ICU 77.1: common/unicode/bytestrie.h Source File

ICU 77.1 77.1

bytestrie.h
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1 // © 2016 and later: Unicode, Inc. and others.
2 // License & terms of use: http://www.unicode.org/copyright.html
3 /*
4 *******************************************************************************
5 * Copyright (C) 2010-2012, International Business Machines
6 * Corporation and others. All Rights Reserved.
7 *******************************************************************************
8 * file name: bytestrie.h
9 * encoding: UTF-8
10 * tab size: 8 (not used)
11 * indentation:4
12 *
13 * created on: 2010sep25
14 * created by: Markus W. Scherer
15 */
16
17 #ifndef __BYTESTRIE_H__
18 #define __BYTESTRIE_H__
19
25 #include "unicode/utypes.h"
26
27 #if U_SHOW_CPLUSPLUS_API
28
29 #include "unicode/stringpiece.h"
30 #include "unicode/uobject.h"
31 #include "unicode/ustringtrie.h"
32
33 class BytesTrieTest;
34
35 U_NAMESPACE_BEGIN
36
37 class ByteSink;
38 class BytesTrieBuilder;
39 class CharString;
40 class UVector32;
41
55 class U_COMMON_API BytesTrie : public UMemory {
56 public:
71 BytesTrie(const void *trieBytes)
72 : ownedArray_(nullptr), bytes_(static_cast<const uint8_t *>(trieBytes)),
73 pos_(bytes_), remainingMatchLength_(-1) {}
74
79 ~BytesTrie();
80
87 BytesTrie(const BytesTrie &other)
88 : ownedArray_(nullptr), bytes_(other.bytes_),
89 pos_(other.pos_), remainingMatchLength_(other.remainingMatchLength_) {}
90
96 BytesTrie &reset() {
97 pos_=bytes_;
98 remainingMatchLength_=-1;
99 return *this;
100 }
101
110 uint64_t getState64() const {
111 return (static_cast<uint64_t>(remainingMatchLength_ + 2) << kState64RemainingShift) |
112 static_cast<uint64_t>(pos_ - bytes_);
113 }
114
129 BytesTrie &resetToState64(uint64_t state) {
130 remainingMatchLength_ = static_cast<int32_t>(state >> kState64RemainingShift) - 2;
131 pos_ = bytes_ + (state & kState64PosMask);
132 return *this;
133 }
134
140 class State : public UMemory {
141 public:
146 State() { bytes=nullptr; }
147 private:
148 friend class BytesTrie;
149
150 const uint8_t *bytes;
151 const uint8_t *pos;
152 int32_t remainingMatchLength;
153 };
154
162 const BytesTrie &saveState(State &state) const {
163 state.bytes=bytes_;
164 state.pos=pos_;
165 state.remainingMatchLength=remainingMatchLength_;
166 return *this;
167 }
168
179 BytesTrie &resetToState(const State &state) {
180 if(bytes_==state.bytes && bytes_!=nullptr) {
181 pos_=state.pos;
182 remainingMatchLength_=state.remainingMatchLength;
183 }
184 return *this;
185 }
186
193 UStringTrieResult current() const;
194
203 inline UStringTrieResult first(int32_t inByte) {
204 remainingMatchLength_=-1;
205 if(inByte<0) {
206 inByte+=0x100;
207 }
208 return nextImpl(bytes_, inByte);
209 }
210
218 UStringTrieResult next(int32_t inByte);
219
235 UStringTrieResult next(const char *s, int32_t length);
236
246 inline int32_t getValue() const {
247 const uint8_t *pos=pos_;
248 int32_t leadByte=*pos++;
249 // U_ASSERT(leadByte>=kMinValueLead);
250 return readValue(pos, leadByte>>1);
251 }
252
262 inline UBool hasUniqueValue(int32_t &uniqueValue) const {
263 const uint8_t *pos=pos_;
264 // Skip the rest of a pending linear-match node.
