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) 1999-2012, International Business Machines
7* Corporation and others. All Rights Reserved.
8*
9*******************************************************************************
10* file name: utf16.h
11* encoding: UTF-8
12* tab size: 8 (not used)
13* indentation:4
14*
15* created on: 1999sep09
16* created by: Markus W. Scherer
17*/
18
19/**
20 * \file
21 * \brief C API: 16-bit Unicode handling macros
22 *
23 * This file defines macros to deal with 16-bit Unicode (UTF-16) code units and strings.
24 *
25 * For more information see utf.h and the ICU User Guide Strings chapter
26 * (http://userguide.icu-project.org/strings).
27 *
28 * <em>Usage:</em>
29 * ICU coding guidelines for if() statements should be followed when using these macros.
30 * Compound statements (curly braces {}) must be used for if-else-while...
31 * bodies and all macro statements should be terminated with semicolon.
32 */
33
34#ifndef __UTF16_H__
35#define __UTF16_H__
36
37#include "unicode/umachine.h"
38#ifndef __UTF_H__
39# include "unicode/utf.h"
40#endif
41
42/* single-code point definitions -------------------------------------------- */
43
44/**
45 * Does this code unit alone encode a code point (BMP, not a surrogate)?
46 * @param c 16-bit code unit
47 * @return TRUE or FALSE
48 * @stable ICU 2.4
49 */
50#define U16_IS_SINGLE(c) !U_IS_SURROGATE(c)
51
52/**
53 * Is this code unit a lead surrogate (U+d800..U+dbff)?
54 * @param c 16-bit code unit
55 * @return TRUE or FALSE
56 * @stable ICU 2.4
57 */
58#define U16_IS_LEAD(c) (((c)&0xfffffc00)==0xd800)
59
60/**
61 * Is this code unit a trail surrogate (U+dc00..U+dfff)?
62 * @param c 16-bit code unit
63 * @return TRUE or FALSE
64 * @stable ICU 2.4
65 */
66#define U16_IS_TRAIL(c) (((c)&0xfffffc00)==0xdc00)
67
68/**
69 * Is this code unit a surrogate (U+d800..U+dfff)?
70 * @param c 16-bit code unit
71 * @return TRUE or FALSE
72 * @stable ICU 2.4
73 */
74#define U16_IS_SURROGATE(c) U_IS_SURROGATE(c)
75
76/**
77 * Assuming c is a surrogate code point (U16_IS_SURROGATE(c)),
78 * is it a lead surrogate?
79 * @param c 16-bit code unit
80 * @return TRUE or FALSE
81 * @stable ICU 2.4
82 */
83#define U16_IS_SURROGATE_LEAD(c) (((c)&0x400)==0)
84
85/**
86 * Assuming c is a surrogate code point (U16_IS_SURROGATE(c)),
87 * is it a trail surrogate?
88 * @param c 16-bit code unit
89 * @return TRUE or FALSE
90 * @stable ICU 4.2
91 */
92#define U16_IS_SURROGATE_TRAIL(c) (((c)&0x400)!=0)
93
94/**
95 * Helper constant for U16_GET_SUPPLEMENTARY.
96 * @internal
97 */
98#define U16_SURROGATE_OFFSET ((0xd800<<10UL)+0xdc00-0x10000)
99
100/**
101 * Get a supplementary code point value (U+10000..U+10ffff)
102 * from its lead and trail surrogates.
103 * The result is undefined if the input values are not
104 * lead and trail surrogates.
105 *
106 * @param lead lead surrogate (U+d800..U+dbff)
107 * @param trail trail surrogate (U+dc00..U+dfff)
108 * @return supplementary code point (U+10000..U+10ffff)
109 * @stable ICU 2.4
110 */
111#define U16_GET_SUPPLEMENTARY(lead, trail) \
112 (((UChar32)(lead)<<10UL)+(UChar32)(trail)-U16_SURROGATE_OFFSET)
113
114
115/**
116 * Get the lead surrogate (0xd800..0xdbff) for a
117 * supplementary code point (0x10000..0x10ffff).
