1 /* Iterating through multibyte strings: macros for multi-byte encodings.
2 Copyright (C) 2001, 2005, 2007, 2009-2020 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 <https://www.gnu.org/licenses/>. */
17 /* Written by Bruno Haible <bruno@clisp.org>. */
19 /* The macros in this file implement forward iteration through a
22 With these macros, an iteration loop that looks like
25 for (iter = buf; iter < buf + buflen; iter++)
33 for (mbi_init (iter, buf, buflen); mbi_avail (iter); mbi_advance (iter))
35 do_something (mbi_cur_ptr (iter), mb_len (mbi_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.
44 is a type usable for variable declarations.
46 mbi_init (iter, startptr, length)
47 initializes the iterator, starting at startptr and crossing length bytes.
50 returns true if there are more multibyte characters available before
51 the end of string is reached. In this case, mbi_cur (iter) is
52 initialized to the next multibyte character.
55 advances the iterator by one multibyte character.
58 returns the current multibyte character, of type mbchar_t. All the
59 macros defined in mbchar.h can be used on it.
62 return a pointer to the beginning of the current multibyte character.
64 mbi_reloc (iter, ptrdiff)
65 relocates iterator when the string is moved by ptrdiff bytes.
67 mbi_copy (&destiter, &srciter)
68 copies srciter to destiter.
70 Here are the function prototypes of the macros.
72 extern void mbi_init (mbi_iterator_t iter,
73 const char *startptr, size_t length);
74 extern bool mbi_avail (mbi_iterator_t iter);
75 extern void mbi_advance (mbi_iterator_t iter);
76 extern mbchar_t mbi_cur (mbi_iterator_t iter);
77 extern const char * mbi_cur_ptr (mbi_iterator_t iter);
78 extern void mbi_reloc (mbi_iterator_t iter, ptrdiff_t ptrdiff);
79 extern void mbi_copy (mbi_iterator_t *new, const mbi_iterator_t *old);
93 #ifndef _GL_INLINE_HEADER_BEGIN
94 #error "Please include config.h first."
96 _GL_INLINE_HEADER_BEGIN
98 # define MBITER_INLINE _GL_INLINE
103 const char *limit
; /* pointer to end of string */
104 bool in_shift
; /* true if next byte may not be interpreted as ASCII */
105 mbstate_t state
; /* if in_shift: current shift state */
106 bool next_done
; /* true if mbi_avail has already filled the following */
107 struct mbchar cur
; /* the current character:
108 const char *cur.ptr pointer to current character
109 The following are only valid after mbi_avail.
110 size_t cur.bytes number of bytes of current character
111 bool cur.wc_valid true if wc is a valid wide character
112 wchar_t cur.wc if wc_valid: the current character
117 mbiter_multi_next (struct mbiter_multi
*iter
)
123 /* Handle most ASCII characters quickly, without calling mbrtowc(). */
124 if (is_basic (*iter
->cur
.ptr
))
126 /* These characters are part of the basic character set. ISO C 99
127 guarantees that their wide character code is identical to their
130 iter
->cur
.wc
= *iter
->cur
.ptr
;
131 iter
->cur
.wc_valid
= true;
135 assert (mbsinit (&iter
->state
));
136 iter
->in_shift
= true;
138 iter
->cur
.bytes
= mbrtowc (&iter
->cur
.wc
, iter
->cur
.ptr
,
139 iter
->limit
- iter
->cur
.ptr
, &iter
->state
);
140 if (iter
->cur
.bytes
== (size_t) -1)
142 /* An invalid multibyte sequence was encountered. */
144 iter
->cur
.wc_valid
= false;
145 /* Whether to set iter->in_shift = false and reset iter->state
146 or not is not very important; the string is bogus anyway. */
148 else if (iter
->cur
.bytes
== (size_t) -2)
150 /* An incomplete multibyte character at the end. */
151 iter
->cur
.bytes
= iter
->limit
- iter
->cur
.ptr
;
152 iter
->cur
.wc_valid
= false;
153 /* Whether to set iter->in_shift = false and reset iter->state
154 or not is not important; the string end is reached anyway. */
158 if (iter
->cur
.bytes
== 0)
160 /* A null wide character was encountered. */
162 assert (*iter
->cur
.ptr
== '\0');
163 assert (iter
->cur
.wc
== 0);
165 iter
->cur
.wc_valid
= true;
167 /* When in the initial state, we can go back treating ASCII
168 characters more quickly. */
169 if (mbsinit (&iter
->state
))
170 iter
->in_shift
= false;
173 iter
->next_done
= true;
177 mbiter_multi_reloc (struct mbiter_multi
*iter
, ptrdiff_t ptrdiff
)
179 iter
->cur
.ptr
+= ptrdiff
;
180 iter
->limit
+= ptrdiff
;
184 mbiter_multi_copy (struct mbiter_multi
*new_iter
, const struct mbiter_multi
*old_iter
)
186 new_iter
->limit
= old_iter
->limit
;
187 if ((new_iter
->in_shift
= old_iter
->in_shift
))
188 memcpy (&new_iter
->state
, &old_iter
->state
, sizeof (mbstate_t));
190 memset (&new_iter
->state
, 0, sizeof (mbstate_t));
191 new_iter
->next_done
= old_iter
->next_done
;
192 mb_copy (&new_iter
->cur
, &old_iter
->cur
);
195 /* Iteration macros. */
196 typedef struct mbiter_multi mbi_iterator_t
;
197 #define mbi_init(iter, startptr, length) \
198 ((iter).cur.ptr = (startptr), (iter).limit = (iter).cur.ptr + (length), \
199 (iter).in_shift = false, memset (&(iter).state, '\0', sizeof (mbstate_t)), \
200 (iter).next_done = false)
201 #define mbi_avail(iter) \
202 ((iter).cur.ptr < (iter).limit && (mbiter_multi_next (&(iter)), true))
203 #define mbi_advance(iter) \
204 ((iter).cur.ptr += (iter).cur.bytes, (iter).next_done = false)
206 /* Access to the current character. */
207 #define mbi_cur(iter) (iter).cur
208 #define mbi_cur_ptr(iter) (iter).cur.ptr
211 #define mbi_reloc(iter, ptrdiff) mbiter_multi_reloc (&iter, ptrdiff)
213 /* Copying an iterator. */
214 #define mbi_copy mbiter_multi_copy
216 _GL_INLINE_HEADER_END
218 #endif /* _MBITER_H */