1 // © 2016 and later: Unicode, Inc. and others.
2 // License & terms of use: http://www.unicode.org/copyright.html
4 *******************************************************************************
5 * Copyright (C) 2010-2012, International Business Machines
6 * Corporation and others. All Rights Reserved.
7 *******************************************************************************
8 * file name: ucharstrie.h
10 * tab size: 8 (not used)
13 * created on: 2010nov14
14 * created by: Markus W. Scherer
17 #ifndef __UCHARSTRIE_H__
18 #define __UCHARSTRIE_H__
22 * \brief C++ API: Trie for mapping Unicode strings (or 16-bit-unit sequences)
26 #include "unicode/utypes.h"
28 #if U_SHOW_CPLUSPLUS_API
30 #include "unicode/unistr.h"
31 #include "unicode/uobject.h"
32 #include "unicode/ustringtrie.h"
37 class UCharsTrieBuilder;
41 * Light-weight, non-const reader class for a UCharsTrie.
42 * Traverses a char16_t-serialized data structure with minimal state,
43 * for mapping strings (16-bit-unit sequences) to non-negative integer values.
45 * This class owns the serialized trie data only if it was constructed by
46 * the builder's build() method.
47 * The public constructor and the copy constructor only alias the data (only copy the pointer).
48 * There is no assignment operator.
50 * This class is not intended for public subclassing.
53 class U_COMMON_API UCharsTrie : public UMemory {
56 * Constructs a UCharsTrie reader instance.
58 * The trieUChars must contain a copy of a char16_t sequence from the UCharsTrieBuilder,
59 * starting with the first char16_t of that sequence.
60 * The UCharsTrie object will not read more char16_ts than
61 * the UCharsTrieBuilder generated in the corresponding build() call.
63 * The array is not copied/cloned and must not be modified while
64 * the UCharsTrie object is in use.
66 * @param trieUChars The char16_t array that contains the serialized trie.
69 UCharsTrie(ConstChar16Ptr trieUChars)
70 : ownedArray_(NULL), uchars_(trieUChars),
71 pos_(uchars_), remainingMatchLength_(-1) {}
80 * Copy constructor, copies the other trie reader object and its state,
81 * but not the char16_t array which will be shared. (Shallow copy.)
82 * @param other Another UCharsTrie object.
85 UCharsTrie(const UCharsTrie &other)
86 : ownedArray_(NULL), uchars_(other.uchars_),
87 pos_(other.pos_), remainingMatchLength_(other.remainingMatchLength_) {}
90 * Resets this trie to its initial state.
96 remainingMatchLength_=-1;
101 * Returns the state of this trie as a 64-bit integer.
102 * The state value is never 0.
104 * @return opaque state value
105 * @see resetToState64
108 uint64_t getState64() const {
109 return (static_cast<uint64_t>(remainingMatchLength_ + 2) << kState64RemainingShift) |
110 (uint64_t)(pos_ - uchars_);
114 * Resets this trie to the saved state.
115 * Unlike resetToState(State), the 64-bit state value
116 * must be from getState64() from the same trie object or
117 * from one initialized the exact same way.
118 * Because of no validation, this method is faster.
120 * @param state The opaque trie state value from getState64().
127 UCharsTrie &resetToState64(uint64_t state) {
128 remainingMatchLength_ = static_cast<int32_t>(state >> kState64RemainingShift) - 2;
129 pos_ = uchars_ + (state & kState64PosMask);
134 * UCharsTrie state object, for saving a trie's current state
135 * and resetting the trie back to this state later.
138 class State : public UMemory {
141 * Constructs an empty State.
144 State() { uchars=NULL; }
146 friend class UCharsTrie;
148 const char16_t *uchars;
150 int32_t remainingMatchLength;
154 * Saves the state of this trie.
155 * @param state The State object to hold the trie's state.
160 const UCharsTrie &saveState(State &state) const {
161 state.uchars=uchars_;
163 state.remainingMatchLength=remainingMatchLength_;
168 * Resets this trie to the saved state.