118 * @param supplementary 32-bit code point (U+10000..U+10ffff)
119 * @return lead surrogate (U+d800..U+dbff) for supplementary
120 * @stable ICU 2.4
121 */
122#define U16_LEAD(supplementary) (UChar)(((supplementary)>>10)+0xd7c0)
123
124/**
125 * Get the trail surrogate (0xdc00..0xdfff) for a
126 * supplementary code point (0x10000..0x10ffff).
127 * @param supplementary 32-bit code point (U+10000..U+10ffff)
128 * @return trail surrogate (U+dc00..U+dfff) for supplementary
129 * @stable ICU 2.4
130 */
131#define U16_TRAIL(supplementary) (UChar)(((supplementary)&0x3ff)|0xdc00)
132
133/**
134 * How many 16-bit code units are used to encode this Unicode code point? (1 or 2)
135 * The result is not defined if c is not a Unicode code point (U+0000..U+10ffff).
136 * @param c 32-bit code point
137 * @return 1 or 2
138 * @stable ICU 2.4
139 */
140#define U16_LENGTH(c) ((uint32_t)(c)<=0xffff ? 1 : 2)
141
142/**
143 * The maximum number of 16-bit code units per Unicode code point (U+0000..U+10ffff).
144 * @return 2
145 * @stable ICU 2.4
146 */
147#define U16_MAX_LENGTH 2
148
149/**
150 * Get a code point from a string at a random-access offset,
151 * without changing the offset.
152 * "Unsafe" macro, assumes well-formed UTF-16.
153 *
154 * The offset may point to either the lead or trail surrogate unit
155 * for a supplementary code point, in which case the macro will read
156 * the adjacent matching surrogate as well.
157 * The result is undefined if the offset points to a single, unpaired surrogate.
158 * Iteration through a string is more efficient with U16_NEXT_UNSAFE or U16_NEXT.
159 *
160 * @param s const UChar * string
161 * @param i string offset
162 * @param c output UChar32 variable
163 * @see U16_GET
164 * @stable ICU 2.4
165 */
166#define U16_GET_UNSAFE(s, i, c) { \
167 (c)=(s)[i]; \
168 if(U16_IS_SURROGATE(c)) { \
169 if(U16_IS_SURROGATE_LEAD(c)) { \
170 (c)=U16_GET_SUPPLEMENTARY((c), (s)[(i)+1]); \
171 } else { \
172 (c)=U16_GET_SUPPLEMENTARY((s)[(i)-1], (c)); \
173 } \
174 } \
175}
176
177/**
178 * Get a code point from a string at a random-access offset,
179 * without changing the offset.
180 * "Safe" macro, handles unpaired surrogates and checks for string boundaries.
181 *
182 * The offset may point to either the lead or trail surrogate unit
183 * for a supplementary code point, in which case the macro will read
184 * the adjacent matching surrogate as well.
185 *
186 * The length can be negative for a NUL-terminated string.
187 *
188 * If the offset points to a single, unpaired surrogate, then
189 * c is set to that unpaired surrogate.
190 * Iteration through a string is more efficient with U16_NEXT_UNSAFE or U16_NEXT.
191 *
192 * @param s const UChar * string
193 * @param start starting string offset (usually 0)
194 * @param i string offset, must be start<=i<length
195 * @param length string length
196 * @param c output UChar32 variable
197 * @see U16_GET_UNSAFE
198 * @stable ICU 2.4
199 */
200#define U16_GET(s, start, i, length, c) { \
201 (c)=(s)[i]; \
202 if(U16_IS_SURROGATE(c)) { \
203 uint16_t __c2; \
204 if(U16_IS_SURROGATE_LEAD(c)) { \
205 if((i)+1!=(length) && U16_IS_TRAIL(__c2=(s)[(i)+1])) { \
206 (c)=U16_GET_SUPPLEMENTARY((c), __c2); \
207 } \
208 } else { \
209 if((i)>(start) && U16_IS_LEAD(__c2=(s)[(i)-1])) { \
210 (c)=U16_GET_SUPPLEMENTARY(__c2, (c)); \
211 } \
212 } \
213 } \
214}
215
216#ifndef U_HIDE_DRAFT_API
217
218/**
219 * Get a code point from a string at a random-access offset,
220 * without changing the offset.
