled
 org.eclipse.jdt.core.compiler.codegen.targetPlatform=1.7
@@ -13,6 +16,7 @@ org.eclipse.jdt.core.compiler.debug.lineNumber=generate
 org.eclipse.jdt.core.compiler.debug.localVariable=generate
 org.eclipse.jdt.core.compiler.debug.sourceFile=generate
 org.eclipse.jdt.core.compiler.doc.comment.support=enabled
+org.eclipse.jdt.core.compiler.problem.APILeak=warning
 org.eclipse.jdt.core.compiler.problem.annotationSuperInterface=warning
 org.eclipse.jdt.core.compiler.problem.assertIdentifier=error
 org.eclipse.jdt.core.compiler.problem.autoboxing=ignore
@@ -62,12 +66,14 @@ org.eclipse.jdt.core.compiler.problem.noEffectAssignment=warning
 org.eclipse.jdt.core.compiler.problem.noImplicitStringConversion=warning
 org.eclipse.jdt.core.compiler.problem.nonExternalizedStringLiteral=ignore
 org.eclipse.jdt.core.compiler.problem.nonnullParameterAnnotationDropped=warning
+org.eclipse.jdt.core.compiler.problem.nonnullTypeVariableFromLegacyInvocation=warning
 org.eclipse.jdt.core.compiler.problem.nullAnnotationInferenceConflict=error
 org.eclipse.jdt.core.compiler.problem.nullReference=warning
 org.eclipse.jdt.core.compiler.problem.nullSpecViolation=error
 org.eclipse.jdt.core.compiler.problem.nullUncheckedConversion=warning
 org.eclipse.jdt.core.compiler.problem.overridingPackageDefaultMethod=warning
 org.eclipse.jdt.core.compiler.problem.parameterAssignment=ignore
+org.eclipse.jdt.core.compiler.problem.pessimisticNullAnalysisForFreeTypeVariables=warning
 org.eclipse.jdt.core.compiler.problem.possibleAccidentalBooleanAssignment=ignore
 org.eclipse.jdt.core.compiler.problem.potentialNullReference=ignore
 org.eclipse.jdt.core.compiler.problem.potentiallyUnclosedCloseable=warning
@@ -84,12 +90,16 @@ org.eclipse.jdt.core.compiler.problem.suppressOptionalErrors=disabled
 org.eclipse.jdt.core.compiler.problem.suppressWarnings=enabled
 org.eclipse.jdt.core.compiler.problem.syntacticNullAnalysisForFields=disabled
 org.eclipse.jdt.core.compiler.problem.syntheticAccessEmulation=ignore
+org.eclipse.jdt.core.compiler.problem.terminalDeprecation=warning
 org.eclipse.jdt.core.compiler.problem.typeParameterHiding=warning
 org.eclipse.jdt.core.compiler.problem.unavoidableGenericTypeProblems=enabled
 org.eclipse.jdt.core.compiler.problem.uncheckedTypeOperation=warning
 org.eclipse.jdt.core.compiler.problem.unclosedCloseable=warning
 org.eclipse.jdt.core.compiler.problem.undocumentedEmptyBlock=ignore
-org.eclipse.jdt.core.compiler.problem.unhandledWarningToken=warning
+org.eclipse.jdt.core.compiler.problem.unhandledWarningToken=info
+org.eclipse.jdt.core.compiler.problem.unlikelyCollectionMethodArgumentType=warning
+org.eclipse.jdt.core.compiler.problem.unlikelyCollectionMethodArgumentTypeStrict=disabled
+org.eclipse.jdt.core.compiler.problem.unlikelyEqualsArgumentType=info
 org.eclipse.jdt.core.compiler.problem.unnecessaryElse=ignore
 org.eclipse.jdt.core.compiler.problem.unnecessaryTypeCheck=ignore
 org.eclipse.jdt.core.compiler.problem.unqualifiedFieldAccess=ignore
@@ -97,6 +107,7 @@ org.eclipse.jdt.core.compiler.problem.unusedDeclaredThrownException=ignore
 org.eclipse.jdt.core.compiler.problem.unusedDeclaredThrownExceptionExemptExceptionAndThrowable=enabled
 org.eclipse.jdt.core.compiler.problem.unusedDeclaredThrownExceptionIncludeDocCommentReference=enabled
 org.eclipse.jdt.core.compiler.problem.unusedDeclaredThrownExceptionWhenOverriding=disabled
+org.eclipse.jdt.core.compiler.problem.unusedExceptionParameter=ignore
 org.eclipse.jdt.core.compiler.problem.unusedImport=warning
 org.eclipse.jdt.core.compiler.problem.unusedLabel=warning
 org.eclipse.jdt.core.compiler.problem.unusedLocal=warning

icu4j/main/classes/core/src/com/ibm/icu/impl/Relation.java

@@ -37,11 +37,11 @@ public class Relation<K, V> implements Freezable<Relation<K,V>> { // TODO: add ,
     Object[] setComparatorParam;
 
     public static <K, V> Relation<K, V> of(Map<K, Set<V>> map, Class<?> setCreator) {
-        return new Relation<K, V>(map, setCreator);
+        return new Relation<>(map, setCreator);
     }
 
     public static <K,V> Relation<K, V> of(Map<K, Set<V>> map, Class<?> setCreator, Comparator<V> setComparator) {
-        return new Relation<K, V>(map, setCreator, setComparator);
+        return new Relation<>(map, setCreator, setComparator);
     }
 
     public Relation(Map<K, Set<V>> map, Class<?> setCreator) {
@@ -91,10 +91,10 @@ public class Relation<K, V> implements Freezable<Relation<K,V>> { // TODO: add ,
     }
 
     public Set<Entry<K, V>> keyValueSet() {
-        Set<Entry<K, V>> result = new LinkedHashSet<Entry<K, V>>();
+        Set<Entry<K, V>> result = new LinkedHashSet<>();
         for (K key : data.keySet()) {
             for (V value : data.get(key)) {
-                result.add(new SimpleEntry<K, V>(key, value));
+                result.add(new SimpleEntry<>(key, value));
             }
         }
         return result;
@@ -320,7 +320,9 @@ public class Relation<K, V> implements Freezable<Relation<K,V>> { // TODO: add ,
         return result;
     }
 
-    public Set<V> removeAll(K... keys) {
+    @SafeVarargs
+    @SuppressWarnings("varargs")    // Not supported by Eclipse, but we need this for javac
+    public final Set<V> removeAll(K... keys) {
         return removeAll(Arrays.asList(keys));
     }
 
@@ -333,7 +335,7 @@ public class Relation<K, V> implements Freezable<Relation<K,V>> { // TODO: add ,
     }
 
     public Set<V> removeAll(Collection<K> toBeRemoved) {
-        Set<V> result = new LinkedHashSet<V>();
+        Set<V> result = new LinkedHashSet<>();
         for (K key : toBeRemoved) {
             try {
                 final Set<V> removals = data.remove(key);

icu4j/main/classes/core/src/com/ibm/icu/impl/locale/XCldrStub.java

@@ -44,7 +44,9 @@ public class XCldrStub {
                     ? setClass
                             : HashSet.class);
         }
-        public Multimap<K, V> putAll(K key, V... values) {
+        @SafeVarargs
+        @SuppressWarnings("varargs")    // Not supported by Eclipse, but we need this for javac
+        public final Multimap<K, V> putAll(K key, V... values) {
             if (values.length != 0) {
                 createSetIfMissing(key).addAll(Arrays.asList(values));
             }
@@ -107,7 +109,7 @@ public class XCldrStub {
             return map.size();
         }
         public Iterable<Entry<K, V>> entries() {
-            return new MultimapIterator<K, V>(map);
+            return new MultimapIterator<>(map);
         }
         @Override
         public boolean equals(Object obj) {
@@ -147,7 +149,7 @@ public class XCldrStub {
     private static class MultimapIterator<K,V> implements Iterator<Entry<K,V>>, Iterable<Entry<K,V>> {
         private final Iterator<Entry<K, Set<V>>> it1;
         private Iterator<V> it2 = null;
-        private final ReusableEntry<K,V> entry = new ReusableEntry<K,V>();
+        private final ReusableEntry<K,V> entry = new ReusableEntry<>();
 
         private MultimapIterator(Map<K,Set<V>> map) {
             it1 = map.entrySet().iterator();
@@ -199,7 +201,7 @@ public class XCldrStub {
             super(new HashMap<K, Set<V>>(), HashSet.class);
         }
         public static <K, V> HashMultimap<K, V> create() {
-            return new HashMultimap<K, V>();
+            return new HashMultimap<>();
         }
     }
 
@@ -208,7 +210,7 @@ public class XCldrStub {
             super(new TreeMap<K, Set<V>>(), TreeSet.class);
         }
         public static <K, V> TreeMultimap<K, V> create() {
-            return new TreeMultimap<K, V>();
+            return new TreeMultimap<>();
         }
     }
 
@@ -217,7 +219,7 @@ public class XCldrStub {
             super(new LinkedHashMap<K, Set<V>>(), LinkedHashSet.class);
         }
         public static <K, V> LinkedHashMultimap<K, V> create() {
-            return new LinkedHashMultimap<K, V>();
+            return new LinkedHashMultimap<>();
         }
     }
 
@@ -315,24 +317,24 @@ public class XCldrStub {
 
     public static class ImmutableSet {
         public static <T> Set<T> copyOf(Set<T> values) {
-            return Collections.unmodifiableSet(new LinkedHashSet<T>(values)); // copy set for safety, preserve order
+            return Collections.unmodifiableSet(new LinkedHashSet<>(values)); // copy set for safety, preserve order
         }
     }
     public static class ImmutableMap {
         public static <K,V> Map<K,V> copyOf(Map<K,V> values) {
-            return Collections.unmodifiableMap(new LinkedHashMap<K,V>(values)); // copy set for safety, preserve order
+            return Collections.unmodifiableMap(new LinkedHashMap<>(values)); // copy set for safety, preserve order
         }
     }
     public static class ImmutableMultimap {
         public static <K,V> Multimap<K,V> copyOf(Multimap<K,V> values) {
-            LinkedHashMap<K, Set<V>> temp = new LinkedHashMap<K,Set<V>>(); // semi-deep copy, preserve order
+            LinkedHashMap<K, Set<V>> temp = new LinkedHashMap<>(); // semi-deep copy, preserve order
             for (Entry<K, Set<V>> entry : values.asMap().entrySet()) {
                 Set<V> value = entry.getValue();
                 temp.put(entry.getKey(), value.size() == 1
                         ? Collections.singleton(value.iterator().next())
-                                : Collections.unmodifiableSet(new LinkedHashSet<V>(value)));
+                                : Collections.unmodifiableSet(new LinkedHashSet<>(value)));
             }
-            return new Multimap<K,V>(Collections.unmodifiableMap(temp), null);
+            return new Multimap<>(Collections.unmodifiableMap(temp), null);
         }
     }
 

icu4j/main/classes/core/src/com/ibm/icu/impl/number/AdoptingModifierStore.java

@@ -5,10 +5,11 @@ package com.ibm.icu.impl.number;
 import com.ibm.icu.impl.StandardPlural;
 
 /**
- * A ParameterizedModifier by itself is NOT a Modifier. Rather, it wraps a data structure containing two
- * or more Modifiers and returns the modifier appropriate for the current situation.
+ * This implementation of ModifierStore adopts references to Modifiers.
+ *
+ * (This is named "adopting" because in C++, this class takes ownership of the Modifiers.)
  */
-public class ParameterizedModifier {
+public class AdoptingModifierStore implements ModifierStore {
     private final Modifier positive;
     private final Modifier zero;
     private final Modifier negative;
@@ -21,7 +22,7 @@ public class ParameterizedModifier {
      * <p>
      * If this constructor is used, a plural form CANNOT be passed to {@link #getModifier}.
      */
-    public ParameterizedModifier(Modifier positive, Modifier zero, Modifier negative) {
+    public AdoptingModifierStore(Modifier positive, Modifier zero, Modifier negative) {
         this.positive = positive;
         this.zero = zero;
         this.negative = negative;
@@ -36,7 +37,7 @@ public class ParameterizedModifier {
      * <p>
      * If this constructor is used, a plural form MUST be passed to {@link #getModifier}.
      */
-    public ParameterizedModifier() {
+    public AdoptingModifierStore() {
         this.positive = null;
         this.zero = null;
         this.negative = null;
@@ -53,7 +54,7 @@ public class ParameterizedModifier {
         frozen = true;
     }
 
-    public Modifier getModifier(int signum) {
+    public Modifier getModifierWithoutPlural(int signum) {
         assert frozen;
         assert mods == null;
         return signum == 0 ? zero : signum < 0 ? negative : positive;
@@ -66,6 +67,8 @@ public class ParameterizedModifier {
     }
 
     private static int getModIndex(int signum, StandardPlural plural) {
+        assert signum >= -1 && signum <= 1;
+        assert plural != null;
         return plural.ordinal() * 3 + (signum + 1);
     }
 }

icu4j/main/classes/core/src/com/ibm/icu/impl/number/ConstantAffixModifier.java

@@ -74,6 +74,28 @@ public class ConstantAffixModifier implements Modifier {
         return strong;
     }
 
