ICU-59173.0.1.tar.gz
[apple/icu.git] / icuSources / common / unicode / utf8.h
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1// © 2016 and later: Unicode, Inc. and others.
2// License & terms of use: http://www.unicode.org/copyright.html
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3/*
4*******************************************************************************
5*
2ca993e8 6* Copyright (C) 1999-2015, International Business Machines
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7* Corporation and others. All Rights Reserved.
8*
9*******************************************************************************
10* file name: utf8.h
f3c0d7a5 11* encoding: UTF-8
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12* tab size: 8 (not used)
13* indentation:4
14*
15* created on: 1999sep13
16* created by: Markus W. Scherer
17*/
18
19/**
20 * \file
21 * \brief C API: 8-bit Unicode handling macros
22 *
23 * This file defines macros to deal with 8-bit Unicode (UTF-8) code units (bytes) and strings.
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24 *
25 * For more information see utf.h and the ICU User Guide Strings chapter
4388f060 26 * (http://userguide.icu-project.org/strings).
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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
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34#ifndef __UTF8_H__
35#define __UTF8_H__
36
4388f060 37#include "unicode/umachine.h"
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38#ifndef __UTF_H__
39# include "unicode/utf.h"
40#endif
41
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42/* internal definitions ----------------------------------------------------- */
43
f3c0d7a5 44
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45
46/**
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47 * Counts the trail bytes for a UTF-8 lead byte.
48 * Returns 0 for 0..0xbf as well as for 0xfe and 0xff.
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49 *
50 * This is internal since it is not meant to be called directly by external clients;
51 * however it is called by public macros in this file and thus must remain stable.
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52 *
53 * Note: Beginning with ICU 50, the implementation uses a multi-condition expression
54 * which was shown in 2012 (on x86-64) to compile to fast, branch-free code.
55 * leadByte is evaluated multiple times.
56 *
57 * The pre-ICU 50 implementation used the exported array utf8_countTrailBytes:
58 * #define U8_COUNT_TRAIL_BYTES(leadByte) (utf8_countTrailBytes[leadByte])
59 * leadByte was evaluated exactly once.
60 *
61 * @param leadByte The first byte of a UTF-8 sequence. Must be 0..0xff.
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62 * @internal
63 */
51004dcb 64#define U8_COUNT_TRAIL_BYTES(leadByte) \
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65 ((uint8_t)(leadByte)<0xf0 ? \
66 ((uint8_t)(leadByte)>=0xc0)+((uint8_t)(leadByte)>=0xe0) : \
67 (uint8_t)(leadByte)<0xfe ? 3+((uint8_t)(leadByte)>=0xf8)+((uint8_t)(leadByte)>=0xfc) : 0)
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68
69/**
70 * Counts the trail bytes for a UTF-8 lead byte of a valid UTF-8 sequence.
71 * The maximum supported lead byte is 0xf4 corresponding to U+10FFFF.
72 * leadByte might be evaluated multiple times.
73 *
74 * This is internal since it is not meant to be called directly by external clients;
75 * however it is called by public macros in this file and thus must remain stable.
76 *
77 * @param leadByte The first byte of a UTF-8 sequence. Must be 0..0xff.
78 * @internal
79 */
80#define U8_COUNT_TRAIL_BYTES_UNSAFE(leadByte) \
81 (((leadByte)>=0xc0)+((leadByte)>=0xe0)+((leadByte)>=0xf0))
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82
83/**
84 * Mask a UTF-8 lead byte, leave only the lower bits that form part of the code point value.
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85 *
86 * This is internal since it is not meant to be called directly by external clients;
87 * however it is called by public macros in this file and thus must remain stable.
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88 * @internal
89 */
90#define U8_MASK_LEAD_BYTE(leadByte, countTrailBytes) ((leadByte)&=(1<<(6-(countTrailBytes)))-1)
91
92/**
93 * Function for handling "next code point" with error-checking.
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94 *
95 * This is internal since it is not meant to be called directly by external clients;
96 * however it is U_STABLE (not U_INTERNAL) since it is called by public macros in this
97 * file and thus must remain stable, and should not be hidden when other internal
98 * functions are hidden (otherwise public macros would fail to compile).
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99 * @internal
100 */
729e4ab9 101U_STABLE UChar32 U_EXPORT2
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102utf8_nextCharSafeBody(const uint8_t *s, int32_t *pi, int32_t length, UChar32 c, UBool strict);
103
104/**
105 * Function for handling "append code point" with error-checking.
