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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 *
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 /**
201  * Returns a UNormalizer2 instance for a variant of Unicode toNFKC_Casefold() normalization
202  * which is equivalent to applying the NFKC_Simple_Casefold mappings and then NFC.
203  * See https://www.unicode.org/reports/tr44/#NFKC_Simple_Casefold
204  *
205  * Same as unorm2_getInstance(NULL, "nfkc_scf", UNORM2_COMPOSE, pErrorCode).
206  * Returns an unmodifiable singleton instance. Do not delete it.
207  * @param pErrorCode Standard ICU error code. Its input value must
208  *                  pass the U_SUCCESS() test, or else the function returns
209  *                  immediately. Check for U_FAILURE() on output or use with
210  *                  function chaining. (See User Guide for details.)
211  * @return the requested Normalizer2, if successful
212  * @stable ICU 74
213  */
214 U_CAPI const UNormalizer2 * U_EXPORT2
215 unorm2_getNFKCSimpleCasefoldInstance(UErrorCode *pErrorCode);
216 
217 /**
218  * Returns a UNormalizer2 instance which uses the specified data file
219  * (packageName/name similar to ucnv_openPackage() and ures_open()/ResourceBundle)
220  * and which composes or decomposes text according to the specified mode.
221  * Returns an unmodifiable singleton instance. Do not delete it.
222  *
223  * Use packageName=NULL for data files that are part of ICU's own data.
224  * Use name="nfc" and UNORM2_COMPOSE/UNORM2_DECOMPOSE for Unicode standard NFC/NFD.
225  * Use name="nfkc" and UNORM2_COMPOSE/UNORM2_DECOMPOSE for Unicode standard NFKC/NFKD.
226  * Use name="nfkc_cf" and UNORM2_COMPOSE for Unicode standard NFKC_CF=NFKC_Casefold.
227  *
228  * @param packageName NULL for ICU built-in data, otherwise application data package name
229  * @param name "nfc" or "nfkc" or "nfkc_cf" or "nfkc_scf" or name of custom data file
230  * @param mode normalization mode (compose or decompose etc.)
231  * @param pErrorCode Standard ICU error code. Its input value must
232  *                  pass the U_SUCCESS() test, or else the function returns
233  *                  immediately. Check for U_FAILURE() on output or use with
234  *                  function chaining. (See User Guide for details.)
235  * @return the requested UNormalizer2, if successful
236  * @stable ICU 4.4
237  */
238 U_CAPI const UNormalizer2 * U_EXPORT2
239 unorm2_getInstance(const char *packageName,
240                    const char *name,
241                    UNormalization2Mode mode,
242                    UErrorCode *pErrorCode);
243 
244 /**
245  * Constructs a filtered normalizer wrapping any UNormalizer2 instance
246  * and a filter set.
247  * Both are aliased and must not be modified or deleted while this object
248  * is used.
249  * The filter set should be frozen; otherwise the performance will suffer greatly.
250  * @param norm2 wrapped UNormalizer2 instance
251  * @param filterSet USet which determines the characters to be normalized
252  * @param pErrorCode Standard ICU error code. Its input value must
253  *                   pass the U_SUCCESS() test, or else the function returns
254  *                   immediately. Check for U_FAILURE() on output or use with
255  *                   function chaining. (See User Guide for details.)
256  * @return the requested UNormalizer2, if successful
257  * @stable ICU 4.4
258  */
259 U_CAPI UNormalizer2 * U_EXPORT2
260 unorm2_openFiltered(const UNormalizer2 *norm2, const USet *filterSet, UErrorCode *pErrorCode);
261 
262 /**
263  * Closes a UNormalizer2 instance from unorm2_openFiltered().
264  * Do not close instances from unorm2_getInstance()!
265  * @param norm2 UNormalizer2 instance to be closed
266  * @stable ICU 4.4
267  */
268 U_CAPI void U_EXPORT2
269 unorm2_close(UNormalizer2 *norm2);
270 
271 #if U_SHOW_CPLUSPLUS_API
272 
273 U_NAMESPACE_BEGIN
274 
275 /**
276  * \class LocalUNormalizer2Pointer
277  * "Smart pointer" class, closes a UNormalizer2 via unorm2_close().
