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-Fran�ois Bignolles <bignolle@ecoledoc.ibp.fr>, 1997.
5
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.
10
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.
15
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
19 02110-1301 USA. */
20
21 #include <ctype.h>
22
23 /*
24 @deftypefun int strverscmp (const char *@var{s1}, const char *@var{s2})
25 The @code{strverscmp} function compares the string @var{s1} against
26 @var{s2}, considering them as holding indices/version numbers. Return
27 value follows the same conventions as found in the @code{strverscmp}
28 function. In fact, if @var{s1} and @var{s2} contain no digits,
29 @code{strverscmp} behaves like @code{strcmp}.
30
31 Basically, we compare strings normally (character by character), until
32 we find a digit in each string - then we enter a special comparison
33 mode, where each sequence of digits is taken as a whole. If we reach the
34 end of these two parts without noticing a difference, we return to the
35 standard comparison mode. There are two types of numeric parts:
36 "integral" and "fractional" (those begin with a '0'). The types
37 of the numeric parts affect the way we sort them:
38
39 @itemize @bullet
40 @item
41 integral/integral: we compare values as you would expect.
42
43 @item
44 fractional/integral: the fractional part is less than the integral one.
45 Again, no surprise.
46
47 @item
48 fractional/fractional: the things become a bit more complex.
49 If the common prefix contains only leading zeroes, the longest part is less
50 than the other one; else the comparison behaves normally.
51 @end itemize
52
53 @smallexample
54 strverscmp ("no digit", "no digit")
55 @result{} 0 // @r{same behavior as strcmp.}
56 strverscmp ("item#99", "item#100")
57 @result{} <0 // @r{same prefix, but 99 < 100.}
58 strverscmp ("alpha1", "alpha001")
59 @result{} >0 // @r{fractional part inferior to integral one.}
60 strverscmp ("part1_f012", "part1_f01")
61 @result{} >0 // @r{two fractional parts.}
62 strverscmp ("foo.009", "foo.0")
63 @result{} <0 // @r{idem, but with leading zeroes only.}
64 @end smallexample
65
66 This function is especially useful when dealing with filename sorting,
67 because filenames frequently hold indices/version numbers.
68 @end deftypefun
69
70 */
71
72 /* states: S_N: normal, S_I: comparing integral part, S_F: comparing
73 fractional parts, S_Z: idem but with leading Zeroes only */
74 #define S_N 0x0
75 #define S_I 0x4
76 #define S_F 0x8
77 #define S_Z 0xC
78
79 /* result_type: CMP: return diff; LEN: compare using len_diff/diff */
80 #define CMP 2
81 #define LEN 3
82
83
84 /* Compare S1 and S2 as strings holding indices/version numbers,
85 returning less than, equal to or greater than zero if S1 is less than,
86 equal to or greater than S2 (for more info, see the Glibc texinfo doc). */
87
88 int
strverscmp(const char * s1,const char * s2)89 strverscmp (const char *s1, const char *s2)
90 {
91 const unsigned char *p1 = (const unsigned char *) s1;
92 const unsigned char *p2 = (const unsigned char *) s2;
93 unsigned char c1, c2;
94 int state;
95 int diff;
96
97 /* Symbol(s) 0 [1-9] others (padding)
98 Transition (10) 0 (01) d (00) x (11) - */
99 static const unsigned int next_state[] =
100 {
101 /* state x d 0 - */
102 /* S_N */ S_N, S_I, S_Z, S_N,
103 /* S_I */ S_N, S_I, S_I, S_I,
104 /* S_F */ S_N, S_F, S_F, S_F,
105 /* S_Z */ S_N, S_F, S_Z, S_Z
106 };
107
108 static const int result_type[] =
109 {
110 /* state x/x x/d x/0 x/- d/x d/d d/0 d/-
111 0/x 0/d 0/0 0/- -/x -/d -/0 -/- */
112
113 /* S_N */ CMP, CMP, CMP, CMP, CMP, LEN, CMP, CMP,
114 CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP,
115 /* S_I */ CMP, -1, -1, CMP, +1, LEN, LEN, CMP,
116 +1, LEN, LEN, CMP, CMP, CMP, CMP, CMP,
117 /* S_F */ CMP, CMP, CMP, CMP, CMP, LEN, CMP, CMP,
118 CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP,
119 /* S_Z */ CMP, +1, +1, CMP, -1, CMP, CMP, CMP,
120 -1, CMP, CMP, CMP
121 };
122
123 if (p1 == p2)
124 return 0;
125
126 c1 = *p1++;
127 c2 = *p2++;
128 /* Hint: '0' is a digit too. */
129 state = S_N | ((c1 == '0') + (isdigit (c1) != 0));
130
131 while ((diff = c1 - c2) == 0 && c1 != '\0')
132 {
133 state = next_state[state];
134 c1 = *p1++;
135 c2 = *p2++;
136 state |= (c1 == '0') + (isdigit (c1) != 0);
137 }
138
139 state = result_type[state << 2 | (((c2 == '0') + (isdigit (c2) != 0)))];
140
141 switch (state)
142 {
143 case CMP:
144 return diff;
145
146 case LEN:
147 while (isdigit (*p1++))
148 if (!isdigit (*p2++))
149 return 1;
150
151 return isdigit (*p2) ? -1 : diff;
152
153 default:
154 return state;
155 }
156 }
157