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[thirdparty/git.git] / xdiff / xmerge.c
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857b933e
JS		 1/*
2 * LibXDiff by Davide Libenzi ( File Differential Library )
3 * Copyright (C) 2003-2006 Davide Libenzi, Johannes E. Schindelin
4 *
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2.1 of the License, or (at your option) any later version.
9 *
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
14 *
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 *
19 * Davide Libenzi <davidel@xmailserver.org>
20 *
21 */
22
23#include "xinclude.h"
24
25typedef struct s_xdmerge {
26 struct s_xdmerge *next;
27 /*
28 * 0 = conflict,
29 * 1 = no conflict, take first,
30 * 2 = no conflict, take second.
31 */
32 int mode;
33 long i1, i2;
34 long chg1, chg2;
35} xdmerge_t;
36
37static int xdl_append_merge(xdmerge_t **merge, int mode,
38 long i1, long chg1, long i2, long chg2)
39{
40 xdmerge_t *m = *merge;
98e6da8a
JS		 41 if (m && (i1 <= m->i1 + m->chg1 || i2 <= m->i2 + m->chg2)) {
42 if (mode != m->mode)
43 m->mode = 0;
857b933e
JS		 44 m->chg1 = i1 + chg1 - m->i1;
45 m->chg2 = i2 + chg2 - m->i2;
46 } else {
47 m = xdl_malloc(sizeof(xdmerge_t));
48 if (!m)
49 return -1;
50 m->next = NULL;
51 m->mode = mode;
52 m->i1 = i1;
53 m->chg1 = chg1;
54 m->i2 = i2;
55 m->chg2 = chg2;
56 if (*merge)
57 (*merge)->next = m;
58 *merge = m;
59 }
60 return 0;
61}
62
63static int xdl_cleanup_merge(xdmerge_t *c)
64{
65 int count = 0;
66 xdmerge_t *next_c;
67
68 /* were there conflicts? */
69 for (; c; c = next_c) {
70 if (c->mode == 0)
71 count++;
72 next_c = c->next;
73 free(c);
74 }
75 return count;
76}
77
78static int xdl_merge_cmp_lines(xdfenv_t *xe1, int i1, xdfenv_t *xe2, int i2,
79 int line_count, long flags)
80{
81 int i;
82 xrecord_t **rec1 = xe1->xdf2.recs + i1;
83 xrecord_t **rec2 = xe2->xdf2.recs + i2;
84
85 for (i = 0; i < line_count; i++) {
86 int result = xdl_recmatch(rec1[i]->ptr, rec1[i]->size,
87 rec2[i]->ptr, rec2[i]->size, flags);
88 if (!result)
89 return -1;
90 }
91 return 0;
92}
93
94static int xdl_recs_copy(xdfenv_t *xe, int i, int count, int add_nl, char *dest)
95{
96 xrecord_t **recs = xe->xdf2.recs + i;
97 int size = 0;
98
99 if (count < 1)
100 return 0;
101
102 for (i = 0; i < count; size += recs[i++]->size)
103 if (dest)
104 memcpy(dest + size, recs[i]->ptr, recs[i]->size);
105 if (add_nl) {
106 i = recs[count - 1]->size;
107 if (i == 0 || recs[count - 1]->ptr[i - 1] != '\n') {
108 if (dest)
109 dest[size] = '\n';
110 size++;
111 }
112 }
113 return size;
114}
115
116static int xdl_fill_merge_buffer(xdfenv_t *xe1, const char *name1,
117 xdfenv_t *xe2, const char *name2, xdmerge_t *m, char *dest)
118{
119 const int marker_size = 7;
120 int marker1_size = (name1 ? strlen(name1) + 1 : 0);
