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 109struct 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 123static inline void 124mbuiter_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 184static inline void 185mbuiter_multi_reloc (struct mbuiter_multi *iter, ptrdiff_t ptrdiff) 186{ 187 iter->cur.ptr += ptrdiff; 188} 189 190static inline void 191mbuiter_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. */ 202typedef 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 */ 223