Where Online Learning is simpler!
The C and C++ Include Header Files
/usr/include/unicode/bytestrie.h
$ cat -n /usr/include/unicode/bytestrie.h 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 20 /** 21 * \file 22 * \brief C++ API: Trie for mapping byte sequences to integer values. 23 */ 24 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 42 /** 43 * Light-weight, non-const reader class for a BytesTrie. 44 * Traverses a byte-serialized data structure with minimal state, 45 * for mapping byte sequences to non-negative integer values. 46 * 47 * This class owns the serialized trie data only if it was constructed by 48 * the builder's build() method. 49 * The public constructor and the copy constructor only alias the data (only copy the pointer). 50 * There is no assignment operator. 51 * 52 * This class is not intended for public subclassing. 53 * @stable ICU 4.8 54 */ 55 class U_COMMON_API BytesTrie : public UMemory { 56 public: 57 /** 58 * Constructs a BytesTrie reader instance. 59 * 60 * The trieBytes must contain a copy of a byte sequence from the BytesTrieBuilder, 61 * starting with the first byte of that sequence. 62 * The BytesTrie object will not read more bytes than 63 * the BytesTrieBuilder generated in the corresponding build() call. 64 * 65 * The array is not copied/cloned and must not be modified while 66 * the BytesTrie object is in use. 67 * 68 * @param trieBytes The byte array that contains the serialized trie. 69 * @stable ICU 4.8 70 */ 71 BytesTrie(const void *trieBytes) 72 : ownedArray_(nullptr), bytes_(static_cast<const uint8_t *>(trieBytes)), 73 pos_(bytes_), remainingMatchLength_(-1) {} 74 75 /** 76 * Destructor. 77 * @stable ICU 4.8 78 */ 79 ~BytesTrie(); 80 81 /** 82 * Copy constructor, copies the other trie reader object and its state, 83 * but not the byte array which will be shared. (Shallow copy.) 84 * @param other Another BytesTrie object. 85 * @stable ICU 4.8 86 */ 87 BytesTrie(const BytesTrie &other) 88 : ownedArray_(nullptr), bytes_(other.bytes_), 89 pos_(other.pos_), remainingMatchLength_(other.remainingMatchLength_) {} 90 91 /** 92 * Resets this trie to its initial state. 93 * @return *this 94 * @stable ICU 4.8 95 */ 96 BytesTrie &reset() { 97 pos_=bytes_; 98 remainingMatchLength_=-1; 99 return *this; 100 } 101 102 /** 103 * Returns the state of this trie as a 64-bit integer. 104 * The state value is never 0. 105 * 106 * @return opaque state value 107 * @see resetToState64 108 * @stable ICU 65 109 */ 110 uint64_t getState64() const { 111 return (static_cast<uint64_t>(remainingMatchLength_ + 2) << kState64RemainingShift) | 112 (uint64_t)(pos_ - bytes_); 113 } 114 115 /** 116 * Resets this trie to the saved state. 117 * Unlike resetToState(State), the 64-bit state value 118 * must be from getState64() from the same trie object or 119 * from one initialized the exact same way. 120 * Because of no validation, this method is faster. 121 * 122 * @param state The opaque trie state value from getState64(). 123 * @return *this 124 * @see getState64 125 * @see resetToState 126 * @see reset 127 * @stable ICU 65 128 */ 129 BytesTrie &resetToState64(uint64_t state) { 130 remainingMatchLength_ = static_cast<int32_t>(state >> kState64RemainingShift) - 2; 131 pos_ = bytes_ + (state & kState64PosMask); 132 return *this; 133 } 134 135 /** 136 * BytesTrie state object, for saving a trie's current state 137 * and resetting the trie back to this state later. 138 * @stable ICU 4.8 139 */ 140 class State : public UMemory { 141 public: 142 /** 143 * Constructs an empty State. 144 * @stable ICU 4.8 145 */ 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 }; 154 155 /** 156 * Saves the state of this trie. 157 * @param state The State object to hold the trie's state. 158 * @return *this 159 * @see resetToState 160 * @stable ICU 4.8 161 */ 162 const BytesTrie &saveState(State &state) const { 163 state.bytes=bytes_; 164 state.pos=pos_; 165 state.remainingMatchLength=remainingMatchLength_; 166 return *this; 167 } 168 169 /** 170 * Resets this trie to the saved state. 171 * If the state object contains no state, or the state of a different trie, 172 * then this trie remains unchanged. 173 * @param state The State object which holds a saved trie state. 174 * @return *this 175 * @see saveState 176 * @see reset 177 * @stable ICU 4.8 178 */ 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 } 186 187 /** 188 * Determines whether the byte sequence so far matches, whether it has a value, 189 * and whether another input byte can continue a matching byte sequence. 190 * @return The match/value Result. 191 * @stable ICU 4.8 192 */ 193 UStringTrieResult current() const; 194 195 /** 196 * Traverses the trie from the initial state for this input byte. 197 * Equivalent to reset().next(inByte). 198 * @param inByte Input byte value. Values -0x100..-1 are treated like 0..0xff. 199 * Values below -0x100 and above 0xff will never match. 200 * @return The match/value Result. 201 * @stable ICU 4.8 202 */ 203 inline UStringTrieResult first(int32_t inByte) { 204 remainingMatchLength_=-1; 205 if(inByte<0) { 206 inByte+=0x100; 207 } 208 return nextImpl(bytes_, inByte); 209 } 210 211 /** 212 * Traverses the trie from the current state for this input byte. 213 * @param inByte Input byte value. Values -0x100..