+int32_t SpoofImpl::findHiddenOverlay(const UnicodeString& input, UErrorCode&) const {
+ bool sawLeadCharacter = false;
+ for (int32_t i=0; i<input.length();) {
+ UChar32 cp = input.char32At(i);
+ if (sawLeadCharacter && cp == 0x0307) {
+ return i;
+ }
+ uint8_t combiningClass = u_getCombiningClass(cp);
+ // Skip over characters except for those with combining class 0 (non-combining characters) or with
+ // combining class 230 (same class as U+0307)
+ U_ASSERT(u_getCombiningClass(0x0307) == 230);
+ if (combiningClass == 0 || combiningClass == 230) {
+ sawLeadCharacter = isIllegalCombiningDotLeadCharacter(cp);
+ }
+ i += U16_LENGTH(cp);
+ }
+ return -1;
+}
+
+static inline bool isIllegalCombiningDotLeadCharacterNoLookup(UChar32 cp) {
+ return cp == u'i' || cp == u'j' || cp == u'ı' || cp == u'ȷ' || cp == u'l' ||
+ u_hasBinaryProperty(cp, UCHAR_SOFT_DOTTED);
+}
+
+bool SpoofImpl::isIllegalCombiningDotLeadCharacter(UChar32 cp) const {
+ if (isIllegalCombiningDotLeadCharacterNoLookup(cp)) {
+ return true;
+ }
+ UnicodeString skelStr;
+ fSpoofData->confusableLookup(cp, skelStr);
+ UChar32 finalCp = skelStr.char32At(skelStr.moveIndex32(skelStr.length(), -1));
+ if (finalCp != cp && isIllegalCombiningDotLeadCharacterNoLookup(finalCp)) {
+ return true;
+ }
+ return false;
+}
+