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+/* Iterating through multibyte strings: macros for multi-byte encodings.
+ Copyright (C) 2001, 2005 Free Software Foundation, Inc.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2, or (at your option)
+ any later version.
+
+ This program 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 General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software Foundation,
+ Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
+
+/* Written by Bruno Haible <bruno@clisp.org>. */
+
+/* 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
+
+ mbi_iterator_t iter;
+ for (mbi_init (iter, buf, buflen); mbi_avail (iter); mbi_advance (iter))
+ {
+ do_something (mbi_cur_ptr (iter), mb_len (mbi_cur (iter)));
+ }
+
+ The benefit of these macros over plain use of mbrtowc is:
+ - Handling of invalid multibyte sequences is possible without
+ making the code more complicated, while still preserving the
+ invalid multibyte sequences.
+
+ mbi_iterator_t
+ is a type usable for variable declarations.
+
+ mbi_init (iter, startptr, length)
+ initializes the iterator, starting at startptr and crossing length bytes.
+
+ mbi_avail (iter)
+ returns true if there are more multibyte chracters available before
+ the end of string is reached. In this case, mbi_cur (iter) is
+ initialized to the next multibyte chracter.
+
+ mbi_advance (iter)
+ advances the iterator by one multibyte character.
+
+ mbi_cur (iter)
+ returns the current multibyte character, of type MB_CHAR. All the macros
+ defined in mbchar_multi.h can be used on it.
+
+ mbi_cur_ptr (iter)
+ return a pointer to the beginning of the current multibyte character.
+
+ mbi_reloc (iter, ptrdiff)
+ relocates iterator when the string is moved by ptrdiff bytes.
+
+ Here are the function prototypes of the macros.
+
+ extern void mbi_init (mbi_iterator_t iter,
+ const char *startptr, size_t length);
+ extern bool mbi_avail (mbi_iterator_t iter);
+ extern void mbi_advance (mbi_iterator_t iter);
+ extern mbchar_t mbi_cur (mbi_iterator_t iter);
+ extern const char * mbi_cur_ptr (mbi_iterator_t iter);
+ extern void mbi_reloc (mbi_iterator_t iter, ptrdiff_t ptrdiff);
+ */
+
+#ifndef _MBITER_H
+#define _MBITER_H 1
+
+#include <assert.h>
+#include <stdbool.h>
+
+/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
+ <wchar.h>.
+ BSD/OS 4.1 has a bug: <stdio.h> and <time.h> must be included before
+ <wchar.h>. */
+#include <stdio.h>
+#include <time.h>
+#include <wchar.h>
+
+#include "mbchar.h"
+
+struct mbiter_multi
+{
+ const char *limit; /* pointer to end of string */
+ bool in_shift; /* true if next byte may not be interpreted as ASCII */
+ mbstate_t state; /* if in_shift: current shift state */
+ bool next_done; /* true if mbi_avail has already filled the following */
+ struct mbchar cur; /* the current character:
+ const char *cur.ptr pointer to current character
+ The following are only valid after mbi_avail.
+ size_t cur.bytes number of bytes of current character
+ bool cur.wc_valid true if wc is a valid wide character
+ wchar_t cur.wc if wc_valid: the current character
+ */
+};
+
+static inline void
+mbiter_multi_next (struct mbiter_multi *iter)
+{
+ if (iter->next_done)
+ return;
+ if (iter->in_shift)
+ goto with_shift;
+ /* Handle most ASCII characters quickly, without calling mbrtowc(). */
+ if (is_basic (*iter->cur.ptr))
+ {
+ /* These characters are part of the basic character set. ISO C 99
+ guarantees that their wide character code is identical to their
+ char code. */
+ iter->cur.bytes = 1;
+ iter->cur.wc = *iter->cur.ptr;
+ iter->cur.wc_valid = true;
+ }
+ else
+ {
+ assert (mbsinit (&iter->state));
+ iter->in_shift = true;
+ with_shift:
+ iter->cur.bytes = mbrtowc (&iter->cur.wc, iter->cur.ptr,
+ iter->limit - iter->cur.ptr, &iter->state);
+ if (iter->cur.bytes == (size_t) -1)
+ {
+ /* An invalid multibyte sequence was encountered. */
+ iter->cur.bytes = 1;
+ iter->cur.wc_valid = false;
+ /* Whether to set iter->in_shift = false and reset iter->state
+ or not is not very important; the string is bogus anyway. */
+ }
+ else if (iter->cur.bytes == (size_t) -2)
+ {
+ /* An incomplete multibyte character at the end. */
+ iter->cur.bytes = iter->limit - iter->cur.ptr;
+ iter->cur.wc_valid = false;
+ /* Whether to set iter->in_shift = false and reset iter->state
+ or not is not important; the string end is reached anyway. */
+ }
+ else
+ {
+ if (iter->cur.bytes == 0)
+ {
+ /* A null wide character was encountered. */
+ iter->cur.bytes = 1;
+ assert (*iter->cur.ptr == '\0');
+ assert (iter->cur.wc == 0);
+ }
+ iter->cur.wc_valid = true;
+
+ /* When in the initial state, we can go back treating ASCII
+ characters more quickly. */
+ if (mbsinit (&iter->state))
+ iter->in_shift = false;
+ }
+ }
+ iter->next_done = true;
+}
+
+static inline void
+mbiter_multi_reloc (struct mbiter_multi *iter, ptrdiff_t ptrdiff)
+{
+ iter->cur.ptr += ptrdiff;
+ iter->limit += ptrdiff;
+}
+
+/* Iteration macros. */
+typedef struct mbiter_multi mbi_iterator_t;
+#define mbi_init(iter, startptr, length) \
+ ((iter).cur.ptr = (startptr), (iter).limit = (iter).cur.ptr + (length), \
+ (iter).in_shift = false, memset (&(iter).state, '\0', sizeof (mbstate_t)), \
+ (iter).next_done = false)
+#define mbi_avail(iter) \
+ ((iter).cur.ptr < (iter).limit && (mbiter_multi_next (&(iter)), true))
+#define mbi_advance(iter) \
+ ((iter).cur.ptr += (iter).cur.bytes, (iter).next_done = false)
+
+/* Access to the current character. */
+#define mbi_cur(iter) (iter).cur
+#define mbi_cur_ptr(iter) (iter).cur.ptr
+
+/* Relocation. */
+#define mbi_reloc(iter, ptrdiff) mbiter_multi_reloc (&iter, ptrdiff)
+
+#endif /* _MBITER_H */
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