221 * "Safe" macro, handles unpaired surrogates and checks for string boundaries.
222 *
223 * The offset may point to either the lead or trail surrogate unit
224 * for a supplementary code point, in which case the macro will read
225 * the adjacent matching surrogate as well.
226 *
227 * The length can be negative for a NUL-terminated string.
228 *
229 * If the offset points to a single, unpaired surrogate, then
230 * c is set to U+FFFD.
231 * Iteration through a string is more efficient with U16_NEXT_UNSAFE or U16_NEXT_OR_FFFD.
232 *
233 * @param s const UChar * string
234 * @param start starting string offset (usually 0)
235 * @param i string offset, must be start<=i<length
236 * @param length string length
237 * @param c output UChar32 variable
238 * @see U16_GET_UNSAFE
239 * @draft ICU 60
240 */
241#define U16_GET_OR_FFFD(s, start, i, length, c) { \
242 (c)=(s)[i]; \
243 if(U16_IS_SURROGATE(c)) { \
244 uint16_t __c2; \
245 if(U16_IS_SURROGATE_LEAD(c)) { \
246 if((i)+1!=(length) && U16_IS_TRAIL(__c2=(s)[(i)+1])) { \
247 (c)=U16_GET_SUPPLEMENTARY((c), __c2); \
248 } else { \
249 (c)=0xfffd; \
250 } \
251 } else { \
252 if((i)>(start) && U16_IS_LEAD(__c2=(s)[(i)-1])) { \
253 (c)=U16_GET_SUPPLEMENTARY(__c2, (c)); \
254 } else { \
255 (c)=0xfffd; \
256 } \
257 } \
258 } \
259}
260
261#endif // U_HIDE_DRAFT_API
262
263/* definitions with forward iteration --------------------------------------- */
264
265/**
266 * Get a code point from a string at a code point boundary offset,
267 * and advance the offset to the next code point boundary.
268 * (Post-incrementing forward iteration.)
269 * "Unsafe" macro, assumes well-formed UTF-16.
270 *
271 * The offset may point to the lead surrogate unit
272 * for a supplementary code point, in which case the macro will read
273 * the following trail surrogate as well.
274 * If the offset points to a trail surrogate, then that itself
275 * will be returned as the code point.
276 * The result is undefined if the offset points to a single, unpaired lead surrogate.
277 *
278 * @param s const UChar * string
279 * @param i string offset
280 * @param c output UChar32 variable
281 * @see U16_NEXT
282 * @stable ICU 2.4
283 */
284#define U16_NEXT_UNSAFE(s, i, c) { \
285 (c)=(s)[(i)++]; \
286 if(U16_IS_LEAD(c)) { \
287 (c)=U16_GET_SUPPLEMENTARY((c), (s)[(i)++]); \
288 } \
289}
290
291/**
292 * Get a code point from a string at a code point boundary offset,
293 * and advance the offset to the next code point boundary.
294 * (Post-incrementing forward iteration.)
295 * "Safe" macro, handles unpaired surrogates and checks for string boundaries.
296 *
297 * The length can be negative for a NUL-terminated string.
298 *
299 * The offset may point to the lead surrogate unit
300 * for a supplementary code point, in which case the macro will read
301 * the following trail surrogate as well.
302 * If the offset points to a trail surrogate or
303 * to a single, unpaired lead surrogate, then c is set to that unpaired surrogate.
304 *
305 * @param s const UChar * string
306 * @param i string offset, must be i<length
307 * @param length string length
308 * @param c output UChar32 variable
309 * @see U16_NEXT_UNSAFE
310 * @stable ICU 2.4
311 */
312#define U16_NEXT(s, i, length, c) { \
313 (c)=(s)[(i)++]; \
314 if(U16_IS_LEAD(c)) { \
315 uint16_t __c2; \
316 if((i)!=(length) && U16_IS_TRAIL(__c2=(s)[(i)])) { \
317 ++(i); \
318 (c)=U16_GET_SUPPLEMENTARY((c), __c2); \
319 } \
320 } \
321}
322
323#ifndef U_HIDE_DRAFT_API
324
325/**
326 * Get a code point from a string at a code point boundary offset,
327 * and advance the offset to the next code point boundary.
