1 /*
2 *******************************************************************************
3 *
4 * Copyright (C) 2001-2007, International Business Machines
5 * Corporation and others. All Rights Reserved.
6 *
7 *******************************************************************************
8 * file name: unormimp.h
9 * encoding: US-ASCII
10 * tab size: 8 (not used)
11 * indentation:4
12 *
13 * created on: 2001may25
14 * created by: Markus W. Scherer
15 */
16
17 #ifndef __UNORMIMP_H__
18 #define __UNORMIMP_H__
19
20 #include "unicode/utypes.h"
21
22 #if !UCONFIG_NO_NORMALIZATION
23
24 #ifdef XP_CPLUSPLUS
25 #include "unicode/uniset.h"
26 #endif
27
28 #include "unicode/uiter.h"
29 #include "unicode/unorm.h"
30 #include "unicode/uset.h"
31 #include "utrie.h"
32 #include "ustr_imp.h"
33 #include "udataswp.h"
34
35 /*
36 * This new implementation of the normalization code loads its data from
37 * unorm.icu, which is generated with the gennorm tool.
38 * The format of that file is described at the end of this file.
39 */
40
41 /* norm32 value constants */
42 enum {
43 /* quick check flags 0..3 set mean "no" for their forms */
44 _NORM_QC_NFC=0x11, /* no|maybe */
45 _NORM_QC_NFKC=0x22, /* no|maybe */
46 _NORM_QC_NFD=4, /* no */
47 _NORM_QC_NFKD=8, /* no */
48
49 _NORM_QC_ANY_NO=0xf,
50
51 /* quick check flags 4..5 mean "maybe" for their forms; test flags>=_NORM_QC_MAYBE */
52 _NORM_QC_MAYBE=0x10,
53 _NORM_QC_ANY_MAYBE=0x30,
54
55 _NORM_QC_MASK=0x3f,
56
57 _NORM_COMBINES_FWD=0x40,
58 _NORM_COMBINES_BACK=0x80,
59 _NORM_COMBINES_ANY=0xc0,
60
61 _NORM_CC_SHIFT=8, /* UnicodeData.txt combining class in bits 15..8 */
62 _NORM_CC_MASK=0xff00,
63
64 _NORM_EXTRA_SHIFT=16, /* 16 bits for the index to UChars and other extra data */
65 _NORM_EXTRA_INDEX_TOP=0xfc00, /* start of surrogate specials after shift */
66
67 _NORM_EXTRA_SURROGATE_MASK=0x3ff,
68 _NORM_EXTRA_SURROGATE_TOP=0x3f0, /* hangul etc. */
69
70 _NORM_EXTRA_HANGUL=_NORM_EXTRA_SURROGATE_TOP,
71 _NORM_EXTRA_JAMO_L,
72 _NORM_EXTRA_JAMO_V,
73 _NORM_EXTRA_JAMO_T
74 };
75
76 /* norm32 value constants using >16 bits */
77 #define _NORM_MIN_SPECIAL 0xfc000000
78 #define _NORM_SURROGATES_TOP 0xfff00000
79 #define _NORM_MIN_HANGUL 0xfff00000
80 #define _NORM_MIN_JAMO_V 0xfff20000
81 #define _NORM_JAMO_V_TOP 0xfff30000
82
83 /* value constants for auxTrie */
84 enum {
85 _NORM_AUX_COMP_EX_SHIFT=10,
86 _NORM_AUX_UNSAFE_SHIFT=11,
87 _NORM_AUX_NFC_SKIPPABLE_F_SHIFT=12
88 };
89
90 #define _NORM_AUX_MAX_FNC ((int32_t)1<<_NORM_AUX_COMP_EX_SHIFT)
91
92 #define _NORM_AUX_FNC_MASK (uint32_t)(_NORM_AUX_MAX_FNC-1)
93 #define _NORM_AUX_COMP_EX_MASK ((uint32_t)1<<_NORM_AUX_COMP_EX_SHIFT)
94 #define _NORM_AUX_UNSAFE_MASK ((uint32_t)1<<_NORM_AUX_UNSAFE_SHIFT)
95 #define _NORM_AUX_NFC_SKIP_F_MASK ((uint32_t)1<<_NORM_AUX_NFC_SKIPPABLE_F_SHIFT)
96
97 /* canonStartSets[0..31] contains indexes for what is in the array */
98 enum {
99 _NORM_SET_INDEX_CANON_SETS_LENGTH, /* number of uint16_t in canonical starter sets */