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106 *
107 * This is internal since it is not meant to be called directly by external clients;
108 * however it is U_STABLE (not U_INTERNAL) since it is called by public macros in this
109 * file and thus must remain stable, and should not be hidden when other internal
110 * functions are hidden (otherwise public macros would fail to compile).
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111 * @internal
112 */
729e4ab9 113U_STABLE int32_t U_EXPORT2
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114utf8_appendCharSafeBody(uint8_t *s, int32_t i, int32_t length, UChar32 c, UBool *pIsError);
115
116/**
117 * Function for handling "previous code point" with error-checking.
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118 *
119 * This is internal since it is not meant to be called directly by external clients;
120 * however it is U_STABLE (not U_INTERNAL) since it is called by public macros in this
121 * file and thus must remain stable, and should not be hidden when other internal
122 * functions are hidden (otherwise public macros would fail to compile).
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123 * @internal
124 */
729e4ab9 125U_STABLE UChar32 U_EXPORT2
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126utf8_prevCharSafeBody(const uint8_t *s, int32_t start, int32_t *pi, UChar32 c, UBool strict);
127
128/**
129 * Function for handling "skip backward one code point" with error-checking.
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130 *
131 * This is internal since it is not meant to be called directly by external clients;
132 * however it is U_STABLE (not U_INTERNAL) since it is called by public macros in this
133 * file and thus must remain stable, and should not be hidden when other internal
134 * functions are hidden (otherwise public macros would fail to compile).
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135 * @internal
136 */
729e4ab9 137U_STABLE int32_t U_EXPORT2
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138utf8_back1SafeBody(const uint8_t *s, int32_t start, int32_t i);
139
140/* single-code point definitions -------------------------------------------- */
141
142/**
143 * Does this code unit (byte) encode a code point by itself (US-ASCII 0..0x7f)?
144 * @param c 8-bit code unit (byte)
145 * @return TRUE or FALSE
374ca955 146 * @stable ICU 2.4
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147 */
148#define U8_IS_SINGLE(c) (((c)&0x80)==0)
149
150/**
151 * Is this code unit (byte) a UTF-8 lead byte?
152 * @param c 8-bit code unit (byte)
153 * @return TRUE or FALSE
374ca955 154 * @stable ICU 2.4
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155 */
156#define U8_IS_LEAD(c) ((uint8_t)((c)-0xc0)<0x3e)
157
158/**
159 * Is this code unit (byte) a UTF-8 trail byte?
160 * @param c 8-bit code unit (byte)
161 * @return TRUE or FALSE
374ca955 162 * @stable ICU 2.4
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163 */
164#define U8_IS_TRAIL(c) (((c)&0xc0)==0x80)
165
166/**
167 * How many code units (bytes) are used for the UTF-8 encoding
168 * of this Unicode code point?
169 * @param c 32-bit code point
170 * @return 1..4, or 0 if c is a surrogate or not a Unicode code point
374ca955 171 * @stable ICU 2.4
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172 */
173#define U8_LENGTH(c) \
174 ((uint32_t)(c)<=0x7f ? 1 : \
175 ((uint32_t)(c)<=0x7ff ? 2 : \
176 ((uint32_t)(c)<=0xd7ff ? 3 : \
177 ((uint32_t)(c)<=0xdfff || (uint32_t)(c)>0x10ffff ? 0 : \
178 ((uint32_t)(c)<=0xffff ? 3 : 4)\
179 ) \
180 ) \
181 ) \
182 )
183
184/**
185 * The maximum number of UTF-8 code units (bytes) per Unicode code point (U+0000..U+10ffff).
186 * @return 4
374ca955 187 * @stable ICU 2.4
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188 */
189#define U8_MAX_LENGTH 4
190
191/**
192 * Get a code point from a string at a random-access offset,
193 * without changing the offset.
194 * The offset may point to either the lead byte or one of the trail bytes
195 * for a code point, in which case the macro will read all of the bytes
196 * for the code point.
197 * The result is undefined if the offset points to an illegal UTF-8
198 * byte sequence.
199 * Iteration through a string is more efficient with U8_NEXT_UNSAFE or U8_NEXT.
