/*
*******************************************************************************
* Copyright (C) 2010-2014, International Business Machines
* Corporation and others. All Rights Reserved.
*******************************************************************************
* collationiterator.cpp
*
* created on: 2010oct27
* created by: Markus W. Scherer
*/
#include "utypeinfo.h" // for 'typeid' to work
#include "unicode/utypes.h"
#if !UCONFIG_NO_COLLATION
#include "unicode/ucharstrie.h"
#include "unicode/ustringtrie.h"
#include "charstr.h"
#include "cmemory.h"
#include "collation.h"
#include "collationdata.h"
#include "collationfcd.h"
#include "collationiterator.h"
#include "normalizer2impl.h"
#include "uassert.h"
#include "uvectr32.h"
U_NAMESPACE_BEGIN
CollationIterator::CEBuffer::~CEBuffer() {}
UBool
CollationIterator::CEBuffer::ensureAppendCapacity(int32_t appCap, UErrorCode &errorCode) {
int32_t capacity = buffer.getCapacity();
if((length + appCap) <= capacity) { return TRUE; }
if(U_FAILURE(errorCode)) { return FALSE; }
do {
if(capacity < 1000) {
capacity *= 4;
} else {
capacity *= 2;
}
} while(capacity < (length + appCap));
int64_t *p = buffer.resize(capacity, length);
if(p == NULL) {
errorCode = U_MEMORY_ALLOCATION_ERROR;
return FALSE;
}
return TRUE;
}
// State of combining marks skipped in discontiguous contraction.
// We create a state object on first use and keep it around deactivated between uses.
class SkippedState : public UMemory {
public:
// Born active but empty.
SkippedState() : pos(0), skipLengthAtMatch(0) {}
void clear() {
oldBuffer.remove();
pos = 0;
// The newBuffer is reset by setFirstSkipped().
}
UBool isEmpty() const { return oldBuffer.isEmpty(); }
UBool hasNext() const { return pos < oldBuffer.length(); }
// Requires hasNext().
UChar32 next() {
UChar32 c = oldBuffer.char32At(pos);
pos += U16_LENGTH(c);
return c;
}
// Accounts for one more input code point read beyond the end of the marks buffer.
void incBeyond() {
U_ASSERT(!hasNext());
++pos;
}
// Goes backward through the skipped-marks buffer.
// Returns the number of code points read beyond the skipped marks
// that need to be backtracked through normal input.
int32_t backwardNumCodePoints(int32_t n) {
int32_t length = oldBuffer.length();
int32_t beyond = pos - length;
if(beyond > 0) {
if(beyond >= n) {
// Not back far enough to re-enter the oldBuffer.
pos -= n;
return n;
} else {
// Back out all beyond-oldBuffer code points and re-enter the buffer.
pos = oldBuffer.moveIndex32(length, beyond - n);
return beyond;
}
} else {
// Go backwards from inside the oldBuffer.
pos = oldBuffer.moveIndex32(pos, -n);
return 0;
}
}
void setFirstSkipped(UChar32 c) {
skipLengthAtMatch = 0;
newBuffer.setTo(c);
}
void skip(UChar32 c) {
newBuffer.append(c);
}
void recordMatch() { skipLengthAtMatch = newBuffer.length(); }
// Replaces the characters we consumed with the newly skipped ones.
void replaceMatch() {
// Note: UnicodeString.replace() pins pos to at most length().
oldBuffer.replace(0, pos, newBuffer, 0, skipLengthAtMatch);
pos = 0;
}
void saveTrieState(const UCharsTrie &trie) { trie.saveState(state); }
void resetToTrieState(UCharsTrie &trie) const { trie.resetToState(state); }
private:
// Combining marks skipped in previous discontiguous-contraction matching.
// After that discontiguous contraction was completed, we start reading them from here.
UnicodeString oldBuffer;
// Combining marks newly skipped in current discontiguous-contraction matching.
// These might have been read from the normal text or from the oldBuffer.
UnicodeString newBuffer;
// Reading index in oldBuffer,
// or counter for how many code points have been read beyond oldBuffer (pos-oldBuffer.length()).
int32_t pos;
// newBuffer.length() at the time of the last matching character.
// When a partial match fails, we back out skipped and partial-matching input characters.
int32_t skipLengthAtMatch;
// We save the trie state before we attempt to match a character,
// so that we can skip it and try the next one.
