scuffed-code/icu4c/source/common/rbbi_cache.cpp
Andy Heninger 1eef362329 ICU-13565 Break Iteration, remove the dictionary bit from the implementation.
For identifying text that needs to be handled by a word dictionary for Break Iteration,
change from using a bit in the character category to sorting all dictionary categories
together, and recording the boundary between the non-dictionary and dictionary ranges.

This is internal to the implementaion. It does not affect behavior.
It does increase the number of character categories that can be handled using a
compact 8 bit Trie, from 127 to 255.
2020-06-17 12:00:14 -07:00

656 lines
24 KiB
C++

// Copyright (C) 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
// file: rbbi_cache.cpp
#include "unicode/utypes.h"
#if !UCONFIG_NO_BREAK_ITERATION
#include "unicode/ubrk.h"
#include "unicode/rbbi.h"
#include "rbbi_cache.h"
#include "brkeng.h"
#include "cmemory.h"
#include "rbbidata.h"
#include "rbbirb.h"
#include "uassert.h"
#include "uvectr32.h"
U_NAMESPACE_BEGIN
/*
* DictionaryCache implementation
*/
RuleBasedBreakIterator::DictionaryCache::DictionaryCache(RuleBasedBreakIterator *bi, UErrorCode &status) :
fBI(bi), fBreaks(status), fPositionInCache(-1),
fStart(0), fLimit(0), fFirstRuleStatusIndex(0), fOtherRuleStatusIndex(0) {
}
RuleBasedBreakIterator::DictionaryCache::~DictionaryCache() {
}
void RuleBasedBreakIterator::DictionaryCache::reset() {
fPositionInCache = -1;
fStart = 0;
fLimit = 0;
fFirstRuleStatusIndex = 0;
fOtherRuleStatusIndex = 0;
fBreaks.removeAllElements();
}
UBool RuleBasedBreakIterator::DictionaryCache::following(int32_t fromPos, int32_t *result, int32_t *statusIndex) {
if (fromPos >= fLimit || fromPos < fStart) {
fPositionInCache = -1;
return FALSE;
}
// Sequential iteration, move from previous boundary to the following
int32_t r = 0;
if (fPositionInCache >= 0 && fPositionInCache < fBreaks.size() && fBreaks.elementAti(fPositionInCache) == fromPos) {
++fPositionInCache;
if (fPositionInCache >= fBreaks.size()) {
fPositionInCache = -1;
return FALSE;
}
r = fBreaks.elementAti(fPositionInCache);
U_ASSERT(r > fromPos);
*result = r;
*statusIndex = fOtherRuleStatusIndex;
return TRUE;
}
// Random indexing. Linear search for the boundary following the given position.
for (fPositionInCache = 0; fPositionInCache < fBreaks.size(); ++fPositionInCache) {
r= fBreaks.elementAti(fPositionInCache);
if (r > fromPos) {
*result = r;
*statusIndex = fOtherRuleStatusIndex;
return TRUE;
}
}
UPRV_UNREACHABLE;
}
UBool RuleBasedBreakIterator::DictionaryCache::preceding(int32_t fromPos, int32_t *result, int32_t *statusIndex) {
if (fromPos <= fStart || fromPos > fLimit) {
fPositionInCache = -1;
return FALSE;
}
if (fromPos == fLimit) {
fPositionInCache = fBreaks.size() - 1;
if (fPositionInCache >= 0) {
U_ASSERT(fBreaks.elementAti(fPositionInCache) == fromPos);
}
}
int32_t r;
if (fPositionInCache > 0 && fPositionInCache < fBreaks.size() && fBreaks.elementAti(fPositionInCache) == fromPos) {
--fPositionInCache;
r = fBreaks.elementAti(fPositionInCache);
U_ASSERT(r < fromPos);
*result = r;
*statusIndex = ( r== fStart) ? fFirstRuleStatusIndex : fOtherRuleStatusIndex;
return TRUE;
}
if (fPositionInCache == 0) {
fPositionInCache = -1;
return FALSE;
}
for (fPositionInCache = fBreaks.size()-1; fPositionInCache >= 0; --fPositionInCache) {
r = fBreaks.elementAti(fPositionInCache);
if (r < fromPos) {
*result = r;
*statusIndex = ( r == fStart) ? fFirstRuleStatusIndex : fOtherRuleStatusIndex;
return TRUE;
}
}
UPRV_UNREACHABLE;
}
void RuleBasedBreakIterator::DictionaryCache::populateDictionary(int32_t startPos, int32_t endPos,
int32_t firstRuleStatus, int32_t otherRuleStatus) {
if ((endPos - startPos) <= 1) {
return;
}
reset();
fFirstRuleStatusIndex = firstRuleStatus;
fOtherRuleStatusIndex = otherRuleStatus;
int32_t rangeStart = startPos;
int32_t rangeEnd = endPos;
uint16_t category;
int32_t current;
UErrorCode status = U_ZERO_ERROR;
int32_t foundBreakCount = 0;
UText *text = &fBI->fText;
// Loop through the text, looking for ranges of dictionary characters.