169 * If the state object contains no state, or the state of a different trie,
170 * then this trie remains unchanged.
171 * @param state The State object which holds a saved trie state.
177 UCharsTrie &resetToState(const State &state) {
178 if(uchars_==state.uchars && uchars_!=NULL) {
180 remainingMatchLength_=state.remainingMatchLength;
186 * Determines whether the string so far matches, whether it has a value,
187 * and whether another input char16_t can continue a matching string.
188 * @return The match/value Result.
191 UStringTrieResult current() const;
194 * Traverses the trie from the initial state for this input char16_t.
195 * Equivalent to reset().next(uchar).
196 * @param uchar Input char value. Values below 0 and above 0xffff will never match.
197 * @return The match/value Result.
200 inline UStringTrieResult first(int32_t uchar) {
201 remainingMatchLength_=-1;
202 return nextImpl(uchars_, uchar);
206 * Traverses the trie from the initial state for the
207 * one or two UTF-16 code units for this input code point.
208 * Equivalent to reset().nextForCodePoint(cp).
209 * @param cp A Unicode code point 0..0x10ffff.
210 * @return The match/value Result.
213 UStringTrieResult firstForCodePoint(UChar32 cp);
216 * Traverses the trie from the current state for this input char16_t.
217 * @param uchar Input char value. Values below 0 and above 0xffff will never match.
218 * @return The match/value Result.
221 UStringTrieResult next(int32_t uchar);
224 * Traverses the trie from the current state for the
225 * one or two UTF-16 code units for this input code point.
226 * @param cp A Unicode code point 0..0x10ffff.
227 * @return The match/value Result.
230 UStringTrieResult nextForCodePoint(UChar32 cp);
233 * Traverses the trie from the current state for this string.
236 * Result result=current();
238 * if(!USTRINGTRIE_HAS_NEXT(result)) return USTRINGTRIE_NO_MATCH;
242 * @param s A string. Can be NULL if length is 0.
243 * @param length The length of the string. Can be -1 if NUL-terminated.
244 * @return The match/value Result.
247 UStringTrieResult next(ConstChar16Ptr s, int32_t length);
250 * Returns a matching string's value if called immediately after
251 * current()/first()/next() returned USTRINGTRIE_INTERMEDIATE_VALUE or USTRINGTRIE_FINAL_VALUE.
252 * getValue() can be called multiple times.
254 * Do not call getValue() after USTRINGTRIE_NO_MATCH or USTRINGTRIE_NO_VALUE!
255 * @return The value for the string so far.
258 inline int32_t getValue() const {
259 const char16_t *pos=pos_;
260 int32_t leadUnit=*pos++;
261 // U_ASSERT(leadUnit>=kMinValueLead);
262 return leadUnit&kValueIsFinal ?
263 readValue(pos, leadUnit&0x7fff) : readNodeValue(pos, leadUnit);
267 * Determines whether all strings reachable from the current state
268 * map to the same value.
269 * @param uniqueValue Receives the unique value, if this function returns true.
271 * @return true if all strings reachable from the current state
272 * map to the same value.
275 inline UBool hasUniqueValue(int32_t &uniqueValue) const {
276 const char16_t *pos=pos_;
277 // Skip the rest of a pending linear-match node.
278 return pos!=NULL && findUniqueValue(pos+remainingMatchLength_+1, false, uniqueValue);
282 * Finds each char16_t which continues the string from the current state.
283 * That is, each char16_t c for which it would be next(c)!=USTRINGTRIE_NO_MATCH now.
284 * @param out Each next char16_t is appended to this object.
285 * @return the number of char16_ts which continue the string from here
288 int32_t getNextUChars(Appendable &out) const;
291 * Iterator for all of the (string, value) pairs in a UCharsTrie.
294 class U_COMMON_API Iterator : public UMemory {
297 * Iterates from the root of a char16_t-serialized UCharsTrie.
298 * @param trieUChars The trie char16_ts.
299 * @param maxStringLength If 0, the iterator returns full strings.
