/**
*******************************************************************************
* Copyright (C) 2006, International Business Machines Corporation and others. *
* All Rights Reserved. *
*******************************************************************************
*/
#include "unicode/utypes.h"
#if !UCONFIG_NO_BREAK_ITERATION
#include "brkeng.h"
#include "dictbe.h"
#include "unicode/uniset.h"
#include "unicode/chariter.h"
#include "unicode/ubrk.h"
#include "uvector.h"
#include "triedict.h"
U_NAMESPACE_BEGIN
/*
******************************************************************
*/
/*DictionaryBreakEngine::DictionaryBreakEngine() {
fTypes = 0;
}*/
DictionaryBreakEngine::DictionaryBreakEngine(uint32_t breakTypes) {
fTypes = breakTypes;
}
DictionaryBreakEngine::~DictionaryBreakEngine() {
}
UBool
DictionaryBreakEngine::handles(UChar32 c, int32_t breakType) const {
return (breakType >= 0 && breakType < 32 && (((uint32_t)1 << breakType) & fTypes)
&& fSet.contains(c));
}
int32_t
DictionaryBreakEngine::findBreaks( UText *text,
int32_t startPos,
int32_t endPos,
UBool reverse,
int32_t breakType,
UStack &foundBreaks ) const {
int32_t result = 0;
// Find the span of characters included in the set.
int32_t start = (int32_t)utext_getNativeIndex(text);
int32_t current;
int32_t rangeStart;
int32_t rangeEnd;
UChar32 c = utext_current32(text);
if (reverse) {
UBool isDict = fSet.contains(c);
while((current = (int32_t)utext_getNativeIndex(text)) > startPos && isDict) {
c = utext_previous32(text);
isDict = fSet.contains(c);
}
rangeStart = (current < startPos) ? startPos : current+(isDict ? 0 : 1);
rangeEnd = start + 1;
}
else {
while((current = (int32_t)utext_getNativeIndex(text)) < endPos && fSet.contains(c)) {
utext_next32(text); // TODO: recast loop for postincrement
c = utext_current32(text);
}
rangeStart = start;
rangeEnd = current;
}
if (breakType >= 0 && breakType < 32 && (((uint32_t)1 << breakType) & fTypes)) {
result = divideUpDictionaryRange(text, rangeStart, rangeEnd, foundBreaks);
utext_setNativeIndex(text, current);
}
return result;
}
void
DictionaryBreakEngine::setCharacters( const UnicodeSet &set ) {
fSet = set;
// Compact for caching
fSet.compact();
}
/*void
DictionaryBreakEngine::setBreakTypes( uint32_t breakTypes ) {
fTypes = breakTypes;
}*/
/*
******************************************************************
*/
// Helper class for improving readability of the Thai word break
// algorithm. The implementation is completely inline.
// List size, limited by the maximum number of words in the dictionary
// that form a nested sequence.
#define POSSIBLE_WORD_LIST_MAX 20
class PossibleWord {
private:
// list of word candidate lengths, in increasing length order
int32_t lengths[POSSIBLE_WORD_LIST_MAX];
int count; // Count of candidates
int32_t prefix; // The longest match with a dictionary word
int32_t offset; // Offset in the text of these candidates
int mark; // The preferred candidate's offset
int current; // The candidate we're currently looking at
public:
PossibleWord();
~PossibleWord();
// Fill the list of candidates if needed, select the longest, and return the number found
int candidates( UText *text, const TrieWordDictionary *dict, int32_t rangeEnd );
// Select the currently marked candidate, point after it in the text, and invalidate self
int32_t acceptMarked( UText *text );
// Back up from the current candidate to the next shorter one; return TRUE if that exists
// and point the text after it
UBool backUp( UText *text );
// Return the longest prefix this candidate location shares with a dictionary word
int32_t longestPrefix();
// Mark the current candidate as the one we like
void markCurrent();
};
inline
PossibleWord::PossibleWord() {
offset = -1;
}
inline
PossibleWord::~PossibleWord() {
}
inline int
PossibleWord::candidates( UText *text, const TrieWordDictionary *dict, int32_t rangeEnd ) {
// TODO: If getIndex is too slow, use offset < 0 and add discardAll()
int32_t start = (int32_t)utext_getNativeIndex(text);
if (start != offset) {
offset = start;
prefix = dict->matches(text, rangeEnd-start, lengths, count, sizeof(lengths)/sizeof(lengths[0]));
// Dictionary leaves text after longest prefix, not longest word. Back up.
if (count <= 0) {
utext_setNativeIndex(text, start);
}
}
if (count > 0) {
utext_setNativeIndex(text, start+lengths[count-1]);
}
current = count-1;
mark = current;
return count;
}
inline int32_t
PossibleWord::acceptMarked( UText *text ) {
utext_setNativeIndex(text, offset + lengths[mark]);
return lengths[mark];
}
inline UBool
PossibleWord::backUp( UText *text ) {
if (current > 0) {
utext_setNativeIndex(text, offset + lengths[--current]);
return TRUE;
}
return FALSE;
}
inline int32_t
PossibleWord::longestPrefix() {
return prefix;
}
inline void
PossibleWord::markCurrent() {
mark = current;
}
// How many words in a row are "good enough"?
