xref: /aosp_15_r20/external/icu/libandroidicu/include/unicode/unorm2.h (revision 0e209d3975ff4a8c132096b14b0e9364a753506e)
1 // © 2016 and later: Unicode, Inc. and others.
2 // License & terms of use: http://www.unicode.org/copyright.html
3 /*
4 *******************************************************************************
5 *
6 *   Copyright (C) 2009-2015, International Business Machines
7 *   Corporation and others.  All Rights Reserved.
8 *
9 *******************************************************************************
10 *   file name:  unorm2.h
11 *   encoding:   UTF-8
12 *   tab size:   8 (not used)
13 *   indentation:4
14 *
15 *   created on: 2009dec15
16 *   created by: Markus W. Scherer
17 */
18 
19 #ifndef __UNORM2_H__
20 #define __UNORM2_H__
21 
22 /**
23  * \file
24  * \brief C API: New API for Unicode Normalization.
25  *
26  * Unicode normalization functionality for standard Unicode normalization or
27  * for using custom mapping tables.
28  * All instances of UNormalizer2 are unmodifiable/immutable.
29  * Instances returned by unorm2_getInstance() are singletons that must not be deleted by the caller.
30  * For more details see the Normalizer2 C++ class.
31  */
32 
33 #include "unicode/utypes.h"
34 #include "unicode/stringoptions.h"
35 #include "unicode/uset.h"
36 
37 #if U_SHOW_CPLUSPLUS_API
38 #include "unicode/localpointer.h"
39 #endif   // U_SHOW_CPLUSPLUS_API
40 
41 /**
42  * Constants for normalization modes.
43  * For details about standard Unicode normalization forms
44  * and about the algorithms which are also used with custom mapping tables
45  * see http://www.unicode.org/unicode/reports/tr15/
46  * @stable ICU 4.4
47  */
48 typedef enum {
49     /**
50      * Decomposition followed by composition.
51      * Same as standard NFC when using an "nfc" instance.
52      * Same as standard NFKC when using an "nfkc" instance.
53      * For details about standard Unicode normalization forms
54      * see http://www.unicode.org/unicode/reports/tr15/
55      * @stable ICU 4.4
56      */
57     UNORM2_COMPOSE,
58     /**
59      * Map, and reorder canonically.
60      * Same as standard NFD when using an "nfc" instance.
61      * Same as standard NFKD when using an "nfkc" instance.
62      * For details about standard Unicode normalization forms
63      * see http://www.unicode.org/unicode/reports/tr15/
64      * @stable ICU 4.4
65      */
66     UNORM2_DECOMPOSE,
67     /**
68      * "Fast C or D" form.
69      * If a string is in this form, then further decomposition <i>without reordering</i>
70      * would yield the same form as DECOMPOSE.
71      * Text in "Fast C or D" form can be processed efficiently with data tables
72      * that are "canonically closed", that is, that provide equivalent data for
73      * equivalent text, without having to be fully normalized.
74      * Not a standard Unicode normalization form.
75      * Not a unique form: Different FCD strings can be canonically equivalent.
76      * For details see http://www.unicode.org/notes/tn5/#FCD
77      * @stable ICU 4.4
78      */
79     UNORM2_FCD,
80     /**
81      * Compose only contiguously.
82      * Also known as "FCC" or "Fast C Contiguous".
83      * The result will often but not always be in NFC.
84      * The result will conform to FCD which is useful for processing.
85      * Not a standard Unicode normalization form.
86      * For details see http://www.unicode.org/notes/tn5/#FCC
87      * @stable ICU 4.4
88      */
89     UNORM2_COMPOSE_CONTIGUOUS
90 } UNormalization2Mode;
91 
92 /**
93  * Result values for normalization quick check functions.
94  * For details see http://www.unicode.org/reports/tr15/#Detecting_Normalization_Forms
95  * @stable ICU 2.0
96  */
97 typedef enum UNormalizationCheckResult {
98   /**
99    * The input string is not in the normalization form.
100    * @stable ICU 2.0
101    */
102   UNORM_NO,
103   /**
104    * The input string is in the normalization form.
