204 lines
6.6 KiB
C
204 lines
6.6 KiB
C
/* Iterating through multibyte strings: macros for multi-byte encodings.
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Copyright (C) 2001, 2005 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software Foundation,
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Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
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/* Written by Bruno Haible <bruno@clisp.org>. */
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/* The macros in this file implement forward iteration through a
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multi-byte string, without knowing its length a-priori.
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With these macros, an iteration loop that looks like
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char *iter;
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for (iter = buf; *iter != '\0'; iter++)
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{
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do_something (*iter);
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}
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becomes
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mbui_iterator_t iter;
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for (mbui_init (iter, buf); mbui_avail (iter); mbui_advance (iter))
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{
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do_something (mbui_cur_ptr (iter), mb_len (mbui_cur (iter)));
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}
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The benefit of these macros over plain use of mbrtowc is:
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- Handling of invalid multibyte sequences is possible without
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making the code more complicated, while still preserving the
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invalid multibyte sequences.
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Compared to mbiter.h, the macros here don't need to know the string's
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length a-priori. The downside is that at each step, the look-ahead
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that guards against overrunning the terminating '\0' is more expensive.
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The mbui_* macros are therefore suitable when there is a high probability
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that only the first few multibyte characters need to be inspected.
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Whereas the mbi_* macros are better if usually the iteration runs
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through the entire string.
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mbui_iterator_t
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is a type usable for variable declarations.
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mbui_init (iter, startptr)
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initializes the iterator, starting at startptr.
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mbui_avail (iter)
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returns true if there are more multibyte chracters available before
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the end of string is reached. In this case, mbui_cur (iter) is
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initialized to the next multibyte chracter.
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mbui_advance (iter)
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advances the iterator by one multibyte character.
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mbui_cur (iter)
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returns the current multibyte character, of type mbchar_t. All the
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macros defined in mbchar.h can be used on it.
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mbui_cur_ptr (iter)
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return a pointer to the beginning of the current multibyte character.
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mbui_reloc (iter, ptrdiff)
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relocates iterator when the string is moved by ptrdiff bytes.
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Here are the function prototypes of the macros.
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extern void mbui_init (mbui_iterator_t iter, const char *startptr);
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extern bool mbui_avail (mbui_iterator_t iter);
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extern void mbui_advance (mbui_iterator_t iter);
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extern mbchar_t mbui_cur (mbui_iterator_t iter);
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extern const char * mbui_cur_ptr (mbui_iterator_t iter);
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extern void mbui_reloc (mbui_iterator_t iter, ptrdiff_t ptrdiff);
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*/
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#ifndef _MBUITER_H
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#define _MBUITER_H 1
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#include <assert.h>
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#include <stdbool.h>
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#include <stdlib.h>
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/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
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<wchar.h>.
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BSD/OS 4.1 has a bug: <stdio.h> and <time.h> must be included before
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<wchar.h>. */
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#include <stdio.h>
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#include <time.h>
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#include <wchar.h>
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#include "mbchar.h"
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#include "strnlen1.h"
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struct mbuiter_multi
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{
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bool in_shift; /* true if next byte may not be interpreted as ASCII */
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mbstate_t state; /* if in_shift: current shift state */
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bool next_done; /* true if mbui_avail has already filled the following */
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struct mbchar cur; /* the current character:
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const char *cur.ptr pointer to current character
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The following are only valid after mbui_avail.
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size_t cur.bytes number of bytes of current character
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bool cur.wc_valid true if wc is a valid wide character
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wchar_t cur.wc if wc_valid: the current character
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*/
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};
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static inline void
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mbuiter_multi_next (struct mbuiter_multi *iter)
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{
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if (iter->next_done)
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return;
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if (iter->in_shift)
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goto with_shift;
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/* Handle most ASCII characters quickly, without calling mbrtowc(). */
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if (is_basic (*iter->cur.ptr))
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{
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/* These characters are part of the basic character set. ISO C 99
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guarantees that their wide character code is identical to their
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char code. */
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iter->cur.bytes = 1;
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iter->cur.wc = *iter->cur.ptr;
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iter->cur.wc_valid = true;
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}
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else
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{
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assert (mbsinit (&iter->state));
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iter->in_shift = true;
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with_shift:
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iter->cur.bytes = mbrtowc (&iter->cur.wc, iter->cur.ptr,
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strnlen1 (iter->cur.ptr, MB_CUR_MAX),
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&iter->state);
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if (iter->cur.bytes == (size_t) -1)
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{
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/* An invalid multibyte sequence was encountered. */
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iter->cur.bytes = 1;
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iter->cur.wc_valid = false;
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/* Whether to set iter->in_shift = false and reset iter->state
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or not is not very important; the string is bogus anyway. */
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}
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else if (iter->cur.bytes == (size_t) -2)
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{
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/* An incomplete multibyte character at the end. */
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iter->cur.bytes = strlen (iter->cur.ptr);
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iter->cur.wc_valid = false;
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/* Whether to set iter->in_shift = false and reset iter->state
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or not is not important; the string end is reached anyway. */
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}
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else
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{
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if (iter->cur.bytes == 0)
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{
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/* A null wide character was encountered. */
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iter->cur.bytes = 1;
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assert (*iter->cur.ptr == '\0');
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assert (iter->cur.wc == 0);
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}
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iter->cur.wc_valid = true;
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/* When in the initial state, we can go back treating ASCII
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characters more quickly. */
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if (mbsinit (&iter->state))
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iter->in_shift = false;
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}
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}
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iter->next_done = true;
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}
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static inline void
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mbuiter_multi_reloc (struct mbuiter_multi *iter, ptrdiff_t ptrdiff)
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{
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iter->cur.ptr += ptrdiff;
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}
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/* Iteration macros. */
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typedef struct mbuiter_multi mbui_iterator_t;
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#define mbui_init(iter, startptr) \
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((iter).cur.ptr = (startptr), \
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(iter).in_shift = false, memset (&(iter).state, '\0', sizeof (mbstate_t)), \
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(iter).next_done = false)
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#define mbui_avail(iter) \
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(mbuiter_multi_next (&(iter)), !mb_isnul ((iter).cur))
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#define mbui_advance(iter) \
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((iter).cur.ptr += (iter).cur.bytes, (iter).next_done = false)
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/* Access to the current character. */
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#define mbui_cur(iter) (iter).cur
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#define mbui_cur_ptr(iter) (iter).cur.ptr
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/* Relocation. */
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#define mbui_reloc(iter, ptrdiff) mbuiter_multi_reloc (&iter, ptrdiff)
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#endif /* _MBUITER_H */
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