intl/icu/source/common/unormcmp.cpp@6474c204b198
intl/icu/source/common/unormcmp.cpp
Wed, 31 Dec 2014 06:09:35 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Wed, 31 Dec 2014 06:09:35 +0100
- changeset 0
- 6474c204b198
- permissions
- -rw-r--r--
Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.
1 /*
2 *******************************************************************************
3 *
4 * Copyright (C) 2001-2011, International Business Machines
5 * Corporation and others. All Rights Reserved.
6 *
7 *******************************************************************************
8 * file name: unormcmp.cpp
9 * encoding: US-ASCII
10 * tab size: 8 (not used)
11 * indentation:4
12 *
13 * created on: 2004sep13
14 * created by: Markus W. Scherer
15 *
16 * unorm_compare() function moved here from unorm.cpp for better modularization.
17 * Depends on both normalization and case folding.
18 * Allows unorm.cpp to not depend on any character properties code.
19 */
21 #include "unicode/utypes.h"
23 #if !UCONFIG_NO_NORMALIZATION
25 #include "unicode/unorm.h"
26 #include "unicode/ustring.h"
27 #include "cmemory.h"
28 #include "normalizer2impl.h"
29 #include "ucase.h"
30 #include "uprops.h"
31 #include "ustr_imp.h"
33 U_NAMESPACE_USE
35 #define LENGTHOF(array) (int32_t)(sizeof(array)/sizeof((array)[0]))
37 /* compare canonically equivalent ------------------------------------------- */
39 /*
40 * Compare two strings for canonical equivalence.
41 * Further options include case-insensitive comparison and
42 * code point order (as opposed to code unit order).
43 *
44 * In this function, canonical equivalence is optional as well.
45 * If canonical equivalence is tested, then both strings must fulfill
46 * the FCD check.
47 *
48 * Semantically, this is equivalent to
49 * strcmp[CodePointOrder](NFD(foldCase(s1)), NFD(foldCase(s2)))
50 * where code point order, NFD and foldCase are all optional.
51 *
52 * String comparisons almost always yield results before processing both strings
53 * completely.
54 * They are generally more efficient working incrementally instead of
55 * performing the sub-processing (strlen, normalization, case-folding)
56 * on the entire strings first.
57 *
58 * It is also unnecessary to not normalize identical characters.
59 *
60 * This function works in principle as follows:
61 *
62 * loop {
63 * get one code unit c1 from s1 (-1 if end of source)
64 * get one code unit c2 from s2 (-1 if end of source)
65 *
66 * if(either string finished) {
67 * return result;
68 * }
69 * if(c1==c2) {
70 * continue;
71 * }
72 *
73 * // c1!=c2
74 * try to decompose/case-fold c1/c2, and continue if one does;
75 *
76 * // still c1!=c2 and neither decomposes/case-folds, return result
77 * return c1-c2;
78 * }
79 *
80 * When a character decomposes, then the pointer for that source changes to
81 * the decomposition, pushing the previous pointer onto a stack.
82 * When the end of the decomposition is reached, then the code unit reader
83 * pops the previous source from the stack.
84 * (Same for case-folding.)
85 *
86 * This is complicated further by operating on variable-width UTF-16.
87 * The top part of the loop works on code units, while lookups for decomposition
88 * and case-folding need code points.
89 * Code points are assembled after the equality/end-of-source part.
90 * The source pointer is only advanced beyond all code units when the code point
91 * actually decomposes/case-folds.
92 *
93 * If we were on a trail surrogate unit when assembling a code point,
94 * and the code point decomposes/case-folds, then the decomposition/folding
95 * result must be compared with the part of the other string that corresponds to
96 * this string's lead surrogate.
97 * Since we only assemble a code point when hitting a trail unit when the
98 * preceding lead units were identical, we back up the other string by one unit
99 * in such a case.
100 *
101 * The optional code point order comparison at the end works with
102 * the same fix-up as the other code point order comparison functions.
103 * See ustring.c and the comment near the end of this function.
