1 /* Iterating through multibyte strings: macros for multi-byte encodings.
2 Copyright (C) 2001, 2005, 2007 Free Software Foundation, Inc.
4 This program is free software: you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 3 of the License, or
7 (at your option) any later version.
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.
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <http://www.gnu.org/licenses/>. */
17 /* Written by Bruno Haible <bruno@clisp.org>. */
19 /* The macros in this file implement forward iteration through a
20 multi-byte string, without knowing its length a-priori.
22 With these macros, an iteration loop that looks like
25 for (iter = buf; *iter != '\0'; iter++)
33 for (mbui_init (iter, buf); mbui_avail (iter); mbui_advance (iter))
35 do_something (mbui_cur_ptr (iter), mb_len (mbui_cur (iter)));
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.
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.
52 is a type usable for variable declarations.
54 mbui_init (iter, startptr)
55 initializes the iterator, starting at startptr.
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.
63 advances the iterator by one multibyte character.
66 returns the current multibyte character, of type mbchar_t. All the
67 macros defined in mbchar.h can be used on it.
70 return a pointer to the beginning of the current multibyte character.
72 mbui_reloc (iter, ptrdiff)
73 relocates iterator when the string is moved by ptrdiff bytes.
75 mbui_copy (&destiter, &srciter)
76 copies srciter to destiter.
78 Here are the function prototypes of the macros.
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);
86 extern void mbui_copy (mbui_iterator_t *new, const mbui_iterator_t *old);
98 /* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
100 BSD/OS 4.1 has a bug: <stdio.h> and <time.h> must be included before
107 #include "strnlen1.h"
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
124 mbuiter_multi_next (struct mbuiter_multi *iter)
130 /* Handle most ASCII characters quickly, without calling mbrtowc(). */
131 if (is_basic (*iter->cur.ptr))
133 /* These characters are part of the basic character set. ISO C 99
134 guarantees that their wide character code is identical to their
137 iter->cur.wc = *iter->cur.ptr;
138 iter->cur.wc_valid = true;
142 assert (mbsinit (&iter->state));
143 iter->in_shift = true;
145 iter->cur.bytes = mbrtowc (&iter->cur.wc, iter->cur.ptr,
146 strnlen1 (iter->cur.ptr, MB_CUR_MAX),
148 if (iter->cur.bytes == (size_t) -1)
150 /* An invalid multibyte sequence was encountered. */
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. */
156 else if (iter->cur.bytes == (size_t) -2)
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. */
166 if (iter->cur.bytes == 0)
168 /* A null wide character was encountered. */
170 assert (*iter->cur.ptr == '\0');
171 assert (iter->cur.wc == 0);
173 iter->cur.wc_valid = true;
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;
181 iter->next_done = true;
185 mbuiter_multi_reloc (struct mbuiter_multi *iter, ptrdiff_t ptrdiff)
187 iter->cur.ptr += ptrdiff;
191 mbuiter_multi_copy (struct mbuiter_multi *new_iter, const struct mbuiter_multi *old_iter)
193 if ((new_iter->in_shift = old_iter->in_shift))
194 memcpy (&new_iter->state, &old_iter->state, sizeof (mbstate_t));
196 memset (&new_iter->state, 0, sizeof (mbstate_t));
197 new_iter->next_done = old_iter->next_done;
198 mb_copy (&new_iter->cur, &old_iter->cur);
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)
212 /* Access to the current character. */
213 #define mbui_cur(iter) (iter).cur
214 #define mbui_cur_ptr(iter) (iter).cur.ptr
217 #define mbui_reloc(iter, ptrdiff) mbuiter_multi_reloc (&iter, ptrdiff)
219 /* Copying an iterator. */
220 #define mbui_copy mbuiter_multi_copy
222 #endif /* _MBUITER_H */