328 * (Post-incrementing forward iteration.)
329 * "Safe" macro, handles unpaired surrogates and checks for string boundaries.
330 *
331 * The length can be negative for a NUL-terminated string.
332 *
333 * The offset may point to the lead surrogate unit
334 * for a supplementary code point, in which case the macro will read
335 * the following trail surrogate as well.
336 * If the offset points to a trail surrogate or
337 * to a single, unpaired lead surrogate, then c is set to U+FFFD.
338 *
339 * @param s const UChar * string
340 * @param i string offset, must be i<length
341 * @param length string length
342 * @param c output UChar32 variable
343 * @see U16_NEXT_UNSAFE
344 * @draft ICU 60
345 */
346#define U16_NEXT_OR_FFFD(s, i, length, c) { \
347 (c)=(s)[(i)++]; \
348 if(U16_IS_SURROGATE(c)) { \
349 uint16_t __c2; \
350 if(U16_IS_SURROGATE_LEAD(c) && (i)!=(length) && U16_IS_TRAIL(__c2=(s)[(i)])) { \
351 ++(i); \
352 (c)=U16_GET_SUPPLEMENTARY((c), __c2); \
353 } else { \
354 (c)=0xfffd; \
355 } \
356 } \
357}
358
359#endif // U_HIDE_DRAFT_API
360
361/**
362 * Append a code point to a string, overwriting 1 or 2 code units.
363 * The offset points to the current end of the string contents
364 * and is advanced (post-increment).
365 * "Unsafe" macro, assumes a valid code point and sufficient space in the string.
366 * Otherwise, the result is undefined.
367 *
368 * @param s const UChar * string buffer
369 * @param i string offset
370 * @param c code point to append
371 * @see U16_APPEND
372 * @stable ICU 2.4
373 */
374#define U16_APPEND_UNSAFE(s, i, c) { \
375 if((uint32_t)(c)<=0xffff) { \
376 (s)[(i)++]=(uint16_t)(c); \
377 } else { \
378 (s)[(i)++]=(uint16_t)(((c)>>10)+0xd7c0); \
379 (s)[(i)++]=(uint16_t)(((c)&0x3ff)|0xdc00); \
380 } \
381}
382
383/**
384 * Append a code point to a string, overwriting 1 or 2 code units.
385 * The offset points to the current end of the string contents
386 * and is advanced (post-increment).
387 * "Safe" macro, checks for a valid code point.
388 * If a surrogate pair is written, checks for sufficient space in the string.
389 * If the code point is not valid or a trail surrogate does not fit,
390 * then isError is set to TRUE.
391 *
392 * @param s const UChar * string buffer
393 * @param i string offset, must be i<capacity
394 * @param capacity size of the string buffer
395 * @param c code point to append
396 * @param isError output UBool set to TRUE if an error occurs, otherwise not modified
397 * @see U16_APPEND_UNSAFE
398 * @stable ICU 2.4
399 */
400#define U16_APPEND(s, i, capacity, c, isError) { \
401 if((uint32_t)(c)<=0xffff) { \
402 (s)[(i)++]=(uint16_t)(c); \
403 } else if((uint32_t)(c)<=0x10ffff && (i)+1<(capacity)) { \
404 (s)[(i)++]=(uint16_t)(((c)>>10)+0xd7c0); \
405 (s)[(i)++]=(uint16_t)(((c)&0x3ff)|0xdc00); \
406 } else /* c>0x10ffff or not enough space */ { \
407 (isError)=TRUE; \
408 } \
409}
410
411/**
412 * Advance the string offset from one code point boundary to the next.
413 * (Post-incrementing iteration.)
414 * "Unsafe" macro, assumes well-formed UTF-16.