// For each span, find the appropriate break engine, and ask it to find
// any breaks within the span.
utext_setNativeIndex(text, rangeStart);
UChar32 c = utext_current32(text);
category = ucptrie_get(fBI->fData->fTrie, c);
uint32_t dictStart = fBI->fData->fForwardTable->fDictCategoriesStart;
while(U_SUCCESS(status)) {
while((current = (int32_t)UTEXT_GETNATIVEINDEX(text)) < rangeEnd
&& (category < dictStart)) {
utext_next32(text); // TODO: cleaner loop structure.
c = utext_current32(text);
category = ucptrie_get(fBI->fData->fTrie, c);
}
if (current >= rangeEnd) {
break;
}
// We now have a dictionary character. Get the appropriate language object
// to deal with it.
const LanguageBreakEngine *lbe = fBI->getLanguageBreakEngine(c);
// Ask the language object if there are any breaks. It will add them to the cache and
// leave the text pointer on the other side of its range, ready to search for the next one.
if (lbe != NULL) {
foundBreakCount += lbe->findBreaks(text, rangeStart, rangeEnd, fBreaks);
}
// Reload the loop variables for the next go-round
c = utext_current32(text);
category = ucptrie_get(fBI->fData->fTrie, c);
}
// If we found breaks, ensure that the first and last entries are
// the original starting and ending position. And initialize the
// cache iteration position to the first entry.
// printf("foundBreakCount = %d\n", foundBreakCount);
if (foundBreakCount > 0) {
U_ASSERT(foundBreakCount == fBreaks.size());
if (startPos < fBreaks.elementAti(0)) {
// The dictionary did not place a boundary at the start of the segment of text.
// Add one now. This should not commonly happen, but it would be easy for interactions
// of the rules for dictionary segments and the break engine implementations to
// inadvertently cause it. Cover it here, just in case.
fBreaks.insertElementAt(startPos, 0, status);
}
if (endPos > fBreaks.peeki()) {
fBreaks.push(endPos, status);
}
fPositionInCache = 0;
// Note: Dictionary matching may extend beyond the original limit.
fStart = fBreaks.elementAti(0);
fLimit = fBreaks.peeki();
} else {
// there were no language-based breaks, even though the segment contained
// dictionary characters. Subsequent attempts to fetch boundaries from the dictionary cache
// for this range will fail, and the calling code will fall back to the rule based boundaries.