105    * @stable ICU 2.0
106    */
107   UNORM_YES,
108   /**
109    * The input string may or may not be in the normalization form.
110    * This value is only returned for composition forms like NFC and FCC,
111    * when a backward-combining character is found for which the surrounding text
112    * would have to be analyzed further.
113    * @stable ICU 2.0
114    */
115   UNORM_MAYBE
116 } UNormalizationCheckResult;
117 
118 /**
119  * Opaque C service object type for the new normalization API.
120  * @stable ICU 4.4
121  */
122 struct UNormalizer2;
123 typedef struct UNormalizer2 UNormalizer2;  /**< C typedef for struct UNormalizer2. @stable ICU 4.4 */
124 
125 #if !UCONFIG_NO_NORMALIZATION
126 
127 /**
128  * Returns a UNormalizer2 instance for Unicode NFC normalization.
129  * Same as unorm2_getInstance(NULL, "nfc", UNORM2_COMPOSE, pErrorCode).
130  * Returns an unmodifiable singleton instance. Do not delete it.
131  * @param pErrorCode Standard ICU error code. Its input value must
132  *                  pass the U_SUCCESS() test, or else the function returns
133  *                  immediately. Check for U_FAILURE() on output or use with
134  *                  function chaining. (See User Guide for details.)
135  * @return the requested Normalizer2, if successful
136  * @stable ICU 49
137  */
138 U_CAPI const UNormalizer2 * U_EXPORT2
139 unorm2_getNFCInstance(UErrorCode *pErrorCode);
140 
141 /**
142  * Returns a UNormalizer2 instance for Unicode NFD normalization.
143  * Same as unorm2_getInstance(NULL, "nfc", UNORM2_DECOMPOSE, pErrorCode).
144  * Returns an unmodifiable singleton instance. Do not delete it.
145  * @param pErrorCode Standard ICU error code. Its input value must
146  *                  pass the U_SUCCESS() test, or else the function returns
147  *                  immediately. Check for U_FAILURE() on output or use with
148  *                  function chaining. (See User Guide for details.)
149  * @return the requested Normalizer2, if successful
150  * @stable ICU 49
151  */
152 U_CAPI const UNormalizer2 * U_EXPORT2
153 unorm2_getNFDInstance(UErrorCode *pErrorCode);
154 
155 /**
156  * Returns a UNormalizer2 instance for Unicode NFKC normalization.
157  * Same as unorm2_getInstance(NULL, "nfkc", UNORM2_COMPOSE, pErrorCode).
158  * Returns an unmodifiable singleton instance. Do not delete it.
159  * @param pErrorCode Standard ICU error code. Its input value must
160  *                  pass the U_SUCCESS() test, or else the function returns
161  *                  immediately. Check for U_FAILURE() on output or use with
162  *                  function chaining. (See User Guide for details.)
163  * @return the requested Normalizer2, if successful
164  * @stable ICU 49
165  */
166 U_CAPI const UNormalizer2 * U_EXPORT2
167 unorm2_getNFKCInstance(UErrorCode *pErrorCode);
168 
169 /**
170  * Returns a UNormalizer2 instance for Unicode NFKD normalization.
171  * Same as unorm2_getInstance(NULL, "nfkc", UNORM2_DECOMPOSE, pErrorCode).
172  * Returns an unmodifiable singleton instance. Do not delete it.
173  * @param pErrorCode Standard ICU error code. Its input value must
174  *                  pass the U_SUCCESS() test, or else the function returns
175  *                  immediately. Check for U_FAILURE() on output or use with
176  *                  function chaining. (See User Guide for details.)
177  * @return the requested Normalizer2, if successful
178  * @stable ICU 49
179  */
180 U_CAPI const UNormalizer2 * U_EXPORT2
181 unorm2_getNFKDInstance(UErrorCode *pErrorCode);
182 
183 /**
184  * Returns a UNormalizer2 instance for Unicode toNFKC_Casefold() normalization
185  * which is equivalent to applying the NFKC_Casefold mappings and then NFC.
186  * See https://www.unicode.org/reports/tr44/#NFKC_Casefold
187  *
188  * Same as unorm2_getInstance(NULL, "nfkc_cf", UNORM2_COMPOSE, pErrorCode).