265 return pos!=nullptr && findUniqueValue(pos+remainingMatchLength_+1, false, uniqueValue);
266 }
267
276 int32_t getNextBytes(ByteSink &out) const;
277
282 class U_COMMON_API Iterator : public UMemory {
283 public:
295 Iterator(const void *trieBytes, int32_t maxStringLength, UErrorCode &errorCode);
296
308 Iterator(const BytesTrie &trie, int32_t maxStringLength, UErrorCode &errorCode);
309
314 ~Iterator();
315
321 Iterator &reset();
322
327 UBool hasNext() const;
328
343 UBool next(UErrorCode &errorCode);
344
349 StringPiece getString() const;
354 int32_t getValue() const { return value_; }
355
356 private:
357 UBool truncateAndStop();
358
359 const uint8_t *branchNext(const uint8_t *pos, int32_t length, UErrorCode &errorCode);
360
361 const uint8_t *bytes_;
362 const uint8_t *pos_;
363 const uint8_t *initialPos_;
364 int32_t remainingMatchLength_;
365 int32_t initialRemainingMatchLength_;
366
367 CharString *str_;
368 int32_t maxLength_;
369 int32_t value_;
370
371 // The stack stores pairs of integers for backtracking to another
372 // outbound edge of a branch node.
373 // The first integer is an offset from bytes_.
374 // The second integer has the str_->length() from before the node in bits 15..0,
375 // and the remaining branch length in bits 24..16. (Bits 31..25 are unused.)
376 // (We could store the remaining branch length minus 1 in bits 23..16 and not use bits 31..24,
377 // but the code looks more confusing that way.)
378 UVector32 *stack_;
379 };
380
381 private:
382 friend class BytesTrieBuilder;
383 friend class ::BytesTrieTest;
384
391 BytesTrie(void *adoptBytes, const void *trieBytes)
392 : ownedArray_(static_cast<uint8_t *>(adoptBytes)),
393 bytes_(static_cast<const uint8_t *>(trieBytes)),
394 pos_(bytes_), remainingMatchLength_(-1) {}
395
396 // No assignment operator.
397 BytesTrie &operator=(const BytesTrie &other) = delete;
398
399 inline void stop() {
400 pos_=nullptr;
401 }
402
403 // Reads a compact 32-bit integer.
404 // pos is already after the leadByte, and the lead byte is already shifted right by 1.
405 static int32_t readValue(const uint8_t *pos, int32_t leadByte);
406 static inline const uint8_t *skipValue(const uint8_t *pos, int32_t leadByte) {
407 // U_ASSERT(leadByte>=kMinValueLead);
408 if(leadByte>=(kMinTwoByteValueLead<<1)) {
409 if(leadByte<(kMinThreeByteValueLead<<1)) {
410 ++pos;
411 } else if(leadByte<(kFourByteValueLead<<1)) {
412 pos+=2;
413 } else {
414 pos+=3+((leadByte>>1)&1);
415 }
416 }
417 return pos;
418 }
419 static inline const uint8_t *skipValue(const uint8_t *pos) {
420 int32_t leadByte=*pos++;
421 return skipValue(pos, leadByte);
422 }
423
424 // Reads a jump delta and jumps.
425 static const uint8_t *jumpByDelta(const uint8_t *pos);
426
427 static inline const uint8_t *skipDelta(const uint8_t *pos) {
428 int32_t delta=*pos++;
429 if(delta>=kMinTwoByteDeltaLead) {
430 if(delta<kMinThreeByteDeltaLead) {
431 ++pos;
432 } else if(delta<kFourByteDeltaLead) {
433 pos+=2;
434 } else {
435 pos+=3+(delta&1);
436 }
437 }
438 return pos;
439 }
440
441 static inline UStringTrieResult valueResult(int32_t node) {
442 return static_cast<UStringTrieResult>(USTRINGTRIE_INTERMEDIATE_VALUE - (node & kValueIsFinal));
443 }
444
445 // Handles a branch node for both next(byte) and next(string).