100 _NORM_SET_INDEX_CANON_BMP_TABLE_LENGTH, /* number of uint16_t in the BMP search table (contains pairs) */
101 _NORM_SET_INDEX_CANON_SUPP_TABLE_LENGTH,/* number of uint16_t in the supplementary search table (contains triplets) */
102
103 /* from formatVersion 2.3: */
104 _NORM_SET_INDEX_NX_CJK_COMPAT_OFFSET, /* uint16_t offset from canonStartSets[0] to the
105 exclusion set for CJK compatibility characters */
106 _NORM_SET_INDEX_NX_UNICODE32_OFFSET, /* uint16_t offset from canonStartSets[0] to the
107 exclusion set for Unicode 3.2 characters */
108 _NORM_SET_INDEX_NX_RESERVED_OFFSET, /* uint16_t offset from canonStartSets[0] to the
109 end of the previous exclusion set */
110
111 _NORM_SET_INDEX_TOP=32 /* changing this requires a new formatVersion */
112 };
113
114 /* more constants for canonical starter sets */
115
116 /* 14 bit indexes to canonical USerializedSets */
117 #define _NORM_MAX_CANON_SETS 0x4000
118
119 /* single-code point BMP sets are encoded directly in the search table except if result=0x4000..0x7fff */
120 #define _NORM_CANON_SET_BMP_MASK 0xc000
121 #define _NORM_CANON_SET_BMP_IS_INDEX 0x4000
122
123 /* indexes[] value names */
124 enum {
125 _NORM_INDEX_TRIE_SIZE, /* number of bytes in normalization trie */
126 _NORM_INDEX_UCHAR_COUNT, /* number of UChars in extra data */
127
128 _NORM_INDEX_COMBINE_DATA_COUNT, /* number of uint16_t words for combining data */
129 _NORM_INDEX_COMBINE_FWD_COUNT, /* number of code points that combine forward */
130 _NORM_INDEX_COMBINE_BOTH_COUNT, /* number of code points that combine forward and backward */
131 _NORM_INDEX_COMBINE_BACK_COUNT, /* number of code points that combine backward */
132
133 _NORM_INDEX_MIN_NFC_NO_MAYBE, /* first code point with quick check NFC NO/MAYBE */
134 _NORM_INDEX_MIN_NFKC_NO_MAYBE, /* first code point with quick check NFKC NO/MAYBE */
135 _NORM_INDEX_MIN_NFD_NO_MAYBE, /* first code point with quick check NFD NO/MAYBE */
136 _NORM_INDEX_MIN_NFKD_NO_MAYBE, /* first code point with quick check NFKD NO/MAYBE */
137
138 _NORM_INDEX_FCD_TRIE_SIZE, /* number of bytes in FCD trie */
139
140 _NORM_INDEX_AUX_TRIE_SIZE, /* number of bytes in the auxiliary trie */
141 _NORM_INDEX_CANON_SET_COUNT, /* number of uint16_t in the array of serialized USet */
142
143 _NORM_INDEX_TOP=32 /* changing this requires a new formatVersion */
144 };
145
146 enum {
147 /* FCD check: everything below this code point is known to have a 0 lead combining class */
148 _NORM_MIN_WITH_LEAD_CC=0x300
149 };
150
151 enum {
152 /**
153 * Bit 7 of the length byte for a decomposition string in extra data is
154 * a flag indicating whether the decomposition string is
155 * preceded by a 16-bit word with the leading and trailing cc
156 * of the decomposition (like for A-umlaut);
157 * if not, then both cc's are zero (like for compatibility ideographs).
158 */
159 _NORM_DECOMP_FLAG_LENGTH_HAS_CC=0x80,
160 /**
161 * Bits 6..0 of the length byte contain the actual length.
