Victor Chang | 7322950 | 2020-09-17 13:39:19 +0100 | [diff] [blame] | 1 | // Copyright (C) 2016 and later: Unicode, Inc. and others. |
| 2 | // License & terms of use: http://www.unicode.org/copyright.html |
| 3 | |
| 4 | // file: rbbi_cache.h |
| 5 | // |
| 6 | #ifndef RBBI_CACHE_H |
| 7 | #define RBBI_CACHE_H |
| 8 | |
| 9 | #include "unicode/utypes.h" |
| 10 | |
| 11 | #if !UCONFIG_NO_BREAK_ITERATION |
| 12 | |
| 13 | #include "unicode/rbbi.h" |
| 14 | #include "unicode/uobject.h" |
| 15 | |
| 16 | #include "uvectr32.h" |
| 17 | |
| 18 | U_NAMESPACE_BEGIN |
| 19 | |
| 20 | /* DictionaryCache stores the boundaries obtained from a run of dictionary characters. |
| 21 | * Dictionary boundaries are moved first to this cache, then from here |
| 22 | * to the main BreakCache, where they may inter-leave with non-dictionary |
| 23 | * boundaries. The public BreakIterator API always fetches directly |
| 24 | * from the main BreakCache, not from here. |
| 25 | * |
| 26 | * In common situations, the number of boundaries in a single dictionary run |
| 27 | * should be quite small, it will be terminated by punctuation, spaces, |
| 28 | * or any other non-dictionary characters. The main BreakCache may end |
| 29 | * up with boundaries from multiple dictionary based runs. |
| 30 | * |
| 31 | * The boundaries are stored in a simple ArrayList (vector), with the |
| 32 | * assumption that they will be accessed sequentially. |
| 33 | */ |
| 34 | class RuleBasedBreakIterator::DictionaryCache: public UMemory { |
| 35 | public: |
| 36 | DictionaryCache(RuleBasedBreakIterator *bi, UErrorCode &status); |
| 37 | ~DictionaryCache(); |
| 38 | |
| 39 | void reset(); |
| 40 | |
| 41 | UBool following(int32_t fromPos, int32_t *pos, int32_t *statusIndex); |
| 42 | UBool preceding(int32_t fromPos, int32_t *pos, int32_t *statusIndex); |
| 43 | |
| 44 | /** |
| 45 | * Populate the cache with the dictionary based boundaries within a region of text. |
| 46 | * @param startPos The start position of a range of text |
| 47 | * @param endPos The end position of a range of text |
| 48 | * @param firstRuleStatus The rule status index that applies to the break at startPos |
| 49 | * @param otherRuleStatus The rule status index that applies to boundaries other than startPos |
| 50 | * @internal |
| 51 | */ |
| 52 | void populateDictionary(int32_t startPos, int32_t endPos, |
| 53 | int32_t firstRuleStatus, int32_t otherRuleStatus); |
| 54 | |
| 55 | |
| 56 | |
| 57 | RuleBasedBreakIterator *fBI; |
| 58 | |
| 59 | UVector32 fBreaks; // A vector containing the boundaries. |
| 60 | int32_t fPositionInCache; // Index in fBreaks of last boundary returned by following() |
| 61 | // or preceding(). Optimizes sequential access. |
| 62 | int32_t fStart; // Text position of first boundary in cache. |
| 63 | int32_t fLimit; // Last boundary in cache. Which is the limit of the |
| 64 | // text segment being handled by the dictionary. |
| 65 | int32_t fFirstRuleStatusIndex; // Rule status info for first boundary. |
| 66 | int32_t fOtherRuleStatusIndex; // Rule status info for 2nd through last boundaries. |
| 67 | }; |
| 68 | |
| 69 | |
| 70 | /* |
| 71 | * class BreakCache |
| 72 | * |
| 73 | * Cache of break boundary positions and rule status values. |
| 74 | * Break iterator API functions, next(), previous(), etc., will use cached results |
| 75 | * when possible, and otherwise cache new results as they are obtained. |
| 76 | * |
| 77 | * Uniformly caches both dictionary and rule based (non-dictionary) boundaries. |
| 78 | * |
| 79 | * The cache is implemented as a single circular buffer. |
| 80 | */ |
| 81 | |
| 82 | /* |
| 83 | * size of the circular cache buffer. |
| 84 | */ |
| 85 | |
| 86 | class RuleBasedBreakIterator::BreakCache: public UMemory { |
| 87 | public: |
| 88 | BreakCache(RuleBasedBreakIterator *bi, UErrorCode &status); |
| 89 | virtual ~BreakCache(); |
| 90 | void reset(int32_t pos = 0, int32_t ruleStatus = 0); |
| 91 | void next() { if (fBufIdx == fEndBufIdx) { |
| 92 | nextOL(); |
| 93 | } else { |
| 94 | fBufIdx = modChunkSize(fBufIdx + 1); |
| 95 | fTextIdx = fBI->fPosition = fBoundaries[fBufIdx]; |
| 96 | fBI->fRuleStatusIndex = fStatuses[fBufIdx]; |
| 97 | } |
| 98 | } |
| 99 | |
| 100 | |
| 101 | void nextOL(); |
| 102 | void previous(UErrorCode &status); |
| 103 | |
| 104 | // Move the iteration state to the position following the startPosition. |
| 105 | // Input position must be pinned to the input length. |
