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author jpayne
date Tue, 18 Mar 2025 17:55:14 -0400
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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) 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) UPRV_BLOCK_MACRO_BEGIN { \
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 } UPRV_BLOCK_MACRO_END
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) UPRV_BLOCK_MACRO_BEGIN { \
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 } UPRV_BLOCK_MACRO_END
215
216 /**
217 * Get a code point from a string at a random-access offset,
218 * without changing the offset.
219 * "Safe" macro, handles unpaired surrogates and checks for string boundaries.
220 *
221 * The offset may point to either the lead or trail surrogate unit
222 * for a supplementary code point, in which case the macro will read
223 * the adjacent matching surrogate as well.
224 *
225 * The length can be negative for a NUL-terminated string.
226 *
227 * If the offset points to a single, unpaired surrogate, then
228 * c is set to U+FFFD.
229 * Iteration through a string is more efficient with U16_NEXT_UNSAFE or U16_NEXT_OR_FFFD.
230 *
231 * @param s const UChar * string
232 * @param start starting string offset (usually 0)
233 * @param i string offset, must be start<=i<length
234 * @param length string length
235 * @param c output UChar32 variable
236 * @see U16_GET_UNSAFE
237 * @stable ICU 60
238 */
239 #define U16_GET_OR_FFFD(s, start, i, length, c) UPRV_BLOCK_MACRO_BEGIN { \
240 (c)=(s)[i]; \
241 if(U16_IS_SURROGATE(c)) { \
242 uint16_t __c2; \
243 if(U16_IS_SURROGATE_LEAD(c)) { \
244 if((i)+1!=(length) && U16_IS_TRAIL(__c2=(s)[(i)+1])) { \
245 (c)=U16_GET_SUPPLEMENTARY((c), __c2); \
246 } else { \
247 (c)=0xfffd; \
248 } \
249 } else { \
250 if((i)>(start) && U16_IS_LEAD(__c2=(s)[(i)-1])) { \
251 (c)=U16_GET_SUPPLEMENTARY(__c2, (c)); \
252 } else { \
253 (c)=0xfffd; \
254 } \
255 } \
256 } \
257 } UPRV_BLOCK_MACRO_END
258
259 /* definitions with forward iteration --------------------------------------- */
260
261 /**
262 * Get a code point from a string at a code point boundary offset,
263 * and advance the offset to the next code point boundary.
264 * (Post-incrementing forward iteration.)
265 * "Unsafe" macro, assumes well-formed UTF-16.
266 *
267 * The offset may point to the lead surrogate unit
268 * for a supplementary code point, in which case the macro will read
269 * the following trail surrogate as well.
270 * If the offset points to a trail surrogate, then that itself
271 * will be returned as the code point.
272 * The result is undefined if the offset points to a single, unpaired lead surrogate.
273 *
274 * @param s const UChar * string
275 * @param i string offset
276 * @param c output UChar32 variable
277 * @see U16_NEXT
278 * @stable ICU 2.4
279 */
280 #define U16_NEXT_UNSAFE(s, i, c) UPRV_BLOCK_MACRO_BEGIN { \
281 (c)=(s)[(i)++]; \
282 if(U16_IS_LEAD(c)) { \
283 (c)=U16_GET_SUPPLEMENTARY((c), (s)[(i)++]); \
284 } \
285 } UPRV_BLOCK_MACRO_END
286
287 /**
288 * Get a code point from a string at a code point boundary offset,
289 * and advance the offset to the next code point boundary.
290 * (Post-incrementing forward iteration.)
291 * "Safe" macro, handles unpaired surrogates and checks for string boundaries.
292 *
293 * The length can be negative for a NUL-terminated string.
294 *
295 * The offset may point to the lead surrogate unit
296 * for a supplementary code point, in which case the macro will read
297 * the following trail surrogate as well.
298 * If the offset points to a trail surrogate or
299 * to a single, unpaired lead surrogate, then c is set to that unpaired surrogate.
300 *
301 * @param s const UChar * string
302 * @param i string offset, must be i<length
303 * @param length string length
304 * @param c output UChar32 variable
305 * @see U16_NEXT_UNSAFE
306 * @stable ICU 2.4
307 */
308 #define U16_NEXT(s, i, length, c) UPRV_BLOCK_MACRO_BEGIN { \
309 (c)=(s)[(i)++]; \
310 if(U16_IS_LEAD(c)) { \
311 uint16_t __c2; \
312 if((i)!=(length) && U16_IS_TRAIL(__c2=(s)[(i)])) { \
313 ++(i); \
314 (c)=U16_GET_SUPPLEMENTARY((c), __c2); \
315 } \
316 } \
317 } UPRV_BLOCK_MACRO_END
318
319 /**
320 * Get a code point from a string at a code point boundary offset,
321 * and advance the offset to the next code point boundary.
