UChar32
FCDUIterCollationIterator::previousCodePoint(UErrorCode &errorCode) {
UChar32 c;
for(;;) {
if(state == ITER_CHECK_BWD) {
c = iter.previous(&iter);
if(c < 0) {
start = pos = 0;
state = ITER_IN_FCD_SEGMENT;
return U_SENTINEL;
}
if(CollationFCD::hasLccc(c)) {
UChar32 prev = U_SENTINEL;
if(CollationFCD::maybeTibetanCompositeVowel(c) ||
CollationFCD::hasTccc(prev = iter.previous(&iter))) {
iter.next(&iter);
if(prev >= 0) {
iter.next(&iter);
}
if(!previousSegment(errorCode)) {
return U_SENTINEL;
}
continue;
}
// hasLccc(trail)=true for all trail surrogates
if(U16_IS_TRAIL(c)) {
if(prev < 0) {
prev = iter.previous(&iter);
}
if(U16_IS_LEAD(prev)) {
return U16_GET_SUPPLEMENTARY(prev, c);
}
}
if(prev >= 0) {
iter.next(&iter);
}
}
return c;
} else if(state == ITER_IN_FCD_SEGMENT && pos != start) {
c = uiter_previous32(&iter);
pos -= U16_LENGTH(c);
U_ASSERT(c >= 0);
return c;
} else if(state >= IN_NORM_ITER_AT_LIMIT && pos != 0) {
c = normalized.char32At(pos - 1);
pos -= U16_LENGTH(c);
return c;
} else {
switchToBackward();
}
}
}
UChar32
FCDUTF8CollationIterator::previousCodePoint(UErrorCode &errorCode) {
UChar32 c;
for(;;) {
if(state == CHECK_BWD) {
if(pos == 0) {
return U_SENTINEL;
}
if((c = u8[pos - 1]) < 0x80) {
--pos;
return c;
}
U8_PREV_OR_FFFD(u8, 0, pos, c);
if(CollationFCD::hasLccc(c <= 0xffff ? c : U16_LEAD(c)) &&
(CollationFCD::maybeTibetanCompositeVowel(c) ||
(pos != 0 && previousHasTccc()))) {
// c is not FCD-inert, therefore it is not U+FFFD and it has a valid byte sequence
// and we can use U8_LENGTH() rather than a previous-position variable.
pos += U8_LENGTH(c);
if(!previousSegment(errorCode)) {
return U_SENTINEL;
}
continue;
}
return c;
} else if(state == IN_FCD_SEGMENT && pos != start) {
U8_PREV_OR_FFFD(u8, 0, pos, c);
return c;
} else if(state >= IN_NORMALIZED && pos != 0) {
c = normalized.char32At(pos - 1);
pos -= U16_LENGTH(c);
return c;
} else {
switchToBackward();
}
}
}