}
}
/*
* BreakCache implemetation
*/
RuleBasedBreakIterator::BreakCache::BreakCache(RuleBasedBreakIterator *bi, UErrorCode &status) :
fBI(bi), fSideBuffer(status) {
reset();
}
RuleBasedBreakIterator::BreakCache::~BreakCache() {
}
void RuleBasedBreakIterator::BreakCache::reset(int32_t pos, int32_t ruleStatus) {
fStartBufIdx = 0;
fEndBufIdx = 0;
fTextIdx = pos;
fBufIdx = 0;
fBoundaries[0] = pos;
fStatuses[0] = (uint16_t)ruleStatus;
}
int32_t RuleBasedBreakIterator::BreakCache::current() {
fBI->fPosition = fTextIdx;
fBI->fRuleStatusIndex = fStatuses[fBufIdx];
fBI->fDone = FALSE;
return fTextIdx;
}
void RuleBasedBreakIterator::BreakCache::following(int32_t startPos, UErrorCode &status) {
if (U_FAILURE(status)) {
return;
}
if (startPos == fTextIdx || seek(startPos) || populateNear(startPos, status)) {
// startPos is in the cache. Do a next() from that position.
// TODO: an awkward set of interactions with bi->fDone
// seek() does not clear it; it can't because of interactions with populateNear().
// next() does not clear it in the fast-path case, where everything matters. Maybe it should.
// So clear it here, for the case where seek() succeeded on an iterator that had previously run off the end.
fBI->fDone = false;
next();
}
return;
}
void RuleBasedBreakIterator::BreakCache::preceding(int32_t startPos, UErrorCode &status) {
if (U_FAILURE(status)) {
return;
}
if (startPos == fTextIdx || seek(startPos) || populateNear(startPos, status)) {
if (startPos == fTextIdx) {
previous(status);
} else {
// seek() leaves the BreakCache positioned at the preceding boundary
// if the requested position is between two bounaries.
// current() pushes the BreakCache position out to the BreakIterator itself.
U_ASSERT(startPos > fTextIdx);
current();
}
}
return;
}
/*
* Out-of-line code for BreakCache::next().
* Cache does not already contain the boundary
*/
void RuleBasedBreakIterator::BreakCache::nextOL() {
fBI->fDone = !populateFollowing();
fBI->fPosition = fTextIdx;
fBI->fRuleStatusIndex = fStatuses[fBufIdx];
return;
}
void RuleBasedBreakIterator::BreakCache::previous(UErrorCode &status) {
if (U_FAILURE(status)) {
return;
}
int32_t initialBufIdx = fBufIdx;
if (fBufIdx == fStartBufIdx) {
// At start of cache. Prepend to it.
populatePreceding(status);
} else {
// Cache already holds the next boundary
fBufIdx = modChunkSize(fBufIdx - 1);
fTextIdx = fBoundaries[fBufIdx];
}
fBI->fDone = (fBufIdx == initialBufIdx);
fBI->fPosition = fTextIdx;
fBI->fRuleStatusIndex = fStatuses[fBufIdx];
return;
}
UBool RuleBasedBreakIterator::BreakCache::seek(int32_t pos) {
if (pos < fBoundaries[fStartBufIdx] || pos > fBoundaries[fEndBufIdx]) {
return FALSE;
}
if (pos == fBoundaries[fStartBufIdx]) {
// Common case: seek(0), from BreakIterator::first()
fBufIdx = fStartBufIdx;
fTextIdx = fBoundaries[fBufIdx];
return TRUE;
}
if (pos == fBoundaries[fEndBufIdx]) {
fBufIdx = fEndBufIdx;
fTextIdx = fBoundaries[fBufIdx];
return TRUE;
}
int32_t min = fStartBufIdx;
int32_t max = fEndBufIdx;
while (min != max) {
int32_t probe = (min + max + (min>max ? CACHE_SIZE : 0)) / 2;
probe = modChunkSize(probe);
if (fBoundaries[probe] > pos) {
max = probe;
} else {
min = modChunkSize(probe + 1);
}
}
U_ASSERT(fBoundaries[max] > pos);
fBufIdx = modChunkSize(max - 1);
fTextIdx = fBoundaries[fBufIdx];
U_ASSERT(fTextIdx <= pos);
return TRUE;
}
UBool RuleBasedBreakIterator::BreakCache::populateNear(int32_t position, UErrorCode &status) {
if (U_FAILURE(status)) {
return FALSE;
}
U_ASSERT(position < fBoundaries[fStartBufIdx] || position > fBoundaries[fEndBufIdx]);
// Find a boundary somewhere in the vicinity of the requested position.
