ICU 68.2: bytestrie.h Source File

ICU 68.2 68.2

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 U_NAMESPACE_BEGIN
34
35 class ByteSink;
36 class BytesTrieBuilder;
37 class CharString;
38 class UVector32;
39
53 class U_COMMON_API BytesTrie : public UMemory {
54 public:
69 BytesTrie(const void *trieBytes)
70 : ownedArray_(NULL), bytes_(static_cast<const uint8_t *>(trieBytes)),
71 pos_(bytes_), remainingMatchLength_(-1) {}
72
77 ~BytesTrie();
78
85 BytesTrie(const BytesTrie &other)
86 : ownedArray_(NULL), bytes_(other.bytes_),
87 pos_(other.pos_), remainingMatchLength_(other.remainingMatchLength_) {}
88
94 BytesTrie &reset() {
95 pos_=bytes_;
96 remainingMatchLength_=-1;
97 return *this;
98 }
99
108 uint64_t getState64() const {
109 return (static_cast<uint64_t>(remainingMatchLength_ + 2) << kState64RemainingShift) |
110 (uint64_t)(pos_ - bytes_);
111 }
112
127 BytesTrie &resetToState64(uint64_t state) {
128 remainingMatchLength_ = static_cast<int32_t>(state >> kState64RemainingShift) - 2;
129 pos_ = bytes_ + (state & kState64PosMask);
130 return *this;
131 }
132
138 class State : public UMemory {
139 public:
144 State() { bytes=NULL; }
145 private:
146 friend class BytesTrie;
147
148 const uint8_t *bytes;
149 const uint8_t *pos;
150 int32_t remainingMatchLength;
151 };
152
160 const BytesTrie &saveState(State &state) const {
161 state.bytes=bytes_;
162 state.pos=pos_;
163 state.remainingMatchLength=remainingMatchLength_;
164 return *this;
165 }
166
177 BytesTrie &resetToState(const State &state) {
178 if(bytes_==state.bytes && bytes_!=NULL) {
179 pos_=state.pos;
180 remainingMatchLength_=state.remainingMatchLength;
181 }
182 return *this;
183 }
184
191 UStringTrieResult current() const;
192
201 inline UStringTrieResult first(int32_t inByte) {
202 remainingMatchLength_=-1;
203 if(inByte<0) {
204 inByte+=0x100;
205 }
206 return nextImpl(bytes_, inByte);
207 }
208
216 UStringTrieResult next(int32_t inByte);
217
233 UStringTrieResult next(const char *s, int32_t length);
234
244 inline int32_t getValue() const {
245 const uint8_t *pos=pos_;
246 int32_t leadByte=*pos++;
247 // U_ASSERT(leadByte>=kMinValueLead);
248 return readValue(pos, leadByte>>1);
249 }
250
260 inline UBool hasUniqueValue(int32_t &uniqueValue) const {
261 const uint8_t *pos=pos_;
262 // Skip the rest of a pending linear-match node.
263 return pos!=NULL && findUniqueValue(pos+remainingMatchLength_+1, false, uniqueValue);
264 }
265
274 int32_t getNextBytes(ByteSink &out) const;
275
280 class U_COMMON_API Iterator : public UMemory {
281 public:
293 Iterator(const void *trieBytes, int32_t maxStringLength, UErrorCode &errorCode);
294
306 Iterator(const BytesTrie &trie, int32_t maxStringLength, UErrorCode &errorCode);
307
312 ~Iterator();
313
319 Iterator &reset();
320
325 UBool hasNext() const;
326
341 UBool next(UErrorCode &errorCode);
342
347 StringPiece getString() const;
352 int32_t getValue() const { return value_; }
353
354 private:
355 UBool truncateAndStop();
356
357 const uint8_t *branchNext(const uint8_t *pos, int32_t length, UErrorCode &errorCode);
358
359 const uint8_t *bytes_;
360 const uint8_t *pos_;
361 const uint8_t *initialPos_;
362 int32_t remainingMatchLength_;
363 int32_t initialRemainingMatchLength_;
364
365 CharString *str_;
366 int32_t maxLength_;
367 int32_t value_;
368
369 // The stack stores pairs of integers for backtracking to another
370 // outbound edge of a branch node.
371 // The first integer is an offset from bytes_.
372 // The second integer has the str_->length() from before the node in bits 15..0,
373 // and the remaining branch length in bits 24..16. (Bits 31..25 are unused.)
