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diff --git a/gl/mbuiter.h b/gl/mbuiter.h
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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, without knowing its length a-priori.
+
+   With these macros, an iteration loop that looks like
+
+      char *iter;
+      for (iter = buf; *iter != '\0'; iter++)
+        {
+          do_something (*iter);
+        }
+
+   becomes
+
+      mbui_iterator_t iter;
+      for (mbui_init (iter, buf); mbui_avail (iter); mbui_advance (iter))
+        {
+          do_something (mbui_cur_ptr (iter), mb_len (mbui_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.
+
+   Compared to mbiter.h, the macros here don't need to know the string's
+   length a-priori.  The downside is that at each step, the look-ahead
+   that guards against overrunning the terminating '\0' is more expensive.
+   The mbui_* macros are therefore suitable when there is a high probability
+   that only the first few multibyte characters need to be inspected.
+   Whereas the mbi_* macros are better if usually the iteration runs
+   through the entire string.
+
+   mbui_iterator_t
+     is a type usable for variable declarations.
+
+   mbui_init (iter, startptr)
+     initializes the iterator, starting at startptr.
+
+   mbui_avail (iter)
+     returns true if there are more multibyte chracters available before
+     the end of string is reached. In this case, mbui_cur (iter) is
+     initialized to the next multibyte chracter.
+
+   mbui_advance (iter)
+     advances the iterator by one multibyte character.
+
+   mbui_cur (iter)
+     returns the current multibyte character, of type mbchar_t.  All the
+     macros defined in mbchar.h can be used on it.
+
+   mbui_cur_ptr (iter)
+     return a pointer to the beginning of the current multibyte character.
+
+   mbui_reloc (iter, ptrdiff)
+     relocates iterator when the string is moved by ptrdiff bytes.
+
+   Here are the function prototypes of the macros.
+
+   extern void          mbui_init (mbui_iterator_t iter, const char *startptr);
+   extern bool          mbui_avail (mbui_iterator_t iter);
+   extern void          mbui_advance (mbui_iterator_t iter);
+   extern mbchar_t      mbui_cur (mbui_iterator_t iter);
+   extern const char *  mbui_cur_ptr (mbui_iterator_t iter);
+   extern void          mbui_reloc (mbui_iterator_t iter, ptrdiff_t ptrdiff);
+ */
+
+#ifndef _MBUITER_H
+#define _MBUITER_H 1
+
+#include <assert.h>
+#include <stdbool.h>
+#include <stdlib.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"
+#include "strnlen1.h"
+
+struct mbuiter_multi
+{
+  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 mbui_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 mbui_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
+mbuiter_multi_next (struct mbuiter_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,
+                                 strnlen1 (iter->cur.ptr, MB_CUR_MAX),
+                                 &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 = strlen (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
+mbuiter_multi_reloc (struct mbuiter_multi *iter, ptrdiff_t ptrdiff)
+{
+  iter->cur.ptr += ptrdiff;
+}
+
+/* Iteration macros.  */
+typedef struct mbuiter_multi mbui_iterator_t;
+#define mbui_init(iter, startptr) \
+  ((iter).cur.ptr = (startptr), \
+   (iter).in_shift = false, memset (&(iter).state, '\0', sizeof (mbstate_t)), \
+   (iter).next_done = false)
+#define mbui_avail(iter) \
+  (mbuiter_multi_next (&(iter)), !mb_isnul ((iter).cur))
+#define mbui_advance(iter) \
+  ((iter).cur.ptr += (iter).cur.bytes, (iter).next_done = false)
+
+/* Access to the current character.  */
+#define mbui_cur(iter) (iter).cur
+#define mbui_cur_ptr(iter) (iter).cur.ptr
+
+/* Relocation.  */
+#define mbui_reloc(iter, ptrdiff) mbuiter_multi_reloc (&iter, ptrdiff)
+
+#endif /* _MBUITER_H */