162 */
163 _NORM_DECOMP_LENGTH_MASK=0x7f
164 };
165
166 #endif /* #if !UCONFIG_NO_NORMALIZATION */
167
168 /* Korean Hangul and Jamo constants */
169 enum {
170 JAMO_L_BASE=0x1100, /* "lead" jamo */
171 JAMO_V_BASE=0x1161, /* "vowel" jamo */
172 JAMO_T_BASE=0x11a7, /* "trail" jamo */
173
174 HANGUL_BASE=0xac00,
175
176 JAMO_L_COUNT=19,
177 JAMO_V_COUNT=21,
178 JAMO_T_COUNT=28,
179
180 HANGUL_COUNT=JAMO_L_COUNT*JAMO_V_COUNT*JAMO_T_COUNT
181 };
182
183 #if !UCONFIG_NO_NORMALIZATION
184
185 /* Constants for options flags for normalization. @draft ICU 2.6 */
186 enum {
187 /** Options bit 0, do not decompose Hangul syllables. @draft ICU 2.6 */
188 UNORM_NX_HANGUL=1,
189 /** Options bit 1, do not decompose CJK compatibility characters. @draft ICU 2.6 */
190 UNORM_NX_CJK_COMPAT=2,
191 /**
192 * Options bit 8, use buggy recomposition described in
193 * Unicode Public Review Issue #29
194 * at http://www.unicode.org/review/resolved-pri.html#pri29
195 *
196 * Used in IDNA implementation according to strict interpretation
197 * of IDNA definition based on Unicode 3.2 which predates PRI #29.
198 */
199 UNORM_BEFORE_PRI_29=0x100
200 };
201
202 /**
203 * Is the normalizer data loaded?
204 * This is used internally before other internal normalizer functions
205 * are called.
206 * It saves this check in each of many normalization calls that
207 * are made for, e.g., collation.
208 *
209 * @param pErrorCode as usual
210 * @return boolean value for whether the normalization data is loaded
211 *
212 * @internal
213 */
214 U_CAPI UBool U_EXPORT2
215 unorm_haveData(UErrorCode *pErrorCode);
216
217 /**
218 * Internal API for normalizing.
219 * Does not check for bad input.
220 * @internal
221 */
222 U_CAPI int32_t U_EXPORT2
223 unorm_internalNormalize(UChar *dest, int32_t destCapacity,
224 const UChar *src, int32_t srcLength,
225 UNormalizationMode mode, int32_t options,
226 UErrorCode *pErrorCode);
227
228 #ifdef XP_CPLUSPLUS
229
230 /**
231 * Internal API for normalizing.
232 * Does not check for bad input.
233 * Requires _haveData() to be true.
234 * @internal
235 */
236 U_CFUNC int32_t
237 unorm_internalNormalizeWithNX(UChar *dest, int32_t destCapacity,
238 const UChar *src, int32_t srcLength,
239 UNormalizationMode mode, int32_t options, const U_NAMESPACE_QUALIFIER UnicodeSet *nx,
240 UErrorCode *pErrorCode);
241
242 #endif
243
244 /**
245 * internal API, used by normlzr.cpp
246 * @internal
247 */
248 U_CAPI int32_t U_EXPORT2
249 unorm_decompose(UChar *dest, int32_t destCapacity,
250 const UChar *src, int32_t srcLength,
251 UBool compat, int32_t options,
252 UErrorCode *pErrorCode);
253
254 /**
255 * internal API, used by normlzr.cpp
256 * @internal
257 */
258 U_CAPI int32_t U_EXPORT2
259 unorm_compose(UChar *dest, int32_t destCapacity,
260 const UChar *src, int32_t srcLength,
261 UBool compat, int32_t options,
262 UErrorCode *pErrorCode);
263
264 #ifdef XP_CPLUSPLUS
265
266 /**
267 * internal API, used by unormcmp.cpp
268 * @internal
269 */
270 U_CFUNC UNormalizationCheckResult
271 unorm_internalQuickCheck(const UChar *src,
272 int32_t srcLength,
273 UNormalizationMode mode,
274 UBool allowMaybe,
275 const U_NAMESPACE_QUALIFIER UnicodeSet *nx,
276 UErrorCode *pErrorCode);
277
278 #endif
279
280 #endif /* #if !UCONFIG_NO_NORMALIZATION */
281
282 /**
283 * Internal option for unorm_cmpEquivFold() for decomposing.
284 * If not set, just do strcasecmp().
285 * @internal
286 */
287 #define _COMPARE_EQUIV 0x80000
288
289 #ifndef U_COMPARE_IGNORE_CASE
290 /* see also unorm.h */
291 /**
292 * Option bit for unorm_compare:
293 * Perform case-insensitive comparison.