+    @Override
+    public boolean containsField(Field field) {
+        // This method is not currently used.
+        assert false;
+        return false;
+    }
+
+    @Override
+    public Parameters getParameters() {
+        return null;
+    }
+
+    @Override
+    public boolean semanticallyEquivalent(Modifier other) {
+        if (!(other instanceof ConstantAffixModifier)) {
+            return false;
+        }
+        ConstantAffixModifier _other = (ConstantAffixModifier) other;
+        return prefix.equals(_other.prefix) && suffix.equals(_other.suffix) && field == _other.field
+                && strong == _other.strong;
+    }
+
     @Override
     public String toString() {
         return String.format("<ConstantAffixModifier prefix:'%s' suffix:'%s'>", prefix, suffix);

icu4j/main/classes/core/src/com/ibm/icu/impl/number/ConstantMultiFieldModifier.java

@@ -2,6 +2,8 @@
 // License & terms of use: http://www.unicode.org/copyright.html#License
 package com.ibm.icu.impl.number;
 
+import java.util.Arrays;
+
 import com.ibm.icu.text.NumberFormat.Field;
 
 /**
@@ -20,17 +22,30 @@ public class ConstantMultiFieldModifier implements Modifier {
     private final boolean overwrite;
     private final boolean strong;
 
+    // Parameters: used for number range formatting
+    private final Parameters parameters;
+
     public ConstantMultiFieldModifier(
             NumberStringBuilder prefix,
             NumberStringBuilder suffix,
             boolean overwrite,
             boolean strong) {
+        this(prefix, suffix, overwrite, strong, null);
+    }
+
+    public ConstantMultiFieldModifier(
+            NumberStringBuilder prefix,
+            NumberStringBuilder suffix,
+            boolean overwrite,
+            boolean strong,
+            Parameters parameters) {
         prefixChars = prefix.toCharArray();
         suffixChars = suffix.toCharArray();
         prefixFields = prefix.toFieldArray();
         suffixFields = suffix.toFieldArray();
         this.overwrite = overwrite;
         this.strong = strong;
+        this.parameters = parameters;
     }
 
     @Override
@@ -59,6 +74,40 @@ public class ConstantMultiFieldModifier implements Modifier {
         return strong;
     }
 
+    @Override
+    public boolean containsField(Field field) {
+        for (int i = 0; i < prefixFields.length; i++) {
+            if (prefixFields[i] == field) {
+                return true;
+            }
+        }
+        for (int i = 0; i < suffixFields.length; i++) {
+            if (suffixFields[i] == field) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    @Override
+    public Parameters getParameters() {
+        return parameters;
+    }
+
+    @Override
+    public boolean semanticallyEquivalent(Modifier other) {
+        if (!(other instanceof ConstantMultiFieldModifier)) {
+            return false;
+        }
+        ConstantMultiFieldModifier _other = (ConstantMultiFieldModifier) other;
+        if (parameters != null && _other.parameters != null && parameters.obj == _other.parameters.obj) {
+            return true;
+        }
+        return Arrays.equals(prefixChars, _other.prefixChars) && Arrays.equals(prefixFields, _other.prefixFields)
+                && Arrays.equals(suffixChars, _other.suffixChars) && Arrays.equals(suffixFields, _other.suffixFields)
+                && overwrite == _other.overwrite && strong == _other.strong;
+    }
+
     @Override
     public String toString() {
         NumberStringBuilder temp = new NumberStringBuilder();

icu4j/main/classes/core/src/com/ibm/icu/impl/number/DecimalQuantity_AbstractBCD.java

@@ -1014,6 +1014,46 @@ public abstract class DecimalQuantity_AbstractBCD implements DecimalQuantity {
         }
     }
 
+    @Override
+    public boolean equals(Object other) {
+        if (this == other) {
+            return true;
+        }
+        if (other == null) {
+            return false;
+        }
+        if (!(other instanceof DecimalQuantity_AbstractBCD)) {
+            return false;
+        }
+        DecimalQuantity_AbstractBCD _other = (DecimalQuantity_AbstractBCD) other;
+
+        boolean basicEquals =
+                scale == _other.scale
+                && precision == _other.precision
+                && flags == _other.flags
+                && lOptPos == _other.lOptPos
+                && lReqPos == _other.lReqPos
+                && rReqPos == _other.rReqPos
+                && rOptPos == _other.rOptPos
+                && isApproximate == _other.isApproximate;
+        if (!basicEquals) {
+            return false;
+        }
+
+        if (precision == 0) {
+            return true;
+        } else if (isApproximate) {
+            return origDouble == _other.origDouble && origDelta == _other.origDelta;
+        } else {
+            for (int m = getUpperDisplayMagnitude(); m >= getLowerDisplayMagnitude(); m--) {
+                if (getDigit(m) != _other.getDigit(m)) {
+                    return false;
+                }
+            }
+            return true;
+        }
+    }
+
     /**
      * Returns a single digit from the BCD list. No internal state is changed by calling this method.
      *

icu4j/main/classes/core/src/com/ibm/icu/impl/number/LongNameHandler.java

@@ -21,7 +21,7 @@ import com.ibm.icu.util.MeasureUnit;
 import com.ibm.icu.util.ULocale;
 import com.ibm.icu.util.UResourceBundle;
 
-public class LongNameHandler implements MicroPropsGenerator {
+public class LongNameHandler implements MicroPropsGenerator, ModifierStore {
 
     private static final int DNAM_INDEX = StandardPlural.COUNT;
     private static final int PER_INDEX = StandardPlural.COUNT + 1;
@@ -175,10 +175,11 @@ public class LongNameHandler implements MicroPropsGenerator {
         String[] simpleFormats = new String[ARRAY_LENGTH];
         getCurrencyLongNameData(locale, currency, simpleFormats);
         // TODO(ICU4J): Reduce the number of object creations here?
-        Map<StandardPlural, SimpleModifier> modifiers = new EnumMap<StandardPlural, SimpleModifier>(
+        Map<StandardPlural, SimpleModifier> modifiers = new EnumMap<>(
                 StandardPlural.class);
-        simpleFormatsToModifiers(simpleFormats, null, modifiers);
-        return new LongNameHandler(modifiers, rules, parent);
+        LongNameHandler result = new LongNameHandler(modifiers, rules, parent);
+        result.simpleFormatsToModifiers(simpleFormats, null);
+        return result;
     }
 
     public static LongNameHandler forMeasureUnit(
@@ -203,10 +204,11 @@ public class LongNameHandler implements MicroPropsGenerator {
         getMeasureData(locale, unit, width, simpleFormats);
         // TODO: What field to use for units?
         // TODO(ICU4J): Reduce the number of object creations here?
-        Map<StandardPlural, SimpleModifier> modifiers = new EnumMap<StandardPlural, SimpleModifier>(
+        Map<StandardPlural, SimpleModifier> modifiers = new EnumMap<>(
                 StandardPlural.class);
-        simpleFormatsToModifiers(simpleFormats, null, modifiers);
-        return new LongNameHandler(modifiers, rules, parent);
+        LongNameHandler result = new LongNameHandler(modifiers, rules, parent);
+        result.simpleFormatsToModifiers(simpleFormats, null);
+        return result;
     }
 
     private static LongNameHandler forCompoundUnit(
@@ -238,29 +240,32 @@ public class LongNameHandler implements MicroPropsGenerator {
             perUnitFormat = SimpleFormatterImpl.formatCompiledPattern(compiled, "{0}", secondaryString);
         }
         // TODO: What field to use for units?
-        Map<StandardPlural, SimpleModifier> modifiers = new EnumMap<StandardPlural, SimpleModifier>(
+        Map<StandardPlural, SimpleModifier> modifiers = new EnumMap<>(
                 StandardPlural.class);
-        multiSimpleFormatsToModifiers(primaryData, perUnitFormat, null, modifiers);
-        return new LongNameHandler(modifiers, rules, parent);
+        LongNameHandler result = new LongNameHandler(modifiers, rules, parent);
+        result.multiSimpleFormatsToModifiers(primaryData, perUnitFormat, null);
+        return result;
     }
 
-    private static void simpleFormatsToModifiers(
+    private void simpleFormatsToModifiers(
             String[] simpleFormats,
-            NumberFormat.Field field,
-            Map<StandardPlural, SimpleModifier> output) {
+            NumberFormat.Field field) {
         StringBuilder sb = new StringBuilder();
         for (StandardPlural plural : StandardPlural.VALUES) {
             String simpleFormat = getWithPlural(simpleFormats, plural);
             String compiled = SimpleFormatterImpl.compileToStringMinMaxArguments(simpleFormat, sb, 0, 1);
-            output.put(plural, new SimpleModifier(compiled, field, false));
+            Modifier.Parameters parameters = new Modifier.Parameters();
+            parameters.obj = this;
+            parameters.signum = 0;
+            parameters.plural = plural;
+            modifiers.put(plural, new SimpleModifier(compiled, field, false, parameters));
         }
     }
 
-    private static void multiSimpleFormatsToModifiers(
+    private void multiSimpleFormatsToModifiers(
             String[] leadFormats,
             String trailFormat,
-            NumberFormat.Field field,
-            Map<StandardPlural, SimpleModifier> output) {
+            NumberFormat.Field field) {
         StringBuilder sb = new StringBuilder();
         String trailCompiled = SimpleFormatterImpl.compileToStringMinMaxArguments(trailFormat, sb, 1, 1);
         for (StandardPlural plural : StandardPlural.VALUES) {
@@ -268,7 +273,11 @@ public class LongNameHandler implements MicroPropsGenerator {
             String compoundFormat = SimpleFormatterImpl.formatCompiledPattern(trailCompiled, leadFormat);
             String compoundCompiled = SimpleFormatterImpl
                     .compileToStringMinMaxArguments(compoundFormat, sb, 0, 1);
-            output.put(plural, new SimpleModifier(compoundCompiled, field, false));
+            Modifier.Parameters parameters = new Modifier.Parameters();
+            parameters.obj = this;
+            parameters.signum = 0;
+            parameters.plural = plural;
+            modifiers.put(plural, new SimpleModifier(compoundCompiled, field, false, parameters));
         }
     }
 
@@ -281,4 +290,9 @@ public class LongNameHandler implements MicroPropsGenerator {
         micros.modOuter = modifiers.get(copy.getStandardPlural(rules));
         return micros;
     }
+
+    @Override
+    public Modifier getModifier(int signum, StandardPlural plural) {
+        return modifiers.get(plural);
+    }
 }

icu4j/main/classes/core/src/com/ibm/icu/impl/number/Modifier.java

@@ -2,6 +2,9 @@
 // License & terms of use: http://www.unicode.org/copyright.html#License
 package com.ibm.icu.impl.number;
 
+import com.ibm.icu.impl.StandardPlural;
+import com.ibm.icu.text.NumberFormat.Field;
+
 /**
  * A Modifier is an object that can be passed through the formatting pipeline until it is finally applied
  * to the string builder. A Modifier usually contains a prefix and a suffix that are applied, but it
@@ -48,4 +51,30 @@ public interface Modifier {
      * @return Whether the modifier is strong.
      */
     public boolean isStrong();
+
+    /**
+     * Whether the modifier contains at least one occurrence of the given field.
+     */
+    public boolean containsField(Field currency);
+
+    /**
+     * A fill-in for getParameters(). obj will always be set; if non-null, the other
+     * two fields are also safe to read.
+     */
+    public static class Parameters {
+        public ModifierStore obj;
+        public int signum;
+        public StandardPlural plural;
+    }
+
+    /**
+     * Gets a set of "parameters" for this Modifier.
+     */
+    public Parameters getParameters();
+
+    /**
+     * Returns whether this Modifier is *semantically equivalent* to the other Modifier;
+     * in many cases, this is the same as equal, but parameters should be ignored.
+     */
+    public boolean semanticallyEquivalent(Modifier other);
 }

icu4j/main/classes/core/src/com/ibm/icu/impl/number/ModifierStore.java

@@ -0,0 +1,18 @@
+// © 2018 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html#License
+package com.ibm.icu.impl.number;
+
+import com.ibm.icu.impl.StandardPlural;
+
+/**
+ * This is *not* a modifier; rather, it is an object that can return modifiers
+ * based on given parameters.
+ *
+ * @author sffc
+ */
+public interface ModifierStore {
+    /**
+     * Returns a Modifier with the given parameters (best-effort).
+     */
+    Modifier getModifier(int signum, StandardPlural plural);
+}

icu4j/main/classes/core/src/com/ibm/icu/impl/number/MutablePatternModifier.java

@@ -7,6 +7,7 @@ import com.ibm.icu.impl.number.AffixUtils.SymbolProvider;
 import com.ibm.icu.number.NumberFormatter.SignDisplay;
 import com.ibm.icu.number.NumberFormatter.UnitWidth;
 import com.ibm.icu.text.DecimalFormatSymbols;
+import com.ibm.icu.text.NumberFormat.Field;
 import com.ibm.icu.text.PluralRules;
 import com.ibm.icu.util.Currency;
 
