summaryrefslogtreecommitdiffstats
path: root/intl/icu/source/common/utrie2.cpp
blob: 74f91bc8139026fda99e0331590aba1e509550c2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
/*
******************************************************************************
*
*   Copyright (C) 2001-2014, International Business Machines
*   Corporation and others.  All Rights Reserved.
*
******************************************************************************
*   file name:  utrie2.cpp
*   encoding:   UTF-8
*   tab size:   8 (not used)
*   indentation:4
*
*   created on: 2008aug16 (starting from a copy of utrie.c)
*   created by: Markus W. Scherer
*
*   This is a common implementation of a Unicode trie.
*   It is a kind of compressed, serializable table of 16- or 32-bit values associated with
*   Unicode code points (0..0x10ffff).
*   This is the second common version of a Unicode trie (hence the name UTrie2).
*   See utrie2.h for a comparison.
*
*   This file contains only the runtime and enumeration code, for read-only access.
*   See utrie2_builder.c for the builder code.
*/
#include "unicode/utypes.h"
#ifdef UCPTRIE_DEBUG
#include "unicode/umutablecptrie.h"
#endif
#include "unicode/utf.h"
#include "unicode/utf8.h"
#include "unicode/utf16.h"
#include "cmemory.h"
#include "utrie2.h"
#include "utrie2_impl.h"
#include "uassert.h"

/* Public UTrie2 API implementation ----------------------------------------- */

static uint32_t
get32(const UNewTrie2 *trie, UChar32 c, UBool fromLSCP) {
    int32_t i2, block;

    if(c>=trie->highStart && (!U_IS_LEAD(c) || fromLSCP)) {
        return trie->data[trie->dataLength-UTRIE2_DATA_GRANULARITY];
    }

    if(U_IS_LEAD(c) && fromLSCP) {
        i2=(UTRIE2_LSCP_INDEX_2_OFFSET-(0xd800>>UTRIE2_SHIFT_2))+
            (c>>UTRIE2_SHIFT_2);
    } else {
        i2=trie->index1[c>>UTRIE2_SHIFT_1]+
            ((c>>UTRIE2_SHIFT_2)&UTRIE2_INDEX_2_MASK);
    }
    block=trie->index2[i2];
    return trie->data[block+(c&UTRIE2_DATA_MASK)];
}

U_CAPI uint32_t U_EXPORT2
utrie2_get32(const UTrie2 *trie, UChar32 c) {
    if(trie->data16!=nullptr) {
        return UTRIE2_GET16(trie, c);
    } else if(trie->data32!=nullptr) {
        return UTRIE2_GET32(trie, c);
    } else if((uint32_t)c>0x10ffff) {
        return trie->errorValue;
    } else {
        return get32(trie->newTrie, c, true);
    }
}

U_CAPI uint32_t U_EXPORT2
utrie2_get32FromLeadSurrogateCodeUnit(const UTrie2 *trie, UChar32 c) {
    if(!U_IS_LEAD(c)) {
        return trie->errorValue;
    }
    if(trie->data16!=nullptr) {
        return UTRIE2_GET16_FROM_U16_SINGLE_LEAD(trie, c);
    } else if(trie->data32!=nullptr) {
        return UTRIE2_GET32_FROM_U16_SINGLE_LEAD(trie, c);
    } else {
        return get32(trie->newTrie, c, false);
    }
}

static inline int32_t
u8Index(const UTrie2 *trie, UChar32 c, int32_t i) {
    int32_t idx=
        _UTRIE2_INDEX_FROM_CP(
            trie,
            trie->data32==nullptr ? trie->indexLength : 0,
            c);
    return (idx<<3)|i;
}

U_CAPI int32_t U_EXPORT2
utrie2_internalU8NextIndex(const UTrie2 *trie, UChar32 c,
                           const uint8_t *src, const uint8_t *limit) {
    int32_t i, length;
    i=0;
    /* support 64-bit pointers by avoiding cast of arbitrary difference */
    if((limit-src)<=7) {
        length=(int32_t)(limit-src);
    } else {
        length=7;
    }
    c=utf8_nextCharSafeBody(src, &i, length, c, -1);
    return u8Index(trie, c, i);
}