// Depending on the safe rules and the text data, it could be either before, at, or after
// the requested position.
// If the requested position is not near already cached positions, clear the existing cache,
// find a near-by boundary and begin new cache contents there.
if ((position < fBoundaries[fStartBufIdx] - 15) || position > (fBoundaries[fEndBufIdx] + 15)) {
int32_t aBoundary = 0;
int32_t ruleStatusIndex = 0;
if (position > 20) {
int32_t backupPos = fBI->handleSafePrevious(position);
if (backupPos > 0) {
// Advance to the boundary following the backup position.
// There is a complication: the safe reverse rules identify pairs of code points
// that are safe. If advancing from the safe point moves forwards by less than
// two code points, we need to advance one more time to ensure that the boundary
// is good, including a correct rules status value.
//
fBI->fPosition = backupPos;
aBoundary = fBI->handleNext();
if (aBoundary <= backupPos + 4) {
// +4 is a quick test for possibly having advanced only one codepoint.
// Four being the length of the longest potential code point, a supplementary in UTF-8
utext_setNativeIndex(&fBI->fText, aBoundary);
if (backupPos == utext_getPreviousNativeIndex(&fBI->fText)) {
// The initial handleNext() only advanced by a single code point. Go again.
aBoundary = fBI->handleNext(); // Safe rules identify safe pairs.
}
}
ruleStatusIndex = fBI->fRuleStatusIndex;
}
}
reset(aBoundary, ruleStatusIndex); // Reset cache to hold aBoundary as a single starting point.
}
// Fill in boundaries between existing cache content and the new requested position.
if (fBoundaries[fEndBufIdx] < position) {
// The last position in the cache precedes the requested position.
// Add following position(s) to the cache.
while (fBoundaries[fEndBufIdx] < position) {
if (!populateFollowing()) {
UPRV_UNREACHABLE;
}
}
fBufIdx = fEndBufIdx; // Set iterator position to the end of the buffer.
fTextIdx = fBoundaries[fBufIdx]; // Required because populateFollowing may add extra boundaries.
while (fTextIdx > position) { // Move backwards to a position at or preceding the requested pos.
previous(status);
}
return true;
}
if (fBoundaries[fStartBufIdx] > position) {
// The first position in the cache is beyond the requested position.
// back up more until we get a boundary <= the requested position.
while (fBoundaries[fStartBufIdx] > position) {
populatePreceding(status);
}
fBufIdx = fStartBufIdx; // Set iterator position to the start of the buffer.
fTextIdx = fBoundaries[fBufIdx]; // Required because populatePreceding may add extra boundaries.
while (fTextIdx < position) { // Move forwards to a position at or following the requested pos.
next();
}
if (fTextIdx > position) {
// If position is not itself a boundary, the next() loop above will overshoot.
// Back up one, leaving cache position at the boundary preceding the requested position.
previous(status);
}
return true;
}
U_ASSERT(fTextIdx == position);
return true;
}
UBool RuleBasedBreakIterator::BreakCache::populateFollowing() {
int32_t fromPosition = fBoundaries[fEndBufIdx];
int32_t fromRuleStatusIdx = fStatuses[fEndBufIdx];
int32_t pos = 0;
int32_t ruleStatusIdx = 0;
if (fBI->fDictionaryCache->following(fromPosition, &pos, &ruleStatusIdx)) {
addFollowing(pos, ruleStatusIdx, UpdateCachePosition);
return TRUE;
}
fBI->fPosition = fromPosition;
pos = fBI->handleNext();
if (pos == UBRK_DONE) {
return FALSE;
}
ruleStatusIdx = fBI->fRuleStatusIndex;
if (fBI->fDictionaryCharCount > 0) {
// The text segment obtained from the rules includes dictionary characters.