@@ -165,7 +166,7 @@ public class MutablePatternModifier implements Modifier, SymbolProvider, MicroPr
         NumberStringBuilder b = new NumberStringBuilder();
         if (needsPlurals()) {
             // Slower path when we require the plural keyword.
-            ParameterizedModifier pm = new ParameterizedModifier();
+            AdoptingModifierStore pm = new AdoptingModifierStore();
             for (StandardPlural plural : StandardPlural.VALUES) {
                 setNumberProperties(1, plural);
                 pm.setModifier(1, plural, createConstantModifier(a, b));
@@ -184,7 +185,7 @@ public class MutablePatternModifier implements Modifier, SymbolProvider, MicroPr
             Modifier zero = createConstantModifier(a, b);
             setNumberProperties(-1, null);
             Modifier negative = createConstantModifier(a, b);
-            ParameterizedModifier pm = new ParameterizedModifier(positive, zero, negative);
+            AdoptingModifierStore pm = new AdoptingModifierStore(positive, zero, negative);
             return new ImmutablePatternModifier(pm, null, parent);
         }
     }
@@ -213,12 +214,12 @@ public class MutablePatternModifier implements Modifier, SymbolProvider, MicroPr
     }
 
     public static class ImmutablePatternModifier implements MicroPropsGenerator {
-        final ParameterizedModifier pm;
+        final AdoptingModifierStore pm;
         final PluralRules rules;
         final MicroPropsGenerator parent;
 
         ImmutablePatternModifier(
-                ParameterizedModifier pm,
+                AdoptingModifierStore pm,
                 PluralRules rules,
                 MicroPropsGenerator parent) {
             this.pm = pm;
@@ -235,7 +236,7 @@ public class MutablePatternModifier implements Modifier, SymbolProvider, MicroPr
 
         public void applyToMicros(MicroProps micros, DecimalQuantity quantity) {
             if (rules == null) {
-                micros.modMiddle = pm.getModifier(quantity.signum());
+                micros.modMiddle = pm.getModifierWithoutPlural(quantity.signum());
             } else {
                 // TODO: Fix this. Avoid the copy.
                 DecimalQuantity copy = quantity.createCopy();
@@ -319,6 +320,27 @@ public class MutablePatternModifier implements Modifier, SymbolProvider, MicroPr
         return isStrong;
     }
 
+    @Override
+    public boolean containsField(Field field) {
+        // This method is not currently used. (unsafe path not used in range formatting)
+        assert false;
+        return false;
+    }
+
+    @Override
+    public Parameters getParameters() {
+        // This method is not currently used.
+        assert false;
+        return null;
+    }
+
+    @Override
+    public boolean semanticallyEquivalent(Modifier other) {
+        // This method is not currently used. (unsafe path not used in range formatting)
+        assert false;
+        return false;
+    }
+
     private int insertPrefix(NumberStringBuilder sb, int position) {
         prepareAffix(true);
         int length = AffixUtils.unescape(currentAffix, sb, position, this);

icu4j/main/classes/core/src/com/ibm/icu/impl/number/SimpleModifier.java

@@ -3,7 +3,9 @@
 package com.ibm.icu.impl.number;
 
 import com.ibm.icu.impl.SimpleFormatterImpl;
+import com.ibm.icu.impl.number.range.PrefixInfixSuffixLengthHelper;
 import com.ibm.icu.text.NumberFormat.Field;
+import com.ibm.icu.util.ICUException;
 
 /**
  * The second primary implementation of {@link Modifier}, this one consuming a
@@ -17,15 +19,24 @@ public class SimpleModifier implements Modifier {
     private final int suffixOffset;
     private final int suffixLength;
 
+    // Parameters: used for number range formatting
+    private final Parameters parameters;
+
     /** TODO: This is copied from SimpleFormatterImpl. */
     private static final int ARG_NUM_LIMIT = 0x100;
 
     /** Creates a modifier that uses the SimpleFormatter string formats. */
     public SimpleModifier(String compiledPattern, Field field, boolean strong) {
+        this(compiledPattern, field, strong, null);
+    }
+
+    /** Creates a modifier that uses the SimpleFormatter string formats. */
+    public SimpleModifier(String compiledPattern, Field field, boolean strong, Parameters parameters) {
         assert compiledPattern != null;
         this.compiledPattern = compiledPattern;
         this.field = field;
         this.strong = strong;
+        this.parameters = parameters;
 
         int argLimit = SimpleFormatterImpl.getArgumentLimit(compiledPattern);
         if (argLimit == 0) {
@@ -80,6 +91,30 @@ public class SimpleModifier implements Modifier {
         return strong;
     }
 
+    @Override
+    public boolean containsField(Field field) {
+        // This method is not currently used.
+        assert false;
+        return false;
+    }
+
+    @Override
+    public Parameters getParameters() {
+        return parameters;
+    }
+
+    @Override
+    public boolean semanticallyEquivalent(Modifier other) {
+        if (!(other instanceof SimpleModifier)) {
+            return false;
+        }
+        SimpleModifier _other = (SimpleModifier) other;
+        if (parameters != null && _other.parameters != null && parameters.obj == _other.parameters.obj) {
+            return true;
+        }
+        return compiledPattern.equals(_other.compiledPattern) && field == _other.field && strong == _other.strong;
+    }
+
     /**
      * TODO: This belongs in SimpleFormatterImpl. The only reason I haven't moved it there yet is because
      * DoubleSidedStringBuilder is an internal class and SimpleFormatterImpl feels like it should not
@@ -123,4 +158,66 @@ public class SimpleModifier implements Modifier {
             return prefixLength + suffixLength;
         }
     }
+
+    /**
+     * TODO: Like above, this belongs with the rest of the SimpleFormatterImpl code.
+     * I put it here so that the SimpleFormatter uses in NumberStringBuilder are near each other.
+     *
+     * <p>
+     * Applies the compiled two-argument pattern to the NumberStringBuilder.
+     *
+     * <p>
+     * This method is optimized for the case where the prefix and suffix are often empty, such as
+     * in the range pattern like "{0}-{1}".
+     */
+    public static void formatTwoArgPattern(String compiledPattern, NumberStringBuilder result, int index, PrefixInfixSuffixLengthHelper h,
+            Field field) {
+        int argLimit = SimpleFormatterImpl.getArgumentLimit(compiledPattern);
+        if (argLimit != 2) {
+            throw new ICUException();
+        }
+        int offset = 1; // offset into compiledPattern
+        int length = 0; // chars added to result
+
+        int prefixLength = compiledPattern.charAt(offset);
+        offset++;
+        if (prefixLength < ARG_NUM_LIMIT) {
+            // No prefix
+            prefixLength = 0;
+        } else {
+            prefixLength -= ARG_NUM_LIMIT;
+            result.insert(index + length, compiledPattern, offset, offset + prefixLength, field);
+            offset += prefixLength;
+            length += prefixLength;
+            offset++;
+        }
+
+        int infixLength = compiledPattern.charAt(offset);
+        offset++;
+        if (infixLength < ARG_NUM_LIMIT) {
+            // No infix
+            infixLength = 0;
+        } else {
+            infixLength -= ARG_NUM_LIMIT;
+            result.insert(index + length, compiledPattern, offset, offset + infixLength, field);
+            offset += infixLength;
+            length += infixLength;
+            offset++;
+        }
+
+        int suffixLength;
+        if (offset == compiledPattern.length()) {
+            // No suffix
+            suffixLength = 0;
+        } else {
+            suffixLength = compiledPattern.charAt(offset) -  ARG_NUM_LIMIT;
+            offset++;
+            result.insert(index + length, compiledPattern, offset, offset + suffixLength, field);
+            length += suffixLength;
+        }
+
+        h.lengthPrefix = prefixLength;
+        h.lengthInfix = infixLength;
+        h.lengthSuffix = suffixLength;
+    }
 }

icu4j/main/classes/core/src/com/ibm/icu/impl/number/parse/ScientificMatcher.java

@@ -54,6 +54,11 @@ public class ScientificMatcher implements NumberParseMatcher {
             return false;
         }
 
+        // Only accept one exponent per string.
+        if (0 != (result.flags & ParsedNumber.FLAG_HAS_EXPONENT)) {
+            return false;
+        }
+
         // First match the scientific separator, and then match another number after it.
         // NOTE: This is guarded by the smoke test; no need to check exponentSeparatorString length again.
         int overlap1 = segment.getCommonPrefixLength(exponentSeparatorString);

icu4j/main/classes/core/src/com/ibm/icu/impl/number/range/PrefixInfixSuffixLengthHelper.java

@@ -0,0 +1,30 @@
+// © 2018 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html#License
+package com.ibm.icu.impl.number.range;
+
+/**
+ * A small, mutable internal helper class for keeping track of offsets on range patterns.
+ */
+public class PrefixInfixSuffixLengthHelper {
+    public int lengthPrefix = 0;
+    public int length1 = 0;
+    public int lengthInfix = 0;
+    public int length2 = 0;
+    public int lengthSuffix = 0;
+
+    public int index0() {
+        return lengthPrefix;
+    }
+
+    public int index1() {
+        return lengthPrefix + length1;
+    }
+
+    public int index2() {
+        return lengthPrefix + length1 + lengthInfix;
+    }
+
+    public int index3() {
+        return lengthPrefix + length1 + lengthInfix + length2;
+    }
+}

icu4j/main/classes/core/src/com/ibm/icu/impl/number/range/RangeMacroProps.java

@@ -0,0 +1,48 @@
+// © 2018 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html#License
+package com.ibm.icu.impl.number.range;
+
+import java.util.Objects;
+
+import com.ibm.icu.number.NumberRangeFormatter.RangeCollapse;
+import com.ibm.icu.number.NumberRangeFormatter.RangeIdentityFallback;
+import com.ibm.icu.number.UnlocalizedNumberFormatter;
+import com.ibm.icu.util.ULocale;
+
+/**
+ * @author sffc
+ *
+ */
+public class RangeMacroProps {
+    public UnlocalizedNumberFormatter formatter1;
+    public UnlocalizedNumberFormatter formatter2;
+    public int sameFormatters = -1; // -1 for unset, 0 for false, 1 for true
+    public RangeCollapse collapse;
+    public RangeIdentityFallback identityFallback;
+    public ULocale loc;
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(formatter1,
+                formatter2,
+                collapse,
+                identityFallback,
+                loc);
+    }
+
+    @Override
+    public boolean equals(Object _other) {
+        if (_other == null)
+            return false;
+        if (this == _other)
+            return true;
+        if (!(_other instanceof RangeMacroProps))
+            return false;
+        RangeMacroProps other = (RangeMacroProps) _other;
+        return Objects.equals(formatter1, other.formatter1)
+                && Objects.equals(formatter2, other.formatter2)
+                && Objects.equals(collapse, other.collapse)
+                && Objects.equals(identityFallback, other.identityFallback)
+                && Objects.equals(loc, other.loc);
+    }
+}

icu4j/main/classes/core/src/com/ibm/icu/impl/number/range/StandardPluralRanges.java