189  * Returns an unmodifiable singleton instance. Do not delete it.
190  * @param pErrorCode Standard ICU error code. Its input value must
191  *                  pass the U_SUCCESS() test, or else the function returns
192  *                  immediately. Check for U_FAILURE() on output or use with
193  *                  function chaining. (See User Guide for details.)
194  * @return the requested Normalizer2, if successful
195  * @stable ICU 49
196  */
197 U_CAPI const UNormalizer2 * U_EXPORT2
198 unorm2_getNFKCCasefoldInstance(UErrorCode *pErrorCode);
199 
200 #ifndef U_HIDE_DRAFT_API
201 /**
202  * Returns a UNormalizer2 instance for a variant of Unicode toNFKC_Casefold() normalization
203  * which is equivalent to applying the NFKC_Simple_Casefold mappings and then NFC.
204  * See https://www.unicode.org/reports/tr44/#NFKC_Simple_Casefold
205  *
206  * Same as unorm2_getInstance(NULL, "nfkc_scf", UNORM2_COMPOSE, pErrorCode).
207  * Returns an unmodifiable singleton instance. Do not delete it.
208  * @param pErrorCode Standard ICU error code. Its input value must
209  *                  pass the U_SUCCESS() test, or else the function returns
210  *                  immediately. Check for U_FAILURE() on output or use with
211  *                  function chaining. (See User Guide for details.)
212  * @return the requested Normalizer2, if successful
213  * @draft ICU 74
214  */
215 U_CAPI const UNormalizer2 * U_EXPORT2
216 unorm2_getNFKCSimpleCasefoldInstance(UErrorCode *pErrorCode);
217 #endif  // U_HIDE_DRAFT_API
218 
219 /**
220  * Returns a UNormalizer2 instance which uses the specified data file
221  * (packageName/name similar to ucnv_openPackage() and ures_open()/ResourceBundle)
222  * and which composes or decomposes text according to the specified mode.
223  * Returns an unmodifiable singleton instance. Do not delete it.
224  *
225  * Use packageName=NULL for data files that are part of ICU's own data.
226  * Use name="nfc" and UNORM2_COMPOSE/UNORM2_DECOMPOSE for Unicode standard NFC/NFD.
227  * Use name="nfkc" and UNORM2_COMPOSE/UNORM2_DECOMPOSE for Unicode standard NFKC/NFKD.
228  * Use name="nfkc_cf" and UNORM2_COMPOSE for Unicode standard NFKC_CF=NFKC_Casefold.
229  *
230  * @param packageName NULL for ICU built-in data, otherwise application data package name
231  * @param name "nfc" or "nfkc" or "nfkc_cf" or "nfkc_scf" or name of custom data file
232  * @param mode normalization mode (compose or decompose etc.)
233  * @param pErrorCode Standard ICU error code. Its input value must
234  *                  pass the U_SUCCESS() test, or else the function returns
235  *                  immediately. Check for U_FAILURE() on output or use with
236  *                  function chaining. (See User Guide for details.)
237  * @return the requested UNormalizer2, if successful
238  * @stable ICU 4.4
239  */
240 U_CAPI const UNormalizer2 * U_EXPORT2
241 unorm2_getInstance(const char *packageName,
242                    const char *name,
243                    UNormalization2Mode mode,
244                    UErrorCode *pErrorCode);
245 
246 /**
247  * Constructs a filtered normalizer wrapping any UNormalizer2 instance
248  * and a filter set.
249  * Both are aliased and must not be modified or deleted while this object
250  * is used.
251  * The filter set should be frozen; otherwise the performance will suffer greatly.
252  * @param norm2 wrapped UNormalizer2 instance
253  * @param filterSet USet which determines the characters to be normalized
254  * @param pErrorCode Standard ICU error code. Its input value must
255  *                   pass the U_SUCCESS() test, or else the function returns
256  *                   immediately. Check for U_FAILURE() on output or use with
257  *                   function chaining. (See User Guide for details.)
