new module mbsncasecmp

[Bruno Haible]

This introduces a function mbsncasecmp(), which is like strncasecmp() except
that it works with characters instead of bytes and the count argument N is
the number of characters, not the number of bytes.

2007-02-11  Bruno Haible  <address@hidden>

        New module mbsncasecmp.
        * modules/mbsncasecmp: New file.
        * lib/mbsncasecmp.c: New file.
        * lib/string_.h (mbsncasecmp): New declaration.
        * m4/mbsncasecmp.m4: New file.
        * m4/string_h.m4 (gl_STRING_MODULE_INDICATOR_DEFAULTS): Initialize
        GNULIB_MBSNCASECMP.
        * modules/string (string.h): Also substitute GNULIB_MBSNCASECMP.
        * MODULES.html.sh (Internationalization functions): Add mbsncasecmp.

============================= modules/mbsncasecmp =============================
Description:
mbsncasecmp() function: case-insensitive string prefix comparison.

Files:
lib/mbsncasecmp.c
m4/mbsncasecmp.m4
m4/mbrtowc.m4

Depends-on:
mbuiter
string

configure.ac:
gl_FUNC_MBSNCASECMP
gl_STRING_MODULE_INDICATOR([mbsncasecmp])

Makefile.am:
lib_SOURCES += mbsncasecmp.c

Include:
<string.h>

License:
LGPL

Maintainer:
Bruno Haible

============================= lib/mbsncasecmp.c ===============================
/* Case-insensitive string comparison function.
   Copyright (C) 1998-1999, 2005-2007 Free Software Foundation, Inc.
   Written by Bruno Haible <address@hidden>, 2005,
   based on earlier glibc code.

   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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */

#include <config.h>

/* Specification.  */
#include <string.h>

#include <ctype.h>
#include <limits.h>

#if HAVE_MBRTOWC
# include "mbuiter.h"
#endif

#define TOLOWER(Ch) (isupper (Ch) ? tolower (Ch) : (Ch))

/* Compare the initial segment of the character string S1 consisting of at most
   N characters with the initial segment of the character string S2 consisting
   of at most N characters, ignoring case, returning less than, equal to or
   greater than zero if the initial segment of S1 is lexicographically less
   than, equal to or greater than the initial segment of S2.
   Note: This function may, in multibyte locales, return 0 for initial segments
   of different lengths!  */
int
mbsncasecmp (const char *s1, const char *s2, size_t n)
{
  if (s1 == s2 || n == 0)
    return 0;

  /* Be careful not to look at the entire extent of s1 or s2 until needed.
     This is useful because when two strings differ, the difference is
     most often already in the very few first characters.  */
#if HAVE_MBRTOWC
  if (MB_CUR_MAX > 1)
    {
      mbui_iterator_t iter1;
      mbui_iterator_t iter2;

      mbui_init (iter1, s1);
      mbui_init (iter2, s2);

      while (mbui_avail (iter1) && mbui_avail (iter2))
        {
          int cmp = mb_casecmp (mbui_cur (iter1), mbui_cur (iter2));

          if (cmp != 0)
            return cmp;

          if (--n == 0)
            return 0;

          mbui_advance (iter1);
          mbui_advance (iter2);
        }
      if (mbui_avail (iter1))
        /* s2 terminated before s1 and n.  */
        return 1;
      if (mbui_avail (iter2))
        /* s1 terminated before s2 and n.  */
        return -1;
      return 0;
    }
  else
#endif
    {
      const unsigned char *p1 = (const unsigned char *) s1;
      const unsigned char *p2 = (const unsigned char *) s2;
      unsigned char c1, c2;

      for (; ; p1++, p2++)
        {
          c1 = TOLOWER (*p1);
          c2 = TOLOWER (*p2);

          if (--n == 0 || c1 == '\0' || c1 != c2)
            break;
        }

      if (UCHAR_MAX <= INT_MAX)
        return c1 - c2;
      else
        /* On machines where 'char' and 'int' are types of the same size, the
           difference of two 'unsigned char' values - including the sign bit -
           doesn't fit in an 'int'.  */
        return (c1 > c2 ? 1 : c1 < c2 ? -1 : 0);
    }
}
============================= m4/mbsncasecmp.m4 ===============================
# mbsncasecmp.m4 serial 1
dnl Copyright (C) 2007 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.