121 int marker2_size = (name2 ? strlen(name2) + 1 : 0);
122 int conflict_marker_size = 3 * (marker_size + 1)
123 + marker1_size + marker2_size;
124 int size, i1, j;
125
126 for (size = i1 = 0; m; m = m->next) {
127 if (m->mode == 0) {
128 size += xdl_recs_copy(xe1, i1, m->i1 - i1, 0,
129 dest ? dest + size : NULL);
130 if (dest) {
131 for (j = 0; j < marker_size; j++)
132 dest[size++] = '<';
133 if (marker1_size) {
134 dest[size] = ' ';
135 memcpy(dest + size + 1, name1,
136 marker1_size - 1);
137 size += marker1_size;
138 }
139 dest[size++] = '\n';
140 } else
141 size += conflict_marker_size;
142 size += xdl_recs_copy(xe1, m->i1, m->chg1, 1,
143 dest ? dest + size : NULL);
144 if (dest) {
145 for (j = 0; j < marker_size; j++)
146 dest[size++] = '=';
147 dest[size++] = '\n';
148 }
149 size += xdl_recs_copy(xe2, m->i2, m->chg2, 1,
150 dest ? dest + size : NULL);
151 if (dest) {
152 for (j = 0; j < marker_size; j++)
153 dest[size++] = '>';
154 if (marker2_size) {
155 dest[size] = ' ';
156 memcpy(dest + size + 1, name2,
157 marker2_size - 1);
158 size += marker2_size;
159 }
160 dest[size++] = '\n';
161 }
162 } else if (m->mode == 1)
163 size += xdl_recs_copy(xe1, i1, m->i1 + m->chg1 - i1, 0,
164 dest ? dest + size : NULL);
165 else if (m->mode == 2)
166 size += xdl_recs_copy(xe2, m->i2 - m->i1 + i1,
167 m->i1 + m->chg2 - i1, 0,
168 dest ? dest + size : NULL);
169 i1 = m->i1 + m->chg1;
170 }
171 size += xdl_recs_copy(xe1, i1, xe1->xdf2.nrec - i1, 0,
172 dest ? dest + size : NULL);
173 return size;
174}
175
176/*
177 * Sometimes, changes are not quite identical, but differ in only a few
178 * lines. Try hard to show only these few lines as conflicting.
179 */
180static int xdl_refine_conflicts(xdfenv_t *xe1, xdfenv_t *xe2, xdmerge_t *m,
181 xpparam_t const *xpp)
182{
183 for (; m; m = m->next) {
184 mmfile_t t1, t2;
185 xdfenv_t xe;
186 xdchange_t *xscr, *x;
187 int i1 = m->i1, i2 = m->i2;
188
189 /* let's handle just the conflicts */
190 if (m->mode)
191 continue;
192
193 /*
194 * This probably does not work outside git, since
195 * we have a very simple mmfile structure.
196 */
197 t1.ptr = (char *)xe1->xdf2.recs[m->i1]->ptr;
875b8ce4
JS		 198 t1.size = xe1->xdf2.recs[m->i1 + m->chg1 - 1]->ptr
199 + xe1->xdf2.recs[m->i1 + m->chg1 - 1]->size - t1.ptr;
200 t2.ptr = (char *)xe2->xdf2.recs[m->i2]->ptr;
201 t2.size = xe2->xdf2.recs[m->i2 + m->chg2 - 1]->ptr
202 + xe2->xdf2.recs[m->i2 + m->chg2 - 1]->size - t2.ptr;
857b933e
JS		 203 if (xdl_do_diff(&t1, &t2, xpp, &xe) < 0)
204 return -1;
205 if (xdl_change_compact(&xe.xdf1, &xe.xdf2, xpp->flags) < 0 ||
206 xdl_change_compact(&xe.xdf2, &xe.xdf1, xpp->flags) < 0 ||
207 xdl_build_script(&xe, &xscr) < 0) {
208 xdl_free_env(&xe);
209 return -1;
210 }
211 if (!xscr) {