| 106 | void following(int32_t startPosition, UErrorCode &status); |
| 107 | |
| 108 | void preceding(int32_t startPosition, UErrorCode &status); |
| 109 | |
| 110 | /* |
| 111 | * Update the state of the public BreakIterator (fBI) to reflect the |
| 112 | * current state of the break iterator cache (this). |
| 113 | */ |
| 114 | int32_t current(); |
| 115 | |
| 116 | /** |
| 117 | * Add boundaries to the cache near the specified position. |
| 118 | * The given position need not be a boundary itself. |
| 119 | * The input position must be within the range of the text, and |
| 120 | * on a code point boundary. |
| 121 | * If the requested position is a break boundary, leave the iteration |
| 122 | * position on it. |
| 123 | * If the requested position is not a boundary, leave the iteration |
| 124 | * position on the preceding boundary and include both the |
| 125 | * preceding and following boundaries in the cache. |
| 126 | * Additional boundaries, either preceding or following, may be added |
| 127 | * to the cache as a side effect. |
| 128 | * |
Victor Chang | ce4bf3c | 2021-01-19 16:34:24 +0000 | [diff] [blame] | 129 | * Return false if the operation failed. |
Victor Chang | 7322950 | 2020-09-17 13:39:19 +0100 | [diff] [blame] | 130 | */ |
| 131 | UBool populateNear(int32_t position, UErrorCode &status); |
| 132 | |
| 133 | /** |
| 134 | * Add boundary(s) to the cache following the current last boundary. |
Victor Chang | ce4bf3c | 2021-01-19 16:34:24 +0000 | [diff] [blame] | 135 | * Return false if at the end of the text, and no more boundaries can be added. |
Victor Chang | 7322950 | 2020-09-17 13:39:19 +0100 | [diff] [blame] | 136 | * Leave iteration position at the first newly added boundary, or unchanged if no boundary was added. |
| 137 | */ |
| 138 | UBool populateFollowing(); |
| 139 | |
| 140 | /** |
| 141 | * Add one or more boundaries to the cache preceding the first currently cached boundary. |
| 142 | * Leave the iteration position on the first added boundary. |
| 143 | * Return false if no boundaries could be added (if at the start of the text.) |
| 144 | */ |
| 145 | UBool populatePreceding(UErrorCode &status); |
| 146 | |
| 147 | enum UpdatePositionValues { |
| 148 | RetainCachePosition = 0, |
| 149 | UpdateCachePosition = 1 |
| 150 | }; |
| 151 | |
| 152 | /* |
| 153 | * Add the boundary following the current position. |
| 154 | * The current position can be left as it was, or changed to the newly added boundary, |
| 155 | * as specified by the update parameter. |
| 156 | */ |
| 157 | void addFollowing(int32_t position, int32_t ruleStatusIdx, UpdatePositionValues update); |
| 158 | |
| 159 | |
| 160 | /* |
| 161 | * Add the boundary preceding the current position. |
| 162 | * The current position can be left as it was, or changed to the newly added boundary, |
| 163 | * as specified by the update parameter. |
| 164 | */ |
| 165 | bool addPreceding(int32_t position, int32_t ruleStatusIdx, UpdatePositionValues update); |
| 166 | |
| 167 | /** |
| 168 | * Set the cache position to the specified position, or, if the position |
| 169 | * falls between to cached boundaries, to the preceding boundary. |
| 170 | * Fails if the requested position is outside of the range of boundaries currently held by the cache. |
| 171 | * The startPosition must be on a code point boundary. |
| 172 | * |
Victor Chang | ce4bf3c | 2021-01-19 16:34:24 +0000 | [diff] [blame] | 173 | * Return true if successful, false if the specified position is after |
Victor Chang | 7322950 | 2020-09-17 13:39:19 +0100 | [diff] [blame] | 174 | * the last cached boundary or before the first. |
| 175 | */ |
| 176 | UBool seek(int32_t startPosition); |
| 177 | |
| 178 | void dumpCache(); |
| 179 | |
| 180 | private: |
| 181 | static inline int32_t modChunkSize(int index) { return index & (CACHE_SIZE - 1); } |
| 182 | |
| 183 | static constexpr int32_t CACHE_SIZE = 128; |
| 184 | static_assert((CACHE_SIZE & (CACHE_SIZE-1)) == 0, "CACHE_SIZE must be power of two."); |
| 185 | |
| 186 | RuleBasedBreakIterator *fBI; |
| 187 | int32_t fStartBufIdx; |
| 188 | int32_t fEndBufIdx; // inclusive |
| 189 | |
| 190 | int32_t fTextIdx; |
| 191 | int32_t fBufIdx; |
| 192 | |
| 193 | int32_t fBoundaries[CACHE_SIZE]; |
| 194 | uint16_t fStatuses[CACHE_SIZE]; |
| 195 | |
| 196 | UVector32 fSideBuffer; |
| 197 | }; |
| 198 | |
| 199 | U_NAMESPACE_END |
| 200 | |
| 201 | #endif // #if !UCONFIG_NO_BREAK_ITERATION |
| 202 | |
| 203 | #endif // RBBI_CACHE_H |