diff3.c revision 251881
1/* 2 * diff3.c : routines for doing diffs 3 * 4 * ==================================================================== 5 * Licensed to the Apache Software Foundation (ASF) under one 6 * or more contributor license agreements. See the NOTICE file 7 * distributed with this work for additional information 8 * regarding copyright ownership. The ASF licenses this file 9 * to you under the Apache License, Version 2.0 (the 10 * "License"); you may not use this file except in compliance 11 * with the License. You may obtain a copy of the License at 12 * 13 * http://www.apache.org/licenses/LICENSE-2.0 14 * 15 * Unless required by applicable law or agreed to in writing, 16 * software distributed under the License is distributed on an 17 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 18 * KIND, either express or implied. See the License for the 19 * specific language governing permissions and limitations 20 * under the License. 21 * ==================================================================== 22 */ 23 24 25#include <apr.h> 26#include <apr_pools.h> 27#include <apr_general.h> 28 29#include "svn_pools.h" 30#include "svn_error.h" 31#include "svn_diff.h" 32#include "svn_types.h" 33 34#include "diff.h" 35 36 37void 38svn_diff__resolve_conflict(svn_diff_t *hunk, 39 svn_diff__position_t **position_list1, 40 svn_diff__position_t **position_list2, 41 svn_diff__token_index_t num_tokens, 42 apr_pool_t *pool) 43{ 44 apr_off_t modified_start = hunk->modified_start + 1; 45 apr_off_t latest_start = hunk->latest_start + 1; 46 apr_off_t common_length; 47 apr_off_t modified_length = hunk->modified_length; 48 apr_off_t latest_length = hunk->latest_length; 49 svn_diff__position_t *start_position[2]; 50 svn_diff__position_t *position[2]; 51 svn_diff__token_index_t *token_counts[2]; 52 svn_diff__lcs_t *lcs = NULL; 53 svn_diff__lcs_t **lcs_ref = &lcs; 54 svn_diff_t **diff_ref = &hunk->resolved_diff; 55 apr_pool_t *subpool; 56 57 /* First find the starting positions for the 58 * comparison 59 */ 60 61 start_position[0] = *position_list1; 62 start_position[1] = *position_list2; 63 64 while (start_position[0]->offset < modified_start) 65 start_position[0] = start_position[0]->next; 66 67 while (start_position[1]->offset < latest_start) 68 start_position[1] = start_position[1]->next; 69 70 position[0] = start_position[0]; 71 position[1] = start_position[1]; 72 73 common_length = modified_length < latest_length 74 ? modified_length : latest_length; 75 76 while (common_length > 0 77 && position[0]->token_index == position[1]->token_index) 78 { 79 position[0] = position[0]->next; 80 position[1] = position[1]->next; 81 82 common_length--; 83 } 84 85 if (common_length == 0 86 && modified_length == latest_length) 87 { 88 hunk->type = svn_diff__type_