UCharsTrie::State state;
};
CollationIterator::CollationIterator(const CollationIterator &other)
: UObject(other),
trie(other.trie),
data(other.data),
cesIndex(other.cesIndex),
skipped(NULL),
numCpFwd(other.numCpFwd),
isNumeric(other.isNumeric) {
UErrorCode errorCode = U_ZERO_ERROR;
int32_t length = other.ceBuffer.length;
if(length > 0 && ceBuffer.ensureAppendCapacity(length, errorCode)) {
for(int32_t i = 0; i < length; ++i) {
ceBuffer.set(i, other.ceBuffer.get(i));
}
ceBuffer.length = length;
} else {
cesIndex = 0;
}
}
CollationIterator::~CollationIterator() {
delete skipped;
}
UBool
CollationIterator::operator==(const CollationIterator &other) const {
// Subclasses: Call this method and then add more specific checks.
// Compare the iterator state but not the collation data (trie & data fields):
// Assume that the caller compares the data.
// Ignore skipped since that should be unused between calls to nextCE().
// (It only stays around to avoid another memory allocation.)
if(!(typeid(*this) == typeid(other) &&
ceBuffer.length == other.ceBuffer.length &&
cesIndex == other.cesIndex &&
numCpFwd == other.numCpFwd &&
isNumeric == other.isNumeric)) {
return FALSE;
}
for(int32_t i = 0; i < ceBuffer.length; ++i) {
if(ceBuffer.get(i) != other.ceBuffer.get(i)) { return FALSE; }
}
return TRUE;
}
void
CollationIterator::reset() {
cesIndex = ceBuffer.length = 0;
if(skipped != NULL) { skipped->clear(); }
}
int32_t
CollationIterator::fetchCEs(UErrorCode &errorCode) {
while(U_SUCCESS(errorCode) && nextCE(errorCode) != Collation::NO_CE) {
// No need to loop for each expansion CE.
cesIndex = ceBuffer.length;
}
return ceBuffer.length;
}
uint32_t
CollationIterator::handleNextCE32(UChar32 &c, UErrorCode &errorCode) {
c = nextCodePoint(errorCode);
return (c < 0) ? Collation::FALLBACK_CE32 : data->getCE32(c);
}
UChar
CollationIterator::handleGetTrailSurrogate() {
return 0;
}
UBool
CollationIterator::foundNULTerminator() {
return FALSE;
}
UBool
CollationIterator::forbidSurrogateCodePoints() const {
return FALSE;
}
uint32_t
CollationIterator::getDataCE32(UChar32 c) const {
return data->getCE32(c);
}
uint32_t
CollationIterator::getCE32FromBuilderData(uint32_t /*ce32*/, UErrorCode &errorCode) {
if(U_SUCCESS(errorCode)) { errorCode = U_INTERNAL_PROGRAM_ERROR; }
return 0;
}
int64_t
CollationIterator::nextCEFromCE32(const CollationData *d, UChar32 c, uint32_t ce32,
UErrorCode &errorCode) {
--ceBuffer.length; // Undo ceBuffer.incLength().
appendCEsFromCE32(d, c, ce32, TRUE, errorCode);
if(U_SUCCESS(errorCode)) {
return ceBuffer.get(cesIndex++);
} else {
return Collation::NO_CE_PRIMARY;
}
}
void
CollationIterator::appendCEsFromCE32(const CollationData *d, UChar32 c, uint32_t ce32,
UBool forward, UErrorCode &errorCode) {
while(Collation::isSpecialCE32(ce32)) {
switch(Collation::tagFromCE32(ce32)) {
case Collation::FALLBACK_TAG:
case Collation::RESERVED_TAG_3:
if(U_SUCCESS(errorCode)) { errorCode = U_INTERNAL_PROGRAM_ERROR; }
return;
case Collation::LONG_PRIMARY_TAG:
ceBuffer.append(Collation::ceFromLongPrimaryCE32(ce32), errorCode);
return;
case Collation::LONG_SECONDARY_TAG:
ceBuffer.append(Collation::ceFromLongSecondaryCE32(ce32), errorCode);
return;
case Collation::LATIN_EXPANSION_TAG:
if(ceBuffer.ensureAppendCapacity(2, errorCode)) {
ceBuffer.set(ceBuffer.length, Collation::latinCE0FromCE32(ce32));