U_CAPI int32_t U_EXPORT2
utrie2_internalU8PrevIndex(const UTrie2 *trie, UChar32 c,
                           const uint8_t *start, const uint8_t *src) {
    int32_t i, length;
    /* support 64-bit pointers by avoiding cast of arbitrary difference */
    if((src-start)<=7) {
        i=length=(int32_t)(src-start);
    } else {
        i=length=7;
        start=src-7;
    }
    c=utf8_prevCharSafeBody(start, 0, &i, c, -1);
    i=length-i;  /* number of bytes read backward from src */
    return u8Index(trie, c, i);
}

U_CAPI UTrie2 * U_EXPORT2
utrie2_openFromSerialized(UTrie2ValueBits valueBits,
                          const void *data, int32_t length, int32_t *pActualLength,
                          UErrorCode *pErrorCode) {
    const UTrie2Header *header;
    const uint16_t *p16;
    int32_t actualLength;

    UTrie2 tempTrie;
    UTrie2 *trie;

    if(U_FAILURE(*pErrorCode)) {
        return 0;
    }

    if( length<=0 || (U_POINTER_MASK_LSB(data, 3)!=0) ||
        valueBits<0 || UTRIE2_COUNT_VALUE_BITS<=valueBits
    ) {
        *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
        return 0;
    }

    /* enough data for a trie header? */
    if(length<(int32_t)sizeof(UTrie2Header)) {
        *pErrorCode=U_INVALID_FORMAT_ERROR;
        return 0;
    }

    /* check the signature */
    header=(const UTrie2Header *)data;
    if(header->signature!=UTRIE2_SIG) {
        *pErrorCode=U_INVALID_FORMAT_ERROR;
        return 0;
    }

    /* get the options */
    if(valueBits!=(UTrie2ValueBits)(header->options&UTRIE2_OPTIONS_VALUE_BITS_MASK)) {
        *pErrorCode=U_INVALID_FORMAT_ERROR;
        return 0;
    }

    /* get the length values and offsets */
    uprv_memset(&tempTrie, 0, sizeof(tempTrie));
    tempTrie.indexLength=header->indexLength;
    tempTrie.dataLength=header->shiftedDataLength<<UTRIE2_INDEX_SHIFT;
    tempTrie.index2NullOffset=header->index2NullOffset;
    tempTrie.dataNullOffset=header->dataNullOffset;

    tempTrie.highStart=header->shiftedHighStart<<UTRIE2_SHIFT_1;
    tempTrie.highValueIndex=tempTrie.dataLength-UTRIE2_DATA_GRANULARITY;
    if(valueBits==UTRIE2_16_VALUE_BITS) {
        tempTrie.highValueIndex+=tempTrie.indexLength;
    }

    /* calculate the actual length */
    actualLength=(int32_t)sizeof(UTrie2Header)+tempTrie.indexLength*2;
    if(valueBits==UTRIE2_16_VALUE_BITS) {
        actualLength+=tempTrie.dataLength*2;
    } else {
        actualLength+=tempTrie.dataLength*4;
    }
    if(length<actualLength) {
        *pErrorCode=U_INVALID_FORMAT_ERROR;  /* not enough bytes */
        return 0;
    }

    /* allocate the trie */
    trie=(UTrie2 *)uprv_malloc(sizeof(UTrie2));
    if(trie==nullptr) {
        *pErrorCode=U_MEMORY_ALLOCATION_ERROR;
        return 0;
    }
    uprv_memcpy(trie, &tempTrie, sizeof(tempTrie));
    trie->memory=(uint32_t *)data;
    trie->length=actualLength;
    trie->isMemoryOwned=false;
#ifdef UTRIE2_DEBUG
    trie->name="fromSerialized";
#endif

    /* set the pointers to its index and data arrays */
    p16=(const uint16_t *)(header+1);
    trie->index=p16;
    p16+=trie->indexLength;