200 *
374ca955 201 * @param s const uint8_t * string
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202 * @param i string offset
203 * @param c output UChar32 variable
204 * @see U8_GET
374ca955 205 * @stable ICU 2.4
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206 */
207#define U8_GET_UNSAFE(s, i, c) { \
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208 int32_t _u8_get_unsafe_index=(int32_t)(i); \
209 U8_SET_CP_START_UNSAFE(s, _u8_get_unsafe_index); \
210 U8_NEXT_UNSAFE(s, _u8_get_unsafe_index, c); \
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211}
212
213/**
214 * Get a code point from a string at a random-access offset,
215 * without changing the offset.
216 * The offset may point to either the lead byte or one of the trail bytes
217 * for a code point, in which case the macro will read all of the bytes
218 * for the code point.
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219 *
220 * The length can be negative for a NUL-terminated string.
221 *
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222 * If the offset points to an illegal UTF-8 byte sequence, then
223 * c is set to a negative value.
224 * Iteration through a string is more efficient with U8_NEXT_UNSAFE or U8_NEXT.
225 *
374ca955 226 * @param s const uint8_t * string
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227 * @param start int32_t starting string offset
228 * @param i int32_t string offset, must be start<=i<length
229 * @param length int32_t string length
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230 * @param c output UChar32 variable, set to <0 in case of an error
231 * @see U8_GET_UNSAFE
374ca955 232 * @stable ICU 2.4
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233 */
234#define U8_GET(s, start, i, length, c) { \
51004dcb 235 int32_t _u8_get_index=(i); \
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236 U8_SET_CP_START(s, start, _u8_get_index); \
237 U8_NEXT(s, _u8_get_index, length, c); \
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238}
239
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240/**
241 * Get a code point from a string at a random-access offset,
242 * without changing the offset.
243 * The offset may point to either the lead byte or one of the trail bytes
244 * for a code point, in which case the macro will read all of the bytes
245 * for the code point.
246 *
247 * The length can be negative for a NUL-terminated string.
248 *
249 * If the offset points to an illegal UTF-8 byte sequence, then
250 * c is set to U+FFFD.
251 * Iteration through a string is more efficient with U8_NEXT_UNSAFE or U8_NEXT_OR_FFFD.
252 *
253 * This macro does not distinguish between a real U+FFFD in the text
254 * and U+FFFD returned for an ill-formed sequence.
255 * Use U8_GET() if that distinction is important.
256 *
257 * @param s const uint8_t * string
258 * @param start int32_t starting string offset
259 * @param i int32_t string offset, must be start<=i<length
260 * @param length int32_t string length
261 * @param c output UChar32 variable, set to U+FFFD in case of an error
262 * @see U8_GET
57a6839d 263 * @stable ICU 51
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264 */
265#define U8_GET_OR_FFFD(s, start, i, length, c) { \
266 int32_t _u8_get_index=(i); \
267 U8_SET_CP_START(s, start, _u8_get_index); \
268 U8_NEXT_OR_FFFD(s, _u8_get_index, length, c); \
269}
51004dcb 270
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271/* definitions with forward iteration --------------------------------------- */
272
273/**
274 * Get a code point from a string at a code point boundary offset,
275 * and advance the offset to the next code point boundary.
276 * (Post-incrementing forward iteration.)
277 * "Unsafe" macro, assumes well-formed UTF-8.
278 *
279 * The offset may point to the lead byte of a multi-byte sequence,
280 * in which case the macro will read the whole sequence.
281 * The result is undefined if the offset points to a trail byte
282 * or an illegal UTF-8 sequence.
283 *
374ca955 284 * @param s const uint8_t * string
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285 * @param i string offset
286 * @param c output UChar32 variable
287 * @see U8_NEXT
374ca955 288 * @stable ICU 2.4
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289 */
290#define U8_NEXT_UNSAFE(s, i, c) { \
73c04bcf 291 (c)=(uint8_t)(s)[(i)++]; \
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292 if((c)>=0x80) { \
293 if((c)<0xe0) { \
294 (c)=(((c)&0x1f)<<6)|((s)[(i)++]&0x3f); \
295 } else if((c)<0xf0) { \
296 /* no need for (c&0xf) because the upper bits are truncated after <<12 in the cast to (UChar) */ \
297 (c)=(UChar)(((c)<<12)|(((s)[i]&0x3f)<<6)|((s)[(i)+1]&0x3f)); \
298 (i)+=2; \
299 } else { \
300 (c)=(((c)&7)<<18)|(((s)[i]&0x3f)<<12)|(((s)[(i)+1]&0x3f)<<6)|((s)[(i)+2]&0x3f); \
301 (i)+=3; \
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302 } \
303 } \
304}
305
306/**
307 * Get a code point from a string at a code point boundary offset,
308 * and advance the offset to the next code point boundary.
