ICU-1438 add Normalizer::compare

X-SVN-Rev: 8699

icu4c/source/common/unicode/normlzr.h

@@ -307,6 +307,70 @@ public:
               UNormalizationMode mode, int32_t options,
               UErrorCode &errorCode);
 
+  /**
+   * Compare two strings for canonical equivalence.
+   * Further options include case-insensitive comparison and
+   * code point order (as opposed to code unit order).
+   *
+   * Canonical equivalence between two strings is defined as their normalized
+   * forms (NFD or NFC) being identical.
+   * This function compares strings incrementally instead of normalizing
+   * (and optionally case-folding) both strings entirely,
+   * improving performance significantly.
+   *
+   * Bulk normalization is only necessary if the strings do not fulfill the FCD
+   * conditions. Only in this case, and only if the strings are relatively long,
+   * is memory allocated temporarily.
+   * For FCD strings and short non-FCD strings there is no memory allocation.
+   *
+   * Semantically, this is equivalent to
+   *   strcmp[CodePointOrder](foldCase(NFD(s1)), foldCase(NFD(s2)))
+   * where code point order and foldCase are all optional.
+   *
+   * @param s1 First source string.
+   * @param s2 Second source string.
+   *
+   * @param options A bit set of options:
+   *   - U_FOLD_CASE_DEFAULT or 0 is used for default options:
+   *     Case-sensitive comparison in code unit order, and the input strings
+   *     are quick-checked for FCD.
+   *
+   *   - UNORM_INPUT_IS_FCD
+   *     Set if the caller knows that both s1 and s2 fulfill the FCD conditions.
+   *     If not set, the function will quickCheck for FCD
+   *     and normalize if necessary.
+   *
+   *   - U_COMPARE_CODE_POINT_ORDER
+   *     Set to choose code point order instead of code unit order
+   *     (see u_strCompare for details).
+   *
+   *   - U_COMPARE_IGNORE_CASE
+   *     Set to compare strings case-insensitively using case folding,
+   *     instead of case-sensitively.
+   *     If set, then the following case folding options are used.
+   *
+   *   - Options as used with case-insensitive comparisons, currently:
+   *
+   *   - U_FOLD_CASE_EXCLUDE_SPECIAL_I
+   *    (see u_strCaseCompare for details)
+   *
+   * @param errorCode ICU error code in/out parameter.
+   *                  Must fulfill U_SUCCESS before the function call.
+   * @return <0 or 0 or >0 as usual for string comparisons
+   *
+   * @see unorm_compare
+   * @see normalize
+   * @see UNORM_FCD
+   * @see u_strCompare
+   * @see u_strCaseCompare
+   *
+   * @draft ICU 2.2
+   */
+  static inline int32_t
+  compare(const UnicodeString &s1, const UnicodeString &s2,
+          uint32_t options,
+          UErrorCode &errorCode);
+
   //-------------------------------------------------------------------------
   // Iteration API
   //-------------------------------------------------------------------------
@@ -977,6 +1041,17 @@ Normalizer::quickCheck(const UnicodeString& source,
   return quickCheck(source, getUNormalizationMode(mode, status), status);
 }
 
+inline int32_t
+Normalizer::compare(const UnicodeString &s1, const UnicodeString &s2,
+                    uint32_t options,
+                    UErrorCode &errorCode) {
+  // all argument checking is done in unorm_compare
+  return unorm_compare(s1.getBuffer(), s1.length(),
+                       s2.getBuffer(), s2.length(),
+                       options,
+                       &errorCode);
+}
+
 inline void
 Normalizer::setMode(EMode newMode) {
   UErrorCode status = U_ZERO_ERROR;