ceBuffer.set(ceBuffer.length + 1, Collation::latinCE1FromCE32(ce32));
ceBuffer.length += 2;
}
return;
case Collation::EXPANSION32_TAG: {
const uint32_t *ce32s = d->ce32s + Collation::indexFromCE32(ce32);
int32_t length = Collation::lengthFromCE32(ce32);
if(ceBuffer.ensureAppendCapacity(length, errorCode)) {
do {
ceBuffer.appendUnsafe(Collation::ceFromCE32(*ce32s++));
} while(--length > 0);
}
return;
}
case Collation::EXPANSION_TAG: {
const int64_t *ces = d->ces + Collation::indexFromCE32(ce32);
int32_t length = Collation::lengthFromCE32(ce32);
if(ceBuffer.ensureAppendCapacity(length, errorCode)) {
do {
ceBuffer.appendUnsafe(*ces++);
} while(--length > 0);
}
return;
}
case Collation::BUILDER_DATA_TAG:
ce32 = getCE32FromBuilderData(ce32, errorCode);
if(U_FAILURE(errorCode)) { return; }
if(ce32 == Collation::FALLBACK_CE32) {
d = data->base;
ce32 = d->getCE32(c);
}
break;
case Collation::PREFIX_TAG:
if(forward) { backwardNumCodePoints(1, errorCode); }
ce32 = getCE32FromPrefix(d, ce32, errorCode);
if(forward) { forwardNumCodePoints(1, errorCode); }
break;
case Collation::CONTRACTION_TAG: {
const UChar *p = d->contexts + Collation::indexFromCE32(ce32);
uint32_t defaultCE32 = CollationData::readCE32(p); // Default if no suffix match.
if(!forward) {
// Backward contractions are handled by previousCEUnsafe().
// c has contractions but they were not found.
ce32 = defaultCE32;
break;
}
UChar32 nextCp;
if(skipped == NULL && numCpFwd < 0) {
// Some portion of nextCE32FromContraction() pulled out here as an ASCII fast path,
// avoiding the function call and the nextSkippedCodePoint() overhead.
nextCp = nextCodePoint(errorCode);
if(nextCp < 0) {
// No more text.
ce32 = defaultCE32;
break;
} else if((ce32 & Collation::CONTRACT_NEXT_CCC) != 0 &&
!CollationFCD::mayHaveLccc(nextCp)) {
// All contraction suffixes start with characters with lccc!=0
// but the next code point has lccc==0.
backwardNumCodePoints(1, errorCode);
ce32 = defaultCE32;
break;
}
} else {
nextCp = nextSkippedCodePoint(errorCode);
if(nextCp < 0) {
// No more text.
ce32 = defaultCE32;
break;
} else if((ce32 & Collation::CONTRACT_NEXT_CCC) != 0 &&
!CollationFCD::mayHaveLccc(nextCp)) {
// All contraction suffixes start with characters with lccc!=0
// but the next code point has lccc==0.
backwardNumSkipped(1, errorCode);
ce32 = defaultCE32;
break;
}
}
ce32 = nextCE32FromContraction(d, ce32, p + 2, defaultCE32, nextCp, errorCode);
if(ce32 == Collation::NO_CE32) {
// CEs from a discontiguous contraction plus the skipped combining marks
// have been appended already.
return;
}
break;
}
case Collation::DIGIT_TAG:
if(isNumeric) {
appendNumericCEs(ce32, forward, errorCode);
return;
} else {
// Fetch the non-numeric-collation CE32 and continue.
ce32 = d->ce32s[Collation::indexFromCE32(ce32)];
break;
}
case Collation::U0000_TAG:
U_ASSERT(c == 0);
if(forward && foundNULTerminator()) {
// Handle NUL-termination. (Not needed in Java.)
ceBuffer.append(Collation::NO_CE, errorCode);
return;
} else {
// Fetch the normal ce32 for U+0000 and continue.
ce32 = d->ce32s[0];
break;
}
case Collation::HANGUL_TAG: {
const uint32_t *jamoCE32s = d->jamoCE32s;
c -= Hangul::HANGUL_BASE;
UChar32 t = c % Hangul::JAMO_T_COUNT;
c /= Hangul::JAMO_T_COUNT;
UChar32 v = c % Hangul::JAMO_V_COUNT;
c /= Hangul::JAMO_V_COUNT;
if((ce32 & Collation::HANGUL_NO_SPECIAL_JAMO) != 0) {
// None of the Jamo CE32s are isSpecialCE32().