309 * (Post-incrementing forward iteration.)
310 * "Safe" macro, checks for illegal sequences and for string boundaries.
311 *
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312 * The length can be negative for a NUL-terminated string.
313 *
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314 * The offset may point to the lead byte of a multi-byte sequence,
315 * in which case the macro will read the whole sequence.
316 * If the offset points to a trail byte or an illegal UTF-8 sequence, then
317 * c is set to a negative value.
318 *
374ca955 319 * @param s const uint8_t * string
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320 * @param i int32_t string offset, must be i<length
321 * @param length int32_t string length
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322 * @param c output UChar32 variable, set to <0 in case of an error
323 * @see U8_NEXT_UNSAFE
374ca955 324 * @stable ICU 2.4
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325 */
326#define U8_NEXT(s, i, length, c) { \
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327 (c)=(uint8_t)(s)[(i)++]; \
328 if((c)>=0x80) { \
329 uint8_t __t1, __t2; \
330 if( /* handle U+1000..U+CFFF inline */ \
331 (0xe0<(c) && (c)<=0xec) && \
51004dcb 332 (((i)+1)<(length) || (length)<0) && \
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333 (__t1=(uint8_t)((s)[i]-0x80))<=0x3f && \
334 (__t2=(uint8_t)((s)[(i)+1]-0x80))<= 0x3f \
335 ) { \
336 /* no need for (c&0xf) because the upper bits are truncated after <<12 in the cast to (UChar) */ \
337 (c)=(UChar)(((c)<<12)|(__t1<<6)|__t2); \
338 (i)+=2; \
339 } else if( /* handle U+0080..U+07FF inline */ \
340 ((c)<0xe0 && (c)>=0xc2) && \
51004dcb 341 ((i)!=(length)) && \
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342 (__t1=(uint8_t)((s)[i]-0x80))<=0x3f \
343 ) { \
51004dcb 344 (c)=(((c)&0x1f)<<6)|__t1; \
73c04bcf 345 ++(i); \
51004dcb 346 } else { \
73c04bcf 347 /* function call for "complicated" and error cases */ \
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348 (c)=utf8_nextCharSafeBody((const uint8_t *)s, &(i), (length), c, -1); \
349 } \
350 } \
351}
352
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353/**
354 * Get a code point from a string at a code point boundary offset,
355 * and advance the offset to the next code point boundary.
356 * (Post-incrementing forward iteration.)
357 * "Safe" macro, checks for illegal sequences and for string boundaries.
358 *
359 * The length can be negative for a NUL-terminated string.
360 *
361 * The offset may point to the lead byte of a multi-byte sequence,
362 * in which case the macro will read the whole sequence.
363 * If the offset points to a trail byte or an illegal UTF-8 sequence, then
364 * c is set to U+FFFD.
365 *
366 * This macro does not distinguish between a real U+FFFD in the text
367 * and U+FFFD returned for an ill-formed sequence.
368 * Use U8_NEXT() if that distinction is important.
369 *
370 * @param s const uint8_t * string
371 * @param i int32_t string offset, must be i<length
372 * @param length int32_t string length
373 * @param c output UChar32 variable, set to U+FFFD in case of an error
374 * @see U8_NEXT
57a6839d 375 * @stable ICU 51
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376 */
377#define U8_NEXT_OR_FFFD(s, i, length, c) { \
378 (c)=(uint8_t)(s)[(i)++]; \
379 if((c)>=0x80) { \
380 uint8_t __t1, __t2; \
381 if( /* handle U+1000..U+CFFF inline */ \
382 (0xe0<(c) && (c)<=0xec) && \
383 (((i)+1)<(length) || (length)<0) && \
384 (__t1=(uint8_t)((s)[i]-0x80))<=0x3f && \
385 (__t2=(uint8_t)((s)[(i)+1]-0x80))<= 0x3f \
386 ) { \
387 /* no need for (c&0xf) because the upper bits are truncated after <<12 in the cast to (UChar) */ \
388 (c)=(UChar)(((c)<<12)|(__t1<<6)|__t2); \
389 (i)+=2; \
390 } else if( /* handle U+0080..U+07FF inline */ \
391 ((c)<0xe0 && (c)>=0xc2) && \
392 ((i)!=(length)) && \
393 (__t1=(uint8_t)((s)[i]-0x80))<=0x3f \
394 ) { \
395 (c)=(((c)&0x1f)<<6)|__t1; \
396 ++(i); \
b75a7d8f 397 } else { \
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398 /* function call for "complicated" and error cases */ \
399 (c)=utf8_nextCharSafeBody((const uint8_t *)s, &(i), (length), c, -3); \
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400 } \
401 } \
402}
403
404/**
405 * Append a code point to a string, overwriting 1 to 4 bytes.