278  * For most methods see the LocalPointerBase base class.
279  *
280  * @see LocalPointerBase
281  * @see LocalPointer
282  * @stable ICU 4.4
283  */
284 U_DEFINE_LOCAL_OPEN_POINTER(LocalUNormalizer2Pointer, UNormalizer2, unorm2_close);
285 
286 U_NAMESPACE_END
287 
288 #endif
289 
290 /**
291  * Writes the normalized form of the source string to the destination string
292  * (replacing its contents) and returns the length of the destination string.
293  * The source and destination strings must be different buffers.
294  * @param norm2 UNormalizer2 instance
295  * @param src source string
296  * @param length length of the source string, or -1 if NUL-terminated
297  * @param dest destination string; its contents is replaced with normalized src
298  * @param capacity number of UChars that can be written to dest
299  * @param pErrorCode Standard ICU error code. Its input value must
300  *                   pass the U_SUCCESS() test, or else the function returns
301  *                   immediately. Check for U_FAILURE() on output or use with
302  *                   function chaining. (See User Guide for details.)
303  * @return dest
304  * @stable ICU 4.4
305  */
306 U_CAPI int32_t U_EXPORT2
307 unorm2_normalize(const UNormalizer2 *norm2,
308                  const UChar *src, int32_t length,
309                  UChar *dest, int32_t capacity,
310                  UErrorCode *pErrorCode);
311 /**
312  * Appends the normalized form of the second string to the first string
313  * (merging them at the boundary) and returns the length of the first string.
314  * The result is normalized if the first string was normalized.
315  * The first and second strings must be different buffers.
316  * @param norm2 UNormalizer2 instance
317  * @param first string, should be normalized
318  * @param firstLength length of the first string, or -1 if NUL-terminated
319  * @param firstCapacity number of UChars that can be written to first
320  * @param second string, will be normalized
321  * @param secondLength length of the source string, or -1 if NUL-terminated
322  * @param pErrorCode Standard ICU error code. Its input value must
323  *                   pass the U_SUCCESS() test, or else the function returns
324  *                   immediately. Check for U_FAILURE() on output or use with
325  *                   function chaining. (See User Guide for details.)
326  * @return first
327  * @stable ICU 4.4
328  */
329 U_CAPI int32_t U_EXPORT2
330 unorm2_normalizeSecondAndAppend(const UNormalizer2 *norm2,
331                                 UChar *first, int32_t firstLength, int32_t firstCapacity,
332                                 const UChar *second, int32_t secondLength,
333                                 UErrorCode *pErrorCode);
334 /**
335  * Appends the second string to the first string
336  * (merging them at the boundary) and returns the length of the first string.
337  * The result is normalized if both the strings were normalized.
338  * The first and second strings must be different buffers.
339  * @param norm2 UNormalizer2 instance
340  * @param first string, should be normalized
341  * @param firstLength length of the first string, or -1 if NUL-terminated
342  * @param firstCapacity number of UChars that can be written to first
343  * @param second string, should be normalized
344  * @param secondLength length of the source string, or -1 if NUL-terminated
345  * @param pErrorCode Standard ICU error code. Its input value must
346  *                   pass the U_SUCCESS() test, or else the function returns
347  *                   immediately. Check for U_FAILURE() on output or use with
348  *                   function chaining. (See User Guide for details.)
349  * @return first
350  * @stable ICU 4.4
351  */
352 U_CAPI int32_t U_EXPORT2
353 unorm2_append(const UNormalizer2 *norm2,
354               UChar *first, int32_t firstLength, int32_t firstCapacity,
355               const UChar *second, int32_t secondLength,
356               UErrorCode *pErrorCode);
357 
358 /**
359  * Gets the decomposition mapping of c.