300 * Otherwise, the iterator returns strings with this maximum length.
301 * @param errorCode Standard ICU error code. Its input value must
302 * pass the U_SUCCESS() test, or else the function returns
303 * immediately. Check for U_FAILURE() on output or use with
304 * function chaining. (See User Guide for details.)
307 Iterator(ConstChar16Ptr trieUChars, int32_t maxStringLength, UErrorCode &errorCode);
310 * Iterates from the current state of the specified UCharsTrie.
311 * @param trie The trie whose state will be copied for iteration.
312 * @param maxStringLength If 0, the iterator returns full strings.
313 * Otherwise, the iterator returns strings with this maximum length.
314 * @param errorCode Standard ICU error code. Its input value must
315 * pass the U_SUCCESS() test, or else the function returns
316 * immediately. Check for U_FAILURE() on output or use with
317 * function chaining. (See User Guide for details.)
320 Iterator(const UCharsTrie &trie, int32_t maxStringLength, UErrorCode &errorCode);
329 * Resets this iterator to its initial state.
336 * @return true if there are more elements.
339 UBool hasNext() const;
342 * Finds the next (string, value) pair if there is one.
344 * If the string is truncated to the maximum length and does not
345 * have a real value, then the value is set to -1.
346 * In this case, this "not a real value" is indistinguishable from
347 * a real value of -1.
348 * @param errorCode Standard ICU error code. Its input value must
349 * pass the U_SUCCESS() test, or else the function returns
350 * immediately. Check for U_FAILURE() on output or use with
351 * function chaining. (See User Guide for details.)
352 * @return true if there is another element.
355 UBool next(UErrorCode &errorCode);
358 * @return The string for the last successful next().
361 const UnicodeString &getString() const { return str_; }
363 * @return The value for the last successful next().
366 int32_t getValue() const { return value_; }
369 UBool truncateAndStop() {
371 value_=-1; // no real value for str
375 const char16_t *branchNext(const char16_t *pos, int32_t length, UErrorCode &errorCode);
377 const char16_t *uchars_;
378 const char16_t *pos_;
379 const char16_t *initialPos_;
380 int32_t remainingMatchLength_;
381 int32_t initialRemainingMatchLength_;
382 UBool skipValue_; // Skip intermediate value which was already delivered.
388 // The stack stores pairs of integers for backtracking to another
389 // outbound edge of a branch node.
390 // The first integer is an offset from uchars_.
391 // The second integer has the str_.length() from before the node in bits 15..0,
392 // and the remaining branch length in bits 31..16.
393 // (We could store the remaining branch length minus 1 in bits 30..16 and not use the sign bit,
394 // but the code looks more confusing that way.)
399 friend class UCharsTrieBuilder;
402 * Constructs a UCharsTrie reader instance.
403 * Unlike the public constructor which just aliases an array,
404 * this constructor adopts the builder's array.
405 * This constructor is only called by the builder.
407 UCharsTrie(char16_t *adoptUChars, const char16_t *trieUChars)
408 : ownedArray_(adoptUChars), uchars_(trieUChars),
409 pos_(uchars_), remainingMatchLength_(-1) {}
411 // No assignment operator.
412 UCharsTrie &operator=(const UCharsTrie &other);
418 // Reads a compact 32-bit integer.
419 // pos is already after the leadUnit, and the lead unit has bit 15 reset.