AC_DEFUN([gl_FUNC_MBSNCASECMP],
[
  gl_PREREQ_MBSNCASECMP
])

# Prerequisites of lib/mbsncasecmp.c.
AC_DEFUN([gl_PREREQ_MBSNCASECMP], [
  AC_REQUIRE([gl_FUNC_MBRTOWC])
  :
])
===============================================================================
--- MODULES.html.sh     12 Feb 2007 18:49:19 -0000      1.192
+++ MODULES.html.sh     15 Feb 2007 02:58:49 -0000
@@ -2166,6 +2166,7 @@
   func_module mbsrchr
   func_module mbsstr
   func_module mbscasecmp
+  func_module mbsncasecmp
   func_module mbscasestr
   func_module mbscspn
   func_module mbspbrk
--- lib/string_.h       13 Feb 2007 01:38:45 -0000      1.22
+++ lib/string_.h       15 Feb 2007 02:58:49 -0000
@@ -415,6 +415,19 @@
 extern int mbscasecmp (const char *s1, const char *s2);
 #endif
 
+#if @GNULIB_MBSNCASECMP@
+/* Compare the initial segment of the character string S1 consisting of at most
+   N characters with the initial segment of the character string S2 consisting
+   of at most N characters, ignoring case, returning less than, equal to or
+   greater than zero if the initial segment of S1 is lexicographically less
+   than, equal to or greater than the initial segment of S2.
+   Note: This function may, in multibyte locales, return 0 for initial segments
+   of different lengths!
+   Unlike strncasecmp(), this function works correctly in multibyte locales.
+   But beware that N is not a byte count but a character count!  */
+extern int mbsncasecmp (const char *s1, const char *s2, size_t n);
+#endif
+
 #if @GNULIB_MBSCASESTR@
 /* Find the first occurrence of the character string NEEDLE in the character
    string HAYSTACK, using case-insensitive comparison.
--- m4/string_h.m4      11 Feb 2007 17:02:31 -0000      1.18
+++ m4/string_h.m4      15 Feb 2007 02:58:49 -0000
@@ -72,6 +72,7 @@
   GNULIB_MBSRCHR=0;     AC_SUBST([GNULIB_MBSRCHR])
   GNULIB_MBSSTR=0;      AC_SUBST([GNULIB_MBSSTR])
   GNULIB_MBSCASECMP=0;  AC_SUBST([GNULIB_MBSCASECMP])
+  GNULIB_MBSNCASECMP=0; AC_SUBST([GNULIB_MBSNCASECMP])
   GNULIB_MBSCASESTR=0;  AC_SUBST([GNULIB_MBSCASESTR])
   GNULIB_MBSCSPN=0;     AC_SUBST([GNULIB_MBSCSPN])
   GNULIB_MBSPBRK=0;     AC_SUBST([GNULIB_MBSPBRK])
--- modules/string      11 Feb 2007 17:02:31 -0000      1.17
+++ modules/string      15 Feb 2007 02:58:49 -0000
@@ -26,6 +26,7 @@
              -e 's|@''GNULIB_MBSRCHR''@|$(GNULIB_MBSRCHR)|g' \
              -e 's|@''GNULIB_MBSSTR''@|$(GNULIB_MBSSTR)|g' \
              -e 's|@''GNULIB_MBSCASECMP''@|$(GNULIB_MBSCASECMP)|g' \
+             -e 's|@''GNULIB_MBSNCASECMP''@|$(GNULIB_MBSNCASECMP)|g' \
              -e 's|@''GNULIB_MBSCASESTR''@|$(GNULIB_MBSCASESTR)|g' \
              -e 's|@''GNULIB_MBSCSPN''@|$(GNULIB_MBSCSPN)|g' \
              -e 's|@''GNULIB_MBSPBRK''@|$(GNULIB_MBSPBRK)|g' \