// Avoid recursive function calls and per-Jamo tests.
if(ceBuffer.ensureAppendCapacity(t == 0 ? 2 : 3, errorCode)) {
ceBuffer.set(ceBuffer.length, Collation::ceFromCE32(jamoCE32s[c]));
ceBuffer.set(ceBuffer.length + 1, Collation::ceFromCE32(jamoCE32s[19 + v]));
ceBuffer.length += 2;
if(t != 0) {
ceBuffer.appendUnsafe(Collation::ceFromCE32(jamoCE32s[39 + t]));
}
}
return;
} else {
// We should not need to compute each Jamo code point.
// In particular, there should be no offset or implicit ce32.
appendCEsFromCE32(d, U_SENTINEL, jamoCE32s[c], forward, errorCode);
appendCEsFromCE32(d, U_SENTINEL, jamoCE32s[19 + v], forward, errorCode);
if(t == 0) { return; }
// offset 39 = 19 + 21 - 1:
// 19 = JAMO_L_COUNT
// 21 = JAMO_T_COUNT
// -1 = omit t==0
ce32 = jamoCE32s[39 + t];
c = U_SENTINEL;
break;
}
}
case Collation::LEAD_SURROGATE_TAG: {
U_ASSERT(forward); // Backward iteration should never see lead surrogate code _unit_ data.
U_ASSERT(U16_IS_LEAD(c));
UChar trail;
if(U16_IS_TRAIL(trail = handleGetTrailSurrogate())) {
c = U16_GET_SUPPLEMENTARY(c, trail);
ce32 &= Collation::LEAD_TYPE_MASK;
if(ce32 == Collation::LEAD_ALL_UNASSIGNED) {
ce32 = Collation::UNASSIGNED_CE32; // unassigned-implicit
} else if(ce32 == Collation::LEAD_ALL_FALLBACK ||
(ce32 = d->getCE32FromSupplementary(c)) == Collation::FALLBACK_CE32) {
// fall back to the base data
d = d->base;
ce32 = d->getCE32FromSupplementary(c);
}
} else {
// c is an unpaired surrogate.
ce32 = Collation::UNASSIGNED_CE32;
}
break;
}
case Collation::OFFSET_TAG:
U_ASSERT(c >= 0);
ceBuffer.append(d->getCEFromOffsetCE32(c, ce32), errorCode);
return;
case Collation::IMPLICIT_TAG:
U_ASSERT(c >= 0);
if(U_IS_SURROGATE(c) && forbidSurrogateCodePoints()) {
ce32 = Collation::FFFD_CE32;
break;
} else {
ceBuffer.append(Collation::unassignedCEFromCodePoint(c), errorCode);
return;
}
}
}
ceBuffer.append(Collation::ceFromSimpleCE32(ce32), errorCode);
}
uint32_t
CollationIterator::getCE32FromPrefix(const CollationData *d, uint32_t ce32,
UErrorCode &errorCode) {
const UChar *p = d->contexts + Collation::indexFromCE32(ce32);
ce32 = CollationData::readCE32(p); // Default if no prefix match.
p += 2;
// Number of code points read before the original code point.
int32_t lookBehind = 0;
UCharsTrie prefixes(p);
for(;;) {
UChar32 c = previousCodePoint(errorCode);
if(c < 0) { break; }
++lookBehind;
UStringTrieResult match = prefixes.nextForCodePoint(c);
if(USTRINGTRIE_HAS_VALUE(match)) {
ce32 = (uint32_t)prefixes.getValue();
}
if(!USTRINGTRIE_HAS_NEXT(match)) { break; }
}
forwardNumCodePoints(lookBehind, errorCode);
return ce32;
}
UChar32
CollationIterator::nextSkippedCodePoint(UErrorCode &errorCode) {
if(skipped != NULL && skipped->hasNext()) { return skipped->next(); }
if(numCpFwd == 0) { return U_SENTINEL; }
UChar32 c = nextCodePoint(errorCode);
if(skipped != NULL && !skipped->isEmpty() && c >= 0) { skipped->incBeyond(); }
if(numCpFwd > 0 && c >= 0) { --numCpFwd; }
return c;
}
void
CollationIterator::backwardNumSkipped(int32_t n, UErrorCode &errorCode) {
if(skipped != NULL && !skipped->isEmpty()) {
n = skipped->backwardNumCodePoints(n);
}
backwardNumCodePoints(n, errorCode);
if(numCpFwd >= 0) { numCpFwd += n; }
}
uint32_t
CollationIterator::nextCE32FromContraction(const CollationData *d, uint32_t contractionCE32,
const UChar *p, uint32_t ce32, UChar32 c,
UErrorCode &errorCode) {
// c: next code point after the original one
// Number of code points read beyond the original code point.