446 UStringTrieResult branchNext(const uint8_t *pos, int32_t length, int32_t inByte);
447
448 // Requires remainingLength_<0.
449 UStringTrieResult nextImpl(const uint8_t *pos, int32_t inByte);
450
451 // Helper functions for hasUniqueValue().
452 // Recursively finds a unique value (or whether there is not a unique one)
453 // from a branch.
454 static const uint8_t *findUniqueValueFromBranch(const uint8_t *pos, int32_t length,
455 UBool haveUniqueValue, int32_t &uniqueValue);
456 // Recursively finds a unique value (or whether there is not a unique one)
457 // starting from a position on a node lead byte.
458 static UBool findUniqueValue(const uint8_t *pos, UBool haveUniqueValue, int32_t &uniqueValue);
459
460 // Helper functions for getNextBytes().
461 // getNextBytes() when pos is on a branch node.
462 static void getNextBranchBytes(const uint8_t *pos, int32_t length, ByteSink &out);
463 static void append(ByteSink &out, int c);
464
465 // BytesTrie data structure
466 //
467 // The trie consists of a series of byte-serialized nodes for incremental
468 // string/byte sequence matching. The root node is at the beginning of the trie data.
469 //
470 // Types of nodes are distinguished by their node lead byte ranges.
471 // After each node, except a final-value node, another node follows to
472 // encode match values or continue matching further bytes.
473 //
474 // Node types:
475 // - Value node: Stores a 32-bit integer in a compact, variable-length format.
476 // The value is for the string/byte sequence so far.
477 // One node bit indicates whether the value is final or whether
478 // matching continues with the next node.
479 // - Linear-match node: Matches a number of bytes.
480 // - Branch node: Branches to other nodes according to the current input byte.
481 // The node byte is the length of the branch (number of bytes to select from)
482 // minus 1. It is followed by a sub-node:
483 // - If the length is at most kMaxBranchLinearSubNodeLength, then
484 // there are length-1 (key, value) pairs and then one more comparison byte.
485 // If one of the key bytes matches, then the value is either a final value for
486 // the string/byte sequence so far, or a "jump" delta to the next node.
487 // If the last byte matches, then matching continues with the next node.
488 // (Values have the same encoding as value nodes.)
489 // - If the length is greater than kMaxBranchLinearSubNodeLength, then
490 // there is one byte and one "jump" delta.
491 // If the input byte is less than the sub-node byte, then "jump" by delta to
492 // the next sub-node which will have a length of length/2.
493 // (The delta has its own compact encoding.)
494 // Otherwise, skip the "jump" delta to the next sub-node
495 // which will have a length of length-length/2.
496
497 // Node lead byte values.
498
499 // 00..0f: Branch node. If node!=0 then the length is node+1, otherwise
500 // the length is one more than the next byte.
501
502 // For a branch sub-node with at most this many entries, we drop down
503 // to a linear search.
504 static const int32_t kMaxBranchLinearSubNodeLength=5;
505
506 // 10..1f: Linear-match node, match 1..16 bytes and continue reading the next node.
507 static const int32_t kMinLinearMatch=0x10;
508 static const int32_t kMaxLinearMatchLength=0x10;
509
510 // 20..ff: Variable-length value node.
511 // If odd, the value is final. (Otherwise, intermediate value or jump delta.)
512 // Then shift-right by 1 bit.
513 // The remaining lead byte value indicates the number of following bytes (0..4)
514 // and contains the value's top bits.
515 static const int32_t kMinValueLead=kMinLinearMatch+kMaxLinearMatchLength; // 0x20
516 // It is a final value if bit 0 is set.
517 static const int32_t kValueIsFinal=1;
518
519 // Compact value: After testing bit 0, shift right by 1 and then use the following thresholds.
520 static const int32_t kMinOneByteValueLead=kMinValueLead/2; // 0x10
521 static const int32_t kMaxOneByteValue=0x40; // At least 6 bits in the first byte.
