🌐 AI搜索 & 代理 主页
Google Git
Sign in
chromium / external / github.com / git / git / refs/tags/v0.99.9 / . / merge-base.c
blob: 286bf0e8d1522ac4cf01f75343da40ddff6bf6e8 [file] [log] [blame]
Daniel Barkalowb5039db2005-04-18 18:39:48[diff] [blame]1#include <stdlib.h>
Linus Torvalds66834632005-04-17 19:18:17[diff] [blame]2#include "cache.h"
Daniel Barkalowb5039db2005-04-18 18:39:48[diff] [blame]3#include "commit.h"
Linus Torvalds66834632005-04-17 19:18:17[diff] [blame]4
Linus Torvalds0b9442d2005-08-10 23:26:32[diff] [blame]5#define PARENT1 1
6#define PARENT2 2
7#define UNINTERESTING 4
8
Junio C Hamanob4ad66b2005-08-12 01:13:55[diff] [blame]9static struct commit *interesting(struct commit_list *list)
Linus Torvalds0b9442d2005-08-10 23:26:32[diff] [blame]10{
11 while (list) {
12 struct commit *commit = list->item;
13 list = list->next;
14 if (commit->object.flags & UNINTERESTING)
15 continue;
Junio C Hamanob4ad66b2005-08-12 01:13:55[diff] [blame]16 return commit;
Linus Torvalds0b9442d2005-08-10 23:26:32[diff] [blame]17 }
Junio C Hamanob4ad66b2005-08-12 01:13:55[diff] [blame]18 return NULL;
Linus Torvalds0b9442d2005-08-10 23:26:32[diff] [blame]19}
20
Junio C Hamanob4ad66b2005-08-12 01:13:55[diff] [blame]21/*
22 * A pathological example of how this thing works.
23 *
24 * Suppose we had this commit graph, where chronologically
25 * the timestamp on the commit are A <= B <= C <= D <= E <= F
26 * and we are trying to figure out the merge base for E and F
27 * commits.
28 *
29 * F
30 * / \
31 * E A D
32 * \ / /
33 * B /
34 * \ /
35 * C
36 *
37 * First we push E and F to list to be processed. E gets bit 1
38 * and F gets bit 2. The list becomes:
39 *
40 * list=F(2) E(1), result=empty
41 *
42 * Then we pop F, the newest commit, from the list. Its flag is 2.
43 * We scan its parents, mark them reachable from the side that F is
44 * reachable from, and push them to the list:
45 *
46 * list=E(1) D(2) A(2), result=empty
47 *
48 * Next pop E and do the same.
49 *
50 * list=D(2) B(1) A(2), result=empty
51 *
52 * Next pop D and do the same.
53 *
54 * list=C(2) B(1) A(2), result=empty
55 *
56 * Next pop C and do the same.
57 *
58 * list=B(1) A(2), result=empty
59 *
60 * Now it is B's turn. We mark its parent, C, reachable from B's side,
61 * and push it to the list:
62 *
63 * list=C(3) A(2), result=empty
64 *
65 * Now pop C and notice it has flags==3. It is placed on the result list,
66 * and the list now contains:
67 *
68 * list=A(2), result=C(3)
69 *
70 * We pop A and do the same.
71 *
72 * list=B(3), result=C(3)
73 *
74 * Next, we pop B and something very interesting happens. It has flags==3
75 * so it is also placed on the result list, and its parents are marked
76 * uninteresting, retroactively, and placed back on the list:
77 *
78 * list=C(7), result=C(7) B(3)
79 *
80 * Now, list does not have any interesting commit. So we find the newest
81 * commit from the result list that is not marked uninteresting. Which is
82 * commit B.