415 *
416 * @param s const UChar * string
417 * @param i string offset
418 * @see U16_FWD_1
419 * @stable ICU 2.4
420 */
421#define U16_FWD_1_UNSAFE(s, i) { \
422 if(U16_IS_LEAD((s)[(i)++])) { \
423 ++(i); \
424 } \
425}
426
427/**
428 * Advance the string offset from one code point boundary to the next.
429 * (Post-incrementing iteration.)
430 * "Safe" macro, handles unpaired surrogates and checks for string boundaries.
431 *
432 * The length can be negative for a NUL-terminated string.
433 *
434 * @param s const UChar * string
435 * @param i string offset, must be i<length
436 * @param length string length
437 * @see U16_FWD_1_UNSAFE
438 * @stable ICU 2.4
439 */
440#define U16_FWD_1(s, i, length) { \
441 if(U16_IS_LEAD((s)[(i)++]) && (i)!=(length) && U16_IS_TRAIL((s)[i])) { \
442 ++(i); \
443 } \
444}
445
446/**
447 * Advance the string offset from one code point boundary to the n-th next one,
448 * i.e., move forward by n code points.
449 * (Post-incrementing iteration.)
450 * "Unsafe" macro, assumes well-formed UTF-16.
451 *
452 * @param s const UChar * string
453 * @param i string offset
454 * @param n number of code points to skip
455 * @see U16_FWD_N
456 * @stable ICU 2.4
457 */
458#define U16_FWD_N_UNSAFE(s, i, n) { \
459 int32_t __N=(n); \
460 while(__N>0) { \
461 U16_FWD_1_UNSAFE(s, i); \
462 --__N; \
463 } \
464}
465
466/**
467 * Advance the string offset from one code point boundary to the n-th next one,
468 * i.e., move forward by n code points.
469 * (Post-incrementing iteration.)
470 * "Safe" macro, handles unpaired surrogates and checks for string boundaries.
471 *
472 * The length can be negative for a NUL-terminated string.
473 *
474 * @param s const UChar * string
475 * @param i int32_t string offset, must be i<length
476 * @param length int32_t string length
477 * @param n number of code points to skip
478 * @see U16_FWD_N_UNSAFE
479 * @stable ICU 2.4
480 */
481#define U16_FWD_N(s, i, length, n) { \
482 int32_t __N=(n); \
483 while(__N>0 && ((i)<(length) || ((length)<0 && (s)[i]!=0))) { \
484 U16_FWD_1(s, i, length); \
485 --__N; \
486 } \
487}
488
489/**
490 * Adjust a random-access offset to a code point boundary
491 * at the start of a code point.
492 * If the offset points to the trail surrogate of a surrogate pair,
493 * then the offset is decremented.
494 * Otherwise, it is not modified.
495 * "Unsafe" macro, assumes well-formed UTF-16.
496 *
497 * @param s const UChar * string
498 * @param i string offset
499 * @see U16_SET_CP_START
500 * @stable ICU 2.4
501 */
502#define U16_SET_CP_START_UNSAFE(s, i) { \
503 if(U16_IS_TRAIL((s)[i])) { \
504 --(i); \
505 } \
506}
507
508/**
509 * Adjust a random-access offset to a code point boundary
510 * at the start of a code point.
511 * If the offset points to the trail surrogate of a surrogate pair,
512 * then the offset is decremented.
513 * Otherwise, it is not modified.
514 * "Safe" macro, handles unpaired surrogates and checks for string boundaries.
515 *
516 * @param s const UChar * string
517 * @param start starting string offset (usually 0)
518 * @param i string offset, must be start<=i
519 * @see U16_SET_CP_START_UNSAFE
520 * @stable ICU 2.4
521 */
522#define U16_SET_CP_START(s, start, i) { \
523 if(U16_IS_TRAIL((s)[i]) && (i)>(start) && U16_IS_LEAD((s)[(i)-1])) { \
524 --(i); \
525 } \
526}
527
528/* definitions with backward iteration -------------------------------------- */
529
530/**
531 * Move the string offset from one code point boundary to the previous one
532 * and get the code point between them.