322 * (Post-incrementing forward iteration.)
323 * "Safe" macro, handles unpaired surrogates and checks for string boundaries.
324 *
325 * The length can be negative for a NUL-terminated string.
326 *
327 * The offset may point to the lead surrogate unit
328 * for a supplementary code point, in which case the macro will read
329 * the following trail surrogate as well.
330 * If the offset points to a trail surrogate or
331 * to a single, unpaired lead surrogate, then c is set to U+FFFD.
332 *
333 * @param s const UChar * string
334 * @param i string offset, must be i<length
335 * @param length string length
336 * @param c output UChar32 variable
337 * @see U16_NEXT_UNSAFE
338 * @stable ICU 60
339 */
340 #define U16_NEXT_OR_FFFD(s, i, length, c) UPRV_BLOCK_MACRO_BEGIN { \
341 (c)=(s)[(i)++]; \
342 if(U16_IS_SURROGATE(c)) { \
343 uint16_t __c2; \
344 if(U16_IS_SURROGATE_LEAD(c) && (i)!=(length) && U16_IS_TRAIL(__c2=(s)[(i)])) { \
345 ++(i); \
346 (c)=U16_GET_SUPPLEMENTARY((c), __c2); \
347 } else { \
348 (c)=0xfffd; \
349 } \
350 } \
351 } UPRV_BLOCK_MACRO_END
352
353 /**
354 * Append a code point to a string, overwriting 1 or 2 code units.
355 * The offset points to the current end of the string contents
356 * and is advanced (post-increment).
357 * "Unsafe" macro, assumes a valid code point and sufficient space in the string.
358 * Otherwise, the result is undefined.
359 *
360 * @param s const UChar * string buffer
361 * @param i string offset
362 * @param c code point to append
363 * @see U16_APPEND
364 * @stable ICU 2.4
365 */
366 #define U16_APPEND_UNSAFE(s, i, c) UPRV_BLOCK_MACRO_BEGIN { \
367 if((uint32_t)(c)<=0xffff) { \
368 (s)[(i)++]=(uint16_t)(c); \
369 } else { \
370 (s)[(i)++]=(uint16_t)(((c)>>10)+0xd7c0); \
371 (s)[(i)++]=(uint16_t)(((c)&0x3ff)|0xdc00); \
372 } \
373 } UPRV_BLOCK_MACRO_END
374
375 /**
376 * Append a code point to a string, overwriting 1 or 2 code units.
377 * The offset points to the current end of the string contents
378 * and is advanced (post-increment).
379 * "Safe" macro, checks for a valid code point.
380 * If a surrogate pair is written, checks for sufficient space in the string.
381 * If the code point is not valid or a trail surrogate does not fit,
382 * then isError is set to TRUE.
383 *
384 * @param s const UChar * string buffer
385 * @param i string offset, must be i<capacity
386 * @param capacity size of the string buffer
387 * @param c code point to append
388 * @param isError output UBool set to TRUE if an error occurs, otherwise not modified
389 * @see U16_APPEND_UNSAFE
390 * @stable ICU 2.4
391 */
392 #define U16_APPEND(s, i, capacity, c, isError) UPRV_BLOCK_MACRO_BEGIN { \
393 if((uint32_t)(c)<=0xffff) { \
394 (s)[(i)++]=(uint16_t)(c); \
395 } else if((uint32_t)(c)<=0x10ffff && (i)+1<(capacity)) { \
396 (s)[(i)++]=(uint16_t)(((c)>>10)+0xd7c0); \
397 (s)[(i)++]=(uint16_t)(((c)&0x3ff)|0xdc00); \
398 } else /* c>0x10ffff or not enough space */ { \
399 (isError)=TRUE; \
400 } \
401 } UPRV_BLOCK_MACRO_END
402
403 /**
404 * Advance the string offset from one code point boundary to the next.
405 * (Post-incrementing iteration.)
406 * "Unsafe" macro, assumes well-formed UTF-16.