83 */
84
Junio C Hamano9585e402005-08-24 04:08:59[diff] [blame]85static int show_all = 0;
86
87static int merge_base(struct commit *rev1, struct commit *rev2)
Linus Torvalds66834632005-04-17 19:18:17[diff] [blame]88{
Linus Torvalds4f7eb2e2005-07-30 22:10:20[diff] [blame]89 struct commit_list *list = NULL;
90 struct commit_list *result = NULL;
Linus Torvalds66834632005-04-17 19:18:17[diff] [blame]91
Junio C Hamano9585e402005-08-24 04:08:59[diff] [blame]92 if (rev1 == rev2) {
93 printf("%s\n", sha1_to_hex(rev1->object.sha1));
94 return 0;
95 }
Daniel Barkalowb5039db2005-04-18 18:39:48[diff] [blame]96
Daniel Barkalowb6b15db32005-04-24 01:47:23[diff] [blame]97 parse_commit(rev1);
98 parse_commit(rev2);
Daniel Barkalowb5039db2005-04-18 18:39:48[diff] [blame]99
Linus Torvalds4f7eb2e2005-07-30 22:10:20[diff] [blame]100 rev1->object.flags |= 1;
101 rev2->object.flags |= 2;
102 insert_by_date(rev1, &list);
103 insert_by_date(rev2, &list);
104
Linus Torvalds0b9442d2005-08-10 23:26:32[diff] [blame]105 while (interesting(list)) {
Linus Torvalds4f7eb2e2005-07-30 22:10:20[diff] [blame]106 struct commit *commit = list->item;
107 struct commit_list *tmp = list, *parents;
Linus Torvalds0b9442d2005-08-10 23:26:32[diff] [blame]108 int flags = commit->object.flags & 7;
Linus Torvalds4f7eb2e2005-07-30 22:10:20[diff] [blame]109
110 list = list->next;
111 free(tmp);
Linus Torvalds0b9442d2005-08-10 23:26:32[diff] [blame]112 if (flags == 3) {
Linus Torvalds4f7eb2e2005-07-30 22:10:20[diff] [blame]113 insert_by_date(commit, &result);
Linus Torvalds0b9442d2005-08-10 23:26:32[diff] [blame]114
Junio C Hamano9585e402005-08-24 04:08:59[diff] [blame]115 /* Mark parents of a found merge uninteresting */
Linus Torvalds0b9442d2005-08-10 23:26:32[diff] [blame]116 flags |= UNINTERESTING;
Linus Torvalds66834632005-04-17 19:18:17[diff] [blame]117 }
Linus Torvalds4f7eb2e2005-07-30 22:10:20[diff] [blame]118 parents = commit->parents;
119 while (parents) {
120 struct commit *p = parents->item;
121 parents = parents->next;
122 if ((p->object.flags & flags) == flags)
123 continue;
124 parse_commit(p);
125 p->object.flags |= flags;
126 insert_by_date(p, &list);
Daniel Barkalowb5039db2005-04-18 18:39:48[diff] [blame]127 }
Linus Torvalds66834632005-04-17 19:18:17[diff] [blame]128 }
Junio C Hamano9585e402005-08-24 04:08:59[diff] [blame]129
130 if (!result)
131 return 1;
132
133 while (result) {
134 struct commit *commit = result->item;
135 result = result->next;
136 if (commit->object.flags & UNINTERESTING)
137 continue;
138 printf("%s\n", sha1_to_hex(commit->object.sha1));
139 if (!show_all)
140 return 0;
141 commit->object.flags |= UNINTERESTING;
142 }
143 return 0;
Linus Torvalds66834632005-04-17 19:18:17[diff] [blame]144}
145
Junio C Hamano9585e402005-08-24 04:08:59[diff] [blame]146static const char merge_base_usage[] =
147"git-merge-base [--all] <commit-id> <commit-id>";
148
Linus Torvalds66834632005-04-17 19:18:17[diff] [blame]149int main(int argc, char **argv)
150{
Junio C Hamano9585e402005-08-24 04:08:59[diff] [blame]151 struct commit *rev1, *rev2;
Daniel Barkalowb5039db2005-04-18 18:39:48[diff] [blame]152 unsigned char rev1key[20], rev2key[20];
Linus Torvalds66834632005-04-17 19:18:17[diff] [blame]153
Junio C Hamano9585e402005-08-24 04:08:59[diff] [blame]154 while (1 < argc && argv[1][0] == '-') {
155 char *arg = argv[1];
156 if (!strcmp(arg, "-a") || !strcmp(arg, "--all"))
157 show_all = 1;
158 else
159 usage(merge_base_usage);
160 argc--; argv++;
161 }
Daniel Barkalowb5039db2005-04-18 18:39:48[diff] [blame]162 if (argc != 3 ||
Linus Torvalds3c249c92005-05-01 23:36:56[diff] [blame]163 get_sha1(argv[1], rev1key) ||
Junio C Hamano9585e402005-08-24 04:08:59[diff] [blame]164 get_sha1(argv[2], rev2key))
165 usage(merge_base_usage);
Linus Torvalds9b632be2005-05-18 23:16:51[diff] [blame]166 rev1 = lookup_commit_reference(rev1key);
167 rev2 = lookup_commit_reference(rev2key);
Linus Torvalds4f7eb2e2005-07-30 22:10:20[diff] [blame]168 if (!rev1 || !rev2)
169 return 1;
Junio C Hamano9585e402005-08-24 04:08:59[diff] [blame]170 return merge_base(rev1, rev2);
Linus Torvalds66834632005-04-17 19:18:17[diff] [blame]171}