258  * @return the requested UNormalizer2, if successful
259  * @stable ICU 4.4
260  */
261 U_CAPI UNormalizer2 * U_EXPORT2
262 unorm2_openFiltered(const UNormalizer2 *norm2, const USet *filterSet, UErrorCode *pErrorCode);
263 
264 /**
265  * Closes a UNormalizer2 instance from unorm2_openFiltered().
266  * Do not close instances from unorm2_getInstance()!
267  * @param norm2 UNormalizer2 instance to be closed
268  * @stable ICU 4.4
269  */
270 U_CAPI void U_EXPORT2
271 unorm2_close(UNormalizer2 *norm2);
272 
273 #if U_SHOW_CPLUSPLUS_API
274 
275 U_NAMESPACE_BEGIN
276 
277 /**
278  * \class LocalUNormalizer2Pointer
279  * "Smart pointer" class, closes a UNormalizer2 via unorm2_close().
280  * For most methods see the LocalPointerBase base class.
281  *
282  * @see LocalPointerBase
283  * @see LocalPointer
284  * @stable ICU 4.4
285  */
286 U_DEFINE_LOCAL_OPEN_POINTER(LocalUNormalizer2Pointer, UNormalizer2, unorm2_close);
287 
288 U_NAMESPACE_END
289 
290 #endif
291 
292 /**
293  * Writes the normalized form of the source string to the destination string
294  * (replacing its contents) and returns the length of the destination string.
295  * The source and destination strings must be different buffers.
296  * @param norm2 UNormalizer2 instance
297  * @param src source string
298  * @param length length of the source string, or -1 if NUL-terminated
299  * @param dest destination string; its contents is replaced with normalized src
300  * @param capacity number of UChars that can be written to dest
301  * @param pErrorCode 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.)
305  * @return dest
306  * @stable ICU 4.4
307  */
308 U_CAPI int32_t U_EXPORT2
309 unorm2_normalize(const UNormalizer2 *norm2,
310                  const UChar *src, int32_t length,
311                  UChar *dest, int32_t capacity,
312                  UErrorCode *pErrorCode);
313 /**
314  * Appends the normalized form of the second string to the first string
315  * (merging them at the boundary) and returns the length of the first string.
316  * The result is normalized if the first string was normalized.
317  * The first and second strings must be different buffers.
318  * @param norm2 UNormalizer2 instance
319  * @param first string, should be normalized
320  * @param firstLength length of the first string, or -1 if NUL-terminated
321  * @param firstCapacity number of UChars that can be written to first
322  * @param second string, will be normalized
323  * @param secondLength length of the source string, or -1 if NUL-terminated
324  * @param pErrorCode Standard ICU error code. Its input value must
325  *                   pass the U_SUCCESS() test, or else the function returns
326  *                   immediately. Check for U_FAILURE() on output or use with
327  *                   function chaining. (See User Guide for details.)
328  * @return first
329  * @stable ICU 4.4
330  */
331 U_CAPI int32_t U_EXPORT2
332 unorm2_normalizeSecondAndAppend(const UNormalizer2 *norm2,
333                                 UChar *first, int32_t firstLength, int32_t firstCapacity,
334                                 const UChar *second, int32_t secondLength,
335                                 UErrorCode *pErrorCode);
336 /**
337  * Appends the second string to the first string
338  * (merging them at the boundary) and returns the length of the first string.
339  * The result is normalized if both the strings were normalized.
340  * The first and second strings must be different buffers.
341  * @param norm2 UNormalizer2 instance
342  * @param first string, should be normalized
343  * @param firstLength length of the first string, or -1 if NUL-terminated
344  * @param firstCapacity number of UChars that can be written to first
345  * @param second string, should be normalized
346  * @param secondLength length of the source string, or -1 if NUL-terminated
347  * @param pErrorCode Standard ICU error code. Its input value must
348  *                   pass the U_SUCCESS() test, or else the function returns
349  *                   immediately. Check for U_FAILURE() on output or use with
350  *                   function chaining. (See User Guide for details.)