374 // (We could store the remaining branch length minus 1 in bits 23..16 and not use bits 31..24,
375 // but the code looks more confusing that way.)
376 UVector32 *stack_;
377 };
378
379 private:
380 friend class BytesTrieBuilder;
381
388 BytesTrie(void *adoptBytes, const void *trieBytes)
389 : ownedArray_(static_cast<uint8_t *>(adoptBytes)),
390 bytes_(static_cast<const uint8_t *>(trieBytes)),
391 pos_(bytes_), remainingMatchLength_(-1) {}
392
393 // No assignment operator.
394 BytesTrie &operator=(const BytesTrie &other);
395
396 inline void stop() {
397 pos_=NULL;
398 }
399
400 // Reads a compact 32-bit integer.
401 // pos is already after the leadByte, and the lead byte is already shifted right by 1.
402 static int32_t readValue(const uint8_t *pos, int32_t leadByte);
403 static inline const uint8_t *skipValue(const uint8_t *pos, int32_t leadByte) {
404 // U_ASSERT(leadByte>=kMinValueLead);
405 if(leadByte>=(kMinTwoByteValueLead<<1)) {
406 if(leadByte<(kMinThreeByteValueLead<<1)) {
407 ++pos;
408 } else if(leadByte<(kFourByteValueLead<<1)) {
409 pos+=2;
410 } else {
411 pos+=3+((leadByte>>1)&1);
412 }
413 }
414 return pos;
415 }
416 static inline const uint8_t *skipValue(const uint8_t *pos) {
417 int32_t leadByte=*pos++;
418 return skipValue(pos, leadByte);
419 }
420
421 // Reads a jump delta and jumps.
422 static const uint8_t *jumpByDelta(const uint8_t *pos);
423
424 static inline const uint8_t *skipDelta(const uint8_t *pos) {
425 int32_t delta=*pos++;
426 if(delta>=kMinTwoByteDeltaLead) {
427 if(delta<kMinThreeByteDeltaLead) {
428 ++pos;
429 } else if(delta<kFourByteDeltaLead) {
430 pos+=2;
431 } else {
432 pos+=3+(delta&1);
433 }
434 }
435 return pos;
436 }
437
438 static inline UStringTrieResult valueResult(int32_t node) {
439 return (UStringTrieResult)(USTRINGTRIE_INTERMEDIATE_VALUE-(node&kValueIsFinal));
440 }
441
442 // Handles a branch node for both next(byte) and next(string).
443 UStringTrieResult branchNext(const uint8_t *pos, int32_t length, int32_t inByte);
444
445 // Requires remainingLength_<0.
446 UStringTrieResult nextImpl(const uint8_t *pos, int32_t inByte);
447
448 // Helper functions for hasUniqueValue().
449 // Recursively finds a unique value (or whether there is not a unique one)
450 // from a branch.
451 static const uint8_t *findUniqueValueFromBranch(const uint8_t *pos, int32_t length,
452 UBool haveUniqueValue, int32_t &uniqueValue);
453 // Recursively finds a unique value (or whether there is not a unique one)
454 // starting from a position on a node lead byte.
455 static UBool findUniqueValue(const uint8_t *pos, UBool haveUniqueValue, int32_t &uniqueValue);
456
457 // Helper functions for getNextBytes().
458 // getNextBytes() when pos is on a branch node.
459 static void getNextBranchBytes(const uint8_t *pos, int32_t length, ByteSink &out);
460 static void append(ByteSink &out, int c);
461
462 // BytesTrie data structure
463 //
464 // The trie consists of a series of byte-serialized nodes for incremental
465 // string/byte sequence matching. The root node is at the beginning of the trie data.
466 //
467 // Types of nodes are distinguished by their node lead byte ranges.
468 // After each node, except a final-value node, another node follows to
469 // encode match values or continue matching further bytes.
470 //
471 // Node types:
472 // - Value node: Stores a 32-bit integer in a compact, variable-length format.
473 // The value is for the string/byte sequence so far.
474 // One node bit indicates whether the value is final or whether
475 // matching continues with the next node.
476 // - Linear-match node: Matches a number of bytes.
477 // - Branch node: Branches to other nodes according to the current input byte.
478 // The node byte is the length of the branch (number of bytes to select from)
479 // minus 1. It is followed by a sub-node:
480 // - If the length is at most kMaxBranchLinearSubNodeLength, then
481 // there are length-1 (key, value) pairs and then one more comparison byte.