// Needed for discontiguous contraction matching.
int32_t lookAhead = 1;
// Number of code points read since the last match (initially only c).
int32_t sinceMatch = 1;
// Normally we only need a contiguous match,
// and therefore need not remember the suffixes state from before a mismatch for retrying.
// If we are already processing skipped combining marks, then we do track the state.
UCharsTrie suffixes(p);
if(skipped != NULL && !skipped->isEmpty()) { skipped->saveTrieState(suffixes); }
UStringTrieResult match = suffixes.firstForCodePoint(c);
for(;;) {
UChar32 nextCp;
if(USTRINGTRIE_HAS_VALUE(match)) {
ce32 = (uint32_t)suffixes.getValue();
if(!USTRINGTRIE_HAS_NEXT(match) || (c = nextSkippedCodePoint(errorCode)) < 0) {
return ce32;
}
if(skipped != NULL && !skipped->isEmpty()) { skipped->saveTrieState(suffixes); }
sinceMatch = 1;
} else if(match == USTRINGTRIE_NO_MATCH || (nextCp = nextSkippedCodePoint(errorCode)) < 0) {
// No match for c, or partial match (USTRINGTRIE_NO_VALUE) and no further text.
// Back up if necessary, and try a discontiguous contraction.
if((contractionCE32 & Collation::CONTRACT_TRAILING_CCC) != 0 &&
// Discontiguous contraction matching extends an existing match.
// If there is no match yet, then there is nothing to do.
((contractionCE32 & Collation::CONTRACT_SINGLE_CP_NO_MATCH) == 0 ||
sinceMatch < lookAhead)) {
// The last character of at least one suffix has lccc!=0,
// allowing for discontiguous contractions.
// UCA S2.1.1 only processes non-starters immediately following
// "a match in the table" (sinceMatch=1).
if(sinceMatch > 1) {
// Return to the state after the last match.
// (Return to sinceMatch=0 and re-fetch the first partially-matched character.)
backwardNumSkipped(sinceMatch, errorCode);
c = nextSkippedCodePoint(errorCode);
lookAhead -= sinceMatch - 1;
sinceMatch = 1;
}
if(d->getFCD16(c) > 0xff) {
return nextCE32FromDiscontiguousContraction(
d, suffixes, ce32, lookAhead, c, errorCode);
}
}
break;
} else {
// Continue after partial match (USTRINGTRIE_NO_VALUE) for c.
// It does not have a result value, therefore it is not itself "a match in the table".
// If a partially-matched c has ccc!=0 then
// it might be skipped in discontiguous contraction.
c = nextCp;
++sinceMatch;
}
++lookAhead;
match = suffixes.nextForCodePoint(c);
}
backwardNumSkipped(sinceMatch, errorCode);
return ce32;
}
uint32_t
CollationIterator::nextCE32FromDiscontiguousContraction(
const CollationData *d, UCharsTrie &suffixes, uint32_t ce32,
int32_t lookAhead, UChar32 c,
UErrorCode &errorCode) {
if(U_FAILURE(errorCode)) { return 0; }
// UCA section 3.3.2 Contractions:
// Contractions that end with non-starter characters
// are known as discontiguous contractions.
// ... discontiguous contractions must be detected in input text
// whenever the final sequence of non-starter characters could be rearranged
// so as to make a contiguous matching sequence that is canonically equivalent.
// UCA: http://www.unicode.org/reports/tr10/#S2.1
// S2.1 Find the longest initial substring S at each point that has a match in the table.
// S2.1.1 If there are any non-starters following S, process each non-starter C.
// S2.1.2 If C is not blocked from S, find if S + C has a match in the table.
// Note: A non-starter in a string is called blocked
// if there is another non-starter of the same canonical combining class or zero
// between it and the last character of canonical combining class 0.
// S2.1.3 If there is a match, replace S by S + C, and remove C.
// First: Is a discontiguous contraction even possible?
uint16_t fcd16 = d->getFCD16(c);
U_ASSERT(fcd16 > 0xff); // The caller checked this already, as a shortcut.
UChar32 nextCp = nextSkippedCodePoint(errorCode);
if(nextCp < 0) {
// No further text.
backwardNumSkipped(1, errorCode);
return ce32;
}
++lookAhead;
uint8_t prevCC = (uint8_t)fcd16;
fcd16 = d->getFCD16(nextCp);
if(fcd16 <= 0xff) {
// The next code point after c is a starter (S2.1.1 "process each non-starter").
backwardNumSkipped(2, errorCode);
return ce32;
}
// We have read and matched (lookAhead-2) code points,
// read non-matching c and peeked ahead at nextCp.
