/* ********************************************************************** * Copyright (C) 1999-2001 IBM Corp. All rights reserved. ********************************************************************** * Date Name Description * 12/1/99 rgillam Complete port from Java. * 01/13/2000 helena Added UErrorCode to ctors. ********************************************************************** */ #include "ucmp8.h" #include "unicode/dbbi.h" #include "dbbi_tbl.h" #include "uvector.h" #include "unicode/schriter.h" #include "cmemory.h" char DictionaryBasedBreakIterator::fgClassID = 0; //======================================================================= // constructors //======================================================================= DictionaryBasedBreakIterator::DictionaryBasedBreakIterator(UDataMemory* tablesImage, char* dictionaryFilename, UErrorCode& status) : RuleBasedBreakIterator((UDataMemory*)NULL), dictionaryCharCount(0), cachedBreakPositions(NULL), numCachedBreakPositions(0), positionInCache(0) { tables = new DictionaryBasedBreakIteratorTables(tablesImage, dictionaryFilename, status); if (U_FAILURE(status)) { delete tables; return; } tables->addReference(); } //======================================================================= // boilerplate //======================================================================= /** * Destructor */ DictionaryBasedBreakIterator::~DictionaryBasedBreakIterator() { delete [] cachedBreakPositions; } /** * Assignment operator. Sets this iterator to have the same behavior, * and iterate over the same text, as the one passed in. */ DictionaryBasedBreakIterator& DictionaryBasedBreakIterator::operator=(const DictionaryBasedBreakIterator& that) { reset(); RuleBasedBreakIterator::operator=(that); return *this; } /** * Returns a newly-constructed RuleBasedBreakIterator with the same * behavior, and iterating over the same text, as this one. */ BreakIterator* DictionaryBasedBreakIterator::clone() const { return new DictionaryBasedBreakIterator(*this); } //======================================================================= // BreakIterator overrides //======================================================================= /** * Advances the iterator one step backwards. * @return The position of the last boundary position before the * current iteration position */ int32_t DictionaryBasedBreakIterator::previous() { // if we have cached break positions and we're still in the range // covered by them, just move one step backward in the cache if (cachedBreakPositions != NULL && positionInCache > 0) { --positionInCache; text->setIndex(cachedBreakPositions[positionInCache]); return cachedBreakPositions[positionInCache]; } // otherwise, dump the cache and use the inherited previous() method to move // backward. This may fill up the cache with new break positions, in which // case we have to mark our position in the cache else { reset(); int32_t result = RuleBasedBreakIterator::previous(); if (cachedBreakPositions != NULL) { positionInCache = numCachedBreakPositions - 2; } return result; } } /** * Sets the current iteration position to the last boundary position * before the specified position. * @param offset The position to begin searching from * @return The position of the last boundary before "offset" */ int32_t DictionaryBasedBreakIterator::preceding(int32_t offset) { // if the offset passed in is already past the end of the text, // just return DONE; if it's before the beginning, return the // text's starting offset if (text == NULL || offset > text->endIndex()) { return BreakIterator::DONE; } else if (offset < text->startIndex()) { return text->startIndex(); } // if we have no cached break positions, or "offset" is outside the // range covered by the cache, we can just call the inherited routine // (which will eventually call other routines in this class that may // refresh the cache) if (cachedBreakPositions == NULL || offset <= cachedBreakPositions[0] || offset > cachedBreakPositions[numCachedBreakPositions - 1]) { reset(); return RuleBasedBreakIterator::preceding(offset); } // on the other hand, if "offset" is within the range covered by the cache, // then all we have to do is search the cache for the last break position // before "offset" else { positionInCache = 0; while (positionInCache < numCachedBreakPositions && offset > cachedBreakPositions[positionInCache]) ++positionInCache; --positionInCache; text->setIndex(cachedBreakPositions[positionInCache]); return text->getIndex(); } } /** * Sets the current iteration position to the first boundary position after * the specified position. * @param offset The position to begin searching forward from * @return The position of the first boundary after "offset" */ int32_t DictionaryBasedBreakIterator::following(int32_t offset) { // if the offset passed in is already past the end of the text, // just return DONE; if it's before the beginning, return the // text's starting offset if (text == NULL || offset > text->endIndex()) { return BreakIterator::DONE; } else if (offset < text->startIndex()) { return text->startIndex(); } // if we have no cached break positions, or if "offset" is outside the // range covered by the cache, then dump the cache and call our // inherited following() method. This will call other methods in this // class that may refresh the cache. if (cachedBreakPositions == NULL || offset < cachedBreakPositions[0] || offset >= cachedBreakPositions[numCachedBreakPositions - 1]) { reset(); return RuleBasedBreakIterator::following(offset); } // on the other hand, if "offset" is within the range covered by the // cache, then just search the cache for the first break position // after "offset" else { positionInCache = 0; while (positionInCache < numCachedBreakPositions && offset >= cachedBreakPositions[positionInCache]) ++positionInCache; text->setIndex(cachedBreakPositions[positionInCache]); return text->getIndex(); } } /** * This is the implementation function for next(). */ int32_t DictionaryBasedBreakIterator::handleNext() { // if there are no cached break positions, or if we've just moved // off the end of the range covered by the cache, we have to dump // and possibly regenerate the cache if (cachedBreakPositions == NULL || positionInCache == numCachedBreakPositions - 1) { // start by using the inherited handleNext() to find a tentative return // value. dictionaryCharCount tells us how many dictionary characters // we passed over on our way to the tentative return value int32_t startPos = text->getIndex(); dictionaryCharCount = 0; int32_t result = RuleBasedBreakIterator::handleNext(); // if we passed over more than one dictionary character, then we use // divideUpDictionaryRange() to regenerate the cached break positions // for the new range if (dictionaryCharCount > 1 && result - startPos > 1) { divideUpDictionaryRange(startPos, result); } // otherwise, the value we got back from the inherited fuction // is our return value, and we can dump the cache else { reset(); return result; } } // if the cache of break positions has been regenerated (or existed all // along), then just advance to the next break position in the cache // and return it if (cachedBreakPositions != NULL) { ++positionInCache; text->setIndex(cachedBreakPositions[positionInCache]); return cachedBreakPositions[positionInCache]; } return -9999; // SHOULD NEVER GET HERE! } void DictionaryBasedBreakIterator::reset() { delete [] cachedBreakPositions; cachedBreakPositions = NULL; numCachedBreakPositions = 0; dictionaryCharCount = 0; positionInCache = 0; } // internal type for BufferClone struct bufferCloneStructUChar { uint8_t bi [sizeof(DictionaryBasedBreakIterator)] ; uint8_t text [sizeof(UCharCharacterIterator)] ; }; struct bufferCloneStructString { uint8_t bi [sizeof(DictionaryBasedBreakIterator)] ; uint8_t text [sizeof(StringCharacterIterator)] ; }; BreakIterator * DictionaryBasedBreakIterator::createBufferClone(void *stackBuffer, int32_t &BufferSize, UErrorCode &status) { DictionaryBasedBreakIterator * localIterator; int32_t bufferSizeNeeded; UBool IterIsUChar; UBool IterIsString; if (U_FAILURE(status)){ return 0; } if (!this){ status = U_ILLEGAL_ARGUMENT_ERROR; return 0; } if (text == NULL) { bufferSizeNeeded = (int32_t) sizeof(DictionaryBasedBreakIterator); IterIsString = IterIsUChar = FALSE; } else if (text->getDynamicClassID() == StringCharacterIterator::getStaticClassID()) { bufferSizeNeeded = (int32_t) sizeof(struct bufferCloneStructString); IterIsString = TRUE; IterIsUChar = FALSE; } else if (text->getDynamicClassID() == UCharCharacterIterator::getStaticClassID()) { bufferSizeNeeded = (int32_t) sizeof(struct bufferCloneStructUChar); IterIsString = FALSE; IterIsUChar = TRUE; } else { // code has changed - time to make a real CharacterIterator::CreateBufferClone() } if (BufferSize == 0){ /* 'preflighting' request - set needed size into *pBufferSize */ BufferSize = bufferSizeNeeded; return 0; } if (BufferSize < bufferSizeNeeded || !stackBuffer) { /* allocate one here...