104 *
105 * Assumption: A decomposition or case-folding result string never contains
106 * a single surrogate. This is a safe assumption in the Unicode Standard.
107 * Therefore, we do not need to check for surrogate pairs across
108 * decomposition/case-folding boundaries.
109 *
110 * Further assumptions (see verifications tstnorm.cpp):
111 * The API function checks for FCD first, while the core function
112 * first case-folds and then decomposes. This requires that case-folding does not
113 * un-FCD any strings.
114 *
115 * The API function may also NFD the input and turn off decomposition.
116 * This requires that case-folding does not un-NFD strings either.
117 *
118 * TODO If any of the above two assumptions is violated,
119 * then this entire code must be re-thought.
120 * If this happens, then a simple solution is to case-fold both strings up front
121 * and to turn off UNORM_INPUT_IS_FCD.
122 * We already do this when not both strings are in FCD because makeFCD
123 * would be a partial NFD before the case folding, which does not work.
124 * Note that all of this is only a problem when case-folding _and_
125 * canonical equivalence come together.
126 * (Comments in unorm_compare() are more up to date than this TODO.)
127 */
129 /* stack element for previous-level source/decomposition pointers */
130 struct CmpEquivLevel {
131 const UChar *start, *s, *limit;
132 };
133 typedef struct CmpEquivLevel CmpEquivLevel;
135 /**
136 * Internal option for unorm_cmpEquivFold() for decomposing.
137 * If not set, just do strcasecmp().
138 */
139 #define _COMPARE_EQUIV 0x80000
141 /* internal function */
142 static int32_t
143 unorm_cmpEquivFold(const UChar *s1, int32_t length1,
144 const UChar *s2, int32_t length2,
145 uint32_t options,
146 UErrorCode *pErrorCode) {
147 const Normalizer2Impl *nfcImpl;
148 const UCaseProps *csp;
150 /* current-level start/limit - s1/s2 as current */
151 const UChar *start1, *start2, *limit1, *limit2;
153 /* decomposition and case folding variables */
154 const UChar *p;
155 int32_t length;
157 /* stacks of previous-level start/current/limit */
158 CmpEquivLevel stack1[2], stack2[2];
160 /* buffers for algorithmic decompositions */
161 UChar decomp1[4], decomp2[4];
163 /* case folding buffers, only use current-level start/limit */
164 UChar fold1[UCASE_MAX_STRING_LENGTH+1], fold2[UCASE_MAX_STRING_LENGTH+1];
166 /* track which is the current level per string */
167 int32_t level1, level2;
169 /* current code units, and code points for lookups */
170 UChar32 c1, c2, cp1, cp2;
172 /* no argument error checking because this itself is not an API */
174 /*
175 * assume that at least one of the options _COMPARE_EQUIV and U_COMPARE_IGNORE_CASE is set
176 * otherwise this function must behave exactly as uprv_strCompare()
177 * not checking for that here makes testing this function easier
178 */
180 /* normalization/properties data loaded? */
181 if((options&_COMPARE_EQUIV)!=0) {
182 nfcImpl=Normalizer2Factory::getNFCImpl(*pErrorCode);
183 } else {
184 nfcImpl=NULL;
185 }
186 if((options&U_COMPARE_IGNORE_CASE)!=0) {
187 csp=ucase_getSingleton();
188 } else {
189 csp=NULL;
190 }
191 if(U_FAILURE(*pErrorCode)) {
192 return 0;
193 }
195 /* initialize */
196 start1=s1;
197 if(length1==-1) {
198 limit1=NULL;
199 } else {
200 limit1=s1+length1;