// Return to the state before the mismatch and continue matching with nextCp.
if(skipped == NULL || skipped->isEmpty()) {
if(skipped == NULL) {
skipped = new SkippedState();
if(skipped == NULL) {
errorCode = U_MEMORY_ALLOCATION_ERROR;
return 0;
}
}
suffixes.reset();
if(lookAhead > 2) {
// Replay the partial match so far.
backwardNumCodePoints(lookAhead, errorCode);
suffixes.firstForCodePoint(nextCodePoint(errorCode));
for(int32_t i = 3; i < lookAhead; ++i) {
suffixes.nextForCodePoint(nextCodePoint(errorCode));
}
// Skip c (which did not match) and nextCp (which we will try now).
forwardNumCodePoints(2, errorCode);
}
skipped->saveTrieState(suffixes);
} else {
// Reset to the trie state before the failed match of c.
skipped->resetToTrieState(suffixes);
}
skipped->setFirstSkipped(c);
// Number of code points read since the last match (at this point: c and nextCp).
int32_t sinceMatch = 2;
c = nextCp;
for(;;) {
UStringTrieResult match;
// "If C is not blocked from S, find if S + C has a match in the table." (S2.1.2)
if(prevCC < (fcd16 >> 8) && USTRINGTRIE_HAS_VALUE(match = suffixes.nextForCodePoint(c))) {
// "If there is a match, replace S by S + C, and remove C." (S2.1.3)
// Keep prevCC unchanged.
ce32 = (uint32_t)suffixes.getValue();
sinceMatch = 0;
skipped->recordMatch();
if(!USTRINGTRIE_HAS_NEXT(match)) { break; }
skipped->saveTrieState(suffixes);
} else {
// No match for "S + C", skip C.
skipped->skip(c);
skipped->resetToTrieState(suffixes);
prevCC = (uint8_t)fcd16;
}
if((c = nextSkippedCodePoint(errorCode)) < 0) { break; }
++sinceMatch;
fcd16 = d->getFCD16(c);
if(fcd16 <= 0xff) {
// The next code point after c is a starter (S2.1.1 "process each non-starter").
break;
}
}
backwardNumSkipped(sinceMatch, errorCode);
UBool isTopDiscontiguous = skipped->isEmpty();
skipped->replaceMatch();
if(isTopDiscontiguous && !skipped->isEmpty()) {
// We did get a match after skipping one or more combining marks,
// and we are not in a recursive discontiguous contraction.
// Append CEs from the contraction ce32
// and then from the combining marks that we skipped before the match.
c = U_SENTINEL;
for(;;) {
appendCEsFromCE32(d, c, ce32, TRUE, errorCode);
// Fetch CE32s for skipped combining marks from the normal data, with fallback,
// rather than from the CollationData where we found the contraction.
if(!skipped->hasNext()) { break; }
c = skipped->next();
ce32 = getDataCE32(c);
if(ce32 == Collation::FALLBACK_CE32) {
d = data->base;
ce32 = d->getCE32(c);
} else {
d = data;
}
// Note: A nested discontiguous-contraction match
// replaces consumed combining marks with newly skipped ones
// and resets the reading position to the beginning.
}
skipped->clear();
ce32 = Collation::NO_CE32; // Signal to the caller that the result is in the ceBuffer.
}
return ce32;
}
void
CollationIterator::appendNumericCEs(uint32_t ce32, UBool forward, UErrorCode &errorCode) {
// Collect digits.
CharString digits;
if(forward) {
for(;;) {
char digit = Collation::digitFromCE32(ce32);
digits.append(digit, errorCode);
if(numCpFwd == 0) { break; }
UChar32 c = nextCodePoint(errorCode);
if(c < 0) { break; }
ce32 = data->getCE32(c);
if(ce32 == Collation::FALLBACK_CE32) {
ce32 = data->base->getCE32(c);
}
if(!Collation::hasCE32Tag(ce32, Collation::DIGIT_TAG)) {
backwardNumCodePoints(1, errorCode);
break;
}
if(numCpFwd > 0) { --numCpFwd; }
}
} else {
for(;;) {
char digit = Collation::digitFromCE32(ce32);
digits.append(digit, errorCode);
UChar32 c = previousCodePoint(errorCode);
if(c < 0) { break; }
ce32 = data->getCE32(c);
if(ce32 == Collation::FALLBACK_CE32) {
ce32 = data->base->getCE32(c);
}
if(!Collation::hasCE32Tag(ce32, Collation::DIGIT_TAG)) {
forwardNumCodePoints(1, errorCode);
break;
}
}
// Reverse the digit string.