351  * @return first
352  * @stable ICU 4.4
353  */
354 U_CAPI int32_t U_EXPORT2
355 unorm2_append(const UNormalizer2 *norm2,
356               UChar *first, int32_t firstLength, int32_t firstCapacity,
357               const UChar *second, int32_t secondLength,
358               UErrorCode *pErrorCode);
359 
360 /**
361  * Gets the decomposition mapping of c.
362  * Roughly equivalent to normalizing the String form of c
363  * on a UNORM2_DECOMPOSE UNormalizer2 instance, but much faster, and except that this function
364  * returns a negative value and does not write a string
365  * if c does not have a decomposition mapping in this instance's data.
366  * This function is independent of the mode of the UNormalizer2.
367  * @param norm2 UNormalizer2 instance
368  * @param c code point
369  * @param decomposition String buffer which will be set to c's
370  *                      decomposition mapping, if there is one.
371  * @param capacity number of UChars that can be written to decomposition
372  * @param pErrorCode Standard ICU error code. Its input value must
373  *                   pass the U_SUCCESS() test, or else the function returns
374  *                   immediately. Check for U_FAILURE() on output or use with
375  *                   function chaining. (See User Guide for details.)
376  * @return the non-negative length of c's decomposition, if there is one; otherwise a negative value
377  * @stable ICU 4.6
378  */
379 U_CAPI int32_t U_EXPORT2
380 unorm2_getDecomposition(const UNormalizer2 *norm2,
381                         UChar32 c, UChar *decomposition, int32_t capacity,
382                         UErrorCode *pErrorCode);
383 
384 /**
385  * Gets the raw decomposition mapping of c.
386  *
387  * This is similar to the unorm2_getDecomposition() function but returns the
388  * raw decomposition mapping as specified in UnicodeData.txt or
389  * (for custom data) in the mapping files processed by the gennorm2 tool.
390  * By contrast, unorm2_getDecomposition() returns the processed,
391  * recursively-decomposed version of this mapping.
392  *
393  * When used on a standard NFKC Normalizer2 instance,
394  * unorm2_getRawDecomposition() returns the Unicode Decomposition_Mapping (dm) property.
395  *
396  * When used on a standard NFC Normalizer2 instance,
397  * it returns the Decomposition_Mapping only if the Decomposition_Type (dt) is Canonical (Can);
398  * in this case, the result contains either one or two code points (=1..4 UChars).
399  *
400  * This function is independent of the mode of the UNormalizer2.
401  * @param norm2 UNormalizer2 instance
402  * @param c code point
403  * @param decomposition String buffer which will be set to c's
404  *                      raw decomposition mapping, if there is one.
405  * @param capacity number of UChars that can be written to decomposition
406  * @param pErrorCode Standard ICU error code. Its input value must
407  *                   pass the U_SUCCESS() test, or else the function returns
408  *                   immediately. Check for U_FAILURE() on output or use with
409  *                   function chaining. (See User Guide for details.)
410  * @return the non-negative length of c's raw decomposition, if there is one; otherwise a negative value
411  * @stable ICU 49
412  */
413 U_CAPI int32_t U_EXPORT2
414 unorm2_getRawDecomposition(const UNormalizer2 *norm2,
415                            UChar32 c, UChar *decomposition, int32_t capacity,
416                            UErrorCode *pErrorCode);
417 
418 /**
419  * Performs pairwise composition of a & b and returns the composite if there is one.
420  *
421  * Returns a composite code point c only if c has a two-way mapping to a+b.
422  * In standard Unicode normalization, this means that
423  * c has a canonical decomposition to a+b
424  * and c does not have the Full_Composition_Exclusion property.
425  *
426  * This function is independent of the mode of the UNormalizer2.
427  * @param norm2 UNormalizer2 instance
428  * @param a A (normalization starter) code point.
429  * @param b Another code point.
430  * @return The non-negative composite code point if there is one; otherwise a negative value.
431  * @stable ICU 49
432  */
433 U_CAPI UChar32 U_EXPORT2
434 unorm2_composePair(const UNormalizer2 *norm2, UChar32 a, UChar32 b);
435 
436 /**
437  * Gets the combining class of c.
438  * The default implementation returns 0
439  * but all standard implementations return the Unicode Canonical_Combining_Class value.