201 }
203 start2=s2;
204 if(length2==-1) {
205 limit2=NULL;
206 } else {
207 limit2=s2+length2;
208 }
210 level1=level2=0;
211 c1=c2=-1;
213 /* comparison loop */
214 for(;;) {
215 /*
216 * here a code unit value of -1 means "get another code unit"
217 * below it will mean "this source is finished"
218 */
220 if(c1<0) {
221 /* get next code unit from string 1, post-increment */
222 for(;;) {
223 if(s1==limit1 || ((c1=*s1)==0 && (limit1==NULL || (options&_STRNCMP_STYLE)))) {
224 if(level1==0) {
225 c1=-1;
226 break;
227 }
228 } else {
229 ++s1;
230 break;
231 }
233 /* reached end of level buffer, pop one level */
234 do {
235 --level1;
236 start1=stack1[level1].start; /*Not uninitialized*/
237 } while(start1==NULL);
238 s1=stack1[level1].s; /*Not uninitialized*/
239 limit1=stack1[level1].limit; /*Not uninitialized*/
240 }
241 }
243 if(c2<0) {
244 /* get next code unit from string 2, post-increment */
245 for(;;) {
246 if(s2==limit2 || ((c2=*s2)==0 && (limit2==NULL || (options&_STRNCMP_STYLE)))) {
247 if(level2==0) {
248 c2=-1;
249 break;
250 }
251 } else {
252 ++s2;
253 break;
254 }
256 /* reached end of level buffer, pop one level */
257 do {
258 --level2;
259 start2=stack2[level2].start; /*Not uninitialized*/
260 } while(start2==NULL);
261 s2=stack2[level2].s; /*Not uninitialized*/
262 limit2=stack2[level2].limit; /*Not uninitialized*/
263 }
264 }
266 /*
267 * compare c1 and c2
268 * either variable c1, c2 is -1 only if the corresponding string is finished
269 */
270 if(c1==c2) {
271 if(c1<0) {
272 return 0; /* c1==c2==-1 indicating end of strings */
273 }
274 c1=c2=-1; /* make us fetch new code units */
275 continue;
276 } else if(c1<0) {
277 return -1; /* string 1 ends before string 2 */
278 } else if(c2<0) {
279 return 1; /* string 2 ends before string 1 */
280 }
281 /* c1!=c2 && c1>=0 && c2>=0 */
283 /* get complete code points for c1, c2 for lookups if either is a surrogate */
284 cp1=c1;
285 if(U_IS_SURROGATE(c1)) {
286 UChar c;
288 if(U_IS_SURROGATE_LEAD(c1)) {
289 if(s1!=limit1 && U16_IS_TRAIL(c=*s1)) {
290 /* advance ++s1; only below if cp1 decomposes/case-folds */
291 cp1=U16_GET_SUPPLEMENTARY(c1, c);
292 }
293 } else /* isTrail(c1) */ {
294 if(start1<=(s1-2) && U16_IS_LEAD(c=*(s1-2))) {
295 cp1=U16_GET_SUPPLEMENTARY(c, c1);
296 }
297 }
298 }
300 cp2=c2;
301 if(U_IS_SURROGATE(c2)) {
302 UChar c;
304 if(U_IS_SURROGATE_LEAD(c2)) {
305 if(s2!=limit2 && U16_IS_TRAIL(c=*s2)) {
306 /* advance ++s2; only below if cp2 decomposes/case-folds */
307 cp2=U16_GET_SUPPLEMENTARY(c2, c);
308 }
309 } else /* isTrail(c2) */ {
310 if(start2<=(s2-2) && U16_IS_LEAD(c=*(s2-2))) {
311 cp2=U16_GET_SUPPLEMENTARY(c, c2);
312 }
313 }
314 }
316 /*
317 * go down one level for each string
318 * continue with the main loop as soon as there is a real change
319 */
321 if( level1==0 && (options&U_COMPARE_IGNORE_CASE) &&
322 (length=ucase_toFullFolding(csp, (UChar32)cp1, &p, options))>=0
323 ) {
324 /* cp1 case-folds to the code point "length" or to p[length] */
325 if(U_IS_SURROGATE(c1)) {
326 if(U_IS_SURROGATE_LEAD(c1)) {
327 /* advance beyond source surrogate pair if it case-folds */
328 ++s1;
329 } else /* isTrail(c1) */ {
330 /*
331 * we got a supplementary code point when hitting its trail surrogate,
332 * therefore the lead surrogate must have been the same as in the other string;