@@ -0,0 +1,104 @@
+// © 2018 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html#License
+package com.ibm.icu.impl.number.range;
+
+import java.util.MissingResourceException;
+
+import com.ibm.icu.impl.ICUData;
+import com.ibm.icu.impl.ICUResourceBundle;
+import com.ibm.icu.impl.StandardPlural;
+import com.ibm.icu.impl.UResource;
+import com.ibm.icu.util.ULocale;
+import com.ibm.icu.util.UResourceBundle;
+
+/**
+ * @author sffc
+ *
+ */
+public class StandardPluralRanges {
+
+    StandardPlural[] flatTriples;
+    int numTriples = 0;
+
+    ////////////////////
+
+    private static final class PluralRangesDataSink extends UResource.Sink {
+
+        StandardPluralRanges output;
+
+        PluralRangesDataSink(StandardPluralRanges output) {
+            this.output = output;
+        }
+
+        @Override
+        public void put(UResource.Key key, UResource.Value value, boolean noFallback) {
+            UResource.Array entriesArray = value.getArray();
+            output.setCapacity(entriesArray.getSize());
+            for (int i = 0; entriesArray.getValue(i, value); ++i) {
+                UResource.Array pluralFormsArray = value.getArray();
+                pluralFormsArray.getValue(0, value);
+                StandardPlural first = StandardPlural.fromString(value.getString());
+                pluralFormsArray.getValue(1, value);
+                StandardPlural second = StandardPlural.fromString(value.getString());
+                pluralFormsArray.getValue(2, value);
+                StandardPlural result = StandardPlural.fromString(value.getString());
+                output.addPluralRange(first, second, result);
+            }
+        }
+    }
+
+    private static void getPluralRangesData(
+            ULocale locale,
+            StandardPluralRanges out) {
+        StringBuilder sb = new StringBuilder();
+        ICUResourceBundle resource;
+        resource = (ICUResourceBundle) UResourceBundle.getBundleInstance(ICUData.ICU_BASE_NAME, "pluralRanges");
+        sb.append("locales/");
+        sb.append(locale.getLanguage());
+        String key = sb.toString();
+        String set;
+        try {
+            set = resource.getStringWithFallback(key);
+        } catch (MissingResourceException e) {
+            // Not all languages are covered: fail gracefully
+            return;
+        }
+
+        sb.setLength(0);
+        sb.append("rules/");
+        sb.append(set);
+        key = sb.toString();
+        PluralRangesDataSink sink = new PluralRangesDataSink(out);
+        resource.getAllItemsWithFallback(key, sink);
+    }
+
+    ////////////////////
+
+    public StandardPluralRanges(ULocale locale) {
+        getPluralRangesData(locale, this);
+    }
+
+    /** Used for data loading. */
+    private void addPluralRange(StandardPlural first, StandardPlural second, StandardPlural result) {
+        flatTriples[3 * numTriples] = first;
+        flatTriples[3 * numTriples + 1] = second;
+        flatTriples[3 * numTriples + 2] = result;
+        numTriples++;
+    }
+
+    /** Used for data loading. */
+    private void setCapacity(int length) {
+        flatTriples = new StandardPlural[length*3];
+    }
+
+    public StandardPlural resolve(StandardPlural first, StandardPlural second) {
+        for (int i = 0; i < numTriples; i++) {
+            if (first == flatTriples[3 * i] && second == flatTriples[3 * i + 1]) {
+                return flatTriples[3 * i + 2];
+            }
+        }
+        // Default fallback
+        return StandardPlural.OTHER;
+    }
+
+}

icu4j/main/classes/core/src/com/ibm/icu/number/FormattedNumber.java

@@ -70,9 +70,9 @@ public class FormattedNumber {
     }
 
     /**
-     * Determine the start and end indices of the first occurrence of the given <em>field</em> in the
-     * output string. This allows you to determine the locations of the integer part, fraction part, and
-     * sign.
+     * Determines the start (inclusive) and end (exclusive) indices of the next occurrence of the given
+     * <em>field</em> in the output string. This allows you to determine the locations of, for example,
+     * the integer part, fraction part, or symbols.
      *
      * <p>
      * If multiple different field attributes are needed, this method can be called repeatedly, or if

icu4j/main/classes/core/src/com/ibm/icu/number/FormattedNumberRange.java

@@ -0,0 +1,209 @@
+// © 2018 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html#License
+package com.ibm.icu.number;
+
+import java.io.IOException;
+import java.math.BigDecimal;
+import java.text.AttributedCharacterIterator;
+import java.text.FieldPosition;
+import java.util.Arrays;
+
+import com.ibm.icu.impl.number.DecimalQuantity;
+import com.ibm.icu.impl.number.NumberStringBuilder;
+import com.ibm.icu.number.NumberRangeFormatter.RangeIdentityResult;
+import com.ibm.icu.util.ICUUncheckedIOException;
+
+/**
+ * The result of a number range formatting operation. This class allows the result to be exported in several data types,
+ * including a String, an AttributedCharacterIterator, and a BigDecimal.
+ *
+ * @author sffc
+ * @draft ICU 63
+ * @provisional This API might change or be removed in a future release.
+ * @see NumberRangeFormatter
+ */
+public class FormattedNumberRange {
+    final NumberStringBuilder string;
+    final DecimalQuantity quantity1;
+    final DecimalQuantity quantity2;
+    final RangeIdentityResult identityResult;
+
+    FormattedNumberRange(NumberStringBuilder string, DecimalQuantity quantity1, DecimalQuantity quantity2,
+            RangeIdentityResult identityResult) {
+        this.string = string;
+        this.quantity1 = quantity1;
+        this.quantity2 = quantity2;
+        this.identityResult = identityResult;
+    }
+
+    /**
+     * Creates a String representation of the the formatted number range.
+     *
+     * @return a String containing the localized number range.
+     * @draft ICU 63
+     * @provisional This API might change or be removed in a future release.
+     * @see NumberRangeFormatter
+     */
+    @Override
+    public String toString() {
+        return string.toString();
+    }
+
+    /**
+     * Append the formatted number range to an Appendable, such as a StringBuilder. This may be slightly more efficient
+     * than creating a String.
+     *
+     * <p>
+     * If an IOException occurs when appending to the Appendable, an unchecked {@link ICUUncheckedIOException} is thrown
+     * instead.
+     *
+     * @param appendable
+     *            The Appendable to which to append the formatted number range string.
+     * @return The same Appendable, for chaining.
+     * @draft ICU 63
+     * @provisional This API might change or be removed in a future release.
+     * @see Appendable
+     * @see NumberRangeFormatter
+     */
+    public <A extends Appendable> A appendTo(A appendable) {
+        try {
+            appendable.append(string);
+        } catch (IOException e) {
+            // Throw as an unchecked exception to avoid users needing try/catch
+            throw new ICUUncheckedIOException(e);
+        }
+        return appendable;
+    }
+
+    /**
+     * Determines the start (inclusive) and end (exclusive) indices of the next occurrence of the given
+     * <em>field</em> in the output string. This allows you to determine the locations of, for example,
+     * the integer part, fraction part, or symbols.
+     * <p>
+     * If both sides of the range have the same field, the field will occur twice, once before the range separator and
+     * once after the range separator, if applicable.
+     * <p>
+     * If a field occurs just once, calling this method will find that occurrence and return it. If a field occurs
+     * multiple times, this method may be called repeatedly with the following pattern:
+     *
+     * <pre>
+     * FieldPosition fpos = new FieldPosition(NumberFormat.Field.INTEGER);
+     * while (formattedNumberRange.nextFieldPosition(fpos, status)) {
+     *     // do something with fpos.
+     * }
+     * </pre>
+     * <p>
+     * This method is useful if you know which field to query. If you want all available field position information, use
+     * {@link #toCharacterIterator()}.
+     *
+     * @param fieldPosition
+     *            Input+output variable. See {@link FormattedNumber#nextFieldPosition(FieldPosition)}.
+     * @return true if a new occurrence of the field was found; false otherwise.
+     * @draft ICU 63
+     * @provisional This API might change or be removed in a future release.
+     * @see com.ibm.icu.text.NumberFormat.Field
+     * @see NumberRangeFormatter
+     */
+    public boolean nextFieldPosition(FieldPosition fieldPosition) {
+        return string.nextFieldPosition(fieldPosition);
+    }
+
+    /**
+     * Export the formatted number range as an AttributedCharacterIterator. This allows you to determine which
+     * characters in the output string correspond to which <em>fields</em>, such as the integer part, fraction part, and
+     * sign.
+     * <p>
+     * If information on only one field is needed, use {@link #nextFieldPosition(FieldPosition)} instead.
+     *
+     * @return An AttributedCharacterIterator, containing information on the field attributes of the number range
+     *         string.
+     * @draft ICU 63
+     * @provisional This API might change or be removed in a future release.
+     * @see com.ibm.icu.text.NumberFormat.Field
+     * @see AttributedCharacterIterator
+     * @see NumberRangeFormatter
+     */
+    public AttributedCharacterIterator toCharacterIterator() {
+        return string.toCharacterIterator();
+    }
+
+    /**
+     * Export the first formatted number as a BigDecimal. This endpoint is useful for obtaining the exact number being
+     * printed after scaling and rounding have been applied by the number range formatting pipeline.
+     *
+     * @return A BigDecimal representation of the first formatted number.
+     * @draft ICU 63
+     * @provisional This API might change or be removed in a future release.
+     * @see NumberRangeFormatter
+     * @see #getSecondBigDecimal
+     */
+    public BigDecimal getFirstBigDecimal() {
+        return quantity1.toBigDecimal();
+    }
+
+    /**
+     * Export the second formatted number as a BigDecimal. This endpoint is useful for obtaining the exact number being
+     * printed after scaling and rounding have been applied by the number range formatting pipeline.
+     *
+     * @return A BigDecimal representation of the second formatted number.
+     * @draft ICU 63
+     * @provisional This API might change or be removed in a future release.
+     * @see NumberRangeFormatter
+     * @see #getFirstBigDecimal
+     */
+    public BigDecimal getSecondBigDecimal() {
+        return quantity2.toBigDecimal();
+    }
+
+    /**
+     * Returns whether the pair of numbers was successfully formatted as a range or whether an identity fallback was
+     * used. For example, if the first and second number were the same either before or after rounding occurred, an
+     * identity fallback was used.
+     *
+     * @return A RangeIdentityType indicating the resulting identity situation in the formatted number range.
+     * @draft ICU 63
+     * @provisional This API might change or be removed in a future release.
+     * @see NumberRangeFormatter
+     * @see NumberRangeFormatter.RangeIdentityFallback
+     */
+    public RangeIdentityResult getIdentityResult() {
+        return identityResult;
+    }
+
+    /**
+     * {@inheritDoc}
+     *
+     * @draft ICU 63
+     * @provisional This API might change or be removed in a future release.
+     */
+    @Override
+    public int hashCode() {
+        // NumberStringBuilder and BigDecimal are mutable, so we can't call
+        // #equals() or #hashCode() on them directly.
+        return Arrays.hashCode(string.toCharArray()) ^ Arrays.hashCode(string.toFieldArray())
+                ^ quantity1.toBigDecimal().hashCode() ^ quantity2.toBigDecimal().hashCode();
+    }
+
+    /**
+     * {@inheritDoc}
+     *
+     * @draft ICU 63
+     * @provisional This API might change or be removed in a future release.
+     */
+    @Override
+    public boolean equals(Object other) {
+        if (this == other)
+            return true;
+        if (other == null)
+            return false;
+        if (!(other instanceof FormattedNumberRange))
+            return false;
+        // NumberStringBuilder and BigDecimal are mutable, so we can't call
+        // #equals() or #hashCode() on them directly.
+        FormattedNumberRange _other = (FormattedNumberRange) other;
+        return Arrays.equals(string.toCharArray(), _other.string.toCharArray())
+                && Arrays.equals(string.toFieldArray(), _other.string.toFieldArray())
+                && quantity1.toBigDecimal().equals(_other.quantity1.toBigDecimal())
+                && quantity2.toBigDecimal().equals(_other.quantity2.toBigDecimal());
+    }
+}

icu4j/main/classes/core/src/com/ibm/icu/number/LocalizedNumberFormatter.java

@@ -152,9 +152,9 @@ public class LocalizedNumberFormatter extends NumberFormatterSettings<LocalizedN
     public FormattedNumber format(DecimalQuantity fq) {
         NumberStringBuilder string = new NumberStringBuilder();
         if (computeCompiled()) {
-            compiled.apply(fq, string);
+            compiled.format(fq, string);
         } else {
-            NumberFormatterImpl.applyStatic(resolve(), fq, string);
+            NumberFormatterImpl.formatStatic(resolve(), fq, string);
         }
         return new FormattedNumber(string, fq);
     }
@@ -190,7 +190,7 @@ public class LocalizedNumberFormatter extends NumberFormatterSettings<LocalizedN
         // Further benchmarking is required.
         long currentCount = callCount.incrementAndGet(this);
         if (currentCount == macros.threshold.longValue()) {
-            compiled = NumberFormatterImpl.fromMacros(macros);
+            compiled = new NumberFormatterImpl(macros);
             return true;
         } else if (compiled != null) {
             return true;

icu4j/main/classes/core/src/com/ibm/icu/number/LocalizedNumberRangeFormatter.java