440  * @param norm2 UNormalizer2 instance
441  * @param c code point
442  * @return c's combining class
443  * @stable ICU 49
444  */
445 U_CAPI uint8_t U_EXPORT2
446 unorm2_getCombiningClass(const UNormalizer2 *norm2, UChar32 c);
447 
448 /**
449  * Tests if the string is normalized.
450  * Internally, in cases where the quickCheck() method would return "maybe"
451  * (which is only possible for the two COMPOSE modes) this method
452  * resolves to "yes" or "no" to provide a definitive result,
453  * at the cost of doing more work in those cases.
454  * @param norm2 UNormalizer2 instance
455  * @param s input string
456  * @param length length of the string, or -1 if NUL-terminated
457  * @param pErrorCode Standard ICU error code. Its input value must
458  *                   pass the U_SUCCESS() test, or else the function returns
459  *                   immediately. Check for U_FAILURE() on output or use with
460  *                   function chaining. (See User Guide for details.)
461  * @return true if s is normalized
462  * @stable ICU 4.4
463  */
464 U_CAPI UBool U_EXPORT2
465 unorm2_isNormalized(const UNormalizer2 *norm2,
466                     const UChar *s, int32_t length,
467                     UErrorCode *pErrorCode);
468 
469 /**
470  * Tests if the string is normalized.
471  * For the two COMPOSE modes, the result could be "maybe" in cases that
472  * would take a little more work to resolve definitively.
473  * Use spanQuickCheckYes() and normalizeSecondAndAppend() for a faster
474  * combination of quick check + normalization, to avoid
475  * re-checking the "yes" prefix.
476  * @param norm2 UNormalizer2 instance
477  * @param s input string
478  * @param length length of the string, or -1 if NUL-terminated
479  * @param pErrorCode Standard ICU error code. Its input value must
480  *                   pass the U_SUCCESS() test, or else the function returns
481  *                   immediately. Check for U_FAILURE() on output or use with
482  *                   function chaining. (See User Guide for details.)
483  * @return UNormalizationCheckResult
484  * @stable ICU 4.4
485  */
486 U_CAPI UNormalizationCheckResult U_EXPORT2
487 unorm2_quickCheck(const UNormalizer2 *norm2,
488                   const UChar *s, int32_t length,
489                   UErrorCode *pErrorCode);
490 
491 /**
492  * Returns the end of the normalized substring of the input string.
493  * In other words, with <code>end=spanQuickCheckYes(s, ec);</code>
494  * the substring <code>UnicodeString(s, 0, end)</code>
495  * will pass the quick check with a "yes" result.
496  *
497  * The returned end index is usually one or more characters before the
498  * "no" or "maybe" character: The end index is at a normalization boundary.
499  * (See the class documentation for more about normalization boundaries.)
500  *
501  * When the goal is a normalized string and most input strings are expected
502  * to be normalized already, then call this method,
503  * and if it returns a prefix shorter than the input string,
504  * copy that prefix and use normalizeSecondAndAppend() for the remainder.
505  * @param norm2 UNormalizer2 instance
506  * @param s input string
507  * @param length length of the string, or -1 if NUL-terminated
508  * @param pErrorCode Standard ICU error code. Its input value must
509  *                   pass the U_SUCCESS() test, or else the function returns
510  *                   immediately. Check for U_FAILURE() on output or use with
511  *                   function chaining. (See User Guide for details.)
512  * @return "yes" span end index
513  * @stable ICU 4.4
514  */
515 U_CAPI int32_t U_EXPORT2
516 unorm2_spanQuickCheckYes(const UNormalizer2 *norm2,
517                          const UChar *s, int32_t length,
518                          UErrorCode *pErrorCode);
519 
520 /**
521  * Tests if the character always has a normalization boundary before it,
522  * regardless of context.
523  * For details see the Normalizer2 base class documentation.
524  * @param norm2 UNormalizer2 instance
525  * @param c character to test
526  * @return true if c has a normalization boundary before it
527  * @stable ICU 4.4
528  */
529 U_CAPI UBool U_EXPORT2
530 unorm2_hasBoundaryBefore(const UNormalizer2 *norm2, UChar32 c);
531 
532 /**
533  * Tests if the character always has a normalization boundary after it,
534  * regardless of context.