294 * @draft ICU 2.2
295 */
296 #define U_COMPARE_IGNORE_CASE 0x10000
297 #endif
298
299 /**
300 * Internal option for unorm_cmpEquivFold() for strncmp style.
301 * If set, checks for both string length and terminating NUL.
302 * @internal
303 */
304 #define _STRNCMP_STYLE 0x1000
305
306 #if !UCONFIG_NO_NORMALIZATION
307
308 /**
309 * Internal API to get the 16-bit FCD value (lccc + tccc) for c,
310 * for u_getIntPropertyValue().
311 * @internal
312 */
313 U_CFUNC uint16_t U_EXPORT2
314 unorm_getFCD16FromCodePoint(UChar32 c);
315
316 /**
317 * Internal API, used by collation code.
318 * Get access to the internal FCD trie table to be able to perform
319 * incremental, per-code unit, FCD checks in collation.
320 * One pointer is sufficient because the trie index values are offset
321 * by the index size, so that the same pointer is used to access the trie data.
322 * @internal
323 */
324 U_CAPI const uint16_t * U_EXPORT2
325 unorm_getFCDTrie(UErrorCode *pErrorCode);
326
327 #ifdef XP_CPLUSPLUS
328
329 /**
330 * Internal API, used by collation code.
331 * Get the FCD value for a code unit, with
332 * bits 15..8 lead combining class
333 * bits 7..0 trail combining class
334 *
335 * If c is a lead surrogate and the value is not 0,
336 * then instead of combining classes the value
337 * is used in unorm_getFCD16FromSurrogatePair() to get the real value
338 * of the supplementary code point.
339 *
340 * @internal
341 */
342 static inline uint16_t
unorm_getFCD16(const uint16_t * fcdTrieIndex,UChar c)343 unorm_getFCD16(const uint16_t *fcdTrieIndex, UChar c) {
344 return
345 fcdTrieIndex[
346 (fcdTrieIndex[
347 c>>UTRIE_SHIFT
348 ]<<UTRIE_INDEX_SHIFT)+
349 (c&UTRIE_MASK)
350 ];
351 }
352
353 /**
354 * Internal API, used by collation code.
355 * Get the FCD value for a supplementary code point, with
356 * bits 15..8 lead combining class
357 * bits 7..0 trail combining class
358 *
359 * @param fcd16 The FCD value for the lead surrogate, not 0.
360 * @param c2 The trail surrogate code unit.
361 *
362 * @internal
363 */
364 static inline uint16_t
unorm_getFCD16FromSurrogatePair(const uint16_t * fcdTrieIndex,uint16_t fcd16,UChar c2)365 unorm_getFCD16FromSurrogatePair(const uint16_t *fcdTrieIndex, uint16_t fcd16, UChar c2) {
366 return
367 fcdTrieIndex[
368 (fcdTrieIndex[
369 (int32_t)fcd16+((c2&0x3ff)>>UTRIE_SHIFT)
370 ]<<UTRIE_INDEX_SHIFT)+
371 (c2&UTRIE_MASK)
372 ];
373 }
374
375
376 #endif
377
378 /**
379 * internal API, used by StringPrep
380 * @internal
381 */
382 U_CAPI void U_EXPORT2
383 unorm_getUnicodeVersion(UVersionInfo *versionInfo, UErrorCode *pErrorCode);
384
385 /**
386 * Get the canonical decomposition for one code point.
387 * Requires unorm_haveData() and buffer!=NULL and pLength!=NULL.
388 * @param c code point
389 * @param buffer out-only buffer for algorithmic decompositions of Hangul
390 * @param length out-only, takes the length of the decomposition, if any
391 * @return pointer to decomposition, or 0 if none
392 * @internal
393 */
394 U_CFUNC const UChar *
395 unorm_getCanonicalDecomposition(UChar32 c, UChar buffer[4], int32_t *pLength);
396
397 /**
398 * internal API, used by the canonical iterator
399 * TODO Consider using signature similar to unorm_getCanonicalDecomposition()
400 * for more efficiency
401 * @internal
402 */
403 U_CAPI int32_t U_EXPORT2
404 unorm_getDecomposition(UChar32 c, UBool compat,
405 UChar *dest, int32_t destCapacity);
406
407 /**
408 * internal API, used by uprops.cpp
409 * @internal
410 */
411 U_CFUNC UBool U_EXPORT2
412 unorm_internalIsFullCompositionExclusion(UChar32 c);
413
414 /**
415 * Internal API, used by enumeration of canonically equivalent strings
416 * @internal
417 */
418 U_CFUNC UBool U_EXPORT2
419 unorm_isCanonSafeStart(UChar32 c);
420
421 /**
422 * Internal API, used by enumeration of canonically equivalent strings
423 * @internal
424 */
425 U_CAPI UBool U_EXPORT2
426 unorm_getCanonStartSet(UChar32 c, USerializedSet *fillSet);
427
428 /**
429 * Is c an NF<mode>-skippable code point? See unormimp.h.