482 // If one of the key bytes matches, then the value is either a final value for
483 // the string/byte sequence so far, or a "jump" delta to the next node.
484 // If the last byte matches, then matching continues with the next node.
485 // (Values have the same encoding as value nodes.)
486 // - If the length is greater than kMaxBranchLinearSubNodeLength, then
487 // there is one byte and one "jump" delta.
488 // If the input byte is less than the sub-node byte, then "jump" by delta to
489 // the next sub-node which will have a length of length/2.
490 // (The delta has its own compact encoding.)
491 // Otherwise, skip the "jump" delta to the next sub-node
492 // which will have a length of length-length/2.
493
494 // Node lead byte values.
495
496 // 00..0f: Branch node. If node!=0 then the length is node+1, otherwise
497 // the length is one more than the next byte.
498
499 // For a branch sub-node with at most this many entries, we drop down
500 // to a linear search.
501 static const int32_t kMaxBranchLinearSubNodeLength=5;
502
503 // 10..1f: Linear-match node, match 1..16 bytes and continue reading the next node.
504 static const int32_t kMinLinearMatch=0x10;
505 static const int32_t kMaxLinearMatchLength=0x10;
506
507 // 20..ff: Variable-length value node.
508 // If odd, the value is final. (Otherwise, intermediate value or jump delta.)
509 // Then shift-right by 1 bit.
510 // The remaining lead byte value indicates the number of following bytes (0..4)
511 // and contains the value's top bits.
512 static const int32_t kMinValueLead=kMinLinearMatch+kMaxLinearMatchLength; // 0x20
513 // It is a final value if bit 0 is set.
514 static const int32_t kValueIsFinal=1;
515
516 // Compact value: After testing bit 0, shift right by 1 and then use the following thresholds.
517 static const int32_t kMinOneByteValueLead=kMinValueLead/2; // 0x10
518 static const int32_t kMaxOneByteValue=0x40; // At least 6 bits in the first byte.
519
520 static const int32_t kMinTwoByteValueLead=kMinOneByteValueLead+kMaxOneByteValue+1; // 0x51
521 static const int32_t kMaxTwoByteValue=0x1aff;
522
523 static const int32_t kMinThreeByteValueLead=kMinTwoByteValueLead+(kMaxTwoByteValue>>8)+1; // 0x6c
524 static const int32_t kFourByteValueLead=0x7e;
525
526 // A little more than Unicode code points. (0x11ffff)
527 static const int32_t kMaxThreeByteValue=((kFourByteValueLead-kMinThreeByteValueLead)<<16)-1;
528
529 static const int32_t kFiveByteValueLead=0x7f;
530
531 // Compact delta integers.
532 static const int32_t kMaxOneByteDelta=0xbf;
533 static const int32_t kMinTwoByteDeltaLead=kMaxOneByteDelta+1; // 0xc0
534 static const int32_t kMinThreeByteDeltaLead=0xf0;
535 static const int32_t kFourByteDeltaLead=0xfe;
536 static const int32_t kFiveByteDeltaLead=0xff;
537
538 static const int32_t kMaxTwoByteDelta=((kMinThreeByteDeltaLead-kMinTwoByteDeltaLead)<<8)-1; // 0x2fff
539 static const int32_t kMaxThreeByteDelta=((kFourByteDeltaLead-kMinThreeByteDeltaLead)<<16)-1; // 0xdffff
540
541 // For getState64():
542 // The remainingMatchLength_ is -1..14=(kMaxLinearMatchLength=0x10)-2
543 // so we need at least 5 bits for that.
544 // We add 2 to store it as a positive value 1..16=kMaxLinearMatchLength.
545 static constexpr int32_t kState64RemainingShift = 59;
546 static constexpr uint64_t kState64PosMask = (UINT64_C(1) << kState64RemainingShift) - 1;
547
548 uint8_t *ownedArray_;
549
550 // Fixed value referencing the BytesTrie bytes.
551 const uint8_t *bytes_;
552
553 // Iterator variables.
554
555 // Pointer to next trie byte to read. NULL if no more matches.
556 const uint8_t *pos_;
557 // Remaining length of a linear-match node, minus 1. Negative if not in such a node.
558 int32_t remainingMatchLength_;
559 };
560
561 U_NAMESPACE_END
562
563 #endif /* U_SHOW_CPLUSPLUS_API */
564
565 #endif // __BYTESTRIE_H__
icu::BytesTrie::next
UStringTrieResult next(int32_t inByte)
Traverses the trie from the current state for this input byte.
icu::BytesTrie::getState64
uint64_t getState64() const
Returns the state of this trie as a 64-bit integer.