212 /* If this happens, it's a bug. */
213 xdl_free_env(&xe);
214 return -2;
215 }
216 x = xscr;
217 m->i1 = xscr->i1 + i1;
218 m->chg1 = xscr->chg1;
219 m->i2 = xscr->i2 + i2;
220 m->chg2 = xscr->chg2;
221 while (xscr->next) {
222 xdmerge_t *m2 = xdl_malloc(sizeof(xdmerge_t));
223 if (!m2) {
224 xdl_free_env(&xe);
225 xdl_free_script(x);
226 return -1;
227 }
228 xscr = xscr->next;
229 m2->next = m->next;
230 m->next = m2;
231 m = m2;
232 m->mode = 0;
233 m->i1 = xscr->i1 + i1;
234 m->chg1 = xscr->chg1;
235 m->i2 = xscr->i2 + i2;
236 m->chg2 = xscr->chg2;
237 }
238 xdl_free_env(&xe);
239 xdl_free_script(x);
240 }
241 return 0;
242}
243
244/*
245 * level == 0: mark all overlapping changes as conflict
246 * level == 1: mark overlapping changes as conflict only if not identical
247 * level == 2: analyze non-identical changes for minimal conflict set
248 *
249 * returns < 0 on error, == 0 for no conflicts, else number of conflicts
250 */
251static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, const char *name1,
252 xdfenv_t *xe2, xdchange_t *xscr2, const char *name2,
253 int level, xpparam_t const *xpp, mmbuffer_t *result) {
254 xdmerge_t *changes, *c;
255 int i1, i2, chg1, chg2;
256
257 c = changes = NULL;
258
259 while (xscr1 && xscr2) {
260 if (!changes)
261 changes = c;
262 if (xscr1->i1 + xscr1->chg1 < xscr2->i1) {
263 i1 = xscr1->i2;
264 i2 = xscr2->i2 - xscr2->i1 + xscr1->i1;
265 chg1 = xscr1->chg2;
266 chg2 = xscr1->chg1;
267 if (xdl_append_merge(&c, 1, i1, chg1, i2, chg2)) {
268 xdl_cleanup_merge(changes);
269 return -1;
270 }
271 xscr1 = xscr1->next;
272 continue;
273 }
274 if (xscr2->i1 + xscr2->chg1 < xscr1->i1) {
275 i1 = xscr1->i2 - xscr1->i1 + xscr2->i1;
276 i2 = xscr2->i2;
277 chg1 = xscr2->chg1;
278 chg2 = xscr2->chg2;
279 if (xdl_append_merge(&c, 2, i1, chg1, i2, chg2)) {
280 xdl_cleanup_merge(changes);
281 return -1;
282 }
283 xscr2 = xscr2->next;
284 continue;
285 }
286 if (level < 1 || xscr1->i1 != xscr2->i1 ||
287 xscr1->chg1 != xscr2->chg1 ||
288 xscr1->chg2 != xscr2->chg2 ||
289 xdl_merge_cmp_lines(xe1, xscr1->i2,
290 xe2, xscr2->i2,
291 xscr1->chg2, xpp->flags)) {
292 /* conflict */
293 int off = xscr1->i1 - xscr2->i1;
294 int ffo = off + xscr1->chg1 - xscr2->chg1;
295
296 i1 = xscr1->i2;
297 i2 = xscr2->i2;
298 if (off > 0)
299 i1 -= off;
300 else
301 i2 += off;
302 chg1 = xscr1->i2 + xscr1->chg2 - i1;
303 chg2 = xscr2->i2 + xscr2->chg2 - i2;
304 if (ffo > 0)
305 chg2 += ffo;
306 else
307 chg1 -= ffo;
308 if (xdl_append_merge(&c, 0, i1, chg1, i2, chg2)) {
309 xdl_cleanup_merge(changes);
310 return -1;
311 }
312 }
313
314 i1 = xscr1->i1 + xscr1->chg1;
315 i2 = xscr2->i1 + xscr2->chg1;
316
98e6da8a 317 if (i1 >= i2)
710daa83 318 xscr2 = xscr2->next;
98e6da8a 319 if (i2 >= i1)
857b933e 320 xscr1 = xscr1->next;