430 * @internal
431 */
432 U_CAPI UBool U_EXPORT2
433 unorm_isNFSkippable(UChar32 c, UNormalizationMode mode);
434
435 #ifdef XP_CPLUSPLUS
436
437 /**
438 * Get normalization exclusion set for the options.
439 * Requires unorm_haveData().
440 * @internal
441 */
442 U_CFUNC const U_NAMESPACE_QUALIFIER UnicodeSet *
443 unorm_getNX(int32_t options, UErrorCode *pErrorCode);
444
445 #endif
446
447 /**
448 * Enumerate each normalization data trie and add the
449 * start of each range of same properties to the set.
450 * @internal
451 */
452 U_CAPI void U_EXPORT2
453 unorm_addPropertyStarts(const USetAdder *sa, UErrorCode *pErrorCode);
454
455 /**
456 * Swap unorm.icu. See udataswp.h.
457 * @internal
458 */
459 U_CAPI int32_t U_EXPORT2
460 unorm_swap(const UDataSwapper *ds,
461 const void *inData, int32_t length, void *outData,
462 UErrorCode *pErrorCode);
463
464 /**
465 * Get the NF*_QC property for a code point, for u_getIntPropertyValue().
466 * @internal
467 */
468 U_CFUNC UNormalizationCheckResult U_EXPORT2
469 unorm_getQuickCheck(UChar32 c, UNormalizationMode mode);
470
471 /**
472 * Description of the format of unorm.icu version 2.3.
473 *
474 * Main change from version 1 to version 2:
475 * Use of new, common UTrie instead of normalization-specific tries.
476 * Change to version 2.1: add third/auxiliary trie with associated data.
477 * Change to version 2.2: add skippable (f) flag data (_NORM_AUX_NFC_SKIP_F_MASK).
478 * Change to version 2.3: add serialized sets for normalization exclusions
479 * stored inside canonStartSets[]
480 *
481 * For more details of how to use the data structures see the code
482 * in unorm.cpp (runtime normalization code) and
483 * in gennorm.c and gennorm/store.c (build-time data generation).
484 *
485 * For the serialized format of UTrie see utrie.c/UTrieHeader.
486 *
487 * - Overall partition
488 *
489 * unorm.dat customarily begins with a UDataInfo structure, see udata.h and .c.
490 * After that there are the following structures:
491 *
492 * int32_t indexes[_NORM_INDEX_TOP]; -- _NORM_INDEX_TOP=32, see enum in this file
493 *
494 * UTrie normTrie; -- size in bytes=indexes[_NORM_INDEX_TRIE_SIZE]
495 *
496 * uint16_t extraData[extraDataTop]; -- extraDataTop=indexes[_NORM_INDEX_UCHAR_COUNT]
497 * extraData[0] contains the number of units for
498 * FC_NFKC_Closure (formatVersion>=2.1)
499 *
500 * uint16_t combiningTable[combiningTableTop]; -- combiningTableTop=indexes[_NORM_INDEX_COMBINE_DATA_COUNT]
501 * combiningTableTop may include one 16-bit padding unit
502 * to make sure that fcdTrie is 32-bit-aligned
503 *
504 * UTrie fcdTrie; -- size in bytes=indexes[_NORM_INDEX_FCD_TRIE_SIZE]
505 *
506 * UTrie auxTrie; -- size in bytes=indexes[_NORM_INDEX_AUX_TRIE_SIZE]
507 *
508 * uint16_t canonStartSets[canonStartSetsTop] -- canonStartSetsTop=indexes[_NORM_INDEX_CANON_SET_COUNT]
509 * serialized USets and binary search tables, see below
510 *
511 *
512 * The indexes array contains lengths and sizes of the following arrays and structures
513 * as well as the following values:
514 * indexes[_NORM_INDEX_COMBINE_FWD_COUNT]=combineFwdTop
515 * -- one more than the highest combining index computed for forward-only-combining characters
516 * indexes[_NORM_INDEX_COMBINE_BOTH_COUNT]=combineBothTop-combineFwdTop
517 * -- number of combining indexes computed for both-ways-combining characters
518 * indexes[_NORM_INDEX_COMBINE_BACK_COUNT]=combineBackTop-combineBothTop
519 * -- number of combining indexes computed for backward-only-combining characters
520 *
521 * indexes[_NORM_INDEX_MIN_NF*_NO_MAYBE] (where *={ C, D, KC, KD })
522 * -- first code point with a quick check NF* value of NO/MAYBE
523 *
524 *
525 * - Tries
526 *
527 * The main structures are two UTrie tables ("compact arrays"),
528 * each with one index array and one data array.