*/ localIterator = new DictionaryBasedBreakIterator(*this); status = U_SAFECLONE_ALLOCATED_ERROR; return localIterator; } if (IterIsUChar) { struct bufferCloneStructUChar * localClone = (struct bufferCloneStructUChar *)stackBuffer; localIterator = (DictionaryBasedBreakIterator *)&localClone->bi; uprv_memcpy(localIterator, this, sizeof(DictionaryBasedBreakIterator)); uprv_memcpy(&localClone->text, text, sizeof(UCharCharacterIterator)); localIterator->text = (CharacterIterator *) &localClone->text; } else if (IterIsString) { struct bufferCloneStructString * localClone = (struct bufferCloneStructString *)stackBuffer; localIterator = (DictionaryBasedBreakIterator *)&localClone->bi; uprv_memcpy(localIterator, this, sizeof(DictionaryBasedBreakIterator)); uprv_memcpy(&localClone->text, text, sizeof(StringCharacterIterator)); localIterator->text = (CharacterIterator *)&localClone->text; } else { DictionaryBasedBreakIterator * localClone = (DictionaryBasedBreakIterator *)stackBuffer; localIterator = localClone; uprv_memcpy(localIterator, this, sizeof(DictionaryBasedBreakIterator)); } // must not use (or delete) the copy of the old cache if it exists - not threadsafe localIterator->fBufferClone = TRUE; localIterator->cachedBreakPositions = NULL; localIterator->numCachedBreakPositions = 0; localIterator->positionInCache = 0; return localIterator; } /** * This is the function that actually implements the dictionary-based * algorithm. Given the endpoints of a range of text, it uses the * dictionary to determine the positions of any boundaries in this * range. It stores all the boundary positions it discovers in * cachedBreakPositions so that we only have to do this work once * for each time we enter the range. */ void DictionaryBasedBreakIterator::divideUpDictionaryRange(int32_t startPos, int32_t endPos) { // to avoid casts throughout the rest of this function DictionaryBasedBreakIteratorTables* dictionaryTables = (DictionaryBasedBreakIteratorTables*)(this->tables); // the range we're dividing may begin or end with non-dictionary characters // (i.e., for line breaking, we may have leading or trailing punctuation // that needs to be kept with the word). Seek from the beginning of the // range to the first dictionary character text->setIndex(startPos); UChar c = text->current(); int category = dictionaryTables->lookupCategory(c, this); while (category == IGNORE || !dictionaryTables->categoryFlags[category]) { c = text->next(); category = dictionaryTables->lookupCategory(c, this); } // initialize. We maintain two stacks: currentBreakPositions contains // the list of break positions that will be returned if we successfully // finish traversing the whole range now. possibleBreakPositions lists // all other possible word ends we've passed along the way. (Whenever // we reach an error [a sequence of characters that can't begin any word // in the dictionary], we back up, possibly delete some breaks from // currentBreakPositions, move a break from possibleBreakPositions // to currentBreakPositions, and start over from there. This process // continues in this way until we either successfully make it all the way // across the range, or exhaust all of our combinations of break // positions.) wrongBreakPositions is used to keep track of paths we've // tried on previous iterations. As the iterator backs up further and // further, this saves us from having to follow each possible path // through the text all the way to the error (hopefully avoiding many // future recursive calls as well). UStack currentBreakPositions; UStack possibleBreakPositions; UVector wrongBreakPositions; // the dictionary is implemented as a trie, which is treated as a state // machine. -1 represents the end of a legal word. Every word in the // dictionary is represented by a path from the root node to -1. A path // that ends in state 0 is an illegal combination of characters. int16_t state = 0; // these two variables are used for error handling. We keep track of the // farthest we've gotten through the range being divided, and the combination // of breaks that got us that far. If we use up all possible break // combinations, the text contains an error or a word that's not in the // dictionary. In this case, we "bless" the break positions that got us the // farthest as real break positions, and then start over from scratch with // the character where the error occurred. int32_t farthestEndPoint = text->getIndex(); UStack bestBreakPositions; UBool bestBreakPositionsInitialized = FALSE; // initialize (we always exit the loop with a break statement) c = text->current(); for (;;) { // if we can transition to state "-1" from our current state, we're // on the last character of a legal word. Push that position onto // the possible-break-positions stack if (dictionaryTables->dictionary.at(state, (int32_t)0) == -1) { possibleBreakPositions.push((void*)text->getIndex()); } // look up the new state to transition to in the dictionary state = dictionaryTables->dictionary.at(state, c); // if the character we're sitting on causes us to transition to // the "end of word" state, then it was a non-dictionary character // and we've successfully traversed the whole range. Drop