Mercurial > hg > octave-nkf > gnulib-hg
annotate lib/mbuiter.h @ 9659:5680cf5b5595
md2: clarify comments to say that alignment is not required.
* lib/md2.h: Remove warning about alignment in comment.
* lib/md2.c (md2_read_ctx, md2_finish_ctx): Doc fix, alignment
has never been required.
| author | Simon Josefsson <simon@josefsson.org> |
|---|---|
| date | Thu, 31 Jan 2008 11:10:36 +0100 |
| parents | bbbbbf4cd1c5 |
| children | e8d2c6fc33ad |
| rev | line source |
|---|---|
| 6055 | 1 /* Iterating through multibyte strings: macros for multi-byte encodings. |
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2 Copyright (C) 2001, 2005, 2007 Free Software Foundation, Inc. |
| 6055 | 3 |
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4 This program is free software: you can redistribute it and/or modify |
| 6055 | 5 it under the terms of the GNU General Public License as published by |
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6 the Free Software Foundation; either version 3 of the License, or |
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7 (at your option) any later version. |
| 6055 | 8 |
| 9 This program is distributed in the hope that it will be useful, | |
| 10 but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| 12 GNU General Public License for more details. | |
| 13 | |
| 14 You should have received a copy of the GNU General Public License | |
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15 along with this program. If not, see <http://www.gnu.org/licenses/>. */ |
| 6055 | 16 |
| 17 /* Written by Bruno Haible <bruno@clisp.org>. */ | |
| 18 | |
| 19 /* The macros in this file implement forward iteration through a | |
| 20 multi-byte string, without knowing its length a-priori. | |
| 21 | |
| 22 With these macros, an iteration loop that looks like | |
| 23 | |
| 24 char *iter; | |
| 25 for (iter = buf; *iter != '\0'; iter++) | |
| 26 { | |
| 27 do_something (*iter); | |
| 28 } | |
| 29 | |
| 30 becomes | |
| 31 | |
| 32 mbui_iterator_t iter; | |
| 33 for (mbui_init (iter, buf); mbui_avail (iter); mbui_advance (iter)) | |
| 34 { | |
| 35 do_something (mbui_cur_ptr (iter), mb_len (mbui_cur (iter))); | |
| 36 } | |
| 37 | |
| 38 The benefit of these macros over plain use of mbrtowc is: | |
| 39 - Handling of invalid multibyte sequences is possible without | |
| 40 making the code more complicated, while still preserving the | |
| 41 invalid multibyte sequences. | |
| 42 | |
| 43 Compared to mbiter.h, the macros here don't need to know the string's | |
| 44 length a-priori. The downside is that at each step, the look-ahead | |
| 45 that guards against overrunning the terminating '\0' is more expensive. | |
| 46 The mbui_* macros are therefore suitable when there is a high probability | |
| 47 that only the first few multibyte characters need to be inspected. | |
| 48 Whereas the mbi_* macros are better if usually the iteration runs | |
| 49 through the entire string. | |
| 50 | |
| 51 mbui_iterator_t | |
| 52 is a type usable for variable declarations. | |
| 53 | |
| 54 mbui_init (iter, startptr) | |
| 55 initializes the iterator, starting at startptr. | |
| 56 | |
| 57 mbui_avail (iter) | |
| 58 returns true if there are more multibyte chracters available before | |
| 59 the end of string is reached. In this case, mbui_cur (iter) is | |
| 60 initialized to the next multibyte chracter. | |
| 61 | |
| 62 mbui_advance (iter) | |
| 63 advances the iterator by one multibyte character. | |
| 64 | |
| 65 mbui_cur (iter) | |
| 66 returns the current multibyte character, of type mbchar_t. All the | |
| 67 macros defined in mbchar.h can be used on it. | |
| 68 | |
| 69 mbui_cur_ptr (iter) | |
| 70 return a pointer to the beginning of the current multibyte character. | |
| 71 | |
| 72 mbui_reloc (iter, ptrdiff) | |
| 73 relocates iterator when the string is moved by ptrdiff bytes. | |
| 74 | |
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75 mbui_copy (&destiter, &srciter) |
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76 copies srciter to destiter. |
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77 |
| 6055 | 78 Here are the function prototypes of the macros. |
| 79 | |
| 80 extern void mbui_init (mbui_iterator_t iter, const char *startptr); | |
| 81 extern bool mbui_avail (mbui_iterator_t iter); | |
| 82 extern void mbui_advance (mbui_iterator_t iter); | |
| 83 extern mbchar_t mbui_cur (mbui_iterator_t iter); | |
| 84 extern const char * mbui_cur_ptr (mbui_iterator_t iter); | |
| 85 extern void mbui_reloc (mbui_iterator_t iter, ptrdiff_t ptrdiff); | |
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86 extern void mbui_copy (mbui_iterator_t *new, const mbui_iterator_t *old); |
| 6055 | 87 */ |
| 88 | |
| 89 #ifndef _MBUITER_H | |
| 90 #define _MBUITER_H 1 | |
| 91 | |
| 92 #include <assert.h> | |
| 93 #include <stdbool.h> | |
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94 #include <stddef.h> |
| 6055 | 95 #include <stdlib.h> |
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96 #include <string.h> |
| 6055 | 97 |
| 98 /* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before | |
| 99 <wchar.h>. | |
| 100 BSD/OS 4.1 has a bug: <stdio.h> and <time.h> must be included before | |
| 101 <wchar.h>. */ | |
