--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libiberty/strverscmp.c	Fri Jul 17 14:47:48 2009 +0900
@@ -0,0 +1,157 @@
+/* Compare strings while treating digits characters numerically.
+   Copyright (C) 1997, 2002, 2005 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.  Return
+value 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), until
+we find a digit in each string - then we enter a special comparison
+mode, where each sequence of digits is taken as a whole.  If we reach the
+end of these two parts without noticing a difference, we return to the
+standard comparison mode.  There are two types of numeric parts:
+"integral" and "fractional" (those  begin with a '0'). The types
+of the numeric parts affect the way we sort them:
+
+@itemize @bullet
+@item
+integral/integral: we compare values as you would expect.
+
+@item
+fractional/integral: the fractional part is less than the integral one.
+Again, no surprise.
+
+@item
+fractional/fractional: the things become a bit more complex.
+If the common prefix contains only leading zeroes, the longest part is less
+than the other one; else the comparison behaves normally.
+@end itemize
+
+@smallexample
+strverscmp ("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).  */
+
+int
+strverscmp (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;
+    }
+}