[PATCH] Add a topological sort procedure to commit.c
[git/git.git] / commit.c
1 #include <ctype.h>
2 #include "tag.h"
3 #include "commit.h"
4 #include "cache.h"
5
6 struct sort_node
7 {
8 /*
9 * the number of children of the associated commit
10 * that also occur in the list being sorted.
11 */
12 unsigned int indegree;
13
14 /*
15 * reference to original list item that we will re-use
16 * on output.
17 */
18 struct commit_list * list_item;
19
20 };
21
22 const char *commit_type = "commit";
23
24 enum cmit_fmt get_commit_format(const char *arg)
25 {
26 if (!*arg)
27 return CMIT_FMT_DEFAULT;
28 if (!strcmp(arg, "=raw"))
29 return CMIT_FMT_RAW;
30 if (!strcmp(arg, "=medium"))
31 return CMIT_FMT_MEDIUM;
32 if (!strcmp(arg, "=short"))
33 return CMIT_FMT_SHORT;
34 if (!strcmp(arg, "=full"))
35 return CMIT_FMT_FULL;
36 die("invalid --pretty format");
37 }
38
39 static struct commit *check_commit(struct object *obj, const unsigned char *sha1)
40 {
41 if (obj->type != commit_type) {
42 error("Object %s is a %s, not a commit",
43 sha1_to_hex(sha1), obj->type);
44 return NULL;
45 }
46 return (struct commit *) obj;
47 }
48
49 struct commit *lookup_commit_reference(const unsigned char *sha1)
50 {
51 struct object *obj = parse_object(sha1);
52
53 if (!obj)
54 return NULL;
55 if (obj->type == tag_type)
56 obj = ((struct tag *)obj)->tagged;
57 return check_commit(obj, sha1);
58 }
59
60 struct commit *lookup_commit(const unsigned char *sha1)
61 {
62 struct object *obj = lookup_object(sha1);
63 if (!obj) {
64 struct commit *ret = xmalloc(sizeof(struct commit));
65 memset(ret, 0, sizeof(struct commit));
66 created_object(sha1, &ret->object);
67 ret->object.type = commit_type;
68 return ret;
69 }
70 if (!obj->type)
71 obj->type = commit_type;
72 return check_commit(obj, sha1);
73 }
74
75 static unsigned long parse_commit_date(const char *buf)
76 {
77 unsigned long date;
78
79 if (memcmp(buf, "author", 6))
80 return 0;
81 while (*buf++ != '\n')
82 /* nada */;
83 if (memcmp(buf, "committer", 9))
84 return 0;
85 while (*buf++ != '>')
86 /* nada */;
87 date = strtoul(buf, NULL, 10);
88 if (date == ULONG_MAX)
89 date = 0;
90 return date;
91 }
92
93 int parse_commit_buffer(struct commit *item, void *buffer, unsigned long size)
94 {
95 void *bufptr = buffer;
96 unsigned char parent[20];
97 struct commit_list **pptr;
98
99 if (item->object.parsed)
100 return 0;
101 item->object.parsed = 1;
102 get_sha1_hex(bufptr + 5, parent);
103 item->tree = lookup_tree(parent);
104 if (item->tree)
105 add_ref(&item->object, &item->tree->object);
106 bufptr += 46; /* "tree " + "hex sha1" + "\n" */
107 pptr = &item->parents;
108 while (!memcmp(bufptr, "parent ", 7) &&
109 !get_sha1_hex(bufptr + 7, parent)) {
110 struct commit *new_parent = lookup_commit(parent);
111 if (new_parent) {
112 pptr = &commit_list_insert(new_parent, pptr)->next;
113 add_ref(&item->object, &new_parent->object);
114 }
115 bufptr += 48;
116 }
117 item->date = parse_commit_date(bufptr);
118 return 0;
119 }
120
121 int parse_commit(struct commit *item)
122 {
123 char type[20];
124 void *buffer;
125 unsigned long size;
126 int ret;
127
128 if (item->object.parsed)
129 return 0;
130 buffer = read_sha1_file(item->object.sha1, type, &size);
131 if (!buffer)
132 return error("Could not read %s",
133 sha1_to_hex(item->object.sha1));
134 if (strcmp(type, commit_type)) {
135 free(buffer);
136 return error("Object %s not a commit",
137 sha1_to_hex(item->object.sha1));
138 }
139 ret = parse_commit_buffer(item, buffer, size);
140 if (!ret) {