535  * For details see the Normalizer2 base class documentation.
536  * @param norm2 UNormalizer2 instance
537  * @param c character to test
538  * @return true if c has a normalization boundary after it
539  * @stable ICU 4.4
540  */
541 U_CAPI UBool U_EXPORT2
542 unorm2_hasBoundaryAfter(const UNormalizer2 *norm2, UChar32 c);
543 
544 /**
545  * Tests if the character is normalization-inert.
546  * For details see the Normalizer2 base class documentation.
547  * @param norm2 UNormalizer2 instance
548  * @param c character to test
549  * @return true if c is normalization-inert
550  * @stable ICU 4.4
551  */
552 U_CAPI UBool U_EXPORT2
553 unorm2_isInert(const UNormalizer2 *norm2, UChar32 c);
554 
555 /**
556  * Compares two strings for canonical equivalence.
557  * Further options include case-insensitive comparison and
558  * code point order (as opposed to code unit order).
559  *
560  * Canonical equivalence between two strings is defined as their normalized
561  * forms (NFD or NFC) being identical.
562  * This function compares strings incrementally instead of normalizing
563  * (and optionally case-folding) both strings entirely,
564  * improving performance significantly.
565  *
566  * Bulk normalization is only necessary if the strings do not fulfill the FCD
567  * conditions. Only in this case, and only if the strings are relatively long,
568  * is memory allocated temporarily.
569  * For FCD strings and short non-FCD strings there is no memory allocation.
570  *
571  * Semantically, this is equivalent to
572  *   strcmp[CodePointOrder](NFD(foldCase(NFD(s1))), NFD(foldCase(NFD(s2))))
573  * where code point order and foldCase are all optional.
574  *
575  * UAX 21 2.5 Caseless Matching specifies that for a canonical caseless match
576  * the case folding must be performed first, then the normalization.
577  *
578  * @param s1 First source string.
579  * @param length1 Length of first source string, or -1 if NUL-terminated.
580  *
581  * @param s2 Second source string.
582  * @param length2 Length of second source string, or -1 if NUL-terminated.
583  *
584  * @param options A bit set of options:
585  *   - U_FOLD_CASE_DEFAULT or 0 is used for default options:
586  *     Case-sensitive comparison in code unit order, and the input strings
587  *     are quick-checked for FCD.
588  *
589  *   - UNORM_INPUT_IS_FCD
590  *     Set if the caller knows that both s1 and s2 fulfill the FCD conditions.
591  *     If not set, the function will quickCheck for FCD
592  *     and normalize if necessary.
593  *
594  *   - U_COMPARE_CODE_POINT_ORDER
595  *     Set to choose code point order instead of code unit order
596  *     (see u_strCompare for details).
597  *
598  *   - U_COMPARE_IGNORE_CASE
599  *     Set to compare strings case-insensitively using case folding,
600  *     instead of case-sensitively.
601  *     If set, then the following case folding options are used.
602  *
603  *   - Options as used with case-insensitive comparisons, currently:
604  *
605  *   - U_FOLD_CASE_EXCLUDE_SPECIAL_I
606  *    (see u_strCaseCompare for details)
607  *
608  *   - regular normalization options shifted left by UNORM_COMPARE_NORM_OPTIONS_SHIFT
609  *
610  * @param pErrorCode ICU error code in/out parameter.
611  *                   Must fulfill U_SUCCESS before the function call.
612  * @return <0 or 0 or >0 as usual for string comparisons
613  *
614  * @see unorm_normalize
615  * @see UNORM_FCD
616  * @see u_strCompare
617  * @see u_strCaseCompare
618  *
619  * @stable ICU 2.2
620  */
621 U_CAPI int32_t U_EXPORT2
622 unorm_compare(const UChar *s1, int32_t length1,
623               const UChar *s2, int32_t length2,
624               uint32_t options,
625               UErrorCode *pErrorCode);
626 
627 #endif  /* !UCONFIG_NO_NORMALIZATION */
628 #endif  /* __UNORM2_H__ */
629