| 102 #include <stdio.h> | |
| 103 #include <time.h> | |
| 104 #include <wchar.h> | |
| 105 | |
| 106 #include "mbchar.h" | |
| 107 #include "strnlen1.h" | |
| 108 | |
| 109 struct mbuiter_multi | |
| 110 { | |
| 111 bool in_shift; /* true if next byte may not be interpreted as ASCII */ | |
| 112 mbstate_t state; /* if in_shift: current shift state */ | |
| 113 bool next_done; /* true if mbui_avail has already filled the following */ | |
| 114 struct mbchar cur; /* the current character: | |
| 115 const char *cur.ptr pointer to current character | |
| 116 The following are only valid after mbui_avail. | |
| 117 size_t cur.bytes number of bytes of current character | |
| 118 bool cur.wc_valid true if wc is a valid wide character | |
| 119 wchar_t cur.wc if wc_valid: the current character | |
| 120 */ | |
| 121 }; | |
| 122 | |
| 123 static inline void | |
| 124 mbuiter_multi_next (struct mbuiter_multi *iter) | |
| 125 { | |
| 126 if (iter->next_done) | |
| 127 return; | |
| 128 if (iter->in_shift) | |
| 129 goto with_shift; | |
| 130 /* Handle most ASCII characters quickly, without calling mbrtowc(). */ | |
| 131 if (is_basic (*iter->cur.ptr)) | |
| 132 { | |
| 133 /* These characters are part of the basic character set. ISO C 99 | |
| 134 guarantees that their wide character code is identical to their | |
| 135 char code. */ | |
| 136 iter->cur.bytes = 1; | |
| 137 iter->cur.wc = *iter->cur.ptr; | |
| 138 iter->cur.wc_valid = true; | |
| 139 } | |
| 140 else | |
| 141 { | |
| 142 assert (mbsinit (&iter->state)); | |
| 143 iter->in_shift = true; | |
| 144 with_shift: | |
| 145 iter->cur.bytes = mbrtowc (&iter->cur.wc, iter->cur.ptr, | |
| 146 strnlen1 (iter->cur.ptr, MB_CUR_MAX), | |
| 147 &iter->state); | |
| 148 if (iter->cur.bytes == (size_t) -1) | |
| 149 { | |
| 150 /* An invalid multibyte sequence was encountered. */ | |
| 151 iter->cur.bytes = 1; | |
| 152 iter->cur.wc_valid = false; | |
| 153 /* Whether to set iter->in_shift = false and reset iter->state | |
| 154 or not is not very important; the string is bogus anyway. */ | |
| 155 } | |
| 156 else if (iter->cur.bytes == (size_t) -2) | |
| 157 { | |
| 158 /* An incomplete multibyte character at the end. */ | |
| 159 iter->cur.bytes = strlen (iter->cur.ptr); | |
| 160 iter->cur.wc_valid = false; | |
| 161 /* Whether to set iter->in_shift = false and reset iter->state | |
| 162 or not is not important; the string end is reached anyway. */ | |
| 163 } | |
| 164 else | |
| 165 { | |
| 166 if (iter->cur.bytes == 0) | |
| 167 { | |
| 168 /* A null wide character was encountered. */ | |
| 169 iter->cur.bytes = 1; | |
| 170 assert (*iter->cur.ptr == '\0'); | |
| 171 assert (iter->cur.wc == 0); | |
| 172 } | |
| 173 iter->cur.wc_valid = true; | |
| 174 | |
| 175 /* When in the initial state, we can go back treating ASCII | |
| 176 characters more quickly. */ | |
| 177 if (mbsinit (&iter->state)) | |
| 178 iter->in_shift = false; | |
| 179 } | |
| 180 } | |
| 181 iter->next_done = true; | |
| 182 } | |
| 183 | |
| 184 static inline void | |
| 185 mbuiter_multi_reloc (struct mbuiter_multi *iter, ptrdiff_t ptrdiff) | |
| 186 { | |
| 187 iter->cur.ptr += ptrdiff; | |
| 188 } | |
| 189 | |
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190 static inline void |
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191 mbuiter_multi_copy (struct mbuiter_multi *new_iter, const struct mbuiter_multi *old_iter) |
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192 { |
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193 if ((new_iter->in_shift = old_iter->in_shift)) |
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194 memcpy (&new_iter->state, &old_iter->state, sizeof (mbstate_t)); |
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195 else |
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196 memset (&new_iter->state, 0, sizeof (mbstate_t)); |
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197 new_iter->next_done = old_iter->next_done; |
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198 mb_copy (&new_iter->cur, &old_iter->cur); |
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199 } |
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200 |
| 6055 | 201 /* Iteration macros. */ |
| 202 typedef struct mbuiter_multi mbui_iterator_t; | |
| 203 #define mbui_init(iter, startptr) \ | |
| 204 ((iter).cur.ptr = (startptr), \ | |
| 205 (iter).in_shift = false, memset (&(iter).state, '\0', sizeof (mbstate_t)), \ | |
| 206 (iter).next_done = false) | |
| 207 #define mbui_avail(iter) \ | |
| 208 (mbuiter_multi_next (&(iter)), !mb_isnul ((iter).cur)) | |
| 209 #define mbui_advance(iter) \ | |
| 210 ((iter).cur.ptr += (iter).cur.bytes, (iter).next_done = false) | |
| 211 | |
| 212 /* Access to the current character. */ | |
| 213 #define mbui_cur(iter) (iter).cur | |
| 214 #define mbui_cur_ptr(iter) (iter).cur.ptr | |
| 215 | |
| 216 /* Relocation. */ | |
| 217 #define mbui_reloc(iter, ptrdiff) mbuiter_multi_reloc (&iter, ptrdiff) | |
| 218 | |
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219 /* Copying an iterator. */ |
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220 #define mbui_copy mbuiter_multi_copy |
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221 |
| 6055 | 222 #endif /* _MBUITER_H */ |