@@ -0,0 +1,98 @@
+// © 2018 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html#License
+package com.ibm.icu.number;
+
+import com.ibm.icu.impl.number.DecimalQuantity;
+import com.ibm.icu.impl.number.DecimalQuantity_DualStorageBCD;
+
+/**
+ * A NumberRangeFormatter that has a locale associated with it; this means .formatRange() methods are available.
+ *
+ * @author sffc
+ * @draft ICU 63
+ * @provisional This API might change or be removed in a future release.
+ * @see NumberRangeFormatter
+ */
+public class LocalizedNumberRangeFormatter extends NumberRangeFormatterSettings<LocalizedNumberRangeFormatter> {
+
+    private volatile NumberRangeFormatterImpl fImpl;
+
+    LocalizedNumberRangeFormatter(NumberRangeFormatterSettings<?> parent, int key, Object value) {
+        super(parent, key, value);
+    }
+
+    /**
+     * Format the given integers to a string using the settings specified in the NumberRangeFormatter fluent setting
+     * chain.
+     *
+     * @param first
+     *            The first number in the range, usually to the left in LTR locales.
+     * @param second
+     *            The second number in the range, usually to the right in LTR locales.
+     * @return A FormattedNumberRange object; call .toString() to get the string.
+     * @draft ICU 63
+     * @provisional This API might change or be removed in a future release.
+     * @see NumberRangeFormatter
+     */
+    public FormattedNumberRange formatRange(int first, int second) {
+        DecimalQuantity dq1 = new DecimalQuantity_DualStorageBCD(first);
+        DecimalQuantity dq2 = new DecimalQuantity_DualStorageBCD(second);
+        return formatImpl(dq1, dq2, first == second);
+    }
+
+    /**
+     * Format the given doubles to a string using the settings specified in the NumberRangeFormatter fluent setting
+     * chain.
+     *
+     * @param first
+     *            The first number in the range, usually to the left in LTR locales.
+     * @param second
+     *            The second number in the range, usually to the right in LTR locales.
+     * @return A FormattedNumberRange object; call .toString() to get the string.
+     * @draft ICU 63
+     * @provisional This API might change or be removed in a future release.
+     * @see NumberRangeFormatter
+     */
+    public FormattedNumberRange formatRange(double first, double second) {
+        DecimalQuantity dq1 = new DecimalQuantity_DualStorageBCD(first);
+        DecimalQuantity dq2 = new DecimalQuantity_DualStorageBCD(second);
+        // Note: double equality could be changed to epsilon equality later if there is demand.
+        // The epsilon should be set via an API method.
+        return formatImpl(dq1, dq2, first == second);
+    }
+
+    /**
+     * Format the given Numbers to a string using the settings specified in the NumberRangeFormatter fluent setting
+     * chain.
+     *
+     * @param first
+     *            The first number in the range, usually to the left in LTR locales.
+     * @param second
+     *            The second number in the range, usually to the right in LTR locales.
+     * @return A FormattedNumberRange object; call .toString() to get the string.
+     * @draft ICU 63
+     * @provisional This API might change or be removed in a future release.
+     * @see NumberRangeFormatter
+     */
+    public FormattedNumberRange formatRange(Number first, Number second) {
+        if (first == null || second == null) {
+            throw new IllegalArgumentException("Cannot format null values in range");
+        }
+        DecimalQuantity dq1 = new DecimalQuantity_DualStorageBCD(first);
+        DecimalQuantity dq2 = new DecimalQuantity_DualStorageBCD(second);
+        return formatImpl(dq1, dq2, first.equals(second));
+    }
+
+    FormattedNumberRange formatImpl(DecimalQuantity first, DecimalQuantity second, boolean equalBeforeRounding) {
+        if (fImpl == null) {
+            fImpl = new NumberRangeFormatterImpl(resolve());
+        }
+        return fImpl.format(first, second, equalBeforeRounding);
+    }
+
+    @Override
+    LocalizedNumberRangeFormatter create(int key, Object value) {
+        return new LocalizedNumberRangeFormatter(this, key, value);
+    }
+
+}

icu4j/main/classes/core/src/com/ibm/icu/number/NumberFormatterImpl.java

@@ -42,21 +42,21 @@ import com.ibm.icu.util.MeasureUnit;
 class NumberFormatterImpl {
 
     /** Builds a "safe" MicroPropsGenerator, which is thread-safe and can be used repeatedly. */
-    public static NumberFormatterImpl fromMacros(MacroProps macros) {
-        MicroPropsGenerator microPropsGenerator = macrosToMicroGenerator(macros, true);
-        return new NumberFormatterImpl(microPropsGenerator);
+    public NumberFormatterImpl(MacroProps macros) {
+        this(macrosToMicroGenerator(macros, true));
     }
 
     /**
      * Builds and evaluates an "unsafe" MicroPropsGenerator, which is cheaper but can be used only once.
      */
-    public static void applyStatic(
+    public static int formatStatic(
             MacroProps macros,
             DecimalQuantity inValue,
             NumberStringBuilder outString) {
-        MicroPropsGenerator microPropsGenerator = macrosToMicroGenerator(macros, false);
-        MicroProps micros = microPropsGenerator.processQuantity(inValue);
-        microsToString(micros, inValue, outString);
+        MicroProps micros = preProcessUnsafe(macros, inValue);
+        int length = writeNumber(micros, inValue, outString, 0);
+        length += writeAffixes(micros, outString, 0, length);
+        return length;
     }
 
     /**
@@ -82,9 +82,40 @@ class NumberFormatterImpl {
         this.microPropsGenerator = microPropsGenerator;
     }
 
-    public void apply(DecimalQuantity inValue, NumberStringBuilder outString) {
+    /**
+     * Evaluates the "safe" MicroPropsGenerator created by "fromMacros".
+     */
+    public int format(DecimalQuantity inValue, NumberStringBuilder outString) {
+        MicroProps micros = preProcess(inValue);
+        int length = writeNumber(micros, inValue, outString, 0);
+        length += writeAffixes(micros, outString, 0, length);
+        return length;
+    }
+
+    /**
+     * Like format(), but saves the result into an output MicroProps without additional processing.
+     */
+    public MicroProps preProcess(DecimalQuantity inValue) {
         MicroProps micros = microPropsGenerator.processQuantity(inValue);
-        microsToString(micros, inValue, outString);
+        micros.rounder.apply(inValue);
+        if (micros.integerWidth.maxInt == -1) {
+            inValue.setIntegerLength(micros.integerWidth.minInt, Integer.MAX_VALUE);
+        } else {
+            inValue.setIntegerLength(micros.integerWidth.minInt, micros.integerWidth.maxInt);
+        }
+        return micros;
+    }
+
+    private static MicroProps preProcessUnsafe(MacroProps macros, DecimalQuantity inValue) {
+        MicroPropsGenerator microPropsGenerator = macrosToMicroGenerator(macros, false);
+        MicroProps micros = microPropsGenerator.processQuantity(inValue);
+        micros.rounder.apply(inValue);
+        if (micros.integerWidth.maxInt == -1) {
+            inValue.setIntegerLength(micros.integerWidth.minInt, Integer.MAX_VALUE);
+        } else {
+            inValue.setIntegerLength(micros.integerWidth.minInt, micros.integerWidth.maxInt);
+        }
+        return micros;
     }
 
     public int getPrefixSuffix(byte signum, StandardPlural plural, NumberStringBuilder output) {
@@ -350,64 +381,55 @@ class NumberFormatterImpl {
     //////////
 
     /**
-     * Synthesizes the output string from a MicroProps and DecimalQuantity.
-     *
-     * @param micros
-     *            The MicroProps after the quantity has been consumed. Will not be mutated.
-     * @param quantity
-     *            The DecimalQuantity to be rendered. May be mutated.
-     * @param string
-     *            The output string. Will be mutated.
+     * Adds the affixes.  Intended to be called immediately after formatNumber.
      */
-    private static void microsToString(
+    public static int writeAffixes(
             MicroProps micros,
-            DecimalQuantity quantity,
-            NumberStringBuilder string) {
-        micros.rounder.apply(quantity);
-        if (micros.integerWidth.maxInt == -1) {
-            quantity.setIntegerLength(micros.integerWidth.minInt, Integer.MAX_VALUE);
-        } else {
-            quantity.setIntegerLength(micros.integerWidth.minInt, micros.integerWidth.maxInt);
-        }
-        int length = writeNumber(micros, quantity, string);
-        // NOTE: When range formatting is added, these modifiers can bubble up.
-        // For now, apply them all here at once.
+            NumberStringBuilder string,
+            int start,
+            int end) {
         // Always apply the inner modifier (which is "strong").
-        length += micros.modInner.apply(string, 0, length);
+        int length = micros.modInner.apply(string, start, end);
         if (micros.padding.isValid()) {
-            micros.padding.padAndApply(micros.modMiddle, micros.modOuter, string, 0, length);
+            micros.padding.padAndApply(micros.modMiddle, micros.modOuter, string, start, end + length);
         } else {
-            length += micros.modMiddle.apply(string, 0, length);
-            length += micros.modOuter.apply(string, 0, length);
+            length += micros.modMiddle.apply(string, start, end + length);
+            length += micros.modOuter.apply(string, start, end + length);
         }
+        return length;
     }
 
-    private static int writeNumber(
+    /**
+     * Synthesizes the output string from a MicroProps and DecimalQuantity.
+     * This method formats only the main number, not affixes.
+     */
+    public static int writeNumber(
             MicroProps micros,
             DecimalQuantity quantity,
-            NumberStringBuilder string) {
+            NumberStringBuilder string,
+            int index) {
         int length = 0;
         if (quantity.isInfinite()) {
-            length += string.insert(length, micros.symbols.getInfinity(), NumberFormat.Field.INTEGER);
+            length += string.insert(length + index, micros.symbols.getInfinity(), NumberFormat.Field.INTEGER);
 
         } else if (quantity.isNaN()) {
-            length += string.insert(length, micros.symbols.getNaN(), NumberFormat.Field.INTEGER);
+            length += string.insert(length + index, micros.symbols.getNaN(), NumberFormat.Field.INTEGER);
 
         } else {
             // Add the integer digits
-            length += writeIntegerDigits(micros, quantity, string);
+            length += writeIntegerDigits(micros, quantity, string, length + index);
 
             // Add the decimal point
             if (quantity.getLowerDisplayMagnitude() < 0
                     || micros.decimal == DecimalSeparatorDisplay.ALWAYS) {
-                length += string.insert(length,
+                length += string.insert(length + index,
                         micros.useCurrency ? micros.symbols.getMonetaryDecimalSeparatorString()
                                 : micros.symbols.getDecimalSeparatorString(),
                         NumberFormat.Field.DECIMAL_SEPARATOR);
             }
 
             // Add the fraction digits
-            length += writeFractionDigits(micros, quantity, string);
+            length += writeFractionDigits(micros, quantity, string, length + index);
         }
 
         return length;
@@ -416,13 +438,14 @@ class NumberFormatterImpl {
     private static int writeIntegerDigits(
             MicroProps micros,
             DecimalQuantity quantity,
-            NumberStringBuilder string) {
+            NumberStringBuilder string,
+            int index) {
         int length = 0;
         int integerCount = quantity.getUpperDisplayMagnitude() + 1;
         for (int i = 0; i < integerCount; i++) {
             // Add grouping separator
             if (micros.grouping.groupAtPosition(i, quantity)) {
-                length += string.insert(0,
+                length += string.insert(index,
                         micros.useCurrency ? micros.symbols.getMonetaryGroupingSeparatorString()
                                 : micros.symbols.getGroupingSeparatorString(),
                         NumberFormat.Field.GROUPING_SEPARATOR);
@@ -431,11 +454,11 @@ class NumberFormatterImpl {
             // Get and append the next digit value
             byte nextDigit = quantity.getDigit(i);
             if (micros.symbols.getCodePointZero() != -1) {
-                length += string.insertCodePoint(0,
+                length += string.insertCodePoint(index,
                         micros.symbols.getCodePointZero() + nextDigit,
                         NumberFormat.Field.INTEGER);
             } else {
-                length += string.insert(0,
+                length += string.insert(index,
                         micros.symbols.getDigitStringsLocal()[nextDigit],
                         NumberFormat.Field.INTEGER);
             }
@@ -446,17 +469,18 @@ class NumberFormatterImpl {
     private static int writeFractionDigits(
             MicroProps micros,
             DecimalQuantity quantity,
-            NumberStringBuilder string) {
+            NumberStringBuilder string,
+            int index) {
         int length = 0;
         int fractionCount = -quantity.getLowerDisplayMagnitude();
         for (int i = 0; i < fractionCount; i++) {
             // Get and append the next digit value
             byte nextDigit = quantity.getDigit(-i - 1);
             if (micros.symbols.getCodePointZero() != -1) {
-                length += string.appendCodePoint(micros.symbols.getCodePointZero() + nextDigit,
+                length += string.insertCodePoint(length + index, micros.symbols.getCodePointZero() + nextDigit,
                         NumberFormat.Field.FRACTION);
             } else {
-                length += string.append(micros.symbols.getDigitStringsLocal()[nextDigit],
+                length += string.insert(length + index, micros.symbols.getDigitStringsLocal()[nextDigit],
                         NumberFormat.Field.FRACTION);
             }
         }

icu4j/main/classes/core/src/com/ibm/icu/number/NumberFormatterSettings.java

@@ -47,10 +47,10 @@ public abstract class NumberFormatterSettings<T extends NumberFormatterSettings<
     static final int KEY_PER_UNIT = 15;
     static final int KEY_MAX = 16;
 
