/* Search character in UTF-8 string.
   Copyright (C) 1999, 2002, 2006-2007, 2009-2017 Free Software Foundation,
   Inc.
   Written by Bruno Haible <bruno@clisp.org>, 2002.

   This program is free software: you can redistribute it and/or
   modify it under the terms of either:

     * the GNU Lesser General Public License as published by the Free
       Software Foundation; either version 3 of the License, or (at your
       option) any later version.

   or

     * the GNU General Public License as published by the Free
       Software Foundation; either version 2 of the License, or (at your
       option) any later version.

   or both in parallel, as here.
   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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License
   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */

#include <config.h>

/* Specification.  */
#include "unistr.h"

uint8_t *
u8_strrchr (const uint8_t *s, ucs4_t uc)
{
  /* Calling u8_strlen and then searching from the other end would cause more
     memory accesses. Avoid that, at the cost of a few more comparisons.  */
  uint8_t *result = NULL;
  uint8_t c[6];

  if (uc < 0x80)
    {
      uint8_t c0 = uc;

      for (;; s++)
        {
          if (*s == c0)
            result = (uint8_t *) s;
          if (*s == 0)
            break;
        }
    }
  else
    switch (u8_uctomb_aux (c, uc, 6))
      {
      case 2:
        if (*s)
          {
            uint8_t c0 = c[0];
            uint8_t c1 = c[1];

            /* FIXME: Maybe walking the string via u8_mblen is a win?  */
            for (;; s++)
              {
                if (s[1] == 0)
                  break;
                if (*s == c0 && s[1] == c1)
                  result = (uint8_t *) s;
              }
          }
        break;

      case 3:
        if (*s && s[1])
          {
            uint8_t c0 = c[0];
            uint8_t c1 = c[1];
            uint8_t c2 = c[2];

            /* FIXME: Maybe walking the string via u8_mblen is a win?  */
            for (;; s++)
              {
                if (s[2] == 0)
                  break;
                if (*s == c0 && s[1] == c1 && s[2] == c2)
                  result = (uint8_t *) s;
              }
          }
        break;

      case 4:
        if (*s && s[1] && s[2])
          {
            uint8_t c0 = c[0];
            uint8_t c1 = c[1];
            uint8_t c2 = c[2];
            uint8_t c3 = c[3];

            /* FIXME: Maybe walking the string via u8_mblen is a win?  */
            for (;; s++)
              {
                if (s[3] == 0)
                  break;
                if (*s == c0 && s[1] == c1 && s[2] == c2 && s[3] == c3)
                  result = (uint8_t *) s;
              }
          }
        break;
      }
  return result;
}