857b933e
JS		 321 }
322 while (xscr1) {
323 if (!changes)
324 changes = c;
325 i1 = xscr1->i2;
326 i2 = xscr1->i1 + xe2->xdf2.nrec - xe2->xdf1.nrec;
327 chg1 = xscr1->chg2;
328 chg2 = xscr1->chg1;
329 if (xdl_append_merge(&c, 1, i1, chg1, i2, chg2)) {
330 xdl_cleanup_merge(changes);
331 return -1;
332 }
333 xscr1 = xscr1->next;
334 }
335 while (xscr2) {
336 if (!changes)
337 changes = c;
338 i1 = xscr2->i1 + xe1->xdf2.nrec - xe1->xdf1.nrec;
339 i2 = xscr2->i2;
340 chg1 = xscr2->chg1;
341 chg2 = xscr2->chg2;
342 if (xdl_append_merge(&c, 2, i1, chg1, i2, chg2)) {
343 xdl_cleanup_merge(changes);
344 return -1;
345 }
346 xscr2 = xscr2->next;
347 }
348 if (!changes)
349 changes = c;
350 /* refine conflicts */
351 if (level > 1 && xdl_refine_conflicts(xe1, xe2, changes, xpp) < 0) {
352 xdl_cleanup_merge(changes);
353 return -1;
354 }
355 /* output */
356 if (result) {
357 int size = xdl_fill_merge_buffer(xe1, name1, xe2, name2,
358 changes, NULL);
359 result->ptr = xdl_malloc(size);
360 if (!result->ptr) {
361 xdl_cleanup_merge(changes);
362 return -1;
363 }
364 result->size = size;
365 xdl_fill_merge_buffer(xe1, name1, xe2, name2, changes,
366 result->ptr);
367 }
368 return xdl_cleanup_merge(changes);
369}
370
371int xdl_merge(mmfile_t *orig, mmfile_t *mf1, const char *name1,
372 mmfile_t *mf2, const char *name2,
373 xpparam_t const *xpp, int level, mmbuffer_t *result) {
374 xdchange_t *xscr1, *xscr2;
375 xdfenv_t xe1, xe2;
53a7085a 376 int status;
857b933e
JS		 377
378 result->ptr = NULL;
379 result->size = 0;
380
381 if (xdl_do_diff(orig, mf1, xpp, &xe1) < 0 ||
382 xdl_do_diff(orig, mf2, xpp, &xe2) < 0) {
383 return -1;
384 }
385 if (xdl_change_compact(&xe1.xdf1, &xe1.xdf2, xpp->flags) < 0 ||
386 xdl_change_compact(&xe1.xdf2, &xe1.xdf1, xpp->flags) < 0 ||
387 xdl_build_script(&xe1, &xscr1) < 0) {
388 xdl_free_env(&xe1);
389 return -1;
390 }
391 if (xdl_change_compact(&xe2.xdf1, &xe2.xdf2, xpp->flags) < 0 ||
392 xdl_change_compact(&xe2.xdf2, &xe2.xdf1, xpp->flags) < 0 ||
393 xdl_build_script(&xe2, &xscr2) < 0) {
394 xdl_free_env(&xe2);
395 return -1;
396 }
53a7085a 397 status = 0;
857b933e
JS		 398 if (xscr1 || xscr2) {
399 if (!xscr1) {
400 result->ptr = xdl_malloc(mf2->size);
401 memcpy(result->ptr, mf2->ptr, mf2->size);
402 result->size = mf2->size;
403 } else if (!xscr2) {
404 result->ptr = xdl_malloc(mf1->size);
405 memcpy(result->ptr, mf1->ptr, mf1->size);
406 result->size = mf1->size;
53a7085a
JH		 407 } else {
408 status = xdl_do_merge(&xe1, xscr1, name1,
409 &xe2, xscr2, name2,
410 level, xpp, result);
857b933e
JS		 411 }
412 xdl_free_script(xscr1);
413 xdl_free_script(xscr2);
414 }
415 xdl_free_env(&xe1);
416 xdl_free_env(&xe2);
417
53a7085a 418 return status;
857b933e 419}
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