/* locale information

   Copyright 2016-2017 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 3, 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.  */

/* Written by Paul Eggert.  */

#include <config.h>

#include <localeinfo.h>

#include <verify.h>

#include <limits.h>

#include <locale.h>

#include <stdlib.h>

#include <string.h>

#include <wctype.h>

/* The sbclen implementation relies on this.  */

verify (MB_LEN_MAX <= SCHAR_MAX);

/* Return true if the locale uses UTF-8.  */

static bool

is_using_utf8 (void)

{

  wchar_t wc;

  mbstate_t mbs = {0};

  return mbrtowc (&wc, "\xc4\x80", 2, &mbs) == 2 && wc == 0x100;

}

/* Initialize *LOCALEINFO from the current locale.  */

void

init_localeinfo (struct localeinfo *localeinfo)

{

  int i;

  localeinfo->multibyte = MB_CUR_MAX > 1;

  localeinfo->using_utf8 = is_using_utf8 ();

  for (i = CHAR_MIN; i <= CHAR_MAX; i++)

    {

      char c = i;

      unsigned char uc = i;

      mbstate_t s = {0};

      wchar_t wc;

      size_t len = mbrtowc (&wc, &c, 1, &s);

      localeinfo->sbclen[uc] = len <= 1 ? 1 : - (int) - len;

      localeinfo->sbctowc[uc] = len <= 1 ? wc : WEOF;

    }

}

/* The set of wchar_t values C such that there's a useful locale

   somewhere where C != towupper (C) && C != towlower (towupper (C)).

   For example, 0x00B5 (U+00B5 MICRO SIGN) is in this table, because

   towupper (0x00B5) == 0x039C (U+039C GREEK CAPITAL LETTER MU), and

   towlower (0x039C) == 0x03BC (U+03BC GREEK SMALL LETTER MU).  */

static short const lonesome_lower[] =

  {

    0x00B5, 0x0131, 0x017F, 0x01C5, 0x01C8, 0x01CB, 0x01F2, 0x0345,

    0x03C2, 0x03D0, 0x03D1, 0x03D5, 0x03D6, 0x03F0, 0x03F1,

    /* U+03F2 GREEK LUNATE SIGMA SYMBOL lacks a specific uppercase

       counterpart in locales predating Unicode 4.0.0 (April 2003).  */

    0x03F2,

    0x03F5, 0x1E9B, 0x1FBE,

  };

/* Verify that the worst case fits.  This is 1 for towupper, 1 for

   towlower, and 1 for each entry in LONESOME_LOWER.  */

verify (1 + 1 + sizeof lonesome_lower / sizeof *lonesome_lower

        <= CASE_FOLDED_BUFSIZE);

/* Find the characters equal to C after case-folding, other than C

   itself, and store them into FOLDED.  Return the number of characters

   stored; this is zero if C is WEOF.  */

int

case_folded_counterparts (wint_t c, wchar_t folded[CASE_FOLDED_BUFSIZE])

{

  int i;

  int n = 0;

  wint_t uc = towupper (c);

  wint_t lc = towlower (uc);

  if (uc != c)

    folded[n++] = uc;

  if (lc != uc && lc != c && towupper (lc) == uc)

    folded[n++] = lc;

  for (i = 0; i < sizeof lonesome_lower / sizeof *lonesome_lower; i++)

    {

      wint_t li = lonesome_lower[i];

      if (li != lc && li != uc && li != c && towupper (li) == uc)

        folded[n++] = li;

    }

  return n;

}