360  * Roughly equivalent to normalizing the String form of c
361  * on a UNORM2_DECOMPOSE UNormalizer2 instance, but much faster, and except that this function
362  * returns a negative value and does not write a string
363  * if c does not have a decomposition mapping in this instance's data.
364  * This function is independent of the mode of the UNormalizer2.
365  * @param norm2 UNormalizer2 instance
366  * @param c code point
367  * @param decomposition String buffer which will be set to c's
368  *                      decomposition mapping, if there is one.
369  * @param capacity number of UChars that can be written to decomposition
370  * @param pErrorCode Standard ICU error code. Its input value must
371  *                   pass the U_SUCCESS() test, or else the function returns
372  *                   immediately. Check for U_FAILURE() on output or use with
373  *                   function chaining. (See User Guide for details.)
374  * @return the non-negative length of c's decomposition, if there is one; otherwise a negative value
375  * @stable ICU 4.6
376  */
377 U_CAPI int32_t U_EXPORT2
378 unorm2_getDecomposition(const UNormalizer2 *norm2,
379                         UChar32 c, UChar *decomposition, int32_t capacity,
380                         UErrorCode *pErrorCode);
381 
382 /**
383  * Gets the raw decomposition mapping of c.
384  *
385  * This is similar to the unorm2_getDecomposition() function but returns the
386  * raw decomposition mapping as specified in UnicodeData.txt or
387  * (for custom data) in the mapping files processed by the gennorm2 tool.
388  * By contrast, unorm2_getDecomposition() returns the processed,
389  * recursively-decomposed version of this mapping.
390  *
391  * When used on a standard NFKC Normalizer2 instance,
392  * unorm2_getRawDecomposition() returns the Unicode Decomposition_Mapping (dm) property.
393  *
394  * When used on a standard NFC Normalizer2 instance,
395  * it returns the Decomposition_Mapping only if the Decomposition_Type (dt) is Canonical (Can);
396  * in this case, the result contains either one or two code points (=1..4 UChars).
397  *
398  * This function is independent of the mode of the UNormalizer2.
399  * @param norm2 UNormalizer2 instance
400  * @param c code point
401  * @param decomposition String buffer which will be set to c's
402  *                      raw decomposition mapping, if there is one.
403  * @param capacity number of UChars that can be written to decomposition
404  * @param pErrorCode Standard ICU error code. Its input value must
405  *                   pass the U_SUCCESS() test, or else the function returns
406  *                   immediately. Check for U_FAILURE() on output or use with
407  *                   function chaining. (See User Guide for details.)
408  * @return the non-negative length of c's raw decomposition, if there is one; otherwise a negative value
409  * @stable ICU 49
410  */
411 U_CAPI int32_t U_EXPORT2
412 unorm2_getRawDecomposition(const UNormalizer2 *norm2,
413                            UChar32 c, UChar *decomposition, int32_t capacity,
414                            UErrorCode *pErrorCode);
415 
416 /**
417  * Performs pairwise composition of a & b and returns the composite if there is one.
418  *
419  * Returns a composite code point c only if c has a two-way mapping to a+b.
420  * In standard Unicode normalization, this means that
421  * c has a canonical decomposition to a+b
422  * and c does not have the Full_Composition_Exclusion property.
423  *
424  * This function is independent of the mode of the UNormalizer2.
425  * @param norm2 UNormalizer2 instance
426  * @param a A (normalization starter) code point.
427  * @param b Another code point.
428  * @return The non-negative composite code point if there is one; otherwise a negative value.
429  * @stable ICU 49
430  */
431 U_CAPI UChar32 U_EXPORT2
432 unorm2_composePair(const UNormalizer2 *norm2, UChar32 a, UChar32 b);
433 
434 /**
435  * Gets the combining class of c.
436  * The default implementation returns 0
437  * but all standard implementations return the Unicode Canonical_Combining_Class value.
438  * @param norm2 UNormalizer2 instance
439  * @param c code point
440  * @return c's combining class
441  * @stable ICU 49
442  */
443 U_CAPI uint8_t U_EXPORT2
444 unorm2_getCombiningClass(const UNormalizer2 *norm2, UChar32 c);
445 
446 /**
447  * Tests if the string is normalized.
