/* Compare strings while treating digits characters numerically.   Copyright (C) 1997-2026 Free Software Foundation, Inc.   This file is part of the libiberty library.   Contributed by Jean-François Bignolles <bignolle@ecoledoc.ibp.fr>, 1997.    Libiberty 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.    Libiberty 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, write to the Free   Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA   02110-1301 USA.  */ #include "libiberty.h"#include "safe-ctype.h" /* @deftypefun int strverscmp (const char *@var{s1}, const char *@var{s2})The @code{strverscmp} function compares the string @var{s1} against@var{s2}, considering them as holding indices/version numbers.  Returnvalue follows the same conventions as found in the @code{strverscmp}function.  In fact, if @var{s1} and @var{s2} contain no digits,@code{strverscmp} behaves like @code{strcmp}. Basically, we compare strings normally (character by character), untilwe find a digit in each string - then we enter a special comparisonmode, where each sequence of digits is taken as a whole.  If we reach theend of these two parts without noticing a difference, we return to thestandard comparison mode.  There are two types of numeric parts:"integral" and "fractional" (those  begin with a '0'). The typesof the numeric parts affect the way we sort them: @itemize @bullet@itemintegral/integral: we compare values as you would expect. @itemfractional/integral: the fractional part is less than the integral one.Again, no surprise. @itemfractional/fractional: the things become a bit more complex.If the common prefix contains only leading zeroes, the longest part is lessthan the other one; else the comparison behaves normally.@end itemize @smallexamplestrverscmp ("no digit", "no digit")    @result{} 0    // @r{same behavior as strcmp.}strverscmp ("item#99", "item#100")    @result{} <0   // @r{same prefix, but 99 < 100.}strverscmp ("alpha1", "alpha001")    @result{} >0   // @r{fractional part inferior to integral one.}strverscmp ("part1_f012", "part1_f01")    @result{} >0   // @r{two fractional parts.}strverscmp ("foo.009", "foo.0")    @result{} <0   // @r{idem, but with leading zeroes only.}@end smallexample This function is especially useful when dealing with filename sorting,because filenames frequently hold indices/version numbers.@end deftypefun */ /* 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    0x4#define  S_F    0x8#define  S_Z    0xC /* result_type: CMP: return diff; LEN: compare using len_diff/diff */#define  CMP    2#define  LEN    3  /* 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 Glibc texinfo doc).  */ intstrverscmp (const char *s1, const char *s2){  const unsigned char *p1 = (const unsigned char *) s1;  const unsigned char *p2 = (const unsigned char *) s2;  unsigned char c1, c2;  int state;  int diff;   /* Symbol(s)    0       [1-9]   others  (padding)     Transition   (10) 0  (01) d  (00) x  (11) -   */  static const unsigned int next_state[] =    {      /* state    x    d    0    - */      /* S_N */  S_N, S_I, S_Z, S_N,      /* S_I */  S_N, S_I, S_I, S_I,      /* S_F */  S_N, S_F, S_F, S_F,      /* S_Z */  S_N, S_F, S_Z, S_Z    };   static const int result_type[] =    {      /* state   x/x  x/d  x/0  x/-  d/x  d/d  d/0  d/-                 0/x  0/d  0/0  0/-  -/x  -/d  -/0  -/- */       /* S_N */  CMP, CMP, CMP, CMP, CMP, LEN, CMP, CMP,                 CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP,      /* S_I */  CMP, -1,  -1,  CMP, +1,  LEN, LEN, CMP,                 +1,  LEN, LEN, CMP, CMP, CMP, CMP, CMP,      /* S_F */  CMP, CMP, CMP, CMP, CMP, LEN, CMP, CMP,                 CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP,      /* S_Z */  CMP, +1,  +1,  CMP, -1,  CMP, CMP, CMP,                 -1,  CMP, CMP, CMP    };   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 && c1 != '\0')    {      state = next_state[state];      c1 = *p1++;      c2 = *p2++;      state |= (c1 == '0') + (ISDIGIT (c1) != 0);    }   state = result_type[state << 2 | (((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;    }}