333 * compare this decomposition with the lead surrogate in the other string
334 * remember that this simulates bulk text replacement:
335 * the decomposition would replace the entire code point
336 */
337 --s2;
338 c2=*(s2-1);
339 }
340 }
342 /* push current level pointers */
343 stack1[0].start=start1;
344 stack1[0].s=s1;
345 stack1[0].limit=limit1;
346 ++level1;
348 /* copy the folding result to fold1[] */
349 if(length<=UCASE_MAX_STRING_LENGTH) {
350 u_memcpy(fold1, p, length);
351 } else {
352 int32_t i=0;
353 U16_APPEND_UNSAFE(fold1, i, length);
354 length=i;
355 }
357 /* set next level pointers to case folding */
358 start1=s1=fold1;
359 limit1=fold1+length;
361 /* get ready to read from decomposition, continue with loop */
362 c1=-1;
363 continue;
364 }
366 if( level2==0 && (options&U_COMPARE_IGNORE_CASE) &&
367 (length=ucase_toFullFolding(csp, (UChar32)cp2, &p, options))>=0
368 ) {
369 /* cp2 case-folds to the code point "length" or to p[length] */
370 if(U_IS_SURROGATE(c2)) {
371 if(U_IS_SURROGATE_LEAD(c2)) {
372 /* advance beyond source surrogate pair if it case-folds */
373 ++s2;
374 } else /* isTrail(c2) */ {
375 /*
376 * we got a supplementary code point when hitting its trail surrogate,
377 * therefore the lead surrogate must have been the same as in the other string;
378 * compare this decomposition with the lead surrogate in the other string
379 * remember that this simulates bulk text replacement:
380 * the decomposition would replace the entire code point
381 */
382 --s1;
383 c1=*(s1-1);
384 }
385 }
387 /* push current level pointers */
388 stack2[0].start=start2;
389 stack2[0].s=s2;
390 stack2[0].limit=limit2;
391 ++level2;
393 /* copy the folding result to fold2[] */
394 if(length<=UCASE_MAX_STRING_LENGTH) {
395 u_memcpy(fold2, p, length);
396 } else {
397 int32_t i=0;
398 U16_APPEND_UNSAFE(fold2, i, length);
399 length=i;
400 }
402 /* set next level pointers to case folding */
403 start2=s2=fold2;
404 limit2=fold2+length;
406 /* get ready to read from decomposition, continue with loop */
407 c2=-1;
408 continue;
409 }
411 if( level1<2 && (options&_COMPARE_EQUIV) &&
412 0!=(p=nfcImpl->getDecomposition((UChar32)cp1, decomp1, length))
413 ) {
414 /* cp1 decomposes into p[length] */
415 if(U_IS_SURROGATE(c1)) {
416 if(U_IS_SURROGATE_LEAD(c1)) {
417 /* advance beyond source surrogate pair if it decomposes */
418 ++s1;
419 } else /* isTrail(c1) */ {
420 /*
421 * we got a supplementary code point when hitting its trail surrogate,
422 * therefore the lead surrogate must have been the same as in the other string;
423 * compare this decomposition with the lead surrogate in the other string
424 * remember that this simulates bulk text replacement:
425 * the decomposition would replace the entire code point
426 */
427 --s2;
428 c2=*(s2-1);
429 }
430 }
432 /* push current level pointers */
433 stack1[level1].start=start1;
434 stack1[level1].s=s1;
435 stack1[level1].limit=limit1;
436 ++level1;
438 /* set empty intermediate level if skipped */
439 if(level1<2) {
440 stack1[level1++].start=NULL;
441 }
443 /* set next level pointers to decomposition */
444 start1=s1=p;
445 limit1=p+length;
447 /* get ready to read from decomposition, continue with loop */
448 c1=-1;
449 continue;
450 }
452 if( level2<2 && (options&_COMPARE_EQUIV) &&