-1 are treated like 0..0xff. 214 * Values below -0x100 and above 0xff will never match. 215 * @return The match/value Result. 216 * @stable ICU 4.8 217 */ 218 UStringTrieResult next(int32_t inByte); 219 220 /** 221 * Traverses the trie from the current state for this byte sequence. 222 * Equivalent to 223 * \code 224 * Result result=current(); 225 * for(each c in s) 226 * if(!USTRINGTRIE_HAS_NEXT(result)) return USTRINGTRIE_NO_MATCH; 227 * result=next(c); 228 * return result; 229 * \endcode 230 * @param s A string or byte sequence. Can be nullptr if length is 0. 231 * @param length The length of the byte sequence. Can be -1 if NUL-terminated. 232 * @return The match/value Result. 233 * @stable ICU 4.8 234 */ 235 UStringTrieResult next(const char *s, int32_t length); 236 237 /** 238 * Returns a matching byte sequence's value if called immediately after 239 * current()/first()/next() returned USTRINGTRIE_INTERMEDIATE_VALUE or USTRINGTRIE_FINAL_VALUE. 240 * getValue() can be called multiple times. 241 * 242 * Do not call getValue() after USTRINGTRIE_NO_MATCH or USTRINGTRIE_NO_VALUE! 243 * @return The value for the byte sequence so far. 244 * @stable ICU 4.8 245 */ 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 } 252 253 /** 254 * Determines whether all byte sequences reachable from the current state 255 * map to the same value. 256 * @param uniqueValue Receives the unique value, if this function returns true. 257 * (output-only) 258 * @return true if all byte sequences reachable from the current state 259 * map to the same value. 260 * @stable ICU 4.8 261 */ 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 } 267 268 /** 269 * Finds each byte which continues the byte sequence from the current state. 270 * That is, each byte b for which it would be next(b)!=USTRINGTRIE_NO_MATCH now. 271 * @param out Each next byte is appended to this object. 272 * (Only uses the out.Append(s, length) method.) 273 * @return the number of bytes which continue the byte sequence from here 274 * @stable ICU 4.8 275 */ 276 int32_t getNextBytes(ByteSink &out) const; 277 278 /** 279 * Iterator for all of the (byte sequence, value) pairs in a BytesTrie. 280 * @stable ICU 4.8 281 */ 282 class U_COMMON_API Iterator : public UMemory { 283 public: 284 /** 285 * Iterates from the root of a byte-serialized BytesTrie. 286 * @param trieBytes The trie bytes. 287 * @param maxStringLength If 0, the iterator returns full strings/byte sequences. 288 * Otherwise, the iterator returns strings with this maximum length. 289 * @param errorCode Standard ICU error code. Its input value must 290 * pass the U_SUCCESS() test, or else the function returns 291 * immediately. Check for U_FAILURE() on output or use with 292 * function chaining. (See User Guide for details.) 293 * @stable ICU 4.8 294 */ 295 Iterator(const void *trieBytes, int32_t maxStringLength, UErrorCode &errorCode); 296 297 /** 298 * Iterates from the current state of the specified BytesTrie. 299 * @param trie The trie whose state will be copied for iteration. 300 * @param maxStringLength If 0, the iterator returns full strings/byte sequences. 301 * Otherwise, the iterator returns strings with this maximum length. 302 * @param errorCode Standard ICU error code. Its input value must 303 * pass the U_SUCCESS() test, or else the function returns 304 * immediately. Check for U_FAILURE() on output or use with 305 * function chaining. (See User Guide for details.) 306 * @stable ICU 4.8 307 */ 308 Iterator(const BytesTrie &trie, int32_t maxStringLength, UErrorCode &errorCode); 309 310 /** 311 * Destructor. 312 * @stable ICU 4.8 313 */ 314 ~Iterator(); 315 316 /** 317 * Resets this iterator to its initial state. 318 * @return *this 319 * @stable ICU 4.8 320 */ 321 Iterator &reset(); 322 323 /** 324 * @return true if there are more elements. 325 * @stable ICU 4.8 326 */ 327 UBool hasNext() const; 328 329 /** 330 * Finds the next (byte sequence, value) pair if there is one. 331 * 332 * If the byte sequence is truncated to the maximum length and does not 333 * have a real value, then the value is set to -1. 334 * In this case, this "not a real value" is indistinguishable from 335 * a real value of -1. 336 * @param errorCode Standard ICU error code. Its input value must 337 * pass the U_SUCCESS() test, or else the function returns 338 * immediately. Check for U_FAILURE() on output or use with 339 * function chaining. (See User Guide for details.) 340 * @return true if there is another element. 341 * @stable ICU 4.8 342 */ 343 UBool next(UErrorCode &errorCode); 344 345 /** 346 * @return The NUL-terminated byte sequence for the last successful next(). 347 * @stable ICU 4.8 348 */ 349 StringPiece getString() const; 350 /** 351 * @return The value for the last successful next(). 352 * @stable ICU 4.8 353 */ 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; 384 385 /** 386 * Constructs a BytesTrie reader instance. 387 * Unlike the public constructor which just aliases an array, 388 * this constructor adopts the builder's array. 389 * This constructor is only called by the builder. 390 */ 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 (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__
Contact us
|
About us
|
Term of use
|
Copyright © 2000-2025 MyWebUniversity.com ™
