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[/] [openrisc/] [trunk/] [gnu-src/] [gcc-4.5.1/] [libiberty/] [strverscmp.c] - Blame information for rev 517

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1 274 jeremybenn
/* Compare strings while treating digits characters numerically.
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   Copyright (C) 1997, 2002, 2005 Free Software Foundation, Inc.
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   This file is part of the libiberty library.
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   Contributed by Jean-François Bignolles <bignolle@ecoledoc.ibp.fr>, 1997.
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   Libiberty is free software; you can redistribute it and/or
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   modify it under the terms of the GNU Lesser General Public
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   License as published by the Free Software Foundation; either
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   version 2.1 of the License, or (at your option) any later version.
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   Libiberty is distributed in the hope that it will be useful,
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   but WITHOUT ANY WARRANTY; without even the implied warranty of
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   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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   Lesser General Public License for more details.
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   You should have received a copy of the GNU Lesser General Public
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   License along with the GNU C Library; if not, write to the Free
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   Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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   02110-1301 USA.  */
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#include "libiberty.h"
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#include "safe-ctype.h"
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/*
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@deftypefun int strverscmp (const char *@var{s1}, const char *@var{s2})
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The @code{strverscmp} function compares the string @var{s1} against
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@var{s2}, considering them as holding indices/version numbers.  Return
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value follows the same conventions as found in the @code{strverscmp}
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function.  In fact, if @var{s1} and @var{s2} contain no digits,
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@code{strverscmp} behaves like @code{strcmp}.
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Basically, we compare strings normally (character by character), until
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we find a digit in each string - then we enter a special comparison
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mode, where each sequence of digits is taken as a whole.  If we reach the
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end of these two parts without noticing a difference, we return to the
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standard comparison mode.  There are two types of numeric parts:
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"integral" and "fractional" (those  begin with a '0'). The types
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of the numeric parts affect the way we sort them:
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@itemize @bullet
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@item
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integral/integral: we compare values as you would expect.
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@item
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fractional/integral: the fractional part is less than the integral one.
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Again, no surprise.
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@item
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fractional/fractional: the things become a bit more complex.
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If the common prefix contains only leading zeroes, the longest part is less
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than the other one; else the comparison behaves normally.
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@end itemize
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@smallexample
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strverscmp ("no digit", "no digit")
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    @result{} 0    // @r{same behavior as strcmp.}
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strverscmp ("item#99", "item#100")
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    @result{} <0   // @r{same prefix, but 99 < 100.}
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strverscmp ("alpha1", "alpha001")
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    @result{} >0   // @r{fractional part inferior to integral one.}
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strverscmp ("part1_f012", "part1_f01")
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    @result{} >0   // @r{two fractional parts.}
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strverscmp ("foo.009", "foo.0")
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    @result{} <0   // @r{idem, but with leading zeroes only.}
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@end smallexample
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This function is especially useful when dealing with filename sorting,
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because filenames frequently hold indices/version numbers.
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@end deftypefun
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*/
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/* states: S_N: normal, S_I: comparing integral part, S_F: comparing
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           fractional parts, S_Z: idem but with leading Zeroes only */
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#define  S_N    0x0
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#define  S_I    0x4
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#define  S_F    0x8
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#define  S_Z    0xC
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/* result_type: CMP: return diff; LEN: compare using len_diff/diff */
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#define  CMP    2
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#define  LEN    3
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/* Compare S1 and S2 as strings holding indices/version numbers,
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   returning less than, equal to or greater than zero if S1 is less than,
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   equal to or greater than S2 (for more info, see the Glibc texinfo doc).  */
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int
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strverscmp (const char *s1, const char *s2)
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{
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  const unsigned char *p1 = (const unsigned char *) s1;
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  const unsigned char *p2 = (const unsigned char *) s2;
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  unsigned char c1, c2;
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  int state;
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  int diff;
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  /* Symbol(s)    0       [1-9]   others  (padding)
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     Transition   (10) 0  (01) d  (00) x  (11) -   */
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  static const unsigned int next_state[] =
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    {
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      /* state    x    d    0    - */
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      /* S_N */  S_N, S_I, S_Z, S_N,
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      /* S_I */  S_N, S_I, S_I, S_I,
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      /* S_F */  S_N, S_F, S_F, S_F,
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      /* S_Z */  S_N, S_F, S_Z, S_Z
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    };
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  static const int result_type[] =
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    {
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      /* state   x/x  x/d  x/0  x/-  d/x  d/d  d/0  d/-
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                 0/x  0/d  0/0  0/-  -/x  -/d  -/0  -/- */
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      /* S_N */  CMP, CMP, CMP, CMP, CMP, LEN, CMP, CMP,
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                 CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP,
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      /* S_I */  CMP, -1,  -1,  CMP, +1,  LEN, LEN, CMP,
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                 +1,  LEN, LEN, CMP, CMP, CMP, CMP, CMP,
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      /* S_F */  CMP, CMP, CMP, CMP, CMP, LEN, CMP, CMP,
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                 CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP,
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      /* S_Z */  CMP, +1,  +1,  CMP, -1,  CMP, CMP, CMP,
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                 -1,  CMP, CMP, CMP
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    };
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  if (p1 == p2)
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    return 0;
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  c1 = *p1++;
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  c2 = *p2++;
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  /* Hint: '0' is a digit too.  */
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  state = S_N | ((c1 == '0') + (ISDIGIT (c1) != 0));
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  while ((diff = c1 - c2) == 0 && c1 != '\0')
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    {
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      state = next_state[state];
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      c1 = *p1++;
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      c2 = *p2++;
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      state |= (c1 == '0') + (ISDIGIT (c1) != 0);
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    }
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  state = result_type[state << 2 | (((c2 == '0') + (ISDIGIT (c2) != 0)))];
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  switch (state)
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    {
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    case CMP:
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      return diff;
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    case LEN:
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      while (ISDIGIT (*p1++))
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        if (!ISDIGIT (*p2++))
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          return 1;
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      return ISDIGIT (*p2) ? -1 : diff;
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    default:
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      return state;
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    }
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}

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