Line data Source code
1 : /* Iterating through multibyte strings: macros for multi-byte encodings.
2 : Copyright (C) 2001, 2005, 2007 Free Software Foundation, Inc.
3 :
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.
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
15 : along with this program. If not, see <http://www.gnu.org/licenses/>. */
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 :
75 : mbui_copy (&destiter, &srciter)
76 : copies srciter to destiter.
77 :
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);
86 : extern void mbui_copy (mbui_iterator_t *new, const mbui_iterator_t *old);
87 : */
88 :
89 : #ifndef _MBUITER_H
90 : #define _MBUITER_H 1
91 :
92 : #include <assert.h>
93 : #include <stdbool.h>
94 : #include <stddef.h>
95 : #include <stdlib.h>
96 : #include <string.h>
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 0 : mbuiter_multi_next (struct mbuiter_multi *iter)
125 : {
126 0 : if (iter->next_done)
127 0 : return;
128 0 : if (iter->in_shift)
129 0 : goto with_shift;
130 : /* Handle most ASCII characters quickly, without calling mbrtowc(). */
131 0 : 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 0 : iter->cur.bytes = 1;
137 0 : iter->cur.wc = *iter->cur.ptr;
138 0 : iter->cur.wc_valid = true;
139 : }
140 : else
141 : {
142 0 : assert (mbsinit (&iter->state));
143 0 : iter->in_shift = true;
144 0 : with_shift:
145 0 : iter->cur.bytes = mbrtowc (&iter->cur.wc, iter->cur.ptr,
146 : strnlen1 (iter->cur.ptr, MB_CUR_MAX),
147 : &iter->state);
148 0 : if (iter->cur.bytes == (size_t) -1)
149 : {
150 : /* An invalid multibyte sequence was encountered. */
151 0 : iter->cur.bytes = 1;
152 0 : 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 0 : else if (iter->cur.bytes == (size_t) -2)
157 : {
158 : /* An incomplete multibyte character at the end. */
159 0 : iter->cur.bytes = strlen (iter->cur.ptr);
160 0 : 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 0 : if (iter->cur.bytes == 0)
167 : {
168 : /* A null wide character was encountered. */
169 0 : iter->cur.bytes = 1;
170 0 : assert (*iter->cur.ptr == '\0');
171 0 : assert (iter->cur.wc == 0);
172 : }
173 0 : iter->cur.wc_valid = true;
174 :
175 : /* When in the initial state, we can go back treating ASCII
176 : characters more quickly. */
177 0 : if (mbsinit (&iter->state))
178 0 : iter->in_shift = false;
179 : }
180 : }
181 0 : 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 :
190 : static inline void
191 : mbuiter_multi_copy (struct mbuiter_multi *new_iter, const struct mbuiter_multi *old_iter)
192 : {
193 : if ((new_iter->in_shift = old_iter->in_shift))
194 : memcpy (&new_iter->state, &old_iter->state, sizeof (mbstate_t));
195 : else
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);
199 : }
200 :
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 :
219 : /* Copying an iterator. */
220 : #define mbui_copy mbuiter_multi_copy
221 :
222 : #endif /* _MBUITER_H */
|