141 item->buffer = buffer;
142 return 0;
143 }
144 free(buffer);
145 return ret;
146 }
147
148 struct commit_list *commit_list_insert(struct commit *item, struct commit_list **list_p)
149 {
150 struct commit_list *new_list = xmalloc(sizeof(struct commit_list));
151 new_list->item = item;
152 new_list->next = *list_p;
153 *list_p = new_list;
154 return new_list;
155 }
156
157 void free_commit_list(struct commit_list *list)
158 {
159 while (list) {
160 struct commit_list *temp = list;
161 list = temp->next;
162 free(temp);
163 }
164 }
165
166 struct commit_list * insert_by_date(struct commit *item, struct commit_list **list)
167 {
168 struct commit_list **pp = list;
169 struct commit_list *p;
170 while ((p = *pp) != NULL) {
171 if (p->item->date < item->date) {
172 break;
173 }
174 pp = &p->next;
175 }
176 return commit_list_insert(item, pp);
177 }
178
179
180 void sort_by_date(struct commit_list **list)
181 {
182 struct commit_list *ret = NULL;
183 while (*list) {
184 insert_by_date((*list)->item, &ret);
185 *list = (*list)->next;
186 }
187 *list = ret;
188 }
189
190 struct commit *pop_most_recent_commit(struct commit_list **list,
191 unsigned int mark)
192 {
193 struct commit *ret = (*list)->item;
194 struct commit_list *parents = ret->parents;
195 struct commit_list *old = *list;
196
197 *list = (*list)->next;
198 free(old);
199
200 while (parents) {
201 struct commit *commit = parents->item;
202 parse_commit(commit);
203 if (!(commit->object.flags & mark)) {
204 commit->object.flags |= mark;
205 insert_by_date(commit, list);
206 }
207 parents = parents->next;
208 }
209 return ret;
210 }
211
212 /*
213 * Generic support for pretty-printing the header
214 */
215 static int get_one_line(const char *msg, unsigned long len)
216 {
217 int ret = 0;
218
219 while (len--) {
220 char c = *msg++;
221 ret++;
222 if (c == '\n')
223 break;
224 if (!c)
225 return 0;
226 }
227 return ret;
228 }
229
230 static int add_user_info(const char *what, enum cmit_fmt fmt, char *buf, const char *line)
231 {
232 char *date;
233 unsigned int namelen;
234 unsigned long time;
235 int tz, ret;
236
237 date = strchr(line, '>');
238 if (!date)
239 return 0;
240 namelen = ++date - line;
241 time = strtoul(date, &date, 10);
242 tz = strtol(date, NULL, 10);
243
244 ret = sprintf(buf, "%s: %.*s\n", what, namelen, line);
245 if (fmt == CMIT_FMT_MEDIUM)
246 ret += sprintf(buf + ret, "Date: %s\n", show_date(time, tz));
247 return ret;
248 }
249
250 static int is_empty_line(const char *line, int len)
251 {
252 while (len && isspace(line[len-1]))
253 len--;
254 return !len;
255 }
256
257 static int add_parent_info(enum cmit_fmt fmt, char *buf, const char *line, int parents)
258 {
259 int offset = 0;
260 switch (parents) {
261 case 1:
262 break;
263 case 2:
264 /* Go back to the previous line: 40 characters of previous parent, and one '\n' */
265 offset = sprintf(buf, "Merge: %.40s\n", line-41);
266 /* Fallthrough */
267 default:
268 /* Replace the previous '\n' with a space */
269 buf[offset-1] = ' ';
270 offset += sprintf(buf + offset, "%.40s\n", line+7);
271 }
272 return offset;
273 }
274
275 unsigned long pretty_print_commit(enum cmit_fmt fmt, const char *msg, unsigned long len, char *buf, unsigned long space)
276 {
277 int hdr = 1, body = 0;
278 unsigned long offset = 0;
279 int parents = 0;
280
281 for (;;) {
282 const char *line = msg;
283 int linelen = get_one_line(msg, len);
284
285 if (!linelen)
286 break;
287
288 /*
289 * We want some slop for indentation and a possible
290 * final "...". Thus the "+ 20".
