From d0c762e71cbf214a73c07f41726c6ac20b61e2ba Mon Sep 17 00:00:00 2001
From: Shane Carr <shane@unicode.org>
Date: Tue, 12 Sep 2017 05:20:50 +0000
Subject: [PATCH] ICU-13351 Adding additional CurrencyUnit constructors and
 stabilizing API constract of MeasureUnit default constructor.

X-SVN-Rev: 40379
---
 icu4c/source/i18n/currunit.cpp       | 24 ++++++++++++++++++++++--
 icu4c/source/i18n/measunit.cpp       |  7 ++++++-
 icu4c/source/i18n/unicode/currunit.h | 16 ++++++++++++++++
 icu4c/source/i18n/unicode/measunit.h |  5 ++---
 4 files changed, 46 insertions(+), 6 deletions(-)

diff --git a/icu4c/source/i18n/currunit.cpp b/icu4c/source/i18n/currunit.cpp
index 197885452f..1750b94fab 100644
--- a/icu4c/source/i18n/currunit.cpp
+++ b/icu4c/source/i18n/currunit.cpp
@@ -16,6 +16,7 @@
 
 #include "unicode/currunit.h"
 #include "unicode/ustring.h"
+#include "cstring.h"
 
 U_NAMESPACE_BEGIN
 
@@ -33,11 +34,30 @@ CurrencyUnit::CurrencyUnit(ConstChar16Ptr _isoCode, UErrorCode& ec) {
     }
 }
 
-CurrencyUnit::CurrencyUnit(const CurrencyUnit& other) :
-    MeasureUnit(other) {
+CurrencyUnit::CurrencyUnit(const CurrencyUnit& other) : MeasureUnit(other) {
     u_strcpy(isoCode, other.isoCode);
 }
 
+CurrencyUnit::CurrencyUnit(const MeasureUnit& other, UErrorCode& ec) : MeasureUnit(other) {
+    // Make sure this is a currency.
+    // OK to hard-code the string because we are comparing against another hard-coded string.
+    if (uprv_strcmp("currency", getType()) != 0) {
+        ec = U_ILLEGAL_ARGUMENT_ERROR;
+        isoCode[0] = 0;
+    } else {
+        // Get the ISO Code from the subtype field.
+        u_charsToUChars(getSubtype(), isoCode, 4);
+        isoCode[3] = 0; // make 100% sure it is NUL-terminated
+    }
+}
+
+CurrencyUnit::CurrencyUnit() : MeasureUnit() {
+    u_strcpy(isoCode, u"XXX");
+    char simpleIsoCode[4];
+    u_UCharsToChars(isoCode, simpleIsoCode, 4);
+    initCurrency(simpleIsoCode);
+}
+
 CurrencyUnit& CurrencyUnit::operator=(const CurrencyUnit& other) {
     if (this == &other) {
         return *this;
diff --git a/icu4c/source/i18n/measunit.cpp b/icu4c/source/i18n/measunit.cpp
index d1244ad353..e9e141789e 100644
--- a/icu4c/source/i18n/measunit.cpp
+++ b/icu4c/source/i18n/measunit.cpp
@@ -1079,7 +1079,12 @@ static int32_t binarySearch(
     }
     return -1;
 }
-    
+
+MeasureUnit::MeasureUnit() {
+    fCurrency[0] = 0;
+    initNoUnit("base");
+}
+
 MeasureUnit::MeasureUnit(const MeasureUnit &other)
         : fTypeId(other.fTypeId), fSubTypeId(other.fSubTypeId) {
     uprv_strcpy(fCurrency, other.fCurrency);
diff --git a/icu4c/source/i18n/unicode/currunit.h b/icu4c/source/i18n/unicode/currunit.h
index fd0f9f2bcc..db36d2b40f 100644
--- a/icu4c/source/i18n/unicode/currunit.h
+++ b/icu4c/source/i18n/unicode/currunit.h
@@ -36,6 +36,12 @@ U_NAMESPACE_BEGIN
  */
 class U_I18N_API CurrencyUnit: public MeasureUnit {
  public:
+    /**
+     * Default constructor.  Initializes currency code to "XXX" (no currency).
+     * @draft ICU 60
+     */
+    CurrencyUnit();
+
     /**
      * Construct an object with the given ISO currency code.
      * @param isoCode the 3-letter ISO 4217 currency code; must not be
@@ -52,6 +58,16 @@ class U_I18N_API CurrencyUnit: public MeasureUnit {
      */
     CurrencyUnit(const CurrencyUnit& other);
 
+    /**
+     * Copy constructor from MeasureUnit. This constructor allows you to
+     * restore a CurrencyUnit that was sliced to MeasureUnit.
+     *
+     * @param measureUnit The MeasureUnit to copy from.
+     * @param ec Set to a failing value if the MeasureUnit is not a currency.
+     * @draft ICU 60
+     */
+    CurrencyUnit(const MeasureUnit& measureUnit, UErrorCode &ec);
+
     /**
      * Assignment operator
      * @stable ICU 3.0
diff --git a/icu4c/source/i18n/unicode/measunit.h b/icu4c/source/i18n/unicode/measunit.h
index 2204e987aa..afd560e30e 100644
--- a/icu4c/source/i18n/unicode/measunit.h
+++ b/icu4c/source/i18n/unicode/measunit.h
@@ -40,11 +40,10 @@ class U_I18N_API MeasureUnit: public UObject {
 
     /**
      * Default constructor.
+     * Populates the instance with the base dimensionless unit.
      * @stable ICU 3.0
      */
-    MeasureUnit() : fTypeId(0), fSubTypeId(0) { 
-        fCurrency[0] = 0;
-    }
+    MeasureUnit();
     
     /**
      * Copy constructor.