533 * (Pre-decrementing backward iteration.)
534 * "Unsafe" macro, assumes well-formed UTF-16.
535 *
536 * The input offset may be the same as the string length.
537 * If the offset is behind a trail surrogate unit
538 * for a supplementary code point, then the macro will read
539 * the preceding lead surrogate as well.
540 * If the offset is behind a lead surrogate, then that itself
541 * will be returned as the code point.
542 * The result is undefined if the offset is behind a single, unpaired trail surrogate.
543 *
544 * @param s const UChar * string
545 * @param i string offset
546 * @param c output UChar32 variable
547 * @see U16_PREV
548 * @stable ICU 2.4
549 */
550#define U16_PREV_UNSAFE(s, i, c) { \
551 (c)=(s)[--(i)]; \
552 if(U16_IS_TRAIL(c)) { \
553 (c)=U16_GET_SUPPLEMENTARY((s)[--(i)], (c)); \
554 } \
555}
556
557/**
558 * Move the string offset from one code point boundary to the previous one
559 * and get the code point between them.
560 * (Pre-decrementing backward iteration.)
561 * "Safe" macro, handles unpaired surrogates and checks for string boundaries.
562 *
563 * The input offset may be the same as the string length.
564 * If the offset is behind a trail surrogate unit
565 * for a supplementary code point, then the macro will read
566 * the preceding lead surrogate as well.
567 * If the offset is behind a lead surrogate or behind a single, unpaired
568 * trail surrogate, then c is set to that unpaired surrogate.
569 *
570 * @param s const UChar * string
571 * @param start starting string offset (usually 0)
572 * @param i string offset, must be start<i
573 * @param c output UChar32 variable
574 * @see U16_PREV_UNSAFE
575 * @stable ICU 2.4
576 */
577#define U16_PREV(s, start, i, c) { \
578 (c)=(s)[--(i)]; \
579 if(U16_IS_TRAIL(c)) { \
580 uint16_t __c2; \
581 if((i)>(start) && U16_IS_LEAD(__c2=(s)[(i)-1])) { \
582 --(i); \
583 (c)=U16_GET_SUPPLEMENTARY(__c2, (c)); \
584 } \
585 } \
586}
587
588#ifndef U_HIDE_DRAFT_API
589
590/**
591 * Move the string offset from one code point boundary to the previous one
592 * and get the code point between them.
593 * (Pre-decrementing backward iteration.)
594 * "Safe" macro, handles unpaired surrogates and checks for string boundaries.
595 *
596 * The input offset may be the same as the string length.
597 * If the offset is behind a trail surrogate unit
598 * for a supplementary code point, then the macro will read
599 * the preceding lead surrogate as well.
600 * If the offset is behind a lead surrogate or behind a single, unpaired
601 * trail surrogate, then c is set to U+FFFD.
602 *
603 * @param s const UChar * string
604 * @param start starting string offset (usually 0)
605 * @param i string offset, must be start<i
606 * @param c output UChar32 variable
607 * @see U16_PREV_UNSAFE
608 * @draft ICU 60
609 */
610#define U16_PREV_OR_FFFD(s, start, i, c) { \
611 (c)=(s)[--(i)]; \
612 if(U16_IS_SURROGATE(c)) { \
613 uint16_t __c2; \
614 if(U16_IS_SURROGATE_TRAIL(c) && (i)>(start) && U16_IS_LEAD(__c2=(s)[(i)-1])) { \
615 --(i); \
616 (c)=U16_GET_SUPPLEMENTARY(__c2, (c)); \
617 } else { \
618 (c)=0xfffd; \
619 } \
620 } \
621}
622
623#endif // U_HIDE_DRAFT_API
624
625/**
626 * Move the string offset from one code point boundary to the previous one.
627 * (Pre-decrementing backward iteration.)
628 * The input offset may be the same as the string length.
629 * "Unsafe" macro, assumes well-formed UTF-16.