406 * The offset points to the current end of the string contents
407 * and is advanced (post-increment).
408 * "Unsafe" macro, assumes a valid code point and sufficient space in the string.
409 * Otherwise, the result is undefined.
410 *
374ca955 411 * @param s const uint8_t * string buffer
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412 * @param i string offset
413 * @param c code point to append
414 * @see U8_APPEND
374ca955 415 * @stable ICU 2.4
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416 */
417#define U8_APPEND_UNSAFE(s, i, c) { \
418 if((uint32_t)(c)<=0x7f) { \
419 (s)[(i)++]=(uint8_t)(c); \
420 } else { \
421 if((uint32_t)(c)<=0x7ff) { \
422 (s)[(i)++]=(uint8_t)(((c)>>6)|0xc0); \
423 } else { \
424 if((uint32_t)(c)<=0xffff) { \
425 (s)[(i)++]=(uint8_t)(((c)>>12)|0xe0); \
426 } else { \
427 (s)[(i)++]=(uint8_t)(((c)>>18)|0xf0); \
428 (s)[(i)++]=(uint8_t)((((c)>>12)&0x3f)|0x80); \
429 } \
430 (s)[(i)++]=(uint8_t)((((c)>>6)&0x3f)|0x80); \
431 } \
432 (s)[(i)++]=(uint8_t)(((c)&0x3f)|0x80); \
433 } \
434}
435
436/**
73c04bcf 437 * Append a code point to a string, overwriting 1 to 4 bytes.
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438 * The offset points to the current end of the string contents
439 * and is advanced (post-increment).
440 * "Safe" macro, checks for a valid code point.
441 * If a non-ASCII code point is written, checks for sufficient space in the string.
442 * If the code point is not valid or trail bytes do not fit,
443 * then isError is set to TRUE.
444 *
374ca955 445 * @param s const uint8_t * string buffer
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446 * @param i int32_t string offset, must be i<capacity
447 * @param capacity int32_t size of the string buffer
448 * @param c UChar32 code point to append
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449 * @param isError output UBool set to TRUE if an error occurs, otherwise not modified
450 * @see U8_APPEND_UNSAFE
374ca955 451 * @stable ICU 2.4
b75a7d8f 452 */
73c04bcf 453#define U8_APPEND(s, i, capacity, c, isError) { \
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454 if((uint32_t)(c)<=0x7f) { \
455 (s)[(i)++]=(uint8_t)(c); \
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456 } else if((uint32_t)(c)<=0x7ff && (i)+1<(capacity)) { \
457 (s)[(i)++]=(uint8_t)(((c)>>6)|0xc0); \
458 (s)[(i)++]=(uint8_t)(((c)&0x3f)|0x80); \
459 } else if((uint32_t)(c)<=0xd7ff && (i)+2<(capacity)) { \
460 (s)[(i)++]=(uint8_t)(((c)>>12)|0xe0); \
461 (s)[(i)++]=(uint8_t)((((c)>>6)&0x3f)|0x80); \
462 (s)[(i)++]=(uint8_t)(((c)&0x3f)|0x80); \
b75a7d8f 463 } else { \
51004dcb 464 (i)=utf8_appendCharSafeBody(s, (i), (capacity), c, &(isError)); \
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465 } \
466}
467
468/**
469 * Advance the string offset from one code point boundary to the next.
470 * (Post-incrementing iteration.)
471 * "Unsafe" macro, assumes well-formed UTF-8.
472 *
374ca955 473 * @param s const uint8_t * string
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474 * @param i string offset
475 * @see U8_FWD_1
374ca955 476 * @stable ICU 2.4
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477 */
478#define U8_FWD_1_UNSAFE(s, i) { \
51004dcb 479 (i)+=1+U8_COUNT_TRAIL_BYTES_UNSAFE((uint8_t)(s)[i]); \
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480}
481
482/**
483 * Advance the string offset from one code point boundary to the next.