// Subdivide it, with subdivided results going into the dictionary cache.
fBI->fDictionaryCache->populateDictionary(fromPosition, pos, fromRuleStatusIdx, ruleStatusIdx);
if (fBI->fDictionaryCache->following(fromPosition, &pos, &ruleStatusIdx)) {
addFollowing(pos, ruleStatusIdx, UpdateCachePosition);
return TRUE;
// TODO: may want to move a sizable chunk of dictionary cache to break cache at this point.
// But be careful with interactions with populateNear().
}
}
// Rule based segment did not include dictionary characters.
// Or, it did contain dictionary chars, but the dictionary segmenter didn't handle them,
// meaning that we didn't take the return, above.
// Add its end point to the cache.
addFollowing(pos, ruleStatusIdx, UpdateCachePosition);
// Add several non-dictionary boundaries at this point, to optimize straight forward iteration.
// (subsequent calls to BreakIterator::next() will take the fast path, getting cached results.
//
for (int count=0; count<6; ++count) {
pos = fBI->handleNext();
if (pos == UBRK_DONE || fBI->fDictionaryCharCount > 0) {
break;
}
addFollowing(pos, fBI->fRuleStatusIndex, RetainCachePosition);
}
return TRUE;
}
UBool RuleBasedBreakIterator::BreakCache::populatePreceding(UErrorCode &status) {
if (U_FAILURE(status)) {
return FALSE;
}
int32_t fromPosition = fBoundaries[fStartBufIdx];
if (fromPosition == 0) {
return FALSE;
}
int32_t position = 0;
int32_t positionStatusIdx = 0;
if (fBI->fDictionaryCache->preceding(fromPosition, &position, &positionStatusIdx)) {
addPreceding(position, positionStatusIdx, UpdateCachePosition);
return TRUE;
}
int32_t backupPosition = fromPosition;
// Find a boundary somewhere preceding the first already-cached boundary
do {
backupPosition = backupPosition - 30;
if (backupPosition <= 0) {
backupPosition = 0;
} else {
backupPosition = fBI->handleSafePrevious(backupPosition);
}
if (backupPosition == UBRK_DONE || backupPosition == 0) {
position = 0;
positionStatusIdx = 0;
} else {
// Advance to the boundary following the backup position.
// There is a complication: the safe reverse rules identify pairs of code points
// that are safe. If advancing from the safe point moves forwards by less than
// two code points, we need to advance one more time to ensure that the boundary
// is good, including a correct rules status value.
//
fBI->fPosition = backupPosition;
position = fBI->handleNext();
if (position <= backupPosition + 4) {
// +4 is a quick test for possibly having advanced only one codepoint.
// Four being the length of the longest potential code point, a supplementary in UTF-8
utext_setNativeIndex(&fBI->fText, position);
if (backupPosition == utext_getPreviousNativeIndex(&fBI->fText)) {
// The initial handleNext() only advanced by a single code point. Go again.
position = fBI->handleNext(); // Safe rules identify safe pairs.
}
}
positionStatusIdx = fBI->fRuleStatusIndex;
}
} while (position >= fromPosition);
// Find boundaries between the one we just located and the first already-cached boundary
// Put them in a side buffer, because we don't yet know where they will fall in the circular cache buffer..
fSideBuffer.removeAllElements();
fSideBuffer.addElement(position, status);
fSideBuffer.addElement(positionStatusIdx, status);
do {
int32_t prevPosition = fBI->fPosition = position;
int32_t prevStatusIdx = positionStatusIdx;
position = fBI->handleNext();
positionStatusIdx = fBI->fRuleStatusIndex;
if (position == UBRK_DONE) {
break;
}
UBool segmentHandledByDictionary = FALSE;
if (fBI->fDictionaryCharCount != 0) {
// Segment from the rules includes dictionary characters.