-    final NumberFormatterSettings<?> parent;
-    final int key;
-    final Object value;
-    volatile MacroProps resolvedMacros;
+    private final NumberFormatterSettings<?> parent;
+    private final int key;
+    private final Object value;
+    private volatile MacroProps resolvedMacros;
 
     NumberFormatterSettings(NumberFormatterSettings<?> parent, int key, Object value) {
         this.parent = parent;

icu4j/main/classes/core/src/com/ibm/icu/number/NumberPropertyMapper.java

@@ -263,8 +263,8 @@ final class NumberPropertyMapper {
             // TODO: Overriding here is a bit of a hack. Should this logic go earlier?
             if (macros.precision instanceof FractionPrecision) {
                 // For the purposes of rounding, get the original min/max int/frac, since the local
-                // variables
-                // have been manipulated for display purposes.
+                // variables have been manipulated for display purposes.
+                int maxInt_ = properties.getMaximumIntegerDigits();
                 int minInt_ = properties.getMinimumIntegerDigits();
                 int minFrac_ = properties.getMinimumFractionDigits();
                 int maxFrac_ = properties.getMaximumFractionDigits();
@@ -275,8 +275,15 @@ final class NumberPropertyMapper {
                     // Patterns like "#.##E0" (no zeros in the mantissa), which mean round to maxFrac+1
                     macros.precision = Precision.constructSignificant(1, maxFrac_ + 1).withMode(mathContext);
                 } else {
-                    // All other scientific patterns, which mean round to minInt+maxFrac
-                    macros.precision = Precision.constructSignificant(minInt_ + minFrac_, minInt_ + maxFrac_)
+                    int maxSig_ = minInt_ + maxFrac_;
+                    // Bug #20058: if maxInt_ > minInt_ > 1, then minInt_ should be 1.
+                    if (maxInt_ > minInt_ && minInt_ > 1) {
+                        minInt_ = 1;
+                    }
+                    int minSig_ = minInt_ + minFrac_;
+                    // To avoid regression, maxSig is not reset when minInt_ set to 1.
+                    // TODO: Reset maxSig_ = 1 + minFrac_ to follow the spec.
+                    macros.precision = Precision.constructSignificant(minSig_, maxSig_)
                             .withMode(mathContext);
                 }
             }

icu4j/main/classes/core/src/com/ibm/icu/number/NumberRangeFormatter.java

@@ -0,0 +1,209 @@
+// © 2018 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html#License
+package com.ibm.icu.number;
+
+import java.util.Locale;
+
+import com.ibm.icu.util.ULocale;
+
+/**
+ * The main entrypoint to the formatting of ranges of numbers, including currencies and other units of measurement.
+ * <p>
+ * Usage example:
+ * <pre>
+ * NumberRangeFormatter.with()
+ *         .identityFallback(RangeIdentityFallback.APPROXIMATELY_OR_SINGLE_VALUE)
+ *         .numberFormatterFirst(NumberFormatter.with().unit(MeasureUnit.METER))
+ *         .numberFormatterSecond(NumberFormatter.with().unit(MeasureUnit.KILOMETER))
+ *         .locale(ULocale.UK)
+ *         .formatRange(750, 1.2)
+ *         .toString();
+ * // => "750 m - 1.2 km"
+ * </pre>
+ * <p>
+ * Like NumberFormatter, NumberRangeFormatter instances are immutable and thread-safe. This API is based on the
+ * <em>fluent</em> design pattern popularized by libraries such as Google's Guava.
+ *
+ * @author sffc
+ * @draft ICU 63
+ * @provisional This API might change or be removed in a future release.
+ * @see NumberFormatter
+ */
+public abstract class NumberRangeFormatter {
+
+    /**
+     * Defines how to merge fields that are identical across the range sign.
+     *
+     * @draft ICU 63
+     * @provisional This API might change or be removed in a future release.
+     * @see NumberRangeFormatter
+     */
+    public enum RangeCollapse {
+        /**
+         * Use locale data and heuristics to determine how much of the string to collapse. Could end up collapsing none,
+         * some, or all repeated pieces in a locale-sensitive way.
+         * <p>
+         * The heuristics used for this option are subject to change over time.
+         *
+         * @draft ICU 63
+         * @provisional This API might change or be removed in a future release.
+         * @see NumberRangeFormatter
+         */
+        AUTO,
+
+        /**
+         * Do not collapse any part of the number. Example: "3.2 thousand kilograms – 5.3 thousand kilograms"
+         *
+         * @draft ICU 63
+         * @provisional This API might change or be removed in a future release.
+         * @see NumberRangeFormatter
+         */
+        NONE,
+
+        /**
+         * Collapse the unit part of the number, but not the notation, if present. Example: "3.2 thousand – 5.3 thousand
+         * kilograms"
+         *
+         * @draft ICU 63
+         * @provisional This API might change or be removed in a future release.
+         * @see NumberRangeFormatter
+         */
+        UNIT,
+
+        /**
+         * Collapse any field that is equal across the range sign. May introduce ambiguity on the magnitude of the
+         * number. Example: "3.2 – 5.3 thousand kilograms"
+         *
+         * @draft ICU 63
+         * @provisional This API might change or be removed in a future release.
+         * @see NumberRangeFormatter
+         */
+        ALL
+    }
+
+    /**
+     * Defines the behavior when the two numbers in the range are identical after rounding. To programmatically detect
+     * when the identity fallback is used, compare the lower and upper BigDecimals via FormattedNumber.
+     *
+     * @draft ICU 63
+     * @provisional This API might change or be removed in a future release.
+     * @see NumberRangeFormatter
+     */
+    public static enum RangeIdentityFallback {
+        /**
+         * Show the number as a single value rather than a range. Example: "$5"
+         *
+         * @draft ICU 63
+         * @provisional This API might change or be removed in a future release.
+         * @see NumberRangeFormatter
+         */
+        SINGLE_VALUE,
+
+        /**
+         * Show the number using a locale-sensitive approximation pattern. If the numbers were the same before rounding,
+         * show the single value. Example: "~$5" or "$5"
+         *
+         * @draft ICU 63
+         * @provisional This API might change or be removed in a future release.
+         * @see NumberRangeFormatter
+         */
+        APPROXIMATELY_OR_SINGLE_VALUE,
+
+        /**
+         * Show the number using a locale-sensitive approximation pattern. Use the range pattern always, even if the
+         * inputs are the same. Example: "~$5"
+         *
+         * @draft ICU 63
+         * @provisional This API might change or be removed in a future release.
+         * @see NumberRangeFormatter
+         */
+        APPROXIMATELY,
+
+        /**
+         * Show the number as the range of two equal values. Use the range pattern always, even if the inputs are the
+         * same. Example (with RangeCollapse.NONE): "$5 – $5"
+         *
+         * @draft ICU 63
+         * @provisional This API might change or be removed in a future release.
+         * @see NumberRangeFormatter
+         */
+        RANGE
+    }
+
+    /**
+     * Used in the result class FormattedNumberRange to indicate to the user whether the numbers formatted in the range
+     * were equal or not, and whether or not the identity fallback was applied.
+     *
+     * @draft ICU 63
+     * @provisional This API might change or be removed in a future release.
+     * @see NumberRangeFormatter
+     */
+    public static enum RangeIdentityResult {
+        /**
+         * Used to indicate that the two numbers in the range were equal, even before any rounding rules were applied.
+         *
+         * @draft ICU 63
+         * @provisional This API might change or be removed in a future release.
+         * @see NumberRangeFormatter
+         */
+        EQUAL_BEFORE_ROUNDING,
+
+        /**
+         * Used to indicate that the two numbers in the range were equal, but only after rounding rules were applied.
+         *
+         * @draft ICU 63
+         * @provisional This API might change or be removed in a future release.
+         * @see NumberRangeFormatter
+         */
+        EQUAL_AFTER_ROUNDING,
+
+        /**
+         * Used to indicate that the two numbers in the range were not equal, even after rounding rules were applied.
+         *
+         * @draft ICU 63
+         * @provisional This API might change or be removed in a future release.
+         * @see NumberRangeFormatter
+         */
+        NOT_EQUAL
+    }
+
+    private static final UnlocalizedNumberRangeFormatter BASE = new UnlocalizedNumberRangeFormatter();
+
+    /**
+     * Call this method at the beginning of a NumberRangeFormatter fluent chain in which the locale is not currently
+     * known at the call site.
+     *
+     * @return An {@link UnlocalizedNumberRangeFormatter}, to be used for chaining.
+     * @draft ICU 63
+     */
+    public static UnlocalizedNumberRangeFormatter with() {
+        return BASE;
+    }
+
+    /**
+     * Call this method at the beginning of a NumberRangeFormatter fluent chain in which the locale is known at the call
+     * site.
+     *
+     * @param locale
+     *            The locale from which to load formats and symbols for number range formatting.
+     * @return A {@link LocalizedNumberRangeFormatter}, to be used for chaining.
+     * @draft ICU 63
+     */
+    public static LocalizedNumberRangeFormatter withLocale(Locale locale) {
+        return BASE.locale(locale);
+    }
+
+    /**
+     * Call this method at the beginning of a NumberRangeFormatter fluent chain in which the locale is known at the call
+     * site.
+     *
+     * @param locale
+     *            The locale from which to load formats and symbols for number range formatting.
+     * @return A {@link LocalizedNumberRangeFormatter}, to be used for chaining.
+     * @draft ICU 63
+     */
+    public static LocalizedNumberRangeFormatter withLocale(ULocale locale) {
+        return BASE.locale(locale);
+    }
+
+}

