doc: MyFirstContribution: fix cmd placement instructions
[git/git.git] / versioncmp.c
CommitLineData
9ef176b5 1#include "cache.h"
b2141fc1 2#include "config.h"
d811c8e1 3#include "string-list.h"
9ef176b5
NTND
4
5/*
6 * versioncmp(): copied from string/strverscmp.c in glibc commit
7 * ee9247c38a8def24a59eb5cfb7196a98bef8cfdc, reformatted to Git coding
8 * style. The implementation is under LGPL-2.1 and Git relicenses it
9 * to GPLv2.
10 */
11
12/*
13 * states: S_N: normal, S_I: comparing integral part, S_F: comparing
14 * fractionnal parts, S_Z: idem but with leading Zeroes only
15 */
16#define S_N 0x0
17#define S_I 0x3
18#define S_F 0x6
19#define S_Z 0x9
20
21/* result_type: CMP: return diff; LEN: compare using len_diff/diff */
22#define CMP 2
23#define LEN 3
24
d811c8e1
NTND
25static const struct string_list *prereleases;
26static int initialized;
27
b1784643
SG
28struct suffix_match {
29 int conf_pos;
30 int start;
31 int len;
32};
33
34static void find_better_matching_suffix(const char *tagname, const char *suffix,
35 int suffix_len, int start, int conf_pos,
36 struct suffix_match *match)
37{
38 /*
39 * A better match either starts earlier or starts at the same offset
40 * but is longer.
41 */
42 int end = match->len < suffix_len ? match->start : match->start-1;
43 int i;
44 for (i = start; i <= end; i++)
45 if (starts_with(tagname + i, suffix)) {
46 match->conf_pos = conf_pos;
47 match->start = i;
48 match->len = suffix_len;
49 break;
50 }
51}
52
d811c8e1 53/*
109064a0 54 * off is the offset of the first different character in the two strings
b8231660 55 * s1 and s2. If either s1 or s2 contains a prerelease suffix containing
51acfa9d
SG
56 * that offset or a suffix ends right before that offset, then that
57 * string will be forced to be on top.
d811c8e1 58 *
b8231660 59 * If both s1 and s2 contain a (different) suffix around that position,
109064a0
SG
60 * their order is determined by the order of those two suffixes in the
61 * configuration.
b8231660
SG
62 * If any of the strings contains more than one different suffixes around
63 * that position, then that string is sorted according to the contained
51acfa9d
SG
64 * suffix which starts at the earliest offset in that string.
65 * If more than one different contained suffixes start at that earliest
66 * offset, then that string is sorted according to the longest of those
67 * suffixes.
d811c8e1
NTND
68 *
69 * Return non-zero if *diff contains the return value for versioncmp()
70 */
109064a0
SG
71static int swap_prereleases(const char *s1,
72 const char *s2,
73 int off,
d811c8e1
NTND
74 int *diff)
75{
b1784643
SG
76 int i;
77 struct suffix_match match1 = { -1, off, -1 };
78 struct suffix_match match2 = { -1, off, -1 };
d811c8e1
NTND
79
80 for (i = 0; i < prereleases->nr; i++) {
81 const char *suffix = prereleases->items[i].string;
b1784643 82 int start, suffix_len = strlen(suffix);
b8231660 83 if (suffix_len < off)
51acfa9d 84 start = off - suffix_len;
b8231660
SG
85 else
86 start = 0;
b1784643
SG
87 find_better_matching_suffix(s1, suffix, suffix_len, start,
88 i, &match1);
89 find_better_matching_suffix(s2, suffix, suffix_len, start,
90 i, &match2);
d811c8e1 91 }
b1784643 92 if (match1.conf_pos == -1 && match2.conf_pos == -1)
d811c8e1 93 return 0;
b1784643 94 if (match1.conf_pos == match2.conf_pos)
51acfa9d
SG
95 /* Found the same suffix in both, e.g. "-rc" in "v1.0-rcX"
96 * and "v1.0-rcY": the caller should decide based on "X"
97 * and "Y". */
98 return 0;
99
b1784643
SG
100 if (match1.conf_pos >= 0 && match2.conf_pos >= 0)
101 *diff = match1.conf_pos - match2.conf_pos;
102 else if (match1.conf_pos >= 0)
d811c8e1 103 *diff = -1;
b1784643 104 else /* if (match2.conf_pos >= 0) */
d811c8e1
NTND
105 *diff = 1;
106 return 1;
107}
9ef176b5
NTND
108
109/*
110 * Compare S1 and S2 as strings holding indices/version numbers,
111 * returning less than, equal to or greater than zero if S1 is less
112 * than, equal to or greater than S2 (for more info, see the texinfo
113 * doc).
114 */
115
116int versioncmp(const char *s1, const char *s2)
117{
118 const unsigned char *p1 = (const unsigned char *) s1;
119 const unsigned char *p2 = (const unsigned char *) s2;
120 unsigned char c1, c2;
121 int state, diff;
122
123 /*
124 * Symbol(s) 0 [1-9] others
125 * Transition (10) 0 (01) d (00) x
126 */
127 static const uint8_t next_state[] = {
128 /* state x d 0 */
129 /* S_N */ S_N, S_I, S_Z,
130 /* S_I */ S_N, S_I, S_I,
131 /* S_F */ S_N, S_F, S_F,
132 /* S_Z */ S_N, S_F, S_Z
133 };
134
135 static const int8_t result_type[] = {
136 /* state x/x x/d x/0 d/x d/d d/0 0/x 0/d 0/0 */
137
138 /* S_N */ CMP, CMP, CMP, CMP, LEN, CMP, CMP, CMP, CMP,
139 /* S_I */ CMP, -1, -1, +1, LEN, LEN, +1, LEN, LEN,
140 /* S_F */ CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP, CMP,
141 /* S_Z */ CMP, +1, +1, -1, CMP, CMP, -1, CMP, CMP
142 };
143
144 if (p1 == p2)
145 return 0;
146
147 c1 = *p1++;
148 c2 = *p2++;
149 /* Hint: '0' is a digit too. */
150 state = S_N + ((c1 == '0') + (isdigit (c1) != 0));
151
152 while ((diff = c1 - c2) == 0) {
153 if (c1 == '\0')
154 return diff;
155
156 state = next_state[state];
157 c1 = *p1++;
158 c2 = *p2++;
159 state += (c1 == '0') + (isdigit (c1) != 0);
160 }
161
d811c8e1 162 if (!initialized) {
c026557a 163 const struct string_list *deprecated_prereleases;
d811c8e1 164 initialized = 1;
c026557a
SG
165 prereleases = git_config_get_value_multi("versionsort.suffix");
166 deprecated_prereleases = git_config_get_value_multi("versionsort.prereleasesuffix");
167 if (prereleases) {
168 if (deprecated_prereleases)
169 warning("ignoring versionsort.prereleasesuffix because versionsort.suffix is set");
170 } else
171 prereleases = deprecated_prereleases;
d811c8e1 172 }
109064a0
SG
173 if (prereleases && swap_prereleases(s1, s2, (const char *) p1 - s1 - 1,
174 &diff))
d811c8e1
NTND
175 return diff;
176
9ef176b5
NTND
177 state = result_type[state * 3 + (((c2 == '0') + (isdigit (c2) != 0)))];
178
179 switch (state) {
180 case CMP:
181 return diff;
182
183 case LEN:
184 while (isdigit (*p1++))
185 if (!isdigit (*p2++))
186 return 1;
187
188 return isdigit (*p2) ? -1 : diff;
189
190 default:
191 return state;
192 }
193}