char *p = digits.data();
char *q = p + digits.length() - 1;
while(p < q) {
char digit = *p;
*p++ = *q;
*q-- = digit;
}
}
if(U_FAILURE(errorCode)) { return; }
int32_t pos = 0;
do {
// Skip leading zeros.
while(pos < (digits.length() - 1) && digits[pos] == 0) { ++pos; }
// Write a sequence of CEs for at most 254 digits at a time.
int32_t segmentLength = digits.length() - pos;
if(segmentLength > 254) { segmentLength = 254; }
appendNumericSegmentCEs(digits.data() + pos, segmentLength, errorCode);
pos += segmentLength;
} while(U_SUCCESS(errorCode) && pos < digits.length());
}
void
CollationIterator::appendNumericSegmentCEs(const char *digits, int32_t length, UErrorCode &errorCode) {
U_ASSERT(1 <= length && length <= 254);
U_ASSERT(length == 1 || digits[0] != 0);
uint32_t numericPrimary = data->numericPrimary;
// Note: We use primary byte values 2..255: digits are not compressible.
if(length <= 7) {
// Very dense encoding for small numbers.
int32_t value = digits[0];
for(int32_t i = 1; i < length; ++i) {
value = value * 10 + digits[i];
}
// Primary weight second byte values:
// 74 byte values 2.. 75 for small numbers in two-byte primary weights.
// 40 byte values 76..115 for medium numbers in three-byte primary weights.
// 16 byte values 116..131 for large numbers in four-byte primary weights.
// 124 byte values 132..255 for very large numbers with 4..127 digit pairs.
int32_t firstByte = 2;
int32_t numBytes = 74;
if(value < numBytes) {
// Two-byte primary for 0..73, good for day & month numbers etc.
uint32_t primary = numericPrimary | ((firstByte + value) << 16);
ceBuffer.append(Collation::makeCE(primary), errorCode);
return;
}
value -= numBytes;
firstByte += numBytes;
numBytes = 40;
if(value < numBytes * 254) {
// Three-byte primary for 74..10233=74+40*254-1, good for year numbers and more.
uint32_t primary = numericPrimary |
((firstByte + value / 254) << 16) | ((2 + value % 254) << 8);
ceBuffer.append(Collation::makeCE(primary), errorCode);
return;
}
value -= numBytes * 254;
firstByte += numBytes;
numBytes = 16;
if(value < numBytes * 254 * 254) {
// Four-byte primary for 10234..1042489=10234+16*254*254-1.
uint32_t primary = numericPrimary | (2 + value % 254);
value /= 254;
primary |= (2 + value % 254) << 8;
value /= 254;
primary |= (firstByte + value % 254) << 16;
ceBuffer.append(Collation::makeCE(primary), errorCode);
return;
}
// original value > 1042489
}
U_ASSERT(length >= 7);
// The second primary byte value 132..255 indicates the number of digit pairs (4..127),
// then we generate primary bytes with those pairs.
// Omit trailing 00 pairs.
// Decrement the value for the last pair.
// Set the exponent. 4 pairs->132, 5 pairs->133, ..., 127 pairs->255.
int32_t numPairs = (length + 1) / 2;
uint32_t primary = numericPrimary | ((132 - 4 + numPairs) << 16);
// Find the length without trailing 00 pairs.
while(digits[length - 1] == 0 && digits[length - 2] == 0) {
length -= 2;
}
// Read the first pair.
uint32_t pair;
int32_t pos;
if(length & 1) {
// Only "half a pair" if we have an odd number of digits.
pair = digits[0];
pos = 1;
} else {
pair = digits[0] * 10 + digits[1];
pos = 2;
}
pair = 11 + 2 * pair;
// Add the pairs of digits between pos and length.
int32_t shift = 8;
while(pos < length) {
if(shift == 0) {
// Every three pairs/bytes we need to store a 4-byte-primary CE
// and start with a new CE with the '0' primary lead byte.
primary |= pair;
ceBuffer.append(Collation::makeCE(primary), errorCode);
primary = numericPrimary;
shift = 16;
} else {
primary |= pair << shift;
shift -= 8;
}
pair = 11 + 2 * (digits[pos] * 10 + digits[pos + 1]);
pos += 2;
}
primary |= (pair - 1) << shift;
ceBuffer.append(Collation::makeCE(primary), errorCode);
}
int64_t
CollationIterator::previousCE(UVector32 &offsets, UErrorCode &errorCode) {
if(ceBuffer.length > 0) {
// Return the previous buffered CE.