407 *
408 * @param s const UChar * string
409 * @param i string offset
410 * @see U16_FWD_1
411 * @stable ICU 2.4
412 */
413 #define U16_FWD_1_UNSAFE(s, i) UPRV_BLOCK_MACRO_BEGIN { \
414 if(U16_IS_LEAD((s)[(i)++])) { \
415 ++(i); \
416 } \
417 } UPRV_BLOCK_MACRO_END
418
419 /**
420 * Advance the string offset from one code point boundary to the next.
421 * (Post-incrementing iteration.)
422 * "Safe" macro, handles unpaired surrogates and checks for string boundaries.
423 *
424 * The length can be negative for a NUL-terminated string.
425 *
426 * @param s const UChar * string
427 * @param i string offset, must be i<length
428 * @param length string length
429 * @see U16_FWD_1_UNSAFE
430 * @stable ICU 2.4
431 */
432 #define U16_FWD_1(s, i, length) UPRV_BLOCK_MACRO_BEGIN { \
433 if(U16_IS_LEAD((s)[(i)++]) && (i)!=(length) && U16_IS_TRAIL((s)[i])) { \
434 ++(i); \
435 } \
436 } UPRV_BLOCK_MACRO_END
437
438 /**
439 * Advance the string offset from one code point boundary to the n-th next one,
440 * i.e., move forward by n code points.
441 * (Post-incrementing iteration.)
442 * "Unsafe" macro, assumes well-formed UTF-16.
443 *
444 * @param s const UChar * string
445 * @param i string offset
446 * @param n number of code points to skip
447 * @see U16_FWD_N
448 * @stable ICU 2.4
449 */
450 #define U16_FWD_N_UNSAFE(s, i, n) UPRV_BLOCK_MACRO_BEGIN { \
451 int32_t __N=(n); \
452 while(__N>0) { \
453 U16_FWD_1_UNSAFE(s, i); \
454 --__N; \
455 } \
456 } UPRV_BLOCK_MACRO_END
457
458 /**
459 * Advance the string offset from one code point boundary to the n-th next one,
460 * i.e., move forward by n code points.
461 * (Post-incrementing iteration.)
462 * "Safe" macro, handles unpaired surrogates and checks for string boundaries.
463 *
464 * The length can be negative for a NUL-terminated string.
465 *
466 * @param s const UChar * string
467 * @param i int32_t string offset, must be i<length
468 * @param length int32_t string length
469 * @param n number of code points to skip
470 * @see U16_FWD_N_UNSAFE
471 * @stable ICU 2.4
472 */
473 #define U16_FWD_N(s, i, length, n) UPRV_BLOCK_MACRO_BEGIN { \
474 int32_t __N=(n); \
475 while(__N>0 && ((i)<(length) || ((length)<0 && (s)[i]!=0))) { \
476 U16_FWD_1(s, i, length); \
477 --__N; \
478 } \
479 } UPRV_BLOCK_MACRO_END
480
481 /**
482 * Adjust a random-access offset to a code point boundary
483 * at the start of a code point.
484 * If the offset points to the trail surrogate of a surrogate pair,
485 * then the offset is decremented.
486 * Otherwise, it is not modified.
487 * "Unsafe" macro, assumes well-formed UTF-16.
488 *
489 * @param s const UChar * string
490 * @param i string offset
491 * @see U16_SET_CP_START
492 * @stable ICU 2.4
493 */
494 #define U16_SET_CP_START_UNSAFE(s, i) UPRV_BLOCK_MACRO_BEGIN { \
495 if(U16_IS_TRAIL((s)[i])) { \
496 --(i); \
497 } \
498 } UPRV_BLOCK_MACRO_END
499
500 /**
501 * Adjust a random-access offset to a code point boundary
502 * at the start of a code point.
503 * If the offset points to the trail surrogate of a surrogate pair,
504 * then the offset is decremented.
505 * Otherwise, it is not modified.
506 * "Safe" macro, handles unpaired surrogates and checks for string boundaries.
507 *
508 * @param s const UChar * string
509 * @param start starting string offset (usually 0)
510 * @param i string offset, must be start<=i
511 * @see U16_SET_CP_START_UNSAFE
512 * @stable ICU 2.4
513 */
514 #define U16_SET_CP_START(s, start, i) UPRV_BLOCK_MACRO_BEGIN { \
515 if(U16_IS_TRAIL((s)[i]) && (i)>(start) && U16_IS_LEAD((s)[(i)-1])) { \
516 --(i); \
517 } \
518 } UPRV_BLOCK_MACRO_END
519
520 /* definitions with backward iteration -------------------------------------- */
521
522 /**
523 * Move the string offset from one code point boundary to the previous one
524 * and get the code point between them.