420 static inline int32_t readValue(const char16_t *pos, int32_t leadUnit) {
422 if(leadUnit<kMinTwoUnitValueLead) {
424 } else if(leadUnit<kThreeUnitValueLead) {
425 value=((leadUnit-kMinTwoUnitValueLead)<<16)|*pos;
427 value=(pos[0]<<16)|pos[1];
431 static inline const char16_t *skipValue(const char16_t *pos, int32_t leadUnit) {
432 if(leadUnit>=kMinTwoUnitValueLead) {
433 if(leadUnit<kThreeUnitValueLead) {
441 static inline const char16_t *skipValue(const char16_t *pos) {
442 int32_t leadUnit=*pos++;
443 return skipValue(pos, leadUnit&0x7fff);
446 static inline int32_t readNodeValue(const char16_t *pos, int32_t leadUnit) {
447 // U_ASSERT(kMinValueLead<=leadUnit && leadUnit<kValueIsFinal);
449 if(leadUnit<kMinTwoUnitNodeValueLead) {
450 value=(leadUnit>>6)-1;
451 } else if(leadUnit<kThreeUnitNodeValueLead) {
452 value=(((leadUnit&0x7fc0)-kMinTwoUnitNodeValueLead)<<10)|*pos;
454 value=(pos[0]<<16)|pos[1];
458 static inline const char16_t *skipNodeValue(const char16_t *pos, int32_t leadUnit) {
459 // U_ASSERT(kMinValueLead<=leadUnit && leadUnit<kValueIsFinal);
460 if(leadUnit>=kMinTwoUnitNodeValueLead) {
461 if(leadUnit<kThreeUnitNodeValueLead) {
470 static inline const char16_t *jumpByDelta(const char16_t *pos) {
471 int32_t delta=*pos++;
472 if(delta>=kMinTwoUnitDeltaLead) {
473 if(delta==kThreeUnitDeltaLead) {
474 delta=(pos[0]<<16)|pos[1];
477 delta=((delta-kMinTwoUnitDeltaLead)<<16)|*pos++;
483 static const char16_t *skipDelta(const char16_t *pos) {
484 int32_t delta=*pos++;
485 if(delta>=kMinTwoUnitDeltaLead) {
486 if(delta==kThreeUnitDeltaLead) {
495 static inline UStringTrieResult valueResult(int32_t node) {
496 return (UStringTrieResult)(USTRINGTRIE_INTERMEDIATE_VALUE-(node>>15));
499 // Handles a branch node for both next(uchar) and next(string).
500 UStringTrieResult branchNext(const char16_t *pos, int32_t length, int32_t uchar);
502 // Requires remainingLength_<0.
503 UStringTrieResult nextImpl(const char16_t *pos, int32_t uchar);
505 // Helper functions for hasUniqueValue().
506 // Recursively finds a unique value (or whether there is not a unique one)
508 static const char16_t *findUniqueValueFromBranch(const char16_t *pos, int32_t length,
509 UBool haveUniqueValue, int32_t &uniqueValue);
510 // Recursively finds a unique value (or whether there is not a unique one)
511 // starting from a position on a node lead unit.
512 static UBool findUniqueValue(const char16_t *pos, UBool haveUniqueValue, int32_t &uniqueValue);
514 // Helper functions for getNextUChars().
515 // getNextUChars() when pos is on a branch node.
516 static void getNextBranchUChars(const char16_t *pos, int32_t length, Appendable &out);
518 // UCharsTrie data structure
520 // The trie consists of a series of char16_t-serialized nodes for incremental
521 // Unicode string/char16_t sequence matching. (char16_t=16-bit unsigned integer)
522 // The root node is at the beginning of the trie data.
524 // Types of nodes are distinguished by their node lead unit ranges.
525 // After each node, except a final-value node, another node follows to
526 // encode match values or continue matching further units.
529 // - Final-value node: Stores a 32-bit integer in a compact, variable-length format.
530 // The value is for the string/char16_t sequence so far.
531 // - Match node, optionally with an intermediate value in a different compact format.
532 // The value, if present, is for the string/char16_t sequence so far.
534 // Aside from the value, which uses the node lead unit's high bits:
536 // - Linear-match node: Matches a number of units.
537 // - Branch node: Branches to other nodes according to the current input unit.
538 // The node unit is the length of the branch (number of units to select from)
539 // minus 1. It is followed by a sub-node:
540 // - If the length is at most kMaxBranchLinearSubNodeLength, then
541 // there are length-1 (key, value) pairs and then one more comparison unit.
542 // If one of the key units matches, then the value is either a final value for
543 // the string so far, or a "jump" delta to the next node.
