1 /* Compare strings while treating digits characters numerically.
2 Copyright (C) 1997, 2002, 2005 Free Software Foundation, Inc.
3 This file is part of the libiberty library.
4 Contributed by Jean-François Bignolles <bignolle@ecoledoc.ibp.fr>, 1997.
6 Libiberty is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
11 Libiberty is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, write to the Free
18 Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
21 #include "libiberty.h"
22 #include "safe-ctype.h"
25 @deftypefun int strverscmp (const char *@var{s1}, const char *@var{s2})
26 The @code{strverscmp} function compares the string @var{s1} against
27 @var{s2}, considering them as holding indices/version numbers. Return
28 value follows the same conventions as found in the @code{strverscmp}
29 function. In fact, if @var{s1} and @var{s2} contain no digits,
30 @code{strverscmp} behaves like @code{strcmp}.
32 Basically, we compare strings normally (character by character), until
33 we find a digit in each string - then we enter a special comparison
34 mode, where each sequence of digits is taken as a whole. If we reach the
35 end of these two parts without noticing a difference, we return to the
36 standard comparison mode. There are two types of numeric parts:
37 "integral" and "fractional" (those begin with a '0'). The types
38 of the numeric parts affect the way we sort them:
42 integral/integral: we compare values as you would expect.
45 fractional/integral: the fractional part is less than the integral one.
49 fractional/fractional: the things become a bit more complex.
50 If the common prefix contains only leading zeroes, the longest part is less
51 than the other one; else the comparison behaves normally.
55 strverscmp ("no digit", "no digit")
56 @result{} 0 // @r{same behavior as strcmp.}
57 strverscmp ("item#99", "item#100")
58 @result{} <0 // @r{same prefix, but 99 < 100.}
59 strverscmp ("alpha1", "alpha001")
60 @result{} >0 // @r{fractional part inferior to integral one.}
61 strverscmp ("part1_f012", "part1_f01")
62 @result{} >0 // @r{two fractional parts.}
63 strverscmp ("foo.009", "foo.0")
64 @result{} <0 // @r{idem, but with leading zeroes only.}
67 This function is especially useful when dealing with filename sorting,
68 because filenames frequently hold indices/version numbers.
73 /* states: S_N: normal, S_I: comparing integral part, S_F: comparing
74 fractional parts, S_Z: idem but with leading Zeroes only */
80 /* result_type: CMP: return diff; LEN: compare using len_diff/diff */
85 /* Compare S1 and S2 as strings holding indices/version numbers,
86 returning less than, equal to or greater than zero if S1 is less than,
87 equal to or greater than S2 (for more info, see the Glibc texinfo doc). */
90 strverscmp (const char *s1
, const char *s2
)
92 const unsigned char *p1
= (const unsigned char *) s1
;
93 const unsigned char *p2
= (const unsigned char *) s2
;
98 /* Symbol(s) 0 [1-9] others (padding)
99 Transition (10) 0 (01) d (00) x (11) - */
100 static const unsigned int next_state
[] =
103 /* S_N */ S_N
, S_I
, S_Z
, S_N
,
104 /* S_I */ S_N
, S_I
, S_I
, S_I
,
105 /* S_F */ S_N
, S_F
, S_F
, S_F
,
106 /* S_Z */ S_N
, S_F
, S_Z
, S_Z
109 static const int result_type
[] =
111 /* state x/x x/d x/0 x/- d/x d/d d/0 d/-
112 0/x 0/d 0/0 0/- -/x -/d -/0 -/- */
114 /* S_N */ CMP
, CMP
, CMP
, CMP
, CMP
, LEN
, CMP
, CMP
,
115 CMP
, CMP
, CMP
, CMP
, CMP
, CMP
, CMP
, CMP
,
116 /* S_I */ CMP
, -1, -1, CMP
, +1, LEN
, LEN
, CMP
,
117 +1, LEN
, LEN
, CMP
, CMP
, CMP
, CMP
, CMP
,
118 /* S_F */ CMP
, CMP
, CMP
, CMP
, CMP
, LEN
, CMP
, CMP
,
119 CMP
, CMP
, CMP
, CMP
, CMP
, CMP
, CMP
, CMP
,
120 /* S_Z */ CMP
, +1, +1, CMP
, -1, CMP
, CMP
, CMP
,
129 /* Hint: '0' is a digit too. */
130 state
= S_N
| ((c1
== '0') + (ISDIGIT (c1
) != 0));
132 while ((diff
= c1
- c2
) == 0 && c1
!= '\0')
134 state
= next_state
[state
];
137 state
|= (c1
== '0') + (ISDIGIT (c1
) != 0);
140 state
= result_type
[state
<< 2 | (((c2
== '0') + (ISDIGIT (c2
) != 0)))];
148 while (ISDIGIT (*p1
++))
149 if (!ISDIGIT (*p2
++))
152 return ISDIGIT (*p2
) ? -1 : diff
;
This page took 0.032658 seconds and 4 git commands to generate.