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83fbfe42 | 1 | /* Compare strings while treating digits characters numerically. |
99dee823 | 2 | Copyright (C) 1997-2021 Free Software Foundation, Inc. |
83fbfe42 | 3 | This file is part of the libiberty library. |
a40718b5 | 4 | Contributed by Jean-François Bignolles <bignolle@ecoledoc.ibp.fr>, 1997. |
83fbfe42 GK |
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 | |
0cbe2a68 KC |
18 | Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
19 | 02110-1301 USA. */ | |
83fbfe42 GK |
20 | |
21 | #include "libiberty.h" | |
22 | #include "safe-ctype.h" | |
23 | ||
24 | /* | |
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}. | |
31 | ||
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: | |
39 | ||
40 | @itemize @bullet | |
41 | @item | |
42 | integral/integral: we compare values as you would expect. | |
43 | ||
44 | @item | |
45 | fractional/integral: the fractional part is less than the integral one. | |
46 | Again, no surprise. | |
47 | ||
48 | @item | |
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. | |
52 | @end itemize | |
53 | ||
54 | @smallexample | |
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.} | |
65 | @end smallexample | |
66 | ||
67 | This function is especially useful when dealing with filename sorting, | |
68 | because filenames frequently hold indices/version numbers. | |
69 | @end deftypefun | |
70 | ||
71 | */ | |
72 | ||
73 | /* states: S_N: normal, S_I: comparing integral part, S_F: comparing | |
74 | fractional parts, S_Z: idem but with leading Zeroes only */ | |
75 | #define S_N 0x0 | |
76 | #define S_I 0x4 | |
77 | #define S_F 0x8 | |
78 | #define S_Z 0xC | |
79 | ||
80 | /* result_type: CMP: return diff; LEN: compare using len_diff/diff */ | |
81 | #define CMP 2 | |
82 | #define LEN 3 | |
83 | ||
84 | ||
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). */ | |
88 | ||
89 | int | |
90 | strverscmp (const char *s1, const char *s2) | |
91 | { | |
92 | const unsigned char *p1 = (const unsigned char *) s1; | |
93 | const unsigned char *p2 = (const unsigned char *) s2; | |
94 | unsigned char c1, c2; | |
95 | int state; | |
96 | int diff; | |
97 | ||
98 | /* Symbol(s) 0 [1-9] others (padding) | |
99 | Transition (10) 0 (01) d (00) x (11) - */ | |
100 | static const unsigned int next_state[] = | |
101 | { | |
102 | /* state x d 0 - */ | |
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 | |
107 | }; | |
108 | ||
109 | static const int result_type[] = | |
110 | { | |
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 -/- */ | |
113 | ||
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, | |
121 | -1, CMP, CMP, CMP | |
122 | }; | |
123 | ||
124 | if (p1 == p2) | |
125 | return 0; | |
126 | ||
127 | c1 = *p1++; | |
128 | c2 = *p2++; | |
129 | /* Hint: '0' is a digit too. */ | |
130 | state = S_N | ((c1 == '0') + (ISDIGIT (c1) != 0)); | |
131 | ||
132 | while ((diff = c1 - c2) == 0 && c1 != '\0') | |
133 | { | |
134 | state = next_state[state]; | |
135 | c1 = *p1++; | |
136 | c2 = *p2++; | |
137 | state |= (c1 == '0') + (ISDIGIT (c1) != 0); | |
138 | } | |
139 | ||
140 | state = result_type[state << 2 | (((c2 == '0') + (ISDIGIT (c2) != 0)))]; | |
141 | ||
142 | switch (state) | |
143 | { | |
144 | case CMP: | |
145 | return diff; | |
146 | ||
147 | case LEN: | |
148 | while (ISDIGIT (*p1++)) | |
149 | if (!ISDIGIT (*p2++)) | |
150 | return 1; | |
151 | ||
152 | return ISDIGIT (*p2) ? -1 : diff; | |
153 | ||
154 | default: | |
155 | return state; | |
156 | } | |
157 | } |