291 */
292 if (offset + linelen + 20 > space) {
293 memcpy(buf + offset, " ...\n", 8);
294 offset += 8;
295 break;
296 }
297
298 msg += linelen;
299 len -= linelen;
300 if (hdr) {
301 if (linelen == 1) {
302 hdr = 0;
303 buf[offset++] = '\n';
304 continue;
305 }
306 if (fmt == CMIT_FMT_RAW) {
307 memcpy(buf + offset, line, linelen);
308 offset += linelen;
309 continue;
310 }
311 if (!memcmp(line, "parent ", 7)) {
312 if (linelen != 48)
313 die("bad parent line in commit");
314 offset += add_parent_info(fmt, buf + offset, line, ++parents);
315 }
316 if (!memcmp(line, "author ", 7))
317 offset += add_user_info("Author", fmt, buf + offset, line + 7);
318 if (fmt == CMIT_FMT_FULL) {
319 if (!memcmp(line, "committer ", 10))
320 offset += add_user_info("Commit", fmt, buf + offset, line + 10);
321 }
322 continue;
323 }
324
325 if (is_empty_line(line, linelen)) {
326 if (!body)
327 continue;
328 if (fmt == CMIT_FMT_SHORT)
329 break;
330 } else {
331 body = 1;
332 }
333 memset(buf + offset, ' ', 4);
334 memcpy(buf + offset + 4, line, linelen);
335 offset += linelen + 4;
336 }
337 /* Make sure there is an EOLN */
338 if (buf[offset - 1] != '\n')
339 buf[offset++] = '\n';
340 buf[offset] = '\0';
341 return offset;
342 }
343
344 struct commit *pop_commit(struct commit_list **stack)
345 {
346 struct commit_list *top = *stack;
347 struct commit *item = top ? top->item : NULL;
348
349 if (top) {
350 *stack = top->next;
351 free(top);
352 }
353 return item;
354 }
355
356 int count_parents(struct commit * commit)
357 {
358 int count = 0;
359 struct commit_list * parents = commit->parents;
360 for (count=0;parents; parents=parents->next,count++)
361 ;
362 return count;
363 }
364
365 /*
366 * Performs an in-place topological sort on the list supplied.
367 */
368 void sort_in_topological_order(struct commit_list ** list)
369 {
370 struct commit_list * next = *list;
371 struct commit_list * work = NULL;
372 struct commit_list ** pptr = list;
373 struct sort_node * nodes;
374 struct sort_node * next_nodes;
375 int count = 0;
376
377 /* determine the size of the list */
378 while (next) {
379 next = next->next;
380 count++;
381 }
382 /* allocate an array to help sort the list */
383 nodes = xcalloc(count, sizeof(*nodes));
384 /* link the list to the array */
385 next_nodes = nodes;
386 next=*list;
387 while (next) {
388 next_nodes->list_item = next;
389 next->item->object.util = next_nodes;
390 next_nodes++;
391 next = next->next;
392 }
393 /* update the indegree */
394 next=*list;
395 while (next) {
396 struct commit_list * parents = next->item->parents;
397 while (parents) {
398 struct commit * parent=parents->item;
399 struct sort_node * pn = (struct sort_node *)parent->object.util;
400
401 if (pn)
402 pn->indegree++;
403 parents=parents->next;
404 }
405 next=next->next;
406 }
407 /*
408 * find the tips
409 *
410 * tips are nodes not reachable from any other node in the list
411 *
412 * the tips serve as a starting set for the work queue.
413 */
414 next=*list;
415 while (next) {
416 struct sort_node * node = (struct sort_node *)next->item->object.util;
417
418 if (node->indegree == 0) {
419 commit_list_insert(next->item, &work);
420 }
421 next=next->next;
422 }
423 /* process the list in topological order */
424 while (work) {
425 struct commit * work_item = pop_commit(&work);
426 struct sort_node * work_node = (struct sort_node *)work_item->object.util;
427 struct commit_list * parents = work_item->parents;
428
429 while (parents) {
430 struct commit * parent=parents->item;
431 struct sort_node * pn = (struct sort_node *)parent->object.util;
432
433 if (pn) {
434 /*
435 * parents are only enqueued for emission
436 * when all their children have been emitted thereby
437 * guaranteeing topological order.
438 */
439 pn->indegree--;
440 if (!pn->indegree)
441 commit_list_insert(parent, &work);
442 }
443 parents=parents->next;
444 }
445 /*
446 * work_item is a commit all of whose children
447 * have already been emitted. we can emit it now.
448 */
449 *pptr = work_node->list_item;
450 pptr = &(*pptr)->next;
451 *pptr = NULL;
452 work_item->object.util = NULL;
453 }
454 free(nodes);
455 }