525 * (Pre-decrementing backward iteration.)
526 * "Unsafe" macro, assumes well-formed UTF-16.
527 *
528 * The input offset may be the same as the string length.
529 * If the offset is behind a trail surrogate unit
530 * for a supplementary code point, then the macro will read
531 * the preceding lead surrogate as well.
532 * If the offset is behind a lead surrogate, then that itself
533 * will be returned as the code point.
534 * The result is undefined if the offset is behind a single, unpaired trail surrogate.
535 *
536 * @param s const UChar * string
537 * @param i string offset
538 * @param c output UChar32 variable
539 * @see U16_PREV
540 * @stable ICU 2.4
541 */
542 #define U16_PREV_UNSAFE(s, i, c) UPRV_BLOCK_MACRO_BEGIN { \
543 (c)=(s)[--(i)]; \
544 if(U16_IS_TRAIL(c)) { \
545 (c)=U16_GET_SUPPLEMENTARY((s)[--(i)], (c)); \
546 } \
547 } UPRV_BLOCK_MACRO_END
548
549 /**
550 * Move the string offset from one code point boundary to the previous one
551 * and get the code point between them.
552 * (Pre-decrementing backward iteration.)
553 * "Safe" macro, handles unpaired surrogates and checks for string boundaries.
554 *
555 * The input offset may be the same as the string length.
556 * If the offset is behind a trail surrogate unit
557 * for a supplementary code point, then the macro will read
558 * the preceding lead surrogate as well.
559 * If the offset is behind a lead surrogate or behind a single, unpaired
560 * trail surrogate, then c is set to that unpaired surrogate.
561 *
562 * @param s const UChar * string
563 * @param start starting string offset (usually 0)
564 * @param i string offset, must be start<i
565 * @param c output UChar32 variable
566 * @see U16_PREV_UNSAFE
567 * @stable ICU 2.4
568 */
569 #define U16_PREV(s, start, i, c) UPRV_BLOCK_MACRO_BEGIN { \
570 (c)=(s)[--(i)]; \
571 if(U16_IS_TRAIL(c)) { \
572 uint16_t __c2; \
573 if((i)>(start) && U16_IS_LEAD(__c2=(s)[(i)-1])) { \
574 --(i); \
575 (c)=U16_GET_SUPPLEMENTARY(__c2, (c)); \
576 } \
577 } \
578 } UPRV_BLOCK_MACRO_END
579
580 /**
581 * Move the string offset from one code point boundary to the previous one
582 * and get the code point between them.
583 * (Pre-decrementing backward iteration.)
584 * "Safe" macro, handles unpaired surrogates and checks for string boundaries.
585 *
586 * The input offset may be the same as the string length.
587 * If the offset is behind a trail surrogate unit
588 * for a supplementary code point, then the macro will read
589 * the preceding lead surrogate as well.
590 * If the offset is behind a lead surrogate or behind a single, unpaired
591 * trail surrogate, then c is set to U+FFFD.
592 *
593 * @param s const UChar * string
594 * @param start starting string offset (usually 0)
595 * @param i string offset, must be start<i
596 * @param c output UChar32 variable
597 * @see U16_PREV_UNSAFE
598 * @stable ICU 60
599 */
600 #define U16_PREV_OR_FFFD(s, start, i, c) UPRV_BLOCK_MACRO_BEGIN { \
601 (c)=(s)[--(i)]; \
602 if(U16_IS_SURROGATE(c)) { \
603 uint16_t __c2; \
604 if(U16_IS_SURROGATE_TRAIL(c) && (i)>(start) && U16_IS_LEAD(__c2=(s)[(i)-1])) { \
605 --(i); \
606 (c)=U16_GET_SUPPLEMENTARY(__c2, (c)); \
607 } else { \
608 (c)=0xfffd; \
609 } \
610 } \
611 } UPRV_BLOCK_MACRO_END
612
613 /**
614 * Move the string offset from one code point boundary to the previous one.
615 * (Pre-decrementing backward iteration.)
616 * The input offset may be the same as the string length.
617 * "Unsafe" macro, assumes well-formed UTF-16.
618 *
619 * @param s const UChar * string
620 * @param i string offset
621 * @see U16_BACK_1
622 * @stable ICU 2.4
623 */
624 #define U16_BACK_1_UNSAFE(s, i) UPRV_BLOCK_MACRO_BEGIN { \
625 if(U16_IS_TRAIL((s)[--(i)])) { \
626 --(i); \
627 } \
628 } UPRV_BLOCK_MACRO_END
629
630 /**
631 * Move the string offset from one code point boundary to the previous one.