522
523 static const int32_t kMinTwoByteValueLead=kMinOneByteValueLead+kMaxOneByteValue+1; // 0x51
524 static const int32_t kMaxTwoByteValue=0x1aff;
525
526 static const int32_t kMinThreeByteValueLead=kMinTwoByteValueLead+(kMaxTwoByteValue>>8)+1; // 0x6c
527 static const int32_t kFourByteValueLead=0x7e;
528
529 // A little more than Unicode code points. (0x11ffff)
530 static const int32_t kMaxThreeByteValue=((kFourByteValueLead-kMinThreeByteValueLead)<<16)-1;
531
532 static const int32_t kFiveByteValueLead=0x7f;
533
534 // Compact delta integers.
535 static const int32_t kMaxOneByteDelta=0xbf;
536 static const int32_t kMinTwoByteDeltaLead=kMaxOneByteDelta+1; // 0xc0
537 static const int32_t kMinThreeByteDeltaLead=0xf0;
538 static const int32_t kFourByteDeltaLead=0xfe;
539 static const int32_t kFiveByteDeltaLead=0xff;
540
541 static const int32_t kMaxTwoByteDelta=((kMinThreeByteDeltaLead-kMinTwoByteDeltaLead)<<8)-1; // 0x2fff
542 static const int32_t kMaxThreeByteDelta=((kFourByteDeltaLead-kMinThreeByteDeltaLead)<<16)-1; // 0xdffff
543
544 // For getState64():
545 // The remainingMatchLength_ is -1..14=(kMaxLinearMatchLength=0x10)-2
546 // so we need at least 5 bits for that.
547 // We add 2 to store it as a positive value 1..16=kMaxLinearMatchLength.
548 static constexpr int32_t kState64RemainingShift = 59;
549 static constexpr uint64_t kState64PosMask = (UINT64_C(1) << kState64RemainingShift) - 1;
550
551 uint8_t *ownedArray_;
552
553 // Fixed value referencing the BytesTrie bytes.
554 const uint8_t *bytes_;
555
556 // Iterator variables.
557
558 // Pointer to next trie byte to read. nullptr if no more matches.
559 const uint8_t *pos_;
560 // Remaining length of a linear-match node, minus 1. Negative if not in such a node.
561 int32_t remainingMatchLength_;
562 };
563
564 U_NAMESPACE_END
565
566 #endif /* U_SHOW_CPLUSPLUS_API */
567
568 #endif // __BYTESTRIE_H__
icu::ByteSink
A ByteSink can be filled with bytes.
Definition: bytestream.h:53
icu::BytesTrieBuilder
Builder class for BytesTrie.
Definition: bytestriebuilder.h:45
icu::BytesTrie::Iterator
Iterator for all of the (byte sequence, value) pairs in a BytesTrie.
Definition: bytestrie.h:282
icu::BytesTrie::Iterator::hasNext
UBool hasNext() const
icu::BytesTrie::Iterator::getString
StringPiece getString() const
icu::BytesTrie::Iterator::reset
Iterator & reset()
Resets this iterator to its initial state.
icu::BytesTrie::Iterator::~Iterator
~Iterator()
Destructor.
icu::BytesTrie::Iterator::getValue
int32_t getValue() const
Definition: bytestrie.h:354
icu::BytesTrie::Iterator::Iterator
Iterator(const void *trieBytes, int32_t maxStringLength, UErrorCode &errorCode)
Iterates from the root of a byte-serialized BytesTrie.
icu::BytesTrie::Iterator::next
UBool next(UErrorCode &errorCode)
Finds the next (byte sequence, value) pair if there is one.
icu::BytesTrie::Iterator::Iterator
Iterator(const BytesTrie &trie, int32_t maxStringLength, UErrorCode &errorCode)
Iterates from the current state of the specified BytesTrie.
icu::BytesTrie::State
BytesTrie state object, for saving a trie's current state and resetting the trie back to this state l...