    /* get the data */
    switch(valueBits) {
    case UTRIE2_16_VALUE_BITS:
        trie->data16=p16;
        trie->data32=nullptr;
        trie->initialValue=trie->index[trie->dataNullOffset];
        trie->errorValue=trie->data16[UTRIE2_BAD_UTF8_DATA_OFFSET];
        break;
    case UTRIE2_32_VALUE_BITS:
        trie->data16=nullptr;
        trie->data32=(const uint32_t *)p16;
        trie->initialValue=trie->data32[trie->dataNullOffset];
        trie->errorValue=trie->data32[UTRIE2_BAD_UTF8_DATA_OFFSET];
        break;
    default:
        *pErrorCode=U_INVALID_FORMAT_ERROR;
        return 0;
    }

    if(pActualLength!=nullptr) {
        *pActualLength=actualLength;
    }
    return trie;
}

U_CAPI UTrie2 * U_EXPORT2
utrie2_openDummy(UTrie2ValueBits valueBits,
                 uint32_t initialValue, uint32_t errorValue,
                 UErrorCode *pErrorCode) {
    UTrie2 *trie;
    UTrie2Header *header;
    uint32_t *p;
    uint16_t *dest16;
    int32_t indexLength, dataLength, length, i;
    int32_t dataMove;  /* >0 if the data is moved to the end of the index array */

    if(U_FAILURE(*pErrorCode)) {
        return 0;
    }

    if(valueBits<0 || UTRIE2_COUNT_VALUE_BITS<=valueBits) {
        *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
        return 0;
    }

    /* calculate the total length of the dummy trie data */
    indexLength=UTRIE2_INDEX_1_OFFSET;
    dataLength=UTRIE2_DATA_START_OFFSET+UTRIE2_DATA_GRANULARITY;
    length=(int32_t)sizeof(UTrie2Header)+indexLength*2;
    if(valueBits==UTRIE2_16_VALUE_BITS) {
        length+=dataLength*2;
    } else {
        length+=dataLength*4;
    }

    /* allocate the trie */
    trie=(UTrie2 *)uprv_malloc(sizeof(UTrie2));
    if(trie==nullptr) {
        *pErrorCode=U_MEMORY_ALLOCATION_ERROR;
        return 0;
    }
    uprv_memset(trie, 0, sizeof(UTrie2));
    trie->memory=uprv_malloc(length);
    if(trie->memory==nullptr) {
        uprv_free(trie);
        *pErrorCode=U_MEMORY_ALLOCATION_ERROR;
        return 0;
    }
    trie->length=length;
    trie->isMemoryOwned=true;

    /* set the UTrie2 fields */
    if(valueBits==UTRIE2_16_VALUE_BITS) {
        dataMove=indexLength;
    } else {
        dataMove=0;
    }

    trie->indexLength=indexLength;
    trie->dataLength=dataLength;
    trie->index2NullOffset=UTRIE2_INDEX_2_OFFSET;
    trie->dataNullOffset=(uint16_t)dataMove;
    trie->initialValue=initialValue;
    trie->errorValue=errorValue;
    trie->highStart=0;
    trie->highValueIndex=dataMove+UTRIE2_DATA_START_OFFSET;
#ifdef UTRIE2_DEBUG
    trie->name="dummy";
#endif

    /* set the header fields */
    header=(UTrie2Header *)trie->memory;

    header->signature=UTRIE2_SIG; /* "Tri2" */
    header->options=(uint16_t)valueBits;

    header->indexLength=(uint16_t)indexLength;
    header->shiftedDataLength=(uint16_t)(dataLength>>UTRIE2_INDEX_SHIFT);
    header->index2NullOffset=(uint16_t)UTRIE2_INDEX_2_OFFSET;
    header->dataNullOffset=(uint16_t)dataMove;
    header->shiftedHighStart=0;

    /* fill the index and data arrays */
    dest16=(uint16_t *)(header+1);
    trie->index=dest16;

    /* write the index-2 array values shifted right by UTRIE2_INDEX_SHIFT */
    for(i=0; i<UTRIE2_INDEX_2_BMP_LENGTH; ++i) {
        *dest16++=(uint16_t)(dataMove>>UTRIE2_INDEX_SHIFT);  /* null data block */
    }