448  * Internally, in cases where the quickCheck() method would return "maybe"
449  * (which is only possible for the two COMPOSE modes) this method
450  * resolves to "yes" or "no" to provide a definitive result,
451  * at the cost of doing more work in those cases.
452  * @param norm2 UNormalizer2 instance
453  * @param s input string
454  * @param length length of the string, or -1 if NUL-terminated
455  * @param pErrorCode Standard ICU error code. Its input value must
456  *                   pass the U_SUCCESS() test, or else the function returns
457  *                   immediately. Check for U_FAILURE() on output or use with
458  *                   function chaining. (See User Guide for details.)
459  * @return true if s is normalized
460  * @stable ICU 4.4
461  */
462 U_CAPI UBool U_EXPORT2
463 unorm2_isNormalized(const UNormalizer2 *norm2,
464                     const UChar *s, int32_t length,
465                     UErrorCode *pErrorCode);
466 
467 /**
468  * Tests if the string is normalized.
469  * For the two COMPOSE modes, the result could be "maybe" in cases that
470  * would take a little more work to resolve definitively.
471  * Use spanQuickCheckYes() and normalizeSecondAndAppend() for a faster
472  * combination of quick check + normalization, to avoid
473  * re-checking the "yes" prefix.
474  * @param norm2 UNormalizer2 instance
475  * @param s input string
476  * @param length length of the string, or -1 if NUL-terminated
477  * @param pErrorCode Standard ICU error code. Its input value must
478  *                   pass the U_SUCCESS() test, or else the function returns
479  *                   immediately. Check for U_FAILURE() on output or use with
480  *                   function chaining. (See User Guide for details.)
481  * @return UNormalizationCheckResult
482  * @stable ICU 4.4
483  */
484 U_CAPI UNormalizationCheckResult U_EXPORT2
485 unorm2_quickCheck(const UNormalizer2 *norm2,
486                   const UChar *s, int32_t length,
487                   UErrorCode *pErrorCode);
488 
489 /**
490  * Returns the end of the normalized substring of the input string.
491  * In other words, with <code>end=spanQuickCheckYes(s, ec);</code>
492  * the substring <code>UnicodeString(s, 0, end)</code>
493  * will pass the quick check with a "yes" result.
494  *
495  * The returned end index is usually one or more characters before the
496  * "no" or "maybe" character: The end index is at a normalization boundary.
497  * (See the class documentation for more about normalization boundaries.)
498  *
499  * When the goal is a normalized string and most input strings are expected
500  * to be normalized already, then call this method,
501  * and if it returns a prefix shorter than the input string,
502  * copy that prefix and use normalizeSecondAndAppend() for the remainder.
503  * @param norm2 UNormalizer2 instance
504  * @param s input string
505  * @param length length of the string, or -1 if NUL-terminated
506  * @param pErrorCode Standard ICU error code. Its input value must
507  *                   pass the U_SUCCESS() test, or else the function returns
508  *                   immediately. Check for U_FAILURE() on output or use with
509  *                   function chaining. (See User Guide for details.)
510  * @return "yes" span end index
511  * @stable ICU 4.4
512  */
513 U_CAPI int32_t U_EXPORT2
514 unorm2_spanQuickCheckYes(const UNormalizer2 *norm2,
515                          const UChar *s, int32_t length,
516                          UErrorCode *pErrorCode);
517 
518 /**
519  * Tests if the character always has a normalization boundary before it,
520  * regardless of context.
521  * For details see the Normalizer2 base class documentation.
522  * @param norm2 UNormalizer2 instance
523  * @param c character to test
524  * @return true if c has a normalization boundary before it
525  * @stable ICU 4.4
526  */
527 U_CAPI UBool U_EXPORT2
528 unorm2_hasBoundaryBefore(const UNormalizer2 *norm2, UChar32 c);
529 
530 /**
531  * Tests if the character always has a normalization boundary after it,
532  * regardless of context.
