/*
   Compare strings while treating digits characters numerically.

   Copyright (C) 1997-2020
   Free Software Foundation, Inc.

   This file is part of the GNU C Library.
   Contributed by Jean-François Bignolles <bignolle@ecoledoc.ibp.fr>, 1997.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library 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 the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.

   This file is part of the Midnight Commander.

   The Midnight Commander 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 of the License,
   or (at your option) any later version.

   The Midnight Commander 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, see <http://www.gnu.org/licenses/>.
 */

#include <config.h>

#include <ctype.h>
#ifdef HAVE_STRVERSCMP
#include <string.h>
#endif /* HAVE_STRVERSCMP */

#include "lib/strutil.h"

/*** global variables ****************************************************************************/

/*** file scope macro definitions ****************************************************************/

#ifndef HAVE_STRVERSCMP

/* states: S_N: normal, S_I: comparing integral part, S_F: comparing
   fractional parts, S_Z: idem but with leading Zeroes only */
#define  S_N    0x0
#define  S_I    0x3
#define  S_F    0x6
#define  S_Z    0x9

/* result_type: CMP: return diff; LEN: compare using len_diff/diff */
#define  CMP    2
#define  LEN    3

#endif /* HAVE_STRVERSCMP */

/*** file scope type declarations ****************************************************************/

/*** file scope variables ************************************************************************/

/* --------------------------------------------------------------------------------------------- */
/*** file scope functions ************************************************************************/
/* --------------------------------------------------------------------------------------------- */

/* --------------------------------------------------------------------------------------------- */
/*** public functions ****************************************************************************/
/* --------------------------------------------------------------------------------------------- */
/* Compare S1 and S2 as strings holding indices/version numbers,
   returning less than, equal to or greater than zero if S1 is less than,
   equal to or greater than S2 (for more info, see the texinfo doc).
 */
int
str_verscmp (const char *s1, const char *s2)
{
#ifdef HAVE_STRVERSCMP
    return strverscmp (s1, s2);

#else /* HAVE_STRVERSCMP */
    const unsigned char *p1 = (const unsigned char *) s1;
    const unsigned char *p2 = (const unsigned char *) s2;
    unsigned char c1, c2;
    int state;
    int diff;

    /* *INDENT-OFF* */
    /* Symbol(s)    0       [1-9]   others
       Transition   (10) 0  (01) d  (00) x   */
    static const unsigned char next_state[] =
    {
        /* state    x    d    0  */
        /* S_N */ S_N, S_I, S_Z,
        /* S_I */ S_N, S_I, S_I,
        /* S_F */ S_N, S_F, S_F,
        /* S_Z */ S_N, S_F, S_Z
    };

    static const signed char result_type[] =
    {
        /* state  x/x  x/d  x/0  d/x  d/d  d/0  0/x  0/d  0/0  */

        /* S_N */ CMP, CMP, CMP, CMP, LEN, CMP, CMP, CMP, CMP,
        /* S_I */ CMP,  -1,  -1,  +1, LEN, LEN,  +1, LEN, LEN,
        /* S_F */ CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP,
        /* S_Z */ CMP,  +1,  +1,  -1, CMP, CMP,  -1, CMP, CMP
    };
    /* *INDENT-ON* */

    if (p1 == p2)
        return 0;

    c1 = *p1++;
    c2 = *p2++;
    /* Hint: '0' is a digit too.  */
    state = S_N + ((c1 == '0') + (isdigit (c1) != 0));

    while ((diff = c1 - c2) == 0)
    {
        if (c1 == '\0')
            return diff;

        state = next_state[state];
        c1 = *p1++;
        c2 = *p2++;
        state += (c1 == '0') + (isdigit (c1) != 0);
    }

    state = result_type[state * 3 + (((c2 == '0') + (isdigit (c2) != 0)))];

    switch (state)
    {
    case CMP:
        return diff;

    case LEN:
        while (isdigit (*p1++))
            if (!isdigit (*p2++))
                return 1;

        return isdigit (*p2) ? -1 : diff;

    default:
        return state;
    }
#endif /* HAVE_STRVERSCMP */
}

/* --------------------------------------------------------------------------------------------- */