529 * See utrie.h and utrie.c.
530 *
531 *
532 * - Tries in unorm.dat
533 *
534 * The first trie (normTrie above)
535 * provides data for the NF* quick checks and normalization.
536 * The second trie (fcdTrie above) provides data just for FCD checks.
537 *
538 *
539 * - norm32 data words from the first trie
540 *
541 * The norm32Table contains one 32-bit word "norm32" per code point.
542 * It contains the following bit fields:
543 * 31..16 extra data index, _NORM_EXTRA_SHIFT is used to shift this field down
544 * if this index is <_NORM_EXTRA_INDEX_TOP then it is an index into
545 * extraData[] where variable-length normalization data for this
546 * code point is found
547 * if this index is <_NORM_EXTRA_INDEX_TOP+_NORM_EXTRA_SURROGATE_TOP
548 * then this is a norm32 for a leading surrogate, and the index
549 * value is used together with the following trailing surrogate
550 * code unit in the second trie access
551 * if this index is >=_NORM_EXTRA_INDEX_TOP+_NORM_EXTRA_SURROGATE_TOP
552 * then this is a norm32 for a "special" character,
553 * i.e., the character is a Hangul syllable or a Jamo
554 * see _NORM_EXTRA_HANGUL etc.
555 * generally, instead of extracting this index from the norm32 and
556 * comparing it with the above constants,
557 * the normalization code compares the entire norm32 value
558 * with _NORM_MIN_SPECIAL, _NORM_SURROGATES_TOP, _NORM_MIN_HANGUL etc.
559 *
560 * 15..8 combining class (cc) according to UnicodeData.txt
561 *
562 * 7..6 _NORM_COMBINES_ANY flags, used in composition to see if a character
563 * combines with any following or preceding character(s)
564 * at all
565 * 7 _NORM_COMBINES_BACK
566 * 6 _NORM_COMBINES_FWD
567 *
568 * 5..0 quick check flags, set for "no" or "maybe", with separate flags for
569 * each normalization form
570 * the higher bits are "maybe" flags; for NF*D there are no such flags
571 * the lower bits are "no" flags for all forms, in the same order
572 * as the "maybe" flags,
573 * which is (MSB to LSB): NFKD NFD NFKC NFC
574 * 5..4 _NORM_QC_ANY_MAYBE
575 * 3..0 _NORM_QC_ANY_NO
576 * see further related constants
577 *
578 *
579 * - Extra data per code point
580 *
581 * "Extra data" is referenced by the index in norm32.
582 * It is variable-length data. It is only present, and only those parts
583 * of it are, as needed for a given character.
584 * The norm32 extra data index is added to the beginning of extraData[]
585 * to get to a vector of 16-bit words with data at the following offsets:
586 *
587 * [-1] Combining index for composition.
588 * Stored only if norm32&_NORM_COMBINES_ANY .
589 * [0] Lengths of the canonical and compatibility decomposition strings.
590 * Stored only if there are decompositions, i.e.,
591 * if norm32&(_NORM_QC_NFD|_NORM_QC_NFKD)
592 * High byte: length of NFKD, or 0 if none
593 * Low byte: length of NFD, or 0 if none
594 * Each length byte also has another flag:
595 * Bit 7 of a length byte is set if there are non-zero
596 * combining classes (cc's) associated with the respective
597 * decomposition. If this flag is set, then the decomposition
598 * is preceded by a 16-bit word that contains the
599 * leading and trailing cc's.
600 * Bits 6..0 of a length byte are the length of the
601 * decomposition string, not counting the cc word.