544 // If the last unit matches, then matching continues with the next node.
545 // (Values have the same encoding as final-value nodes.)
546 // - If the length is greater than kMaxBranchLinearSubNodeLength, then
547 // there is one unit and one "jump" delta.
548 // If the input unit is less than the sub-node unit, then "jump" by delta to
549 // the next sub-node which will have a length of length/2.
550 // (The delta has its own compact encoding.)
551 // Otherwise, skip the "jump" delta to the next sub-node
552 // which will have a length of length-length/2.
554 // Match-node lead unit values, after masking off intermediate-value bits:
556 // 0000..002f: Branch node. If node!=0 then the length is node+1, otherwise
557 // the length is one more than the next unit.
559 // For a branch sub-node with at most this many entries, we drop down
560 // to a linear search.
561 static const int32_t kMaxBranchLinearSubNodeLength=5;
563 // 0030..003f: Linear-match node, match 1..16 units and continue reading the next node.
564 static const int32_t kMinLinearMatch=0x30;
565 static const int32_t kMaxLinearMatchLength=0x10;
567 // Match-node lead unit bits 14..6 for the optional intermediate value.
568 // If these bits are 0, then there is no intermediate value.
569 // Otherwise, see the *NodeValue* constants below.
570 static const int32_t kMinValueLead=kMinLinearMatch+kMaxLinearMatchLength; // 0x0040
571 static const int32_t kNodeTypeMask=kMinValueLead-1; // 0x003f
573 // A final-value node has bit 15 set.
574 static const int32_t kValueIsFinal=0x8000;
576 // Compact value: After testing and masking off bit 15, use the following thresholds.
577 static const int32_t kMaxOneUnitValue=0x3fff;
579 static const int32_t kMinTwoUnitValueLead=kMaxOneUnitValue+1; // 0x4000
580 static const int32_t kThreeUnitValueLead=0x7fff;
582 static const int32_t kMaxTwoUnitValue=((kThreeUnitValueLead-kMinTwoUnitValueLead)<<16)-1; // 0x3ffeffff
584 // Compact intermediate-value integer, lead unit shared with a branch or linear-match node.
585 static const int32_t kMaxOneUnitNodeValue=0xff;
586 static const int32_t kMinTwoUnitNodeValueLead=kMinValueLead+((kMaxOneUnitNodeValue+1)<<6); // 0x4040
587 static const int32_t kThreeUnitNodeValueLead=0x7fc0;
589 static const int32_t kMaxTwoUnitNodeValue=
590 ((kThreeUnitNodeValueLead-kMinTwoUnitNodeValueLead)<<10)-1; // 0xfdffff
592 // Compact delta integers.
593 static const int32_t kMaxOneUnitDelta=0xfbff;
594 static const int32_t kMinTwoUnitDeltaLead=kMaxOneUnitDelta+1; // 0xfc00
595 static const int32_t kThreeUnitDeltaLead=0xffff;
597 static const int32_t kMaxTwoUnitDelta=((kThreeUnitDeltaLead-kMinTwoUnitDeltaLead)<<16)-1; // 0x03feffff
600 // The remainingMatchLength_ is -1..14=(kMaxLinearMatchLength=0x10)-2
601 // so we need at least 5 bits for that.
602 // We add 2 to store it as a positive value 1..16=kMaxLinearMatchLength.
603 static constexpr int32_t kState64RemainingShift = 59;
604 static constexpr uint64_t kState64PosMask = (UINT64_C(1) << kState64RemainingShift) - 1;
606 char16_t *ownedArray_;
608 // Fixed value referencing the UCharsTrie words.
609 const char16_t *uchars_;
611 // Iterator variables.
613 // Pointer to next trie unit to read. NULL if no more matches.
614 const char16_t *pos_;
615 // Remaining length of a linear-match node, minus 1. Negative if not in such a node.
616 int32_t remainingMatchLength_;
621 #endif /* U_SHOW_CPLUSPLUS_API */
623 #endif // __UCHARSTRIE_H__