out // of the loop. if (state == -1) { currentBreakPositions.push((void*)text->getIndex()); break; } // if the character we're sitting on causes us to transition to // the error state, or if we've gone off the end of the range // without transitioning to the "end of word" state, we've hit // an error... else if (state == 0 || text->getIndex() >= endPos) { // if this is the farthest we've gotten, take note of it in // case there's an error in the text if (text->getIndex() > farthestEndPoint) { farthestEndPoint = text->getIndex(); bestBreakPositions.removeAllElements(); bestBreakPositionsInitialized = TRUE; for (int32_t i = 0; i < currentBreakPositions.size(); i++) { bestBreakPositions.push(currentBreakPositions.elementAt(i)); } } // wrongBreakPositions is a list of all break positions we've tried starting // that didn't allow us to traverse all the way through the text. Every time // we pop a break position off of currentBreakPositions, we put it into // wrongBreakPositions to avoid trying it again later. If we make it to this // spot, we're either going to back up to a break in possibleBreakPositions // and try starting over from there, or we've exhausted all possible break // positions and are going to do the fallback procedure. This loop prevents // us from messing with anything in possibleBreakPositions that didn't work as // a starting point the last time we tried it (this is to prevent a bunch of // repetitive checks from slowing down some extreme cases) while (!possibleBreakPositions.isEmpty() && wrongBreakPositions.contains( possibleBreakPositions.peek())) { possibleBreakPositions.pop(); } // if we've used up all possible break-position combinations, there's // an error or an unknown word in the text. In this case, we start // over, treating the farthest character we've reached as the beginning // of the range, and "blessing" the break positions that got us that // far as real break positions if (possibleBreakPositions.isEmpty()) { if (bestBreakPositionsInitialized) { currentBreakPositions.removeAllElements(); for (int32_t i = 0; i < bestBreakPositions.size(); i++) { currentBreakPositions.push(bestBreakPositions.elementAt(i)); } bestBreakPositions.removeAllElements(); if (farthestEndPoint < endPos) { text->setIndex(farthestEndPoint + 1); } else { break; } } else { if ((currentBreakPositions.isEmpty() || (int32_t)(unsigned long)currentBreakPositions.peek() != text->getIndex()) && text->getIndex() != startPos) { currentBreakPositions.push((void*)text->getIndex()); } text->next(); currentBreakPositions.push((void*)text->getIndex()); } } // if we still have more break positions we can try, then promote the // last break in possibleBreakPositions into currentBreakPositions, // and get rid of all entries in currentBreakPositions that come after // it. Then back up to that position and start over from there (i.e., // treat that position as the beginning of a new word) else { int32_t temp = (int32_t)(unsigned long)possibleBreakPositions.pop(); void* temp2 = NULL; while (!currentBreakPositions.isEmpty() && temp < (int32_t)(unsigned long)currentBreakPositions.peek()) { temp2 = currentBreakPositions.pop(); wrongBreakPositions.addElement(temp2); } currentBreakPositions.push((void*)temp); text->setIndex((int32_t)(unsigned long)currentBreakPositions.peek()); } // re-sync "c" for the next go-round, and drop out of the loop if // we've made it off the end of the range c = text->current(); if (text->getIndex() >= endPos) { break; } } // if we didn't hit any exceptional conditions on this last iteration, // just advance to the next character and loop else { c = text->next(); } } // dump the last break position in the list, and replace it with the actual // end of the range (which may be the same character, or may be further on // because the range actually ended with non-dictionary characters we want to // keep with the word) if (!currentBreakPositions.isEmpty()) { currentBreakPositions.pop(); } currentBreakPositions.push((void*)endPos); // create a regular array to hold the break positions and copy // the break positions from the stack to the array (in addition, // our starting position goes into this array as a break position). // This array becomes the cache of break positions used by next() // and previous(), so this is where we actually refresh the cache. if (cachedBreakPositions != NULL) { delete []cachedBreakPositions; } cachedBreakPositions = new int32_t[currentBreakPositions.size() + 1]; numCachedBreakPositions = currentBreakPositions.size() + 1; cachedBreakPositions[0] = startPos; for (int32_t i = 0; i < currentBreakPositions.size(); i++) { cachedBreakPositions[i + 1] = (int32_t)(unsigned long)currentBreakPositions.elementAt(i); } positionInCache = 0; }