icu4j/main/classes/core/src/com/ibm/icu/number/NumberRangeFormatterImpl.java

@@ -0,0 +1,370 @@
+// © 2018 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html#License
+package com.ibm.icu.number;
+
+import com.ibm.icu.impl.ICUData;
+import com.ibm.icu.impl.ICUResourceBundle;
+import com.ibm.icu.impl.PatternProps;
+import com.ibm.icu.impl.SimpleFormatterImpl;
+import com.ibm.icu.impl.StandardPlural;
+import com.ibm.icu.impl.UResource;
+import com.ibm.icu.impl.number.DecimalQuantity;
+import com.ibm.icu.impl.number.MicroProps;
+import com.ibm.icu.impl.number.Modifier;
+import com.ibm.icu.impl.number.NumberStringBuilder;
+import com.ibm.icu.impl.number.SimpleModifier;
+import com.ibm.icu.impl.number.range.PrefixInfixSuffixLengthHelper;
+import com.ibm.icu.impl.number.range.RangeMacroProps;
+import com.ibm.icu.impl.number.range.StandardPluralRanges;
+import com.ibm.icu.number.NumberRangeFormatter.RangeCollapse;
+import com.ibm.icu.number.NumberRangeFormatter.RangeIdentityFallback;
+import com.ibm.icu.number.NumberRangeFormatter.RangeIdentityResult;
+import com.ibm.icu.text.NumberFormat;
+import com.ibm.icu.util.ULocale;
+import com.ibm.icu.util.UResourceBundle;
+
+/**
+ * Business logic behind NumberRangeFormatter.
+ */
+class NumberRangeFormatterImpl {
+
+    final NumberFormatterImpl formatterImpl1;
+    final NumberFormatterImpl formatterImpl2;
+    final boolean fSameFormatters;
+
+    final NumberRangeFormatter.RangeCollapse fCollapse;
+    final NumberRangeFormatter.RangeIdentityFallback fIdentityFallback;
+
+    // Should be final, but they are set in a helper function, not the constructor proper.
+    // TODO: Clean up to make these fields actually final.
+    /* final */ String fRangePattern;
+    /* final */ SimpleModifier fApproximatelyModifier;
+
+    final StandardPluralRanges fPluralRanges;
+
+    ////////////////////
+
+     // Helper function for 2-dimensional switch statement
+     int identity2d(RangeIdentityFallback a, RangeIdentityResult b) {
+         return a.ordinal() | (b.ordinal() << 4);
+     }
+
+    private static final class NumberRangeDataSink extends UResource.Sink {
+
+        String rangePattern;
+        String approximatelyPattern;
+
+        // For use with SimpleFormatterImpl
+        StringBuilder sb;
+
+        NumberRangeDataSink(StringBuilder sb) {
+            this.sb = sb;
+        }
+
+        @Override
+        public void put(UResource.Key key, UResource.Value value, boolean noFallback) {
+            UResource.Table miscTable = value.getTable();
+            for (int i = 0; miscTable.getKeyAndValue(i, key, value); ++i) {
+                if (key.contentEquals("range") && rangePattern == null) {
+                    String pattern = value.getString();
+                    rangePattern = SimpleFormatterImpl.compileToStringMinMaxArguments(pattern, sb, 2, 2);
+                }
+                if (key.contentEquals("approximately") && approximatelyPattern == null) {
+                    String pattern = value.getString();
+                    approximatelyPattern = SimpleFormatterImpl.compileToStringMinMaxArguments(pattern, sb, 2, 2);
+                }
+            }
+        }
+    }
+
+    private static void getNumberRangeData(
+            ULocale locale,
+            String nsName,
+            NumberRangeFormatterImpl out) {
+        StringBuilder sb = new StringBuilder();
+        NumberRangeDataSink sink = new NumberRangeDataSink(sb);
+        ICUResourceBundle resource;
+        resource = (ICUResourceBundle) UResourceBundle.getBundleInstance(ICUData.ICU_BASE_NAME, locale);
+        sb.append("NumberElements/");
+        sb.append(nsName);
+        sb.append("/miscPatterns");
+        String key = sb.toString();
+        resource.getAllItemsWithFallback(key, sink);
+
+        // TODO: Is it necessary to manually fall back to latn, or does the data sink take care of that?
+
+        if (sink.rangePattern == null) {
+            sink.rangePattern = SimpleFormatterImpl.compileToStringMinMaxArguments("{0}–{1}", sb, 2, 2);
+        }
+        if (sink.approximatelyPattern == null) {
+            sink.approximatelyPattern = SimpleFormatterImpl.compileToStringMinMaxArguments("~{0}", sb, 1, 1);
+        }
+
+        out.fRangePattern = sink.rangePattern;
+        out.fApproximatelyModifier = new SimpleModifier(sink.approximatelyPattern, null, false);
+    }
+
+    ////////////////////
+
+    public NumberRangeFormatterImpl(RangeMacroProps macros) {
+        formatterImpl1 = new NumberFormatterImpl(macros.formatter1 != null ? macros.formatter1.resolve()
+                : NumberFormatter.withLocale(macros.loc).resolve());
+        formatterImpl2 = new NumberFormatterImpl(macros.formatter2 != null ? macros.formatter2.resolve()
+                : NumberFormatter.withLocale(macros.loc).resolve());
+        fSameFormatters = macros.sameFormatters != 0;
+        fCollapse = macros.collapse != null ? macros.collapse : NumberRangeFormatter.RangeCollapse.AUTO;
+        fIdentityFallback = macros.identityFallback != null ? macros.identityFallback
+                : NumberRangeFormatter.RangeIdentityFallback.APPROXIMATELY;
+
+        // TODO: As of this writing (ICU 63), there is no locale that has different number miscPatterns
+        // based on numbering system. Therefore, data is loaded only from latn. If this changes,
+        // this part of the code should be updated to load from the local numbering system.
+        // The numbering system could come from the one specified in the NumberFormatter passed to
+        // numberFormatterBoth() or similar.
+        // See ICU-20144
+
+        getNumberRangeData(macros.loc, "latn", this);
+
+        // TODO: Get locale from PluralRules instead?
+        fPluralRanges = new StandardPluralRanges(macros.loc);
+    }
+
+    public FormattedNumberRange format(DecimalQuantity quantity1, DecimalQuantity quantity2, boolean equalBeforeRounding) {
+        NumberStringBuilder string = new NumberStringBuilder();
+        MicroProps micros1 = formatterImpl1.preProcess(quantity1);
+        MicroProps micros2;
+        if (fSameFormatters) {
+            micros2 = formatterImpl1.preProcess(quantity2);
+        } else {
+            micros2 = formatterImpl2.preProcess(quantity2);
+        }
+
+        // If any of the affixes are different, an identity is not possible
+        // and we must use formatRange().
+        // TODO: Write this as MicroProps operator==() ?
+        // TODO: Avoid the redundancy of these equality operations with the
+        // ones in formatRange?
+        if (!micros1.modInner.semanticallyEquivalent(micros2.modInner)
+                || !micros1.modMiddle.semanticallyEquivalent(micros2.modMiddle)
+                || !micros1.modOuter.semanticallyEquivalent(micros2.modOuter)) {
+            formatRange(quantity1, quantity2, string, micros1, micros2);
+            return new FormattedNumberRange(string, quantity1, quantity2, RangeIdentityResult.NOT_EQUAL);
+        }
+
+        // Check for identity
+        RangeIdentityResult identityResult;
+        if (equalBeforeRounding) {
+            identityResult = RangeIdentityResult.EQUAL_BEFORE_ROUNDING;
+        } else if (quantity1.equals(quantity2)) {
+            identityResult = RangeIdentityResult.EQUAL_AFTER_ROUNDING;
+        } else {
+            identityResult = RangeIdentityResult.NOT_EQUAL;
+        }
+
+        // Java does not let us use a constexpr like C++;
+        // we need to expand identity2d calls.
+        switch (identity2d(fIdentityFallback, identityResult)) {
+        case (3 | (2 << 4)): // RANGE, NOT_EQUAL
+        case (3 | (1 << 4)): // RANGE, EQUAL_AFTER_ROUNDING
+        case (3 | (0 << 4)): // RANGE, EQUAL_BEFORE_ROUNDING
+        case (2 | (2 << 4)): // APPROXIMATELY, NOT_EQUAL
+        case (1 | (2 << 4)): // APPROXIMATE_OR_SINGLE_VALUE, NOT_EQUAL
+        case (0 | (2 << 4)): // SINGLE_VALUE, NOT_EQUAL
+            formatRange(quantity1, quantity2, string, micros1, micros2);
+            break;
+
+        case (2 | (1 << 4)): // APPROXIMATELY, EQUAL_AFTER_ROUNDING
+        case (2 | (0 << 4)): // APPROXIMATELY, EQUAL_BEFORE_ROUNDING
+        case (1 | (1 << 4)): // APPROXIMATE_OR_SINGLE_VALUE, EQUAL_AFTER_ROUNDING
+            formatApproximately(quantity1, quantity2, string, micros1, micros2);
+            break;
+
+        case (1 | (0 << 4)): // APPROXIMATE_OR_SINGLE_VALUE, EQUAL_BEFORE_ROUNDING
+        case (0 | (1 << 4)): // SINGLE_VALUE, EQUAL_AFTER_ROUNDING
+        case (0 | (0 << 4)): // SINGLE_VALUE, EQUAL_BEFORE_ROUNDING
+            formatSingleValue(quantity1, quantity2, string, micros1, micros2);
+            break;
+
+        default:
+            assert false;
+            break;
+        }
+
+        return new FormattedNumberRange(string, quantity1, quantity2, identityResult);
+    }
+
+    private void formatSingleValue(DecimalQuantity quantity1, DecimalQuantity quantity2, NumberStringBuilder string,
+            MicroProps micros1, MicroProps micros2) {
+        if (fSameFormatters) {
+            int length = NumberFormatterImpl.writeNumber(micros1, quantity1, string, 0);
+            NumberFormatterImpl.writeAffixes(micros1, string, 0, length);
+        } else {
+            formatRange(quantity1, quantity2, string, micros1, micros2);
+        }
+
+    }
+
+    private void formatApproximately(DecimalQuantity quantity1, DecimalQuantity quantity2, NumberStringBuilder string,
+            MicroProps micros1, MicroProps micros2) {
+        if (fSameFormatters) {
+            int length = NumberFormatterImpl.writeNumber(micros1, quantity1, string, 0);
+            length += NumberFormatterImpl.writeAffixes(micros1, string, 0, length);
+            fApproximatelyModifier.apply(string, 0, length);
+        } else {
+            formatRange(quantity1, quantity2, string, micros1, micros2);
+        }
+    }
+
+    private void formatRange(DecimalQuantity quantity1, DecimalQuantity quantity2, NumberStringBuilder string,
+            MicroProps micros1, MicroProps micros2) {
+        // modInner is always notation (scientific); collapsable in ALL.
+        // modOuter is always units; collapsable in ALL, AUTO, and UNIT.
+        // modMiddle could be either; collapsable in ALL and sometimes AUTO and UNIT.
+        // Never collapse an outer mod but not an inner mod.
+        boolean collapseOuter, collapseMiddle, collapseInner;
+        switch (fCollapse) {
+            case ALL:
+            case AUTO:
+            case UNIT:
+            {
+                // OUTER MODIFIER
+                collapseOuter = micros1.modOuter.semanticallyEquivalent(micros2.modOuter);
+
+                if (!collapseOuter) {
+                    // Never collapse inner mods if outer mods are not collapsable
+                    collapseMiddle = false;
+                    collapseInner = false;
+                    break;
+                }
+
+                // MIDDLE MODIFIER
+                collapseMiddle = micros1.modMiddle.semanticallyEquivalent(micros2.modMiddle);
+
+                if (!collapseMiddle) {
+                    // Never collapse inner mods if outer mods are not collapsable
+                    collapseInner = false;
+                    break;
+                }
+
+                // MIDDLE MODIFIER HEURISTICS
+                // (could disable collapsing of the middle modifier)
+                // The modifiers are equal by this point, so we can look at just one of them.
+                Modifier mm = micros1.modMiddle;
+                if (fCollapse == RangeCollapse.UNIT) {
+                    // Only collapse if the modifier is a unit.
+                    // TODO: Make a better way to check for a unit?
+                    // TODO: Handle case where the modifier has both notation and unit (compact currency)?
+                    if (!mm.containsField(NumberFormat.Field.CURRENCY) && !mm.containsField(NumberFormat.Field.PERCENT)) {
+                        collapseMiddle = false;
+                    }
+                } else if (fCollapse == RangeCollapse.AUTO) {
+                    // Heuristic as of ICU 63: collapse only if the modifier is more than one code point.
+                    if (mm.getCodePointCount() <= 1) {
+                        collapseMiddle = false;
+                    }
+                }
+
+                if (!collapseMiddle || fCollapse != RangeCollapse.ALL) {
+                    collapseInner = false;
+                    break;
+                }
+
+                // INNER MODIFIER
+                collapseInner = micros1.modInner.semanticallyEquivalent(micros2.modInner);
+
+                // All done checking for collapsability.
+                break;
+            }
+
+            default:
+                collapseOuter = false;
+                collapseMiddle = false;
+                collapseInner = false;
+                break;
+        }
+
+        // Java doesn't have macros, constexprs, or stack objects.
+        // Use a helper object instead.
+        PrefixInfixSuffixLengthHelper h = new PrefixInfixSuffixLengthHelper();
+
+        SimpleModifier.formatTwoArgPattern(fRangePattern, string, 0, h, null);
+        assert h.lengthInfix > 0;
+
+        // SPACING HEURISTIC
+        // Add spacing unless all modifiers are collapsed.
+        // TODO: add API to control this?
+        // TODO: Use a data-driven heuristic like currency spacing?
+        // TODO: Use Unicode [:whitespace:] instead of PatternProps whitespace? (consider speed implications)
+        {
+            boolean repeatInner = !collapseInner && micros1.modInner.getCodePointCount() > 0;
+            boolean repeatMiddle = !collapseMiddle && micros1.modMiddle.getCodePointCount() > 0;
+            boolean repeatOuter = !collapseOuter && micros1.modOuter.getCodePointCount() > 0;
+            if (repeatInner || repeatMiddle || repeatOuter) {
+                // Add spacing if there is not already spacing
+                if (!PatternProps.isWhiteSpace(string.charAt(h.index1()))) {
+                    h.lengthInfix += string.insertCodePoint(h.index1(), '\u0020', null);
+                }
+                if (!PatternProps.isWhiteSpace(string.charAt(h.index2() - 1))) {
+                    h.lengthInfix += string.insertCodePoint(h.index2(), '\u0020', null);
+                }
+            }
+        }
+
+        h.length1 += NumberFormatterImpl.writeNumber(micros1, quantity1, string, h.index0());
+        h.length2 += NumberFormatterImpl.writeNumber(micros2, quantity2, string, h.index2());
+
+        // TODO: Support padding?
+
+        if (collapseInner) {
+            // Note: this is actually a mix of prefix and suffix, but adding to infix length works
+            Modifier mod = resolveModifierPlurals(micros1.modInner, micros2.modInner);
+            h.lengthInfix += mod.apply(string, h.index0(), h.index3());
+        } else {
+            h.length1 += micros1.modInner.apply(string, h.index0(), h.index1());
+            h.length2 += micros2.modInner.apply(string, h.index2(), h.index3());
+        }
+
+        if (collapseMiddle) {
+            // Note: this is actually a mix of prefix and suffix, but adding to infix length works
+            Modifier mod = resolveModifierPlurals(micros1.modMiddle, micros2.modMiddle);
+            h.lengthInfix += mod.apply(string, h.index0(), h.index3());
+        } else {
+            h.length1 += micros1.modMiddle.apply(string, h.index0(), h.index1());
+            h.length2 += micros2.modMiddle.apply(string, h.index2(), h.index3());
+        }
+
+        if (collapseOuter) {
+            // Note: this is actually a mix of prefix and suffix, but adding to infix length works
+            Modifier mod = resolveModifierPlurals(micros1.modOuter, micros2.modOuter);
+            h.lengthInfix += mod.apply(string, h.index0(), h.index3());
+        } else {
+            h.length1 += micros1.modOuter.apply(string, h.index0(), h.index1());
+            h.length2 += micros2.modOuter.apply(string, h.index2(), h.index3());
+        }
+    }
+
+    Modifier resolveModifierPlurals(Modifier first, Modifier second) {
+        Modifier.Parameters firstParameters = first.getParameters();
+        if (firstParameters == null) {
+            // No plural form; return a fallback (e.g., the first)
+            return first;
+        }
+
+        Modifier.Parameters secondParameters = second.getParameters();
+        if (secondParameters == null) {
+            // No plural form; return a fallback (e.g., the first)
+            return first;
+        }
+
+        // Get the required plural form from data
+        StandardPlural resultPlural = fPluralRanges.resolve(firstParameters.plural, secondParameters.plural);
+
+        // Get and return the new Modifier
+        assert firstParameters.obj == secondParameters.obj;
+        assert firstParameters.signum == secondParameters.signum;
+        Modifier mod = firstParameters.obj.getModifier(firstParameters.signum, resultPlural);
+        assert mod != null;
+        return mod;
+    }
+
+}