    /* write UTF-8 2-byte index-2 values, not right-shifted */
    for(i=0; i<(0xc2-0xc0); ++i) {                                  /* C0..C1 */
        *dest16++=(uint16_t)(dataMove+UTRIE2_BAD_UTF8_DATA_OFFSET);
    }
    for(; i<(0xe0-0xc0); ++i) {                                     /* C2..DF */
        *dest16++=(uint16_t)dataMove;
    }

    /* write the 16/32-bit data array */
    switch(valueBits) {
    case UTRIE2_16_VALUE_BITS:
        /* write 16-bit data values */
        trie->data16=dest16;
        trie->data32=nullptr;
        for(i=0; i<0x80; ++i) {
            *dest16++=(uint16_t)initialValue;
        }
        for(; i<0xc0; ++i) {
            *dest16++=(uint16_t)errorValue;
        }
        /* highValue and reserved values */
        for(i=0; i<UTRIE2_DATA_GRANULARITY; ++i) {
            *dest16++=(uint16_t)initialValue;
        }
        break;
    case UTRIE2_32_VALUE_BITS:
        /* write 32-bit data values */
        p=(uint32_t *)dest16;
        trie->data16=nullptr;
        trie->data32=p;
        for(i=0; i<0x80; ++i) {
            *p++=initialValue;
        }
        for(; i<0xc0; ++i) {
            *p++=errorValue;
        }
        /* highValue and reserved values */
        for(i=0; i<UTRIE2_DATA_GRANULARITY; ++i) {
            *p++=initialValue;
        }
        break;
    default:
        *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
        return 0;
    }

    return trie;
}

U_CAPI void U_EXPORT2
utrie2_close(UTrie2 *trie) {
    if(trie!=nullptr) {
        if(trie->isMemoryOwned) {
            uprv_free(trie->memory);
        }
        if(trie->newTrie!=nullptr) {
            uprv_free(trie->newTrie->data);
#ifdef UCPTRIE_DEBUG
            umutablecptrie_close(trie->newTrie->t3);
#endif
            uprv_free(trie->newTrie);
        }
        uprv_free(trie);
    }
}

U_CAPI UBool U_EXPORT2
utrie2_isFrozen(const UTrie2 *trie) {
    return (UBool)(trie->newTrie==nullptr);
}

U_CAPI int32_t U_EXPORT2
utrie2_serialize(const UTrie2 *trie,
                 void *data, int32_t capacity,
                 UErrorCode *pErrorCode) {
    /* argument check */
    if(U_FAILURE(*pErrorCode)) {
        return 0;
    }

    if( trie==nullptr || trie->memory==nullptr || trie->newTrie!=nullptr ||
        capacity<0 || (capacity>0 && (data==nullptr || (U_POINTER_MASK_LSB(data, 3)!=0)))
    ) {
        *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
        return 0;
    }

    if(capacity>=trie->length) {
        uprv_memcpy(data, trie->memory, trie->length);
    } else {
        *pErrorCode=U_BUFFER_OVERFLOW_ERROR;
    }
    return trie->length;
}

/* enumeration -------------------------------------------------------------- */

#define MIN_VALUE(a, b) ((a)<(b) ? (a) : (b))

/* default UTrie2EnumValue() returns the input value itself */
static uint32_t U_CALLCONV
enumSameValue(const void * /*context*/, uint32_t value) {
    return value;
}

/**
 * Enumerate all ranges of code points with the same relevant values.
 * The values are transformed from the raw trie entries by the enumValue function.
 *
 * Currently requires start<limit and both start and limit must be multiples
 * of UTRIE2_DATA_BLOCK_LENGTH.
 *
 * Optimizations:
 * - Skip a whole block if we know that it is filled with a single value,
 *   and it is the same as we visited just before.
 * - Handle the null block specially because we know a priori that it is filled
 *   with a single value.
 */
static void
enumEitherTrie(const UTrie2 *trie,
               UChar32 start, UChar32 limit,
               UTrie2EnumValue *enumValue, UTrie2EnumRange *enumRange, const void *context) {
    const uint32_t *data32;
    const uint16_t *idx;