602 * [1..n] NFD
603 * [n+1..] NFKD
604 *
605 * Each of the two decompositions consists of up to two parts:
606 * - The 16-bit words with the leading and trailing cc's.
607 * This is only stored if bit 7 of the corresponding length byte
608 * is set. In this case, at least one of the cc's is not zero.
609 * High byte: leading cc==cc of the first code point in the decomposition string
610 * Low byte: trailing cc==cc of the last code point in the decomposition string
611 * - The decomposition string in UTF-16, with length code units.
612 *
613 *
614 * - Combining indexes and combiningTable[]
615 *
616 * Combining indexes are stored at the [-1] offset of the extra data
617 * if the character combines forward or backward with any other characters.
618 * They are used for (re)composition in NF*C.
619 * Values of combining indexes are arranged according to whether a character
620 * combines forward, backward, or both ways:
621 * forward-only < both ways < backward-only
622 *
623 * The index values for forward-only and both-ways combining characters
624 * are indexes into the combiningTable[].
625 * The index values for backward-only combining characters are simply
626 * incremented from the preceding index values to be unique.
627 *
628 * In the combiningTable[], a variable-length list
629 * of variable-length (back-index, code point) pair entries is stored
630 * for each forward-combining character.
631 *
632 * These back-indexes are the combining indexes of both-ways or backward-only
633 * combining characters that the forward-combining character combines with.
634 *
635 * Each list is sorted in ascending order of back-indexes.
636 * Each list is terminated with the last back-index having bit 15 set.
637 *
638 * Each pair (back-index, code point) takes up either 2 or 3
639 * 16-bit words.
640 * The first word of a list entry is the back-index, with its bit 15 set if
641 * this is the last pair in the list.
642 *
643 * The second word contains flags in bits 15..13 that determine
644 * if there is a third word and how the combined character is encoded:
645 * 15 set if there is a third word in this list entry
646 * 14 set if the result is a supplementary character
647 * 13 set if the result itself combines forward
648 *
649 * According to these bits 15..14 of the second word,
650 * the result character is encoded as follows:
651 * 00 or 01 The result is <=0x1fff and stored in bits 12..0 of
652 * the second word.
653 * 10 The result is 0x2000..0xffff and stored in the third word.
654 * Bits 12..0 of the second word are not used.
655 * 11 The result is a supplementary character.
656 * Bits 9..0 of the leading surrogate are in bits 9..0 of
657 * the second word.
658 * Add 0xd800 to these bits to get the complete surrogate.
659 * Bits 12..10 of the second word are not used.
660 * The trailing surrogate is stored in the third word.
661 *
662 *
663 * - FCD trie
664 *
665 * The FCD trie is very simple.
666 * It is a folded trie with 16-bit data words.
667 * In each word, the high byte contains the leading cc of the character,
668 * and the low byte contains the trailing cc of the character.
669 * These cc's are the cc's of the first and last code points in the
670 * canonical decomposition of the character.
671 *
672 * Since all 16 bits are used for cc's, lead surrogates must be tested
673 * by checking the code unit instead of the trie data.
674 * This is done only if the 16-bit data word is not zero.
675 * If the code unit is a leading surrogate and the data word is not zero,
676 * then instead of cc's it contains the offset for the second trie lookup.
677 *
678 *
679 * - Auxiliary trie and data
680 *
681 * The auxiliary 16-bit trie contains data for additional properties.
682 * Bits
683 * 15..13 reserved
684 * 12 not NFC_Skippable (f) (formatVersion>=2.2)
685 * 11 flag: not a safe starter for canonical closure
686 * 10 composition exclusion
687 * 9.. 0 index into extraData[] to FC_NFKC_Closure string
688 * (not for lead surrogate),
689 * or lead surrogate offset (for lead surrogate, if 9..0 not zero)
690 *
691 * - FC_NFKC_Closure strings in extraData[]
692 *
693 * Strings are either stored as a single code unit or as the length
694 * followed by that many units.
695 * const UChar *s=extraData+(index from auxTrie data bits 9..0);
696 * int32_t length;
697 * if(*s<0xff00) {
698 * // s points to the single-unit string
699 * length=1;
700 * } else {
701 * length=*s&0xff;
702 * ++s;
703 * }
704 *
705 * Conditions for "NF* Skippable" from Mark Davis' com.ibm.text.UCD.NFSkippable:
706 * (used in NormalizerTransliterator)
707 *
708 * A skippable character is
709 * a) unassigned, or ALL of the following:
710 * b) of combining class 0.
