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// Copyright (C) 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
// file: rbbi_cache.h
//
#ifndef RBBI_CACHE_H
#define RBBI_CACHE_H
#include "unicode/utypes.h"
#if !UCONFIG_NO_BREAK_ITERATION
#include "unicode/rbbi.h"
#include "unicode/uobject.h"
#include "uvectr32.h"
U_NAMESPACE_BEGIN
/* DictionaryCache stores the boundaries obtained from a run of dictionary characters.
* Dictionary boundaries are moved first to this cache, then from here
* to the main BreakCache, where they may inter-leave with non-dictionary
* boundaries. The public BreakIterator API always fetches directly
* from the main BreakCache, not from here.
*
* In common situations, the number of boundaries in a single dictionary run
* should be quite small, it will be terminated by punctuation, spaces,
* or any other non-dictionary characters. The main BreakCache may end
* up with boundaries from multiple dictionary based runs.
*
* The boundaries are stored in a simple ArrayList (vector), with the
* assumption that they will be accessed sequentially.
*/
class RuleBasedBreakIterator::DictionaryCache: public UMemory {
public:
DictionaryCache(RuleBasedBreakIterator *bi, UErrorCode &status);
~DictionaryCache();
void reset();
UBool following(int32_t fromPos, int32_t *pos, int32_t *statusIndex);
UBool preceding(int32_t fromPos, int32_t *pos, int32_t *statusIndex);
/**
* Populate the cache with the dictionary based boundaries within a region of text.
* @param startPos The start position of a range of text
* @param endPos The end position of a range of text
* @param firstRuleStatus The rule status index that applies to the break at startPos
* @param otherRuleStatus The rule status index that applies to boundaries other than startPos
* @internal
*/
void populateDictionary(int32_t startPos, int32_t endPos,
int32_t firstRuleStatus, int32_t otherRuleStatus);
RuleBasedBreakIterator *fBI;
UVector32 *fBreaks; // A vector containing the boundaries.
int32_t fPositionInCache; // Index in fBreaks of last boundary returned by following()
// or preceding(). Optimizes sequential access.
int32_t fStart; // Text position of first boundary in cache.
int32_t fLimit; // Last boundary in cache. Which is the limit of the
// text segment being handled by the dictionary.
int32_t fFirstRuleStatusIndex; // Rule status info for first boundary.
int32_t fOtherRuleStatusIndex; // Rule status info for 2nd through last boundaries.
};
/*
* class BreakCache
*
* Cache of break boundary positions and rule status values.
* Break iterator API functions, next(), previous(), etc., will use cached results
* when possible, and otherwise cache new results as they are obtained.
*
* Uniformly caches both dictionary and rule based (non-dictionary) boundaries.
*
* The cache is implemented as a single circular buffer.
*/
/*
* size of the circular cache buffer.
*/
class RuleBasedBreakIterator::BreakCache: public UMemory {
public:
BreakCache(RuleBasedBreakIterator *bi, UErrorCode &status);
virtual ~BreakCache();
void reset(int32_t pos = 0, int32_t ruleStatus = 0);
void next() { if (fBufIdx == fEndBufIdx) {
nextOL();
} else {
fBufIdx = modChunkSize(fBufIdx + 1);
fTextIdx = fBI->fPosition = fBoundaries[fBufIdx];
fBI->fRuleStatusIndex = fStatuses[fBufIdx];
}
};
void nextOL();
void previous(UErrorCode &status);
// Move the iteration state to the position following the startPosition.
// Input position must be pinned to the input length.
void following(int32_t startPosition, UErrorCode &status);
void preceding(int32_t startPosition, UErrorCode &status);
/*
* Update the state of the public BreakIterator (fBI) to reflect the
* current state of the break iterator cache (this).
*/
int32_t current();
/**
* Add boundaries to the cache near the specified position.
* The given position need not be a boundary itself.
* The input position must be within the range of the text, and
* on a code point boundary.
* If the requested position is a break boundary, leave the iteration
* position on it.
* If the requested position is not a boundary, leave the iteration
* position on the preceding boundary and include both the
* preceding and following boundaries in the cache.
* Additional boundaries, either preceding or following, may be added
* to the cache as a side effect.
*
* Return FALSE if the operation failed.
*/
UBool populateNear(int32_t position, UErrorCode &status);
/**
* Add boundary(s) to the cache following the current last boundary.
* Return FALSE if at the end of the text, and no more boundaries can be added.
* Leave iteration position at the first newly added boundary, or unchanged if no boundary was added.
*/
UBool populateFollowing();
/**
* Add one or more boundaries to the cache preceding the first currently cached boundary.
* Leave the iteration position on the first added boundary.
* Return false if no boundaries could be added (if at the start of the text.)
*/
UBool populatePreceding(UErrorCode &status);
enum UpdatePositionValues {
RetainCachePosition = 0,
UpdateCachePosition = 1
};
/*
* Add the boundary following the current position.
* The current position can be left as it was, or changed to the newly added boundary,
* as specified by the update parameter.
*/
void addFollowing(int32_t position, int32_t ruleStatusIdx, UpdatePositionValues update);
/*
* Add the boundary preceding the current position.
* The current position can be left as it was, or changed to the newly added boundary,
* as specified by the update parameter.
*/
bool addPreceding(int32_t position, int32_t ruleStatusIdx, UpdatePositionValues update);
/**
* Set the cache position to the specified position, or, if the position
* falls between to cached boundaries, to the preceding boundary.
* Fails if the requested position is outside of the range of boundaries currently held by the cache.
* The startPosition must be on a code point boundary.
*
* Return TRUE if successful, FALSE if the specified position is after
* the last cached boundary or before the first.
*/
UBool seek(int32_t startPosition);
void dumpCache();
private:
static inline int32_t modChunkSize(int index) { return index & (CACHE_SIZE - 1); };
static constexpr int32_t CACHE_SIZE = 128;
static_assert((CACHE_SIZE & (CACHE_SIZE-1)) == 0, "CACHE_SIZE must be power of two.");
RuleBasedBreakIterator *fBI;
int32_t fStartBufIdx;
int32_t fEndBufIdx; // inclusive
int32_t fTextIdx;
int32_t fBufIdx;
int32_t fBoundaries[CACHE_SIZE];
uint16_t fStatuses[CACHE_SIZE];
UVector32 fSideBuffer;
};
U_NAMESPACE_END
#endif // #if !UCONFIG_NO_BREAK_ITERATION
#endif // RBBI_CACHE_H
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