1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
|
/* Iterating through multibyte strings, faster: macros for multi-byte encodings.
Copyright (C) 2001, 2005, 2007, 2009-2024 Free Software Foundation, Inc.
This file is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.
This file is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
/* Written by Bruno Haible <bruno@clisp.org>,
with insights from Paul Eggert. */
/* The macros in this file implement forward iteration through a
multi-byte string.
With these macros, an iteration loop that looks like
char *iter;
for (iter = buf; iter < buf + buflen; iter++)
{
do_something (*iter);
}
becomes
const char *buf_end = buf + buflen;
mbif_state_t state;
[const] char *iter;
for (mbif_init (state), iter = buf; mbif_avail (state, iter, buf_end); )
{
mbchar_t cur = mbif_next (state, iter, buf_end);
// Note: Here always mb_ptr (cur) == iter.
do_something (iter, mb_len (cur));
iter += mb_len (cur);
}
The benefit of these macros over plain use of mbrtowc or mbrtoc32 is:
- Handling of invalid multibyte sequences is possible without
making the code more complicated, while still preserving the
invalid multibyte sequences.
The benefit of these macros over those from mbiter.h is that it
produces faster code with today's optimizing compilers (because mbif_next
returns its result by value).
mbif_state_t
is a type usable for variable declarations.
mbif_init (state)
initializes the state.
mbif_avail (state, iter, endptr)
returns true if another loop round is needed.
mbif_next (state, iter, endptr)
returns the next multibyte character.
It asssumes that the state is initialized and that iter < endptr.
Here are the function prototypes of the macros.
extern void mbif_init (mbif_state_t state);
extern bool mbif_avail (mbif_state_t state, const char *iter, const char *endptr);
extern mbchar_t mbif_next (mbif_state_t state, const char *iter, const char *endptr);
*/
#ifndef _MBITERF_H
#define _MBITERF_H 1
/* This file uses _GL_INLINE_HEADER_BEGIN, _GL_INLINE,
_GL_ATTRIBUTE_ALWAYS_INLINE. */
#if !_GL_CONFIG_H_INCLUDED
#error "Please include config.h first."
#endif
#include <assert.h>
#include <stddef.h>
#include <string.h>
#include <uchar.h>
#include <wchar.h>
#include "mbchar.h"
_GL_INLINE_HEADER_BEGIN
#ifndef MBITERF_INLINE
# define MBITERF_INLINE _GL_INLINE _GL_ATTRIBUTE_ALWAYS_INLINE
#endif
struct mbif_state
{
#if !GNULIB_MBRTOC32_REGULAR
bool in_shift; /* true if next byte may not be interpreted as ASCII */
/* If GNULIB_MBRTOC32_REGULAR, it is always false,
so optimize it away. */
#endif
mbstate_t state; /* if in_shift: current shift state */
/* If GNULIB_MBRTOC32_REGULAR, it is in an initial state
before and after every mbiterf_next invocation.
*/
};
MBITERF_INLINE mbchar_t
mbiterf_next (struct mbif_state *ps, const char *iter, const char *endptr)
{
#if !GNULIB_MBRTOC32_REGULAR
if (ps->in_shift)
goto with_shift;
#endif
/* Handle most ASCII characters quickly, without calling mbrtowc(). */
if (is_basic (*iter))
{
/* These characters are part of the POSIX portable character set.
For most of them, namely those in the ISO C basic character set,
ISO C 99 guarantees that their wide character code is identical to
their char code. For the few other ones, this is the case as well,
in all locale encodings that are in use. The 32-bit wide character
code is the same as well. */
return (mbchar_t) { .ptr = iter, .bytes = 1, .wc_valid = true, .wc = *iter };
}
else
{
assert (mbsinit (&ps->state));
#if !GNULIB_MBRTOC32_REGULAR
ps->in_shift = true;
with_shift:;
#endif
size_t bytes;
char32_t wc;
bytes = mbrtoc32 (&wc, iter, endptr - iter, &ps->state);
if (bytes == (size_t) -1)
{
/* An invalid multibyte sequence was encountered. */
/* Allow the next invocation to continue from a sane state. */
#if !GNULIB_MBRTOC32_REGULAR
ps->in_shift = false;
#endif
mbszero (&ps->state);
return (mbchar_t) { .ptr = iter, .bytes = 1, .wc_valid = false };
}
else if (bytes == (size_t) -2)
{
/* An incomplete multibyte character at the end. */
#if !GNULIB_MBRTOC32_REGULAR
ps->in_shift = false;
#endif
/* Whether to reset ps->state or not is not important; the string end
is reached anyway. */
return (mbchar_t) { .ptr = iter, .bytes = endptr - iter, .wc_valid = false };
}
else
{
if (bytes == 0)
{
/* A null wide character was encountered. */
bytes = 1;
assert (*iter == '\0');
assert (wc == 0);
}
#if !GNULIB_MBRTOC32_REGULAR
else if (bytes == (size_t) -3)
/* The previous multibyte sequence produced an additional 32-bit
wide character. */
bytes = 0;
#endif
/* When in an initial state, we can go back treating ASCII
characters more quickly. */
#if !GNULIB_MBRTOC32_REGULAR
if (mbsinit (&ps->state))
ps->in_shift = false;
#endif
return (mbchar_t) { .ptr = iter, .bytes = bytes, .wc_valid = true, .wc = wc };
}
}
}
/* Iteration macros. */
typedef struct mbif_state mbif_state_t;
#if !GNULIB_MBRTOC32_REGULAR
#define mbif_init(st) \
((st).in_shift = false, mbszero (&(st).state))
#else
/* Optimized: no in_shift. */
#define mbif_init(st) \
(mbszero (&(st).state))
#endif
#if !GNULIB_MBRTOC32_REGULAR
#define mbif_avail(st, iter, endptr) ((st).in_shift || ((iter) < (endptr)))
#else
/* Optimized: no in_shift. */
#define mbif_avail(st, iter, endptr) ((iter) < (endptr))
#endif
#define mbif_next(st, iter, endptr) \
mbiterf_next (&(st), (iter), (endptr))
_GL_INLINE_HEADER_END
#endif /* _MBITERF_H */
|