Definition: bytestrie.h:108
icu::BytesTrie::Iterator::Iterator
Iterator(const void *trieBytes, int32_t maxStringLength, UErrorCode &errorCode)
Iterates from the root of a byte-serialized BytesTrie.
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
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:85
icu::BytesTrie::current
UStringTrieResult current() const
Determines whether the byte sequence so far matches, whether it has a value, and whether another inpu...
utypes.h
Basic definitions for ICU, for both C and C++ APIs.
UINT64_C
#define UINT64_C(c)
Provides a platform independent way to specify an unsigned 64-bit integer constant.
Definition: umachine.h:241
icu::BytesTrie::Iterator::next
UBool next(UErrorCode &errorCode)
Finds the next (byte sequence, value) pair if there is one.
UBool
int8_t UBool
The ICU boolean type, a signed-byte integer.
Definition: umachine.h:269
icu::BytesTrie::getNextBytes
int32_t getNextBytes(ByteSink &out) const
Finds each byte which continues the byte sequence from the current state.
icu::BytesTrie::Iterator::getValue
int32_t getValue() const
Definition: bytestrie.h:352
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:300
icu::BytesTrie::~BytesTrie
~BytesTrie()
Destructor.
NULL
#define NULL
Define NULL if necessary, to nullptr for C++ and to ((void *)0) for C.
Definition: utypes.h:188
icu::BytesTrie::Iterator::getString
StringPiece getString() const
stringpiece.h
C++ API: StringPiece: Read-only byte string wrapper class.
icu::BytesTrie::Iterator::Iterator
Iterator(const BytesTrie &trie, int32_t maxStringLength, UErrorCode &errorCode)
Iterates from the current state of the specified BytesTrie.
icu::BytesTrie::Iterator
Iterator for all of the (byte sequence, value) pairs in a BytesTrie.
Definition: bytestrie.h:280
UErrorCode
UErrorCode
Standard ICU4C error code type, a substitute for exceptions.
Definition: utypes.h:415
icu::BytesTrie::saveState
const BytesTrie & saveState(State &state) const
Saves the state of this trie.
Definition: bytestrie.h:160
icu::ByteSink
A ByteSink can be filled with bytes.
Definition: bytestream.h:53
icu::UMemory
UMemory is the common ICU base class.
Definition: uobject.h:115
icu::BytesTrie::resetToState
BytesTrie & resetToState(const State &state)
Resets this trie to the saved state.
Definition: bytestrie.h:177
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:138
icu::BytesTrie
Light-weight, non-const reader class for a BytesTrie.
Definition: bytestrie.h:53
icu::BytesTrie::resetToState64
BytesTrie & resetToState64(uint64_t state)
Resets this trie to the saved state.
Definition: bytestrie.h:127
ustringtrie.h
C API: Helper definitions for dictionary trie APIs.
icu::BytesTrieBuilder
Builder class for BytesTrie.
Definition: bytestriebuilder.h:43
icu::BytesTrie::Iterator::reset
Iterator & reset()
Resets this iterator to its initial state.
icu::BytesTrie::reset
BytesTrie & reset()
Resets this trie to its initial state.
Definition: bytestrie.h:94
icu::BytesTrie::State::State
State()
Constructs an empty State.
Definition: bytestrie.h:144
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:260
icu::BytesTrie::next
UStringTrieResult next(const char *s, int32_t length)
Traverses the trie from the current state for this byte sequence.
UStringTrieResult
UStringTrieResult
Return values for BytesTrie::next(), UCharsTrie::next() and similar methods.
Definition: ustringtrie.h:35
uobject.h
C++ API: Common ICU base class UObject.
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:244
icu::StringPiece
A string-like object that points to a sized piece of memory.
Definition: stringpiece.h:60
icu::BytesTrie::first
UStringTrieResult first(int32_t inByte)
Traverses the trie from the initial state for this input byte.
Definition: bytestrie.h:201
icu::BytesTrie::BytesTrie
BytesTrie(const void *trieBytes)
Constructs a BytesTrie reader instance.
Definition: bytestrie.h:69
icu::BytesTrie::Iterator::~Iterator
~Iterator()
Destructor.
icu::BytesTrie::Iterator::hasNext
UBool hasNext() const