630 *
631 * @param s const UChar * string
632 * @param i string offset
633 * @see U16_BACK_1
634 * @stable ICU 2.4
635 */
636#define U16_BACK_1_UNSAFE(s, i) { \
637 if(U16_IS_TRAIL((s)[--(i)])) { \
638 --(i); \
639 } \
640}
641
642/**
643 * Move the string offset from one code point boundary to the previous one.
644 * (Pre-decrementing backward iteration.)
645 * The input offset may be the same as the string length.
646 * "Safe" macro, handles unpaired surrogates and checks for string boundaries.
647 *
648 * @param s const UChar * string
649 * @param start starting string offset (usually 0)
650 * @param i string offset, must be start<i
651 * @see U16_BACK_1_UNSAFE
652 * @stable ICU 2.4
653 */
654#define U16_BACK_1(s, start, i) { \
655 if(U16_IS_TRAIL((s)[--(i)]) && (i)>(start) && U16_IS_LEAD((s)[(i)-1])) { \
656 --(i); \
657 } \
658}
659
660/**
661 * Move the string offset from one code point boundary to the n-th one before it,
662 * i.e., move backward by n code points.
663 * (Pre-decrementing backward iteration.)
664 * The input offset may be the same as the string length.
665 * "Unsafe" macro, assumes well-formed UTF-16.
666 *
667 * @param s const UChar * string
668 * @param i string offset
669 * @param n number of code points to skip
670 * @see U16_BACK_N
671 * @stable ICU 2.4
672 */
673#define U16_BACK_N_UNSAFE(s, i, n) { \
674 int32_t __N=(n); \
675 while(__N>0) { \
676 U16_BACK_1_UNSAFE(s, i); \
677 --__N; \
678 } \
679}
680
681/**
682 * Move the string offset from one code point boundary to the n-th one before it,
683 * i.e., move backward by n code points.
684 * (Pre-decrementing backward iteration.)
685 * The input offset may be the same as the string length.
686 * "Safe" macro, handles unpaired surrogates and checks for string boundaries.
687 *
688 * @param s const UChar * string
689 * @param start start of string
690 * @param i string offset, must be start<i
691 * @param n number of code points to skip
692 * @see U16_BACK_N_UNSAFE
693 * @stable ICU 2.4
694 */
695#define U16_BACK_N(s, start, i, n) { \
696 int32_t __N=(n); \
697 while(__N>0 && (i)>(start)) { \
698 U16_BACK_1(s, start, i); \
699 --__N; \
700 } \
701}
702
703/**
704 * Adjust a random-access offset to a code point boundary after a code point.
705 * If the offset is behind the lead surrogate of a surrogate pair,
706 * then the offset is incremented.
707 * Otherwise, it is not modified.
708 * The input offset may be the same as the string length.
709 * "Unsafe" macro, assumes well-formed UTF-16.
710 *
711 * @param s const UChar * string
712 * @param i string offset
713 * @see U16_SET_CP_LIMIT
714 * @stable ICU 2.4
715 */
716#define U16_SET_CP_LIMIT_UNSAFE(s, i) { \
717 if(U16_IS_LEAD((s)[(i)-1])) { \
718 ++(i); \
719 } \
720}
721
722/**
723 * Adjust a random-access offset to a code point boundary after a code point.
724 * If the offset is behind the lead surrogate of a surrogate pair,
725 * then the offset is incremented.
726 * Otherwise, it is not modified.
727 * The input offset may be the same as the string length.
728 * "Safe" macro, handles unpaired surrogates and checks for string boundaries.
729 *
730 * The length can be negative for a NUL-terminated string.
731 *
732 * @param s const UChar * string
733 * @param start int32_t starting string offset (usually 0)
734 * @param i int32_t string offset, start<=i<=length
735 * @param length int32_t string length
736 * @see U16_SET_CP_LIMIT_UNSAFE
737 * @stable ICU 2.4
738 */
739#define U16_SET_CP_LIMIT(s, start, i, length) { \
740 if((start)<(i) && ((i)<(length) || (length)<0) && U16_IS_LEAD((s)[(i)-1]) && U16_IS_TRAIL((s)[i])) { \
741 ++(i); \
742 } \
743}
744
745#endif
746