#define THAI_LOOKAHEAD 3
// Will not combine a non-word with a preceding dictionary word longer than this
#define THAI_ROOT_COMBINE_THRESHOLD 3
// Will not combine a non-word that shares at least this much prefix with a
// dictionary word, with a preceding word
#define THAI_PREFIX_COMBINE_THRESHOLD 3
// Ellision character
#define THAI_PAIYANNOI 0x0E2F
// Repeat character
#define THAI_MAIYAMOK 0x0E46
// Minimum word size
#define THAI_MIN_WORD 2
// Minimum number of characters for two words
#define THAI_MIN_WORD_SPAN (THAI_MIN_WORD * 2)
ThaiBreakEngine::ThaiBreakEngine(const TrieWordDictionary *adoptDictionary, UErrorCode &status)
: DictionaryBreakEngine((1<<UBRK_WORD) | (1<<UBRK_LINE)),
fDictionary(adoptDictionary)
{
fThaiWordSet.applyPattern(UNICODE_STRING_SIMPLE("[[:Thai:]&[:LineBreak=SA:]]"), status);
if (U_SUCCESS(status)) {
setCharacters(fThaiWordSet);
}
fMarkSet.applyPattern(UNICODE_STRING_SIMPLE("[[:Thai:]&[:LineBreak=SA:]&[:M:]]"), status);
fEndWordSet = fThaiWordSet;
fEndWordSet.remove(0x0E31); // MAI HAN-AKAT
fEndWordSet.remove(0x0E40, 0x0E44); // SARA E through SARA AI MAIMALAI
fBeginWordSet.add(0x0E01, 0x0E2E); // KO KAI through HO NOKHUK
fBeginWordSet.add(0x0E40, 0x0E44); // SARA E through SARA AI MAIMALAI
fSuffixSet.add(THAI_PAIYANNOI);
fSuffixSet.add(THAI_MAIYAMOK);
// Compact for caching.
fMarkSet.compact();
fEndWordSet.compact();
fBeginWordSet.compact();
fSuffixSet.compact();
}
ThaiBreakEngine::~ThaiBreakEngine() {
delete fDictionary;
}
int32_t
ThaiBreakEngine::divideUpDictionaryRange( UText *text,
int32_t rangeStart,
int32_t rangeEnd,
UStack &foundBreaks ) const {
if ((rangeEnd - rangeStart) < THAI_MIN_WORD_SPAN) {
return 0; // Not enough characters for two words
}
uint32_t wordsFound = 0;
int32_t wordLength;
int32_t current;
UErrorCode status = U_ZERO_ERROR;
PossibleWord words[THAI_LOOKAHEAD];
UChar32 uc;
utext_setNativeIndex(text, rangeStart);
while (U_SUCCESS(status) && (current = (int32_t)utext_getNativeIndex(text)) < rangeEnd) {
wordLength = 0;
// Look for candidate words at the current position
int candidates = words[wordsFound%THAI_LOOKAHEAD].candidates(text, fDictionary, rangeEnd);
// If we found exactly one, use that
if (candidates == 1) {
wordLength = words[wordsFound%THAI_LOOKAHEAD].acceptMarked(text);
wordsFound += 1;
}
// If there was more than one, see which one can take us forward the most words
else if (candidates > 1) {
// If we're already at the end of the range, we're done
if ((int32_t)utext_getNativeIndex(text) >= rangeEnd) {
goto foundBest;
}
do {
int wordsMatched = 1;
if (words[(wordsFound+1)%THAI_LOOKAHEAD].candidates(text, fDictionary, rangeEnd) > 0) {
if (wordsMatched < 2) {
// Followed by another dictionary word; mark first word as a good candidate
words[wordsFound%THAI_LOOKAHEAD].markCurrent();
wordsMatched = 2;
}
// If we're already at the end of the range, we're done
if ((int32_t)utext_getNativeIndex(text) >= rangeEnd) {
goto foundBest;
}
// See if any of the possible second words is followed by a third word
do {
// If we find a third word, stop right away
if (words[(wordsFound+2)%THAI_LOOKAHEAD].candidates(text, fDictionary, rangeEnd)) {
words[wordsFound%THAI_LOOKAHEAD].markCurrent();
goto foundBest;
}
}
while (words[(wordsFound+1)%THAI_LOOKAHEAD].backUp(text));
}
}
while (words[wordsFound%THAI_LOOKAHEAD].backUp(text));
foundBest:
wordLength = words[wordsFound%THAI_LOOKAHEAD].acceptMarked(text);
wordsFound += 1;
}
// We come here after having either found a word or not. We look ahead to the
// next word. If it's not a dictionary word, we will combine it withe the word we
// just found (if there is one), but only if the preceding word does not exceed
// the threshold.