484 * (Post-incrementing iteration.)
485 * "Safe" macro, checks for illegal sequences and for string boundaries.
486 *
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487 * The length can be negative for a NUL-terminated string.
488 *
374ca955 489 * @param s const uint8_t * string
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490 * @param i int32_t string offset, must be i<length
491 * @param length int32_t string length
b75a7d8f 492 * @see U8_FWD_1_UNSAFE
374ca955 493 * @stable ICU 2.4
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494 */
495#define U8_FWD_1(s, i, length) { \
73c04bcf 496 uint8_t __b=(uint8_t)(s)[(i)++]; \
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497 if(U8_IS_LEAD(__b)) { \
498 uint8_t __count=U8_COUNT_TRAIL_BYTES(__b); \
51004dcb 499 if((i)+__count>(length) && (length)>=0) { \
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500 __count=(uint8_t)((length)-(i)); \
501 } \
502 while(__count>0 && U8_IS_TRAIL((s)[i])) { \
503 ++(i); \
504 --__count; \
505 } \
506 } \
507}
508
509/**
510 * Advance the string offset from one code point boundary to the n-th next one,
511 * i.e., move forward by n code points.
512 * (Post-incrementing iteration.)
513 * "Unsafe" macro, assumes well-formed UTF-8.
514 *
374ca955 515 * @param s const uint8_t * string
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516 * @param i string offset
517 * @param n number of code points to skip
518 * @see U8_FWD_N
374ca955 519 * @stable ICU 2.4
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520 */
521#define U8_FWD_N_UNSAFE(s, i, n) { \
522 int32_t __N=(n); \
523 while(__N>0) { \
524 U8_FWD_1_UNSAFE(s, i); \
525 --__N; \
526 } \
527}
528
529/**
530 * Advance the string offset from one code point boundary to the n-th next one,
531 * i.e., move forward by n code points.
532 * (Post-incrementing iteration.)
533 * "Safe" macro, checks for illegal sequences and for string boundaries.
534 *
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535 * The length can be negative for a NUL-terminated string.
536 *
374ca955 537 * @param s const uint8_t * string
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538 * @param i int32_t string offset, must be i<length
539 * @param length int32_t string length
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540 * @param n number of code points to skip
541 * @see U8_FWD_N_UNSAFE
374ca955 542 * @stable ICU 2.4
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543 */
544#define U8_FWD_N(s, i, length, n) { \
545 int32_t __N=(n); \
51004dcb 546 while(__N>0 && ((i)<(length) || ((length)<0 && (s)[i]!=0))) { \
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547 U8_FWD_1(s, i, length); \
548 --__N; \
549 } \
550}
551
552/**
553 * Adjust a random-access offset to a code point boundary
554 * at the start of a code point.
555 * If the offset points to a UTF-8 trail byte,
556 * then the offset is moved backward to the corresponding lead byte.
557 * Otherwise, it is not modified.
558 * "Unsafe" macro, assumes well-formed UTF-8.
559 *
374ca955 560 * @param s const uint8_t * string
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561 * @param i string offset
562 * @see U8_SET_CP_START
374ca955 563 * @stable ICU 2.4
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564 */
565#define U8_SET_CP_START_UNSAFE(s, i) { \
566 while(U8_IS_TRAIL((s)[i])) { --(i); } \
567}
568
569/**
570 * Adjust a random-access offset to a code point boundary
571 * at the start of a code point.
572 * If the offset points to a UTF-8 trail byte,
573 * then the offset is moved backward to the corresponding lead byte.
574 * Otherwise, it is not modified.
575 * "Safe" macro, checks for illegal sequences and for string boundaries.
576 *
374ca955 577 * @param s const uint8_t * string
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578 * @param start int32_t starting string offset (usually 0)
579 * @param i int32_t string offset, must be start<=i
b75a7d8f 580 * @see U8_SET_CP_START_UNSAFE
374ca955 581 * @stable ICU 2.4
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582 */
583#define U8_SET_CP_START(s, start, i) { \
584 if(U8_IS_TRAIL((s)[(i)])) { \
51004dcb 585 (i)=utf8_back1SafeBody(s, start, (i)); \
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586 } \
587}
588
589/* definitions with backward iteration -------------------------------------- */
590
591/**
592 * Move the string offset from one code point boundary to the previous one
593 * and get the code point between them.