icu4j/main/classes/core/src/com/ibm/icu/number/NumberRangeFormatterSettings.java

@@ -0,0 +1,240 @@
+// © 2018 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html#License
+package com.ibm.icu.number;
+
+import com.ibm.icu.impl.number.range.RangeMacroProps;
+import com.ibm.icu.number.NumberRangeFormatter.RangeCollapse;
+import com.ibm.icu.number.NumberRangeFormatter.RangeIdentityFallback;
+import com.ibm.icu.util.ULocale;
+
+/**
+ * An abstract base class for specifying settings related to number formatting. This class is implemented by
+ * {@link UnlocalizedNumberRangeFormatter} and {@link LocalizedNumberRangeFormatter}. This class is not intended for
+ * public subclassing.
+ *
+ * @author sffc
+ * @draft ICU 63
+ * @provisional This API might change or be removed in a future release.
+ * @see NumberRangeFormatter
+ */
+public abstract class NumberRangeFormatterSettings<T extends NumberRangeFormatterSettings<?>> {
+
+    static final int KEY_MACROS = 0; // not used
+    static final int KEY_LOCALE = 1;
+    static final int KEY_FORMATTER_1 = 2;
+    static final int KEY_FORMATTER_2 = 3;
+    static final int KEY_SAME_FORMATTERS = 4;
+    static final int KEY_COLLAPSE = 5;
+    static final int KEY_IDENTITY_FALLBACK = 6;
+    static final int KEY_MAX = 7;
+
+    private final NumberRangeFormatterSettings<?> parent;
+    private final int key;
+    private final Object value;
+    private volatile RangeMacroProps resolvedMacros;
+
+    NumberRangeFormatterSettings(NumberRangeFormatterSettings<?> parent, int key, Object value) {
+        this.parent = parent;
+        this.key = key;
+        this.value = value;
+    }
+
+    /**
+     * Sets the NumberFormatter instance to use for the numbers in the range. The same formatter is applied to both
+     * sides of the range.
+     * <p>
+     * The NumberFormatter instances must not have a locale applied yet; the locale specified on the
+     * NumberRangeFormatter will be used.
+     *
+     * @param formatter
+     *            The formatter to use for both numbers in the range.
+     * @return The fluent chain.
+     * @draft ICU 63
+     * @provisional This API might change or be removed in a future release.
+     * @see NumberFormatter
+     * @see NumberRangeFormatter
+     */
+    @SuppressWarnings("unchecked")
+    public T numberFormatterBoth(UnlocalizedNumberFormatter formatter) {
+        return (T) create(KEY_SAME_FORMATTERS, true).create(KEY_FORMATTER_1, formatter);
+    }
+
+    /**
+     * Sets the NumberFormatter instance to use for the first number in the range.
+     * <p>
+     * The NumberFormatter instance must not have a locale applied yet; the locale specified on the
+     * NumberRangeFormatter will be used.
+     *
+     * @param formatterFirst
+     *            The formatter to use for the first number in the range.
+     * @return The fluent chain.
+     * @draft ICU 63
+     * @provisional This API might change or be removed in a future release.
+     * @see NumberFormatter
+     * @see NumberRangeFormatter
+     */
+    @SuppressWarnings("unchecked")
+    public T numberFormatterFirst(UnlocalizedNumberFormatter formatterFirst) {
+        return (T) create(KEY_SAME_FORMATTERS, false).create(KEY_FORMATTER_1, formatterFirst);
+    }
+
+    /**
+     * Sets the NumberFormatter instances to use for the second number in the range.
+     * <p>
+     * The NumberFormatter instance must not have a locale applied yet; the locale specified on the
+     * NumberRangeFormatter will be used.
+     *
+     * @param formatterSecond
+     *            The formatter to use for the second number in the range.
+     * @return The fluent chain.
+     * @draft ICU 63
+     * @provisional This API might change or be removed in a future release.
+     * @see NumberFormatter
+     * @see NumberRangeFormatter
+     */
+    @SuppressWarnings("unchecked")
+    public T numberFormatterSecond(UnlocalizedNumberFormatter formatterSecond) {
+        return (T) create(KEY_SAME_FORMATTERS, false).create(KEY_FORMATTER_2, formatterSecond);
+    }
+
+    /**
+     * Sets the aggressiveness of "collapsing" fields across the range separator. Possible values:
+     * <ul>
+     * <li>ALL: "3-5K miles"</li>
+     * <li>UNIT: "3K - 5K miles"</li>
+     * <li>NONE: "3K miles - 5K miles"</li>
+     * <li>AUTO: usually UNIT or NONE, depending on the locale and formatter settings</li>
+     * </ul>
+     * <p>
+     * The default value is AUTO.
+     *
+     * @param collapse
+     *            The collapsing strategy to use for this range.
+     * @return The fluent chain.
+     * @draft ICU 63
+     * @provisional This API might change or be removed in a future release.
+     * @see NumberRangeFormatter
+     */
+    public T collapse(RangeCollapse collapse) {
+        return create(KEY_COLLAPSE, collapse);
+    }
+
+    /**
+     * Sets the behavior when the two sides of the range are the same. This could happen if the same two numbers are
+     * passed to the formatRange function, or if different numbers are passed to the function but they become the same
+     * after rounding rules are applied. Possible values:
+     * <ul>
+     * <li>SINGLE_VALUE: "5 miles"</li>
+     * <li>APPROXIMATELY_OR_SINGLE_VALUE: "~5 miles" or "5 miles", depending on whether the number was the same before
+     * rounding was applied</li>
+     * <li>APPROXIMATELY: "~5 miles"</li>
+     * <li>RANGE: "5-5 miles" (with collapse=UNIT)</li>
+     * </ul>
+     * <p>
+     * The default value is APPROXIMATELY.
+     *
+     * @param identityFallback
+     *            The strategy to use when formatting two numbers that end up being the same.
+     * @return The fluent chain.
+     * @draft ICU 63
+     * @provisional This API might change or be removed in a future release.
+     * @see NumberRangeFormatter
+     */
+    public T identityFallback(RangeIdentityFallback identityFallback) {
+        return create(KEY_IDENTITY_FALLBACK, identityFallback);
+    }
+
+    /* package-protected */ abstract T create(int key, Object value);
+
+    RangeMacroProps resolve() {
+        if (resolvedMacros != null) {
+            return resolvedMacros;
+        }
+        // Although the linked-list fluent storage approach requires this method,
+        // my benchmarks show that linked-list is still faster than a full clone
+        // of a MacroProps object at each step.
+        // TODO: Remove the reference to the parent after the macros are resolved?
+        RangeMacroProps macros = new RangeMacroProps();
+        NumberRangeFormatterSettings<?> current = this;
+        while (current != null) {
+            switch (current.key) {
+            case KEY_MACROS:
+                // ignored for now
+                break;
+            case KEY_LOCALE:
+                if (macros.loc == null) {
+                    macros.loc = (ULocale) current.value;
+                }
+                break;
+            case KEY_FORMATTER_1:
+                if (macros.formatter1 == null) {
+                    macros.formatter1 = (UnlocalizedNumberFormatter) current.value;
+                }
+                break;
+            case KEY_FORMATTER_2:
+                if (macros.formatter2 == null) {
+                    macros.formatter2 = (UnlocalizedNumberFormatter) current.value;
+                }
+                break;
+            case KEY_SAME_FORMATTERS:
+                if (macros.sameFormatters == -1) {
+                    macros.sameFormatters = (boolean) current.value ? 1 : 0;
+                }
+                break;
+            case KEY_COLLAPSE:
+                if (macros.collapse == null) {
+                    macros.collapse = (RangeCollapse) current.value;
+                }
+                break;
+            case KEY_IDENTITY_FALLBACK:
+                if (macros.identityFallback == null) {
+                    macros.identityFallback = (RangeIdentityFallback) current.value;
+                }
+                break;
+            default:
+                throw new AssertionError("Unknown key: " + current.key);
+            }
+            current = current.parent;
+        }
+        // Copy the locale into the children (see touchRangeLocales in C++)
+        if (macros.formatter1 != null) {
+            macros.formatter1.resolve().loc = macros.loc;
+        }
+        if (macros.formatter2 != null) {
+            macros.formatter2.resolve().loc = macros.loc;
+        }
+        resolvedMacros = macros;
+        return macros;
+    }
+
+    /**
+     * {@inheritDoc}
+     *
+     * @draft ICU 63
+     * @provisional This API might change or be removed in a future release.
+     */
+    @Override
+    public int hashCode() {
+        return resolve().hashCode();
+    }
+
+    /**
+     * {@inheritDoc}
+     *
+     * @draft ICU 63
+     * @provisional This API might change or be removed in a future release.
+     */
+    @Override
+    public boolean equals(Object other) {
+        if (this == other) {
+            return true;
+        }
+        if (other == null) {
+            return false;
+        }
+        if (!(other instanceof NumberRangeFormatterSettings)) {
+            return false;
+        }
+        return resolve().equals(((NumberRangeFormatterSettings<?>) other).resolve());
+    }
+}

icu4j/main/classes/core/src/com/ibm/icu/number/ScientificNotation.java

@@ -13,6 +13,7 @@ import com.ibm.icu.number.NumberFormatter.SignDisplay;
 import com.ibm.icu.number.Precision.SignificantRounderImpl;
 import com.ibm.icu.text.DecimalFormatSymbols;
 import com.ibm.icu.text.NumberFormat;
+import com.ibm.icu.text.NumberFormat.Field;
 
 /**
  * A class that defines the scientific notation style to be used when formatting numbers in
@@ -221,8 +222,10 @@ public class ScientificNotation extends Notation implements Cloneable {
 
         @Override
         public int getCodePointCount() {
-            // This method is not used for strong modifiers.
-            throw new AssertionError();
+            // NOTE: This method is only called one place, NumberRangeFormatterImpl.
+            // The call site only cares about != 0 and != 1.
+            // Return a very large value so that if this method is used elsewhere, we should notice.
+            return 999;
         }
 
         @Override
@@ -231,6 +234,27 @@ public class ScientificNotation extends Notation implements Cloneable {
             return true;
         }
 
+        @Override
+        public boolean containsField(Field field) {
+            // This method is not currently used. (unsafe path not used in range formatting)
+            assert false;
+            return false;
+        }
+
+        @Override
+        public Parameters getParameters() {
+            // This method is not currently used.
+            assert false;
+            return null;
+        }
+
+        @Override
+        public boolean semanticallyEquivalent(Modifier other) {
+            // This method is not currently used. (unsafe path not used in range formatting)
+            assert false;
+            return false;
+        }
+
         @Override
         public int apply(NumberStringBuilder output, int leftIndex, int rightIndex) {
             return doApply(exponent, output, rightIndex);
@@ -279,8 +303,10 @@ public class ScientificNotation extends Notation implements Cloneable {
 
         @Override
         public int getCodePointCount() {
-            // This method is not used for strong modifiers.
-            throw new AssertionError();
+            // NOTE: This method is only called one place, NumberRangeFormatterImpl.
+            // The call site only cares about != 0 and != 1.
+            // Return a very large value so that if this method is used elsewhere, we should notice.
+            return 999;
         }
 
         @Override
@@ -288,5 +314,27 @@ public class ScientificNotation extends Notation implements Cloneable {
             // Scientific is always strong
             return true;
         }
+
+        @Override
+        public boolean containsField(Field field) {
+            // This method is not used for inner modifiers.
+            assert false;
+            return false;
+        }
+
+        @Override
+        public Parameters getParameters() {
+            return null;
+        }
+
+        @Override
+        public boolean semanticallyEquivalent(Modifier other) {
+            if (!(other instanceof ScientificModifier)) {
+                return false;
+            }
+            ScientificModifier _other = (ScientificModifier) other;
+            // TODO: Check for locale symbols and settings as well? Could be less efficient.
+            return exponent == _other.exponent;
+        }
     }
 }