632 * (Pre-decrementing backward iteration.)
633 * The input offset may be the same as the string length.
634 * "Safe" macro, handles unpaired surrogates and checks for string boundaries.
635 *
636 * @param s const UChar * string
637 * @param start starting string offset (usually 0)
638 * @param i string offset, must be start<i
639 * @see U16_BACK_1_UNSAFE
640 * @stable ICU 2.4
641 */
642 #define U16_BACK_1(s, start, i) UPRV_BLOCK_MACRO_BEGIN { \
643 if(U16_IS_TRAIL((s)[--(i)]) && (i)>(start) && U16_IS_LEAD((s)[(i)-1])) { \
644 --(i); \
645 } \
646 } UPRV_BLOCK_MACRO_END
647
648 /**
649 * Move the string offset from one code point boundary to the n-th one before it,
650 * i.e., move backward by n code points.
651 * (Pre-decrementing backward iteration.)
652 * The input offset may be the same as the string length.
653 * "Unsafe" macro, assumes well-formed UTF-16.
654 *
655 * @param s const UChar * string
656 * @param i string offset
657 * @param n number of code points to skip
658 * @see U16_BACK_N
659 * @stable ICU 2.4
660 */
661 #define U16_BACK_N_UNSAFE(s, i, n) UPRV_BLOCK_MACRO_BEGIN { \
662 int32_t __N=(n); \
663 while(__N>0) { \
664 U16_BACK_1_UNSAFE(s, i); \
665 --__N; \
666 } \
667 } UPRV_BLOCK_MACRO_END
668
669 /**
670 * Move the string offset from one code point boundary to the n-th one before it,
671 * i.e., move backward by n code points.
672 * (Pre-decrementing backward iteration.)
673 * The input offset may be the same as the string length.
674 * "Safe" macro, handles unpaired surrogates and checks for string boundaries.
675 *
676 * @param s const UChar * string
677 * @param start start of string
678 * @param i string offset, must be start<i
679 * @param n number of code points to skip
680 * @see U16_BACK_N_UNSAFE
681 * @stable ICU 2.4
682 */
683 #define U16_BACK_N(s, start, i, n) UPRV_BLOCK_MACRO_BEGIN { \
684 int32_t __N=(n); \
685 while(__N>0 && (i)>(start)) { \
686 U16_BACK_1(s, start, i); \
687 --__N; \
688 } \
689 } UPRV_BLOCK_MACRO_END
690
691 /**
692 * Adjust a random-access offset to a code point boundary after a code point.
693 * If the offset is behind the lead surrogate of a surrogate pair,
694 * then the offset is incremented.
695 * Otherwise, it is not modified.
696 * The input offset may be the same as the string length.
697 * "Unsafe" macro, assumes well-formed UTF-16.
698 *
699 * @param s const UChar * string
700 * @param i string offset
701 * @see U16_SET_CP_LIMIT
702 * @stable ICU 2.4
703 */
704 #define U16_SET_CP_LIMIT_UNSAFE(s, i) UPRV_BLOCK_MACRO_BEGIN { \
705 if(U16_IS_LEAD((s)[(i)-1])) { \
706 ++(i); \
707 } \
708 } UPRV_BLOCK_MACRO_END
709
710 /**
711 * Adjust a random-access offset to a code point boundary after a code point.
712 * If the offset is behind the lead surrogate of a surrogate pair,
713 * then the offset is incremented.
714 * Otherwise, it is not modified.
715 * The input offset may be the same as the string length.
716 * "Safe" macro, handles unpaired surrogates and checks for string boundaries.
717 *
718 * The length can be negative for a NUL-terminated string.
719 *
720 * @param s const UChar * string
721 * @param start int32_t starting string offset (usually 0)
722 * @param i int32_t string offset, start<=i<=length
723 * @param length int32_t string length
724 * @see U16_SET_CP_LIMIT_UNSAFE
725 * @stable ICU 2.4
726 */
727 #define U16_SET_CP_LIMIT(s, start, i, length) UPRV_BLOCK_MACRO_BEGIN { \
728 if((start)<(i) && ((i)<(length) || (length)<0) && U16_IS_LEAD((s)[(i)-1]) && U16_IS_TRAIL((s)[i])) { \
729 ++(i); \
730 } \
731 } UPRV_BLOCK_MACRO_END
732
733 #endif