594 * (Pre-decrementing backward iteration.)
595 * "Unsafe" macro, assumes well-formed UTF-8.
596 *
597 * The input offset may be the same as the string length.
598 * If the offset is behind a multi-byte sequence, then the macro will read
599 * the whole sequence.
600 * If the offset is behind a lead byte, then that itself
601 * will be returned as the code point.
602 * The result is undefined if the offset is behind an illegal UTF-8 sequence.
603 *
374ca955 604 * @param s const uint8_t * string
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605 * @param i string offset
606 * @param c output UChar32 variable
607 * @see U8_PREV
374ca955 608 * @stable ICU 2.4
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609 */
610#define U8_PREV_UNSAFE(s, i, c) { \
73c04bcf 611 (c)=(uint8_t)(s)[--(i)]; \
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612 if(U8_IS_TRAIL(c)) { \
613 uint8_t __b, __count=1, __shift=6; \
614\
615 /* c is a trail byte */ \
616 (c)&=0x3f; \
617 for(;;) { \
73c04bcf 618 __b=(uint8_t)(s)[--(i)]; \
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619 if(__b>=0xc0) { \
620 U8_MASK_LEAD_BYTE(__b, __count); \
621 (c)|=(UChar32)__b<<__shift; \
622 break; \
623 } else { \
624 (c)|=(UChar32)(__b&0x3f)<<__shift; \
625 ++__count; \
626 __shift+=6; \
627 } \
628 } \
629 } \
630}
631
632/**
633 * Move the string offset from one code point boundary to the previous one
634 * and get the code point between them.
635 * (Pre-decrementing backward iteration.)
636 * "Safe" macro, checks for illegal sequences and for string boundaries.
637 *
638 * The input offset may be the same as the string length.
639 * If the offset is behind a multi-byte sequence, then the macro will read
640 * the whole sequence.
641 * If the offset is behind a lead byte, then that itself
642 * will be returned as the code point.
643 * If the offset is behind an illegal UTF-8 sequence, then c is set to a negative value.
644 *
374ca955 645 * @param s const uint8_t * string
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646 * @param start int32_t starting string offset (usually 0)
647 * @param i int32_t string offset, must be start<i
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648 * @param c output UChar32 variable, set to <0 in case of an error
649 * @see U8_PREV_UNSAFE
374ca955 650 * @stable ICU 2.4
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651 */
652#define U8_PREV(s, start, i, c) { \
73c04bcf 653 (c)=(uint8_t)(s)[--(i)]; \
b75a7d8f 654 if((c)>=0x80) { \
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655 (c)=utf8_prevCharSafeBody((const uint8_t *)s, start, &(i), c, -1); \
656 } \
657}
658
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659/**
660 * Move the string offset from one code point boundary to the previous one
661 * and get the code point between them.
662 * (Pre-decrementing backward iteration.)
663 * "Safe" macro, checks for illegal sequences and for string boundaries.
664 *
665 * The input offset may be the same as the string length.
666 * If the offset is behind a multi-byte sequence, then the macro will read
667 * the whole sequence.
668 * If the offset is behind a lead byte, then that itself
669 * will be returned as the code point.
670 * If the offset is behind an illegal UTF-8 sequence, then c is set to U+FFFD.
671 *
672 * This macro does not distinguish between a real U+FFFD in the text
673 * and U+FFFD returned for an ill-formed sequence.
674 * Use U8_PREV() if that distinction is important.
675 *
676 * @param s const uint8_t * string
677 * @param start int32_t starting string offset (usually 0)
678 * @param i int32_t string offset, must be start<i
679 * @param c output UChar32 variable, set to U+FFFD in case of an error
680 * @see U8_PREV
57a6839d 681 * @stable ICU 51
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682 */
683#define U8_PREV_OR_FFFD(s, start, i, c) { \
684 (c)=(uint8_t)(s)[--(i)]; \
685 if((c)>=0x80) { \
686 (c)=utf8_prevCharSafeBody((const uint8_t *)s, start, &(i), c, -3); \
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687 } \
688}
689
690/**
691 * Move the string offset from one code point boundary to the previous one.
692 * (Pre-decrementing backward iteration.)
693 * The input offset may be the same as the string length.
694 * "Unsafe" macro, assumes well-formed UTF-8.