// Subdivide it, with subdivided results going into the dictionary cache.
int32_t dictSegEndPosition = position;
fBI->fDictionaryCache->populateDictionary(prevPosition, dictSegEndPosition, prevStatusIdx, positionStatusIdx);
while (fBI->fDictionaryCache->following(prevPosition, &position, &positionStatusIdx)) {
segmentHandledByDictionary = true;
U_ASSERT(position > prevPosition);
if (position >= fromPosition) {
break;
}
U_ASSERT(position <= dictSegEndPosition);
fSideBuffer.addElement(position, status);
fSideBuffer.addElement(positionStatusIdx, status);
prevPosition = position;
}
U_ASSERT(position==dictSegEndPosition || position>=fromPosition);
}
if (!segmentHandledByDictionary && position < fromPosition) {
fSideBuffer.addElement(position, status);
fSideBuffer.addElement(positionStatusIdx, status);
}
} while (position < fromPosition);
// Move boundaries from the side buffer to the main circular buffer.
UBool success = FALSE;
if (!fSideBuffer.isEmpty()) {
positionStatusIdx = fSideBuffer.popi();
position = fSideBuffer.popi();
addPreceding(position, positionStatusIdx, UpdateCachePosition);
success = TRUE;
}
while (!fSideBuffer.isEmpty()) {
positionStatusIdx = fSideBuffer.popi();
position = fSideBuffer.popi();
if (!addPreceding(position, positionStatusIdx, RetainCachePosition)) {
// No space in circular buffer to hold a new preceding result while
// also retaining the current cache (iteration) position.
// Bailing out is safe; the cache will refill again if needed.
break;
}
}
return success;
}
void RuleBasedBreakIterator::BreakCache::addFollowing(int32_t position, int32_t ruleStatusIdx, UpdatePositionValues update) {
U_ASSERT(position > fBoundaries[fEndBufIdx]);
U_ASSERT(ruleStatusIdx <= UINT16_MAX);
int32_t nextIdx = modChunkSize(fEndBufIdx + 1);
if (nextIdx == fStartBufIdx) {
fStartBufIdx = modChunkSize(fStartBufIdx + 6); // TODO: experiment. Probably revert to 1.
}
fBoundaries[nextIdx] = position;
fStatuses[nextIdx] = static_cast<uint16_t>(ruleStatusIdx);
fEndBufIdx = nextIdx;
if (update == UpdateCachePosition) {
// Set current position to the newly added boundary.
fBufIdx = nextIdx;
fTextIdx = position;
} else {
// Retaining the original cache position.
// Check if the added boundary wraps around the buffer, and would over-write the original position.
// It's the responsibility of callers of this function to not add too many.
U_ASSERT(nextIdx != fBufIdx);
}
}
bool RuleBasedBreakIterator::BreakCache::addPreceding(int32_t position, int32_t ruleStatusIdx, UpdatePositionValues update) {
U_ASSERT(position < fBoundaries[fStartBufIdx]);
U_ASSERT(ruleStatusIdx <= UINT16_MAX);
int32_t nextIdx = modChunkSize(fStartBufIdx - 1);
if (nextIdx == fEndBufIdx) {
if (fBufIdx == fEndBufIdx && update == RetainCachePosition) {
// Failure. The insertion of the new boundary would claim the buffer position that is the
// current iteration position. And we also want to retain the current iteration position.
// (The buffer is already completely full of entries that precede the iteration position.)
return false;
}
fEndBufIdx = modChunkSize(fEndBufIdx - 1);
}
fBoundaries[nextIdx] = position;
fStatuses[nextIdx] = static_cast<uint16_t>(ruleStatusIdx);
fStartBufIdx = nextIdx;
if (update == UpdateCachePosition) {
fBufIdx = nextIdx;
fTextIdx = position;
}
return true;
}
void RuleBasedBreakIterator::BreakCache::dumpCache() {
#ifdef RBBI_DEBUG
RBBIDebugPrintf("fTextIdx:%d fBufIdx:%d\n", fTextIdx, fBufIdx);
for (int32_t i=fStartBufIdx; ; i=modChunkSize(i+1)) {
RBBIDebugPrintf("%d %d\n", i, fBoundaries[i]);
if (i == fEndBufIdx) {
break;
}
}
#endif
}
U_NAMESPACE_END
#endif // #if !UCONFIG_NO_BREAK_ITERATION