453 0!=(p=nfcImpl->getDecomposition((UChar32)cp2, decomp2, length))
454 ) {
455 /* cp2 decomposes into p[length] */
456 if(U_IS_SURROGATE(c2)) {
457 if(U_IS_SURROGATE_LEAD(c2)) {
458 /* advance beyond source surrogate pair if it decomposes */
459 ++s2;
460 } else /* isTrail(c2) */ {
461 /*
462 * we got a supplementary code point when hitting its trail surrogate,
463 * therefore the lead surrogate must have been the same as in the other string;
464 * compare this decomposition with the lead surrogate in the other string
465 * remember that this simulates bulk text replacement:
466 * the decomposition would replace the entire code point
467 */
468 --s1;
469 c1=*(s1-1);
470 }
471 }
473 /* push current level pointers */
474 stack2[level2].start=start2;
475 stack2[level2].s=s2;
476 stack2[level2].limit=limit2;
477 ++level2;
479 /* set empty intermediate level if skipped */
480 if(level2<2) {
481 stack2[level2++].start=NULL;
482 }
484 /* set next level pointers to decomposition */
485 start2=s2=p;
486 limit2=p+length;
488 /* get ready to read from decomposition, continue with loop */
489 c2=-1;
490 continue;
491 }
493 /*
494 * no decomposition/case folding, max level for both sides:
495 * return difference result
496 *
497 * code point order comparison must not just return cp1-cp2
498 * because when single surrogates are present then the surrogate pairs
499 * that formed cp1 and cp2 may be from different string indexes
500 *
501 * example: { d800 d800 dc01 } vs. { d800 dc00 }, compare at second code units
502 * c1=d800 cp1=10001 c2=dc00 cp2=10000
503 * cp1-cp2>0 but c1-c2<0 and in fact in UTF-32 it is { d800 10001 } < { 10000 }
504 *
505 * therefore, use same fix-up as in ustring.c/uprv_strCompare()
506 * except: uprv_strCompare() fetches c=*s while this functions fetches c=*s++
507 * so we have slightly different pointer/start/limit comparisons here
508 */
510 if(c1>=0xd800 && c2>=0xd800 && (options&U_COMPARE_CODE_POINT_ORDER)) {
511 /* subtract 0x2800 from BMP code points to make them smaller than supplementary ones */
512 if(
513 (c1<=0xdbff && s1!=limit1 && U16_IS_TRAIL(*s1)) ||
514 (U16_IS_TRAIL(c1) && start1!=(s1-1) && U16_IS_LEAD(*(s1-2)))
515 ) {
516 /* part of a surrogate pair, leave >=d800 */
517 } else {
518 /* BMP code point - may be surrogate code point - make <d800 */
519 c1-=0x2800;
520 }
522 if(
523 (c2<=0xdbff && s2!=limit2 && U16_IS_TRAIL(*s2)) ||
524 (U16_IS_TRAIL(c2) && start2!=(s2-1) && U16_IS_LEAD(*(s2-2)))
525 ) {
526 /* part of a surrogate pair, leave >=d800 */
527 } else {
528 /* BMP code point - may be surrogate code point - make <d800 */
529 c2-=0x2800;
530 }
531 }
533 return c1-c2;
534 }
535 }
537 static
538 UBool _normalize(const Normalizer2 *n2, const UChar *s, int32_t length,
539 UnicodeString &normalized, UErrorCode *pErrorCode) {
540 UnicodeString str(length<0, s, length);
542 // check if s fulfill the conditions
543 int32_t spanQCYes=n2->spanQuickCheckYes(str, *pErrorCode);
544 if (U_FAILURE(*pErrorCode)) {
545 return FALSE;
546 }
547 /*
548 * ICU 2.4 had a further optimization:
549 * If both strings were not in FCD, then they were both NFD'ed,
550 * and the _COMPARE_EQUIV option was turned off.
551 * It is not entirely clear that this is valid with the current
552 * definition of the canonical caseless match.