695 *
374ca955 696 * @param s const uint8_t * string
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697 * @param i string offset
698 * @see U8_BACK_1
374ca955 699 * @stable ICU 2.4
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700 */
701#define U8_BACK_1_UNSAFE(s, i) { \
702 while(U8_IS_TRAIL((s)[--(i)])) {} \
703}
704
705/**
706 * Move the string offset from one code point boundary to the previous one.
707 * (Pre-decrementing backward iteration.)
708 * The input offset may be the same as the string length.
709 * "Safe" macro, checks for illegal sequences and for string boundaries.
710 *
374ca955 711 * @param s const uint8_t * string
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712 * @param start int32_t starting string offset (usually 0)
713 * @param i int32_t string offset, must be start<i
b75a7d8f 714 * @see U8_BACK_1_UNSAFE
374ca955 715 * @stable ICU 2.4
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716 */
717#define U8_BACK_1(s, start, i) { \
718 if(U8_IS_TRAIL((s)[--(i)])) { \
51004dcb 719 (i)=utf8_back1SafeBody(s, start, (i)); \
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720 } \
721}
722
723/**
724 * Move the string offset from one code point boundary to the n-th one before it,
725 * i.e., move backward by n code points.
726 * (Pre-decrementing backward iteration.)
727 * The input offset may be the same as the string length.
728 * "Unsafe" macro, assumes well-formed UTF-8.
729 *
374ca955 730 * @param s const uint8_t * string
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731 * @param i string offset
732 * @param n number of code points to skip
733 * @see U8_BACK_N
374ca955 734 * @stable ICU 2.4
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735 */
736#define U8_BACK_N_UNSAFE(s, i, n) { \
737 int32_t __N=(n); \
738 while(__N>0) { \
739 U8_BACK_1_UNSAFE(s, i); \
740 --__N; \
741 } \
742}
743
744/**
745 * Move the string offset from one code point boundary to the n-th one before it,
746 * i.e., move backward by n code points.
747 * (Pre-decrementing backward iteration.)
748 * The input offset may be the same as the string length.
749 * "Safe" macro, checks for illegal sequences and for string boundaries.
750 *
374ca955 751 * @param s const uint8_t * string
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752 * @param start int32_t index of the start of the string
753 * @param i int32_t string offset, must be start<i
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754 * @param n number of code points to skip
755 * @see U8_BACK_N_UNSAFE
374ca955 756 * @stable ICU 2.4
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757 */
758#define U8_BACK_N(s, start, i, n) { \
759 int32_t __N=(n); \
760 while(__N>0 && (i)>(start)) { \
761 U8_BACK_1(s, start, i); \
762 --__N; \
763 } \
764}
765
766/**
767 * Adjust a random-access offset to a code point boundary after a code point.
768 * If the offset is behind a partial multi-byte sequence,
769 * then the offset is incremented to behind the whole sequence.
770 * Otherwise, it is not modified.
771 * The input offset may be the same as the string length.
772 * "Unsafe" macro, assumes well-formed UTF-8.
773 *
374ca955 774 * @param s const uint8_t * string
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775 * @param i string offset
776 * @see U8_SET_CP_LIMIT
374ca955 777 * @stable ICU 2.4
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778 */
779#define U8_SET_CP_LIMIT_UNSAFE(s, i) { \
780 U8_BACK_1_UNSAFE(s, i); \
781 U8_FWD_1_UNSAFE(s, i); \
782}
783
784/**
785 * Adjust a random-access offset to a code point boundary after a code point.
786 * If the offset is behind a partial multi-byte sequence,
787 * then the offset is incremented to behind the whole sequence.
788 * Otherwise, it is not modified.
789 * The input offset may be the same as the string length.
790 * "Safe" macro, checks for illegal sequences and for string boundaries.
791 *
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792 * The length can be negative for a NUL-terminated string.
793 *
374ca955 794 * @param s const uint8_t * string
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795 * @param start int32_t starting string offset (usually 0)
796 * @param i int32_t string offset, must be start<=i<=length
797 * @param length int32_t string length
b75a7d8f 798 * @see U8_SET_CP_LIMIT_UNSAFE
374ca955 799 * @stable ICU 2.4
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800 */
801#define U8_SET_CP_LIMIT(s, start, i, length) { \
2ca993e8 802 if((start)<(i) && ((i)<(length) || (length)<0)) { \
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803 U8_BACK_1(s, start, i); \
804 U8_FWD_1(s, i, length); \
805 } \
806}
807
808#endif