ICU-1267 add UnicodeString::countChar32()

X-SVN-Rev: 6197

icu4c/source/common/unicode/unistr.h

@@ -1390,6 +1390,21 @@ public:
    */
   inline int32_t  length(void) const;
 
+  /**
+   * Count Unicode code points in the length UChar code units of the string.
+   * A code point may occupy either one or two UChar code units.
+   * Counting code points involves reading all code units.
+   *
+   * This functions is basically the inverse of moveIndex32().
+   *
+   * @param start the index of the first code unit to check
+   * @param length the number of UChar code units to check
+   * @return the number of code points in the specified code units
+   * @draft ICU 2.0
+   */
+  int32_t
+  countChar32(UTextOffset start=0, int32_t length=0x7fffffff) const;
+
   /**
    * Determine if this string is empty.
    * @return TRUE if this string contains 0 characters, FALSE otherwise.

icu4c/source/common/unistr.cpp

@@ -675,6 +675,13 @@ UnicodeString::getChar32At(UTextOffset offset) const {
   return char32At(offset);
 }
 
+int32_t
+UnicodeString::countChar32(UTextOffset start, int32_t length) const {
+  pinIndices(start, length);
+  // if(isBogus()) then fArray==0 and start==0 - u_countChar32() checks for NULL
+  return u_countChar32(fArray+start, length);
+}
+
 UTextOffset
 UnicodeString::moveIndex32(UTextOffset index, int32_t delta) const {
   // pin index