711 * c) not decomposed by this normalization form.
712 * AND if NFC or NFKC,
713 * d) can never compose with a previous character.
714 * e) can never compose with a following character.
715 * f) can never change if another character is added.
716 * Example: a-breve might satisfy all but f, but if you
717 * add an ogonek it changes to a-ogonek + breve
718 *
719 * a)..e) must be tested from norm32.
720 * Since f) is more complicated, the (not-)NFC_Skippable flag (f) is built
721 * into the auxiliary trie.
722 * The same bit is used for NFC and NFKC; (c) differs for them.
723 * As usual, we build the "not skippable" flags so that unassigned
724 * code points get a 0 bit.
725 * This bit is only valid after (a)..(e) test FALSE; test NFD_NO before (f) as well.
726 * Test Hangul LV syllables entirely in code.
727 *
728 *
729 * - structure inside canonStartSets[]
730 *
731 * This array maps from code points c to sets of code points (USerializedSet).
732 * The result sets are the code points whose canonical decompositions start
733 * with c.
734 *
735 * canonStartSets[] contains the following sub-arrays:
736 *
737 * indexes[_NORM_SET_INDEX_TOP]
738 * - contains lengths of sub-arrays etc.
739 *
740 * startSets[indexes[_NORM_SET_INDEX_CANON_SETS_LENGTH]-_NORM_SET_INDEX_TOP]
741 * - contains serialized sets (USerializedSet) of canonical starters for
742 * enumerating canonically equivalent strings
743 * indexes[_NORM_SET_INDEX_CANON_SETS_LENGTH] includes _NORM_SET_INDEX_TOP
744 * for details about the structure see uset.c
745 *
746 * bmpTable[indexes[_NORM_SET_INDEX_CANON_BMP_TABLE_LENGTH]]
747 * - a sorted search table for BMP code points whose results are
748 * either indexes to USerializedSets or single code points for
749 * single-code point sets;
750 * each entry is a pair of { code point, result } with result=(binary) yy xxxxxx xxxxxxxx
751 * if yy==01 then there is a USerializedSet at canonStartSets+x
752 * else build a USerializedSet with result as the single code point
753 *
754 * suppTable[indexes[_NORM_SET_INDEX_CANON_SUPP_TABLE_LENGTH]]
755 * - a sorted search table for supplementary code points whose results are
756 * either indexes to USerializedSets or single code points for
757 * single-code point sets;
758 * each entry is a triplet of { high16(cp), low16(cp), result }
759 * each code point's high-word may contain extra data in bits 15..5:
760 * if the high word has bit 15 set, then build a set with a single code point
761 * which is (((high16(cp)&0x1f00)<<8)|result;
762 * else there is a USerializedSet at canonStartSets+result
763 *
764 * FormatVersion 2.3 adds 2 serialized sets for normalization exclusions.
765 * They are stored in the data file so that the runtime normalization code need
766 * not depend on other properties and their data and implementation files.
767 * The _NORM_SET_INDEX_NX_..._OFFSET offsets in the canonStartSets index table
768 * give the location for each set.
769 * There is no set stored for UNORM_NX_HANGUL because it's trivial to create
770 * without using properties.
771 *
772 * Set contents:
773 *
774 * _NORM_SET_INDEX_NX_CJK_COMPAT_OFFSET (for UNORM_NX_CJK_COMPAT)
775 * [[:Ideographic:]&[:NFD_QC=No:]]
776 * =[CJK Ideographs]&[has canonical decomposition]
777 *
778 * _NORM_SET_INDEX_NX_UNICODE32_OFFSET (for UNORM_UNICODE_3_2)
779 * [:^Age=3.2:]
780 * =set with all code points that were not designated by the specified Unicode version
781 *
782 * _NORM_SET_INDEX_NX_RESERVED_OFFSET
783 * This is an offset that points to where the next, future set would start.
784 * Currently it indicates where the previous set ends, and thus its length.
785 * The name for this enum constant may in the future be applied to different
786 * index slots. In order to get the limit of a set, use its index slot and
787 * the immediately following one regardless of that one's enum name.
788 */
789
790 #endif /* #if !UCONFIG_NO_NORMALIZATION */
791
792 #endif
793