533  * For details see the Normalizer2 base class documentation.
534  * @param norm2 UNormalizer2 instance
535  * @param c character to test
536  * @return true if c has a normalization boundary after it
537  * @stable ICU 4.4
538  */
539 U_CAPI UBool U_EXPORT2
540 unorm2_hasBoundaryAfter(const UNormalizer2 *norm2, UChar32 c);
541 
542 /**
543  * Tests if the character is normalization-inert.
544  * For details see the Normalizer2 base class documentation.
545  * @param norm2 UNormalizer2 instance
546  * @param c character to test
547  * @return true if c is normalization-inert
548  * @stable ICU 4.4
549  */
550 U_CAPI UBool U_EXPORT2
551 unorm2_isInert(const UNormalizer2 *norm2, UChar32 c);
552 
553 /**
554  * Compares two strings for canonical equivalence.
555  * Further options include case-insensitive comparison and
556  * code point order (as opposed to code unit order).
557  *
558  * Canonical equivalence between two strings is defined as their normalized
559  * forms (NFD or NFC) being identical.
560  * This function compares strings incrementally instead of normalizing
561  * (and optionally case-folding) both strings entirely,
562  * improving performance significantly.
563  *
564  * Bulk normalization is only necessary if the strings do not fulfill the FCD
565  * conditions. Only in this case, and only if the strings are relatively long,
566  * is memory allocated temporarily.
567  * For FCD strings and short non-FCD strings there is no memory allocation.
568  *
569  * Semantically, this is equivalent to
570  *   strcmp[CodePointOrder](NFD(foldCase(NFD(s1))), NFD(foldCase(NFD(s2))))
571  * where code point order and foldCase are all optional.
572  *
573  * UAX 21 2.5 Caseless Matching specifies that for a canonical caseless match
574  * the case folding must be performed first, then the normalization.
575  *
576  * @param s1 First source string.
577  * @param length1 Length of first source string, or -1 if NUL-terminated.
578  *
579  * @param s2 Second source string.
580  * @param length2 Length of second source string, or -1 if NUL-terminated.
581  *
582  * @param options A bit set of options:
583  *   - U_FOLD_CASE_DEFAULT or 0 is used for default options:
584  *     Case-sensitive comparison in code unit order, and the input strings
585  *     are quick-checked for FCD.
586  *
587  *   - UNORM_INPUT_IS_FCD
588  *     Set if the caller knows that both s1 and s2 fulfill the FCD conditions.
589  *     If not set, the function will quickCheck for FCD
590  *     and normalize if necessary.
591  *
592  *   - U_COMPARE_CODE_POINT_ORDER
593  *     Set to choose code point order instead of code unit order
594  *     (see u_strCompare for details).
595  *
596  *   - U_COMPARE_IGNORE_CASE
597  *     Set to compare strings case-insensitively using case folding,
598  *     instead of case-sensitively.
599  *     If set, then the following case folding options are used.
600  *
601  *   - Options as used with case-insensitive comparisons, currently:
602  *
603  *   - U_FOLD_CASE_EXCLUDE_SPECIAL_I
604  *    (see u_strCaseCompare for details)
605  *
606  *   - regular normalization options shifted left by UNORM_COMPARE_NORM_OPTIONS_SHIFT
607  *
608  * @param pErrorCode ICU error code in/out parameter.
609  *                   Must fulfill U_SUCCESS before the function call.
610  * @return <0 or 0 or >0 as usual for string comparisons
611  *
612  * @see unorm_normalize
613  * @see UNORM_FCD
614  * @see u_strCompare
615  * @see u_strCaseCompare
616  *
617  * @stable ICU 2.2
618  */
619 U_CAPI int32_t U_EXPORT2
620 unorm_compare(const UChar *s1, int32_t length1,
621               const UChar *s2, int32_t length2,
622               uint32_t options,
623               UErrorCode *pErrorCode);
624 
625 #endif  /* !UCONFIG_NO_NORMALIZATION */
626 #endif  /* __UNORM2_H__ */
627