// The text iterator should now be positioned at the end of the word we found.
if ((int32_t)utext_getNativeIndex(text) < rangeEnd && wordLength < THAI_ROOT_COMBINE_THRESHOLD) {
// if it is a dictionary word, do nothing. If it isn't, then if there is
// no preceding word, or the non-word shares less than the minimum threshold
// of characters with a dictionary word, then scan to resynchronize
if (words[wordsFound%THAI_LOOKAHEAD].candidates(text, fDictionary, rangeEnd) <= 0
&& (wordLength == 0
|| words[wordsFound%THAI_LOOKAHEAD].longestPrefix() < THAI_PREFIX_COMBINE_THRESHOLD)) {
// Look for a plausible word boundary
//TODO: This section will need a rework for UText.
int32_t remaining = rangeEnd - (current+wordLength);
UChar32 pc = utext_current32(text);
int32_t chars = 0;
for (;;) {
utext_next32(text);
uc = utext_current32(text);
// TODO: Here we're counting on the fact that the SA languages are all
// in the BMP. This should get fixed with the UText rework.
chars += 1;
if (--remaining <= 0) {
break;
}
if (fEndWordSet.contains(pc) && fBeginWordSet.contains(uc)) {
// Maybe. See if it's in the dictionary.
// NOTE: In the original Apple code, checked that the next
// two characters after uc were not 0x0E4C THANTHAKHAT before
// checking the dictionary. That is just a performance filter,
// but it's not clear it's faster than checking the trie.
int candidates = words[(wordsFound+1)%THAI_LOOKAHEAD].candidates(text, fDictionary, rangeEnd);
utext_setNativeIndex(text, current+wordLength+chars);
if (candidates > 0) {
break;
}
}
pc = uc;
}
// Bump the word count if there wasn't already one
if (wordLength <= 0) {
wordsFound += 1;
}
// Update the length with the passed-over characters
wordLength += chars;
}
else {
// Back up to where we were for next iteration
utext_setNativeIndex(text, current+wordLength);
}
}
// Never stop before a combining mark.
int32_t currPos;
while ((currPos = (int32_t)utext_getNativeIndex(text)) < rangeEnd && fMarkSet.contains(utext_current32(text))) {
utext_next32(text);
wordLength += (int32_t)utext_getNativeIndex(text) - currPos;
}
// Look ahead for possible suffixes if a dictionary word does not follow.
// We do this in code rather than using a rule so that the heuristic
// resynch continues to function. For example, one of the suffix characters
// could be a typo in the middle of a word.
if ((int32_t)utext_getNativeIndex(text) < rangeEnd && wordLength > 0) {
if (words[wordsFound%THAI_LOOKAHEAD].candidates(text, fDictionary, rangeEnd) <= 0
&& fSuffixSet.contains(uc = utext_current32(text))) {
if (uc == THAI_PAIYANNOI) {
if (!fSuffixSet.contains(utext_previous32(text))) {
// Skip over previous end and PAIYANNOI
utext_next32(text);
utext_next32(text);
wordLength += 1; // Add PAIYANNOI to word
uc = utext_current32(text); // Fetch next character
}
else {
// Restore prior position
utext_next32(text);
}
}
if (uc == THAI_MAIYAMOK) {
if (utext_previous32(text) != THAI_MAIYAMOK) {
// Skip over previous end and MAIYAMOK
utext_next32(text);
utext_next32(text);
wordLength += 1; // Add MAIYAMOK to word
}
else {
// Restore prior position
utext_next32(text);
}
}
}
else {
utext_setNativeIndex(text, current+wordLength);
}
}
// Did we find a word on this iteration? If so, push it on the break stack
if (wordLength > 0) {
foundBreaks.push((current+wordLength), status);
}
}
// Don't return a break for the end of the dictionary range if there is one there.
if (foundBreaks.peeki() >= rangeEnd) {
(void) foundBreaks.popi();
wordsFound -= 1;
}
return wordsFound;
}
U_NAMESPACE_END
#endif /* #if !UCONFIG_NO_BREAK_ITERATION */