scuffed-code/icu4c/source/common/dbbi.cpp

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/*
**********************************************************************
* 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"
U_NAMESPACE_BEGIN
const char DictionaryBasedBreakIterator::fgClassID = 0;
//=======================================================================
// constructors
//=======================================================================
DictionaryBasedBreakIterator::DictionaryBasedBreakIterator(UDataMemory* tablesImage,
const 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()
{
UErrorCode status = U_ZERO_ERROR;
// 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, status);
if (U_FAILURE(status)) {
return -9999; // SHOULD NEVER GET HERE!
}
}
// 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 = 0;
UBool IterIsUChar = FALSE;
UBool IterIsString = FALSE;
char *stackBufferChars = (char *)stackBuffer;
if (U_FAILURE(status)){
return 0;
}
/* Pointers on 64-bit platforms need to be aligned
* on a 64-bit boundry in memory.
*/
if (U_ALIGNMENT_OFFSET(stackBuffer) != 0) {
int32_t offsetUp = (int32_t)U_ALIGNMENT_OFFSET_UP(stackBufferChars);
BufferSize -= offsetUp;
stackBufferChars += offsetUp;
}
stackBuffer = (void *)stackBufferChars;
if (text == NULL)
{
bufferSizeNeeded = (int32_t) sizeof(DictionaryBasedBreakIterator);
}
else if (text->getDynamicClassID() == StringCharacterIterator::getStaticClassID())
{
bufferSizeNeeded = (int32_t) sizeof(struct bufferCloneStructString);
IterIsString = TRUE;
}
else if (text->getDynamicClassID() == UCharCharacterIterator::getStaticClassID())
{
bufferSizeNeeded = (int32_t) sizeof(struct bufferCloneStructUChar);
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, UErrorCode &status)
{
// 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(status);
UStack possibleBreakPositions(status);
UVector wrongBreakPositions(status);
// 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(status);
UBool bestBreakPositionsInitialized = FALSE;
if (U_FAILURE(status)) {
return;
}
// 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(), status);
}
// 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(), status);
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), status);
}
}
// 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), status);
}
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(), status);
}
text->next();
currentBreakPositions.push((void*)text->getIndex(), status);
}
}
// 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, status);
}
currentBreakPositions.push((void*)temp, status);
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, status);
// 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;
}
U_NAMESPACE_END
/* eof */