    uint32_t value, prevValue, initialValue;
    UChar32 c, prev, highStart;
    int32_t j, i2Block, prevI2Block, index2NullOffset, block, prevBlock, nullBlock;

    if(enumRange==nullptr) {
        return;
    }
    if(enumValue==nullptr) {
        enumValue=enumSameValue;
    }

    if(trie->newTrie==nullptr) {
        /* frozen trie */
        idx=trie->index;
        U_ASSERT(idx!=nullptr); /* the following code assumes trie->newTrie is not nullptr when idx is nullptr */
        data32=trie->data32;

        index2NullOffset=trie->index2NullOffset;
        nullBlock=trie->dataNullOffset;
    } else {
        /* unfrozen, mutable trie */
        idx=nullptr;
        data32=trie->newTrie->data;
        U_ASSERT(data32!=nullptr); /* the following code assumes idx is not nullptr when data32 is nullptr */

        index2NullOffset=trie->newTrie->index2NullOffset;
        nullBlock=trie->newTrie->dataNullOffset;
    }

    highStart=trie->highStart;

    /* get the enumeration value that corresponds to an initial-value trie data entry */
    initialValue=enumValue(context, trie->initialValue);

    /* set variables for previous range */
    prevI2Block=-1;
    prevBlock=-1;
    prev=start;
    prevValue=0;

    /* enumerate index-2 blocks */
    for(c=start; c<limit && c<highStart;) {
        /* Code point limit for iterating inside this i2Block. */
        UChar32 tempLimit=c+UTRIE2_CP_PER_INDEX_1_ENTRY;
        if(limit<tempLimit) {
            tempLimit=limit;
        }
        if(c<=0xffff) {
            if(!U_IS_SURROGATE(c)) {
                i2Block=c>>UTRIE2_SHIFT_2;
            } else if(U_IS_SURROGATE_LEAD(c)) {
                /*
                 * Enumerate values for lead surrogate code points, not code units:
                 * This special block has half the normal length.
                 */
                i2Block=UTRIE2_LSCP_INDEX_2_OFFSET;
                tempLimit=MIN_VALUE(0xdc00, limit);
            } else {
                /*
                 * Switch back to the normal part of the index-2 table.
                 * Enumerate the second half of the surrogates block.
                 */
                i2Block=0xd800>>UTRIE2_SHIFT_2;
                tempLimit=MIN_VALUE(0xe000, limit);
            }
        } else {
            /* supplementary code points */
            if(idx!=nullptr) {
                i2Block=idx[(UTRIE2_INDEX_1_OFFSET-UTRIE2_OMITTED_BMP_INDEX_1_LENGTH)+
                              (c>>UTRIE2_SHIFT_1)];
            } else {
                i2Block=trie->newTrie->index1[c>>UTRIE2_SHIFT_1];
            }
            if(i2Block==prevI2Block && (c-prev)>=UTRIE2_CP_PER_INDEX_1_ENTRY) {
                /*
                 * The index-2 block is the same as the previous one, and filled with prevValue.
                 * Only possible for supplementary code points because the linear-BMP index-2
                 * table creates unique i2Block values.
                 */
                c+=UTRIE2_CP_PER_INDEX_1_ENTRY;
                continue;
            }
        }
        prevI2Block=i2Block;
        if(i2Block==index2NullOffset) {
            /* this is the null index-2 block */
            if(prevValue!=initialValue) {
                if(prev<c && !enumRange(context, prev, c-1, prevValue)) {
                    return;
                }
                prevBlock=nullBlock;
                prev=c;
                prevValue=initialValue;
            }
            c+=UTRIE2_CP_PER_INDEX_1_ENTRY;
        } else {
            /* enumerate data blocks for one index-2 block */
            int32_t i2, i2Limit;
            i2=(c>>UTRIE2_SHIFT_2)&UTRIE2_INDEX_2_MASK;
            if((c>>UTRIE2_SHIFT_1)==(tempLimit>>UTRIE2_SHIFT_1)) {
                i2Limit=(tempLimit>>UTRIE2_SHIFT_2)&UTRIE2_INDEX_2_MASK;
            } else {
                i2Limit=UTRIE2_INDEX_2_BLOCK_LENGTH;
            }
            for(; i2<i2Limit; ++i2) {
                if(idx!=nullptr) {
                    block=(int32_t)idx[i2Block+i2]<<UTRIE2_INDEX_SHIFT;
                } else {
                    block=trie->newTrie->index2[i2Block+i2];
                }
                if(block==prevBlock && (c-prev)>=UTRIE2_DATA_BLOCK_LENGTH) {
                    /* the block is the same as the previous one, and filled with prevValue */
                    c+=UTRIE2_DATA_BLOCK_LENGTH;
                    continue;
                }
                prevBlock=block;
                if(block==nullBlock) {
                    /* this is the null data block */
                    if(prevValue!=initialValue) {
                        if(prev<c && !enumRange(context, prev, c-1, prevValue)) {
                            return;
                        }
                        prev=c;
                        prevValue=initialValue;
                    }
                    c+=UTRIE2_DATA_BLOCK_LENGTH;
                } else {
                    for(j=0; j<UTRIE2_DATA_BLOCK_LENGTH; ++j) {
                        value=enumValue(context, data32!=nullptr ? data32[block+j] : idx[block+j]);
                        if(value!=prevValue) {
                            if(prev<c && !enumRange(context, prev, c-1, prevValue)) {
                                return;
                            }
                            prev=c;
                            prevValue=value;
                        }
                        ++c;
                    }
                }
            }
        }
    }