return ceBuffer.get(--ceBuffer.length);
}
offsets.removeAllElements();
int32_t limitOffset = getOffset();
UChar32 c = previousCodePoint(errorCode);
if(c < 0) { return Collation::NO_CE; }
if(data->isUnsafeBackward(c, isNumeric)) {
return previousCEUnsafe(c, offsets, errorCode);
}
// Simple, safe-backwards iteration:
// Get a CE going backwards, handle prefixes but no contractions.
uint32_t ce32 = data->getCE32(c);
const CollationData *d;
if(ce32 == Collation::FALLBACK_CE32) {
d = data->base;
ce32 = d->getCE32(c);
} else {
d = data;
}
if(Collation::isSimpleOrLongCE32(ce32)) {
return Collation::ceFromCE32(ce32);
}
appendCEsFromCE32(d, c, ce32, FALSE, errorCode);
if(U_SUCCESS(errorCode)) {
if(ceBuffer.length > 1) {
offsets.addElement(getOffset(), errorCode);
// For an expansion, the offset of each non-initial CE is the limit offset,
// consistent with forward iteration.
while(offsets.size() <= ceBuffer.length) {
offsets.addElement(limitOffset, errorCode);
};
}
return ceBuffer.get(--ceBuffer.length);
} else {
return Collation::NO_CE_PRIMARY;
}
}
int64_t
CollationIterator::previousCEUnsafe(UChar32 c, UVector32 &offsets, UErrorCode &errorCode) {
// We just move through the input counting safe and unsafe code points
// without collecting the unsafe-backward substring into a buffer and
// switching to it.
// This is to keep the logic simple. Otherwise we would have to handle
// prefix matching going before the backward buffer, switching
// to iteration and back, etc.
// In the most important case of iterating over a normal string,
// reading from the string itself is already maximally fast.
// The only drawback there is that after getting the CEs we always
// skip backward to the safe character rather than switching out
// of a backwardBuffer.
// But this should not be the common case for previousCE(),
// and correctness and maintainability are more important than
// complex optimizations.
// Find the first safe character before c.
int32_t numBackward = 1;
while((c = previousCodePoint(errorCode)) >= 0) {
++numBackward;
if(!data->isUnsafeBackward(c, isNumeric)) {
break;
}
}
// Set the forward iteration limit.
// Note: This counts code points.
// We cannot enforce a limit in the middle of a surrogate pair or similar.
numCpFwd = numBackward;
// Reset the forward iterator.
cesIndex = 0;
U_ASSERT(ceBuffer.length == 0);
// Go forward and collect the CEs.
int32_t offset = getOffset();
while(numCpFwd > 0) {
// nextCE() normally reads one code point.
// Contraction matching and digit specials read more and check numCpFwd.
--numCpFwd;
// Append one or more CEs to the ceBuffer.
(void)nextCE(errorCode);
U_ASSERT(U_FAILURE(errorCode) || ceBuffer.get(ceBuffer.length - 1) != Collation::NO_CE);
// No need to loop for getting each expansion CE from nextCE().
cesIndex = ceBuffer.length;
// However, we need to write an offset for each CE.
// This is for CollationElementIterator::getOffset() to return
// intermediate offsets from the unsafe-backwards segment.
U_ASSERT(offsets.size() < ceBuffer.length);
offsets.addElement(offset, errorCode);
// For an expansion, the offset of each non-initial CE is the limit offset,
// consistent with forward iteration.
offset = getOffset();
while(offsets.size() < ceBuffer.length) {
offsets.addElement(offset, errorCode);
};
}
U_ASSERT(offsets.size() == ceBuffer.length);
// End offset corresponding to just after the unsafe-backwards segment.
offsets.addElement(offset, errorCode);
// Reset the forward iteration limit
// and move backward to before the segment for which we fetched CEs.
numCpFwd = -1;
backwardNumCodePoints(numBackward, errorCode);
// Use the collected CEs and return the last one.
cesIndex = 0; // Avoid cesIndex > ceBuffer.length when that gets decremented.
if(U_SUCCESS(errorCode)) {
return ceBuffer.get(--ceBuffer.length);
} else {
return Collation::NO_CE_PRIMARY;
}
}
U_NAMESPACE_END
#endif // !UCONFIG_NO_COLLATION