553 * Therefore, ICU 2.6 removes that optimization.
554 */
555 if(spanQCYes<str.length()) {
556 UnicodeString unnormalized=str.tempSubString(spanQCYes);
557 normalized.setTo(FALSE, str.getBuffer(), spanQCYes);
558 n2->normalizeSecondAndAppend(normalized, unnormalized, *pErrorCode);
559 if (U_SUCCESS(*pErrorCode)) {
560 return TRUE;
561 }
562 }
563 return FALSE;
564 }
566 U_CAPI int32_t U_EXPORT2
567 unorm_compare(const UChar *s1, int32_t length1,
568 const UChar *s2, int32_t length2,
569 uint32_t options,
570 UErrorCode *pErrorCode) {
571 /* argument checking */
572 if(U_FAILURE(*pErrorCode)) {
573 return 0;
574 }
575 if(s1==0 || length1<-1 || s2==0 || length2<-1) {
576 *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
577 return 0;
578 }
580 UnicodeString fcd1, fcd2;
581 int32_t normOptions=(int32_t)(options>>UNORM_COMPARE_NORM_OPTIONS_SHIFT);
582 options|=_COMPARE_EQUIV;
584 /*
585 * UAX #21 Case Mappings, as fixed for Unicode version 4
586 * (see Jitterbug 2021), defines a canonical caseless match as
587 *
588 * A string X is a canonical caseless match
589 * for a string Y if and only if
590 * NFD(toCasefold(NFD(X))) = NFD(toCasefold(NFD(Y)))
591 *
592 * For better performance, we check for FCD (or let the caller tell us that
593 * both strings are in FCD) for the inner normalization.
594 * BasicNormalizerTest::FindFoldFCDExceptions() makes sure that
595 * case-folding preserves the FCD-ness of a string.
596 * The outer normalization is then only performed by unorm_cmpEquivFold()
597 * when there is a difference.
598 *
599 * Exception: When using the Turkic case-folding option, we do perform
600 * full NFD first. This is because in the Turkic case precomposed characters
601 * with 0049 capital I or 0069 small i fold differently whether they
602 * are first decomposed or not, so an FCD check - a check only for
603 * canonical order - is not sufficient.
604 */
605 if(!(options&UNORM_INPUT_IS_FCD) || (options&U_FOLD_CASE_EXCLUDE_SPECIAL_I)) {
606 const Normalizer2 *n2;
607 if(options&U_FOLD_CASE_EXCLUDE_SPECIAL_I) {
608 n2=Normalizer2Factory::getNFDInstance(*pErrorCode);
609 } else {
610 n2=Normalizer2Factory::getFCDInstance(*pErrorCode);
611 }
612 if (U_FAILURE(*pErrorCode)) {
613 return 0;
614 }
616 if(normOptions&UNORM_UNICODE_3_2) {
617 const UnicodeSet *uni32=uniset_getUnicode32Instance(*pErrorCode);
618 FilteredNormalizer2 fn2(*n2, *uni32);
619 if(_normalize(&fn2, s1, length1, fcd1, pErrorCode)) {
620 s1=fcd1.getBuffer();
621 length1=fcd1.length();
622 }
623 if(_normalize(&fn2, s2, length2, fcd2, pErrorCode)) {
624 s2=fcd2.getBuffer();
625 length2=fcd2.length();
626 }
627 } else {
628 if(_normalize(n2, s1, length1, fcd1, pErrorCode)) {
629 s1=fcd1.getBuffer();
630 length1=fcd1.length();
631 }
632 if(_normalize(n2, s2, length2, fcd2, pErrorCode)) {
633 s2=fcd2.getBuffer();
634 length2=fcd2.length();
635 }
636 }
637 }
639 if(U_SUCCESS(*pErrorCode)) {
640 return unorm_cmpEquivFold(s1, length1, s2, length2, options, pErrorCode);
641 } else {
642 return 0;
643 }
644 }
646 #endif /* #if !UCONFIG_NO_NORMALIZATION */