    if(c>limit) {
        c=limit;  /* could be higher if in the index2NullOffset */
    } else if(c<limit) {
        /* c==highStart<limit */
        uint32_t highValue;
        if(idx!=nullptr) {
            highValue=
                data32!=nullptr ?
                    data32[trie->highValueIndex] :
                    idx[trie->highValueIndex];
        } else {
            highValue=trie->newTrie->data[trie->newTrie->dataLength-UTRIE2_DATA_GRANULARITY];
        }
        value=enumValue(context, highValue);
        if(value!=prevValue) {
            if(prev<c && !enumRange(context, prev, c-1, prevValue)) {
                return;
            }
            prev=c;
            prevValue=value;
        }
        c=limit;
    }

    /* deliver last range */
    enumRange(context, prev, c-1, prevValue);
}

U_CAPI void U_EXPORT2
utrie2_enum(const UTrie2 *trie,
            UTrie2EnumValue *enumValue, UTrie2EnumRange *enumRange, const void *context) {
    enumEitherTrie(trie, 0, 0x110000, enumValue, enumRange, context);
}

U_CAPI void U_EXPORT2
utrie2_enumForLeadSurrogate(const UTrie2 *trie, UChar32 lead,
                            UTrie2EnumValue *enumValue, UTrie2EnumRange *enumRange,
                            const void *context) {
    if(!U16_IS_LEAD(lead)) {
        return;
    }
    lead=(lead-0xd7c0)<<10;   /* start code point */
    enumEitherTrie(trie, lead, lead+0x400, enumValue, enumRange, context);
}

/* C++ convenience wrappers ------------------------------------------------- */

U_NAMESPACE_BEGIN

uint16_t BackwardUTrie2StringIterator::previous16() {
    codePointLimit=codePointStart;
    if(start>=codePointStart) {
        codePoint=U_SENTINEL;
        return static_cast<uint16_t>(trie->errorValue);
    }
    uint16_t result;
    UTRIE2_U16_PREV16(trie, start, codePointStart, codePoint, result);
    return result;
}

uint16_t ForwardUTrie2StringIterator::next16() {
    codePointStart=codePointLimit;
    if(codePointLimit==limit) {
        codePoint=U_SENTINEL;
        return static_cast<uint16_t>(trie->errorValue);
    }
    uint16_t result;
    UTRIE2_U16_NEXT16(trie, codePointLimit, limit, codePoint, result);
    return result;
}

U_NAMESPACE_END