Definition: bytestrie.h:140
icu::BytesTrie::State::State
State()
Constructs an empty State.
Definition: bytestrie.h:146
icu::BytesTrie
Light-weight, non-const reader class for a BytesTrie.
Definition: bytestrie.h:55
icu::BytesTrie::resetToState64
BytesTrie & resetToState64(uint64_t state)
Resets this trie to the saved state.
Definition: bytestrie.h:129
icu::BytesTrie::getValue
int32_t getValue() const
Returns a matching byte sequence's value if called immediately after current()/first()/next() returne...
Definition: bytestrie.h:246
icu::BytesTrie::current
UStringTrieResult current() const
Determines whether the byte sequence so far matches, whether it has a value, and whether another inpu...
icu::BytesTrie::next
UStringTrieResult next(const char *s, int32_t length)
Traverses the trie from the current state for this byte sequence.
icu::BytesTrie::first
UStringTrieResult first(int32_t inByte)
Traverses the trie from the initial state for this input byte.
Definition: bytestrie.h:203
icu::BytesTrie::hasUniqueValue
UBool hasUniqueValue(int32_t &uniqueValue) const
Determines whether all byte sequences reachable from the current state map to the same value.
Definition: bytestrie.h:262
icu::BytesTrie::resetToState
BytesTrie & resetToState(const State &state)
Resets this trie to the saved state.
Definition: bytestrie.h:179
icu::BytesTrie::reset
BytesTrie & reset()
Resets this trie to its initial state.
Definition: bytestrie.h:96
icu::BytesTrie::~BytesTrie
~BytesTrie()
Destructor.
icu::BytesTrie::BytesTrie
BytesTrie(const BytesTrie &other)
Copy constructor, copies the other trie reader object and its state, but not the byte array which wil...
Definition: bytestrie.h:87
icu::BytesTrie::getNextBytes
int32_t getNextBytes(ByteSink &out) const
Finds each byte which continues the byte sequence from the current state.
icu::BytesTrie::saveState
const BytesTrie & saveState(State &state) const
Saves the state of this trie.
Definition: bytestrie.h:162
icu::BytesTrie::getState64
uint64_t getState64() const
Returns the state of this trie as a 64-bit integer.
Definition: bytestrie.h:110
icu::BytesTrie::BytesTrie
BytesTrie(const void *trieBytes)
Constructs a BytesTrie reader instance.
Definition: bytestrie.h:71
icu::BytesTrie::next
UStringTrieResult next(int32_t inByte)
Traverses the trie from the current state for this input byte.
icu::StringPiece
A string-like object that points to a sized piece of memory.
Definition: stringpiece.h:61
icu::UMemory
UMemory is the common ICU base class.
Definition: uobject.h:115
stringpiece.h
C++ API: StringPiece: Read-only byte string wrapper class.
UINT64_C
#define UINT64_C(c)
Provides a platform independent way to specify an unsigned 64-bit integer constant.
Definition: umachine.h:219
UBool
int8_t UBool
The ICU boolean type, a signed-byte integer.
Definition: umachine.h:247
uobject.h
C++ API: Common ICU base class UObject.
ustringtrie.h
C API: Helper definitions for dictionary trie APIs.
UStringTrieResult
UStringTrieResult
Return values for BytesTrie::next(), UCharsTrie::next() and similar methods.
Definition: ustringtrie.h:35
USTRINGTRIE_INTERMEDIATE_VALUE
@ USTRINGTRIE_INTERMEDIATE_VALUE
The input unit(s) continued a matching string and there is a value for the string so far.
Definition: ustringtrie.h:66
utypes.h
Basic definitions for ICU, for both C and C++ APIs.
UErrorCode
UErrorCode
Standard ICU4C error code type, a substitute for exceptions.
Definition: utypes.h:430
U_COMMON_API
#define U_COMMON_API
Set to export library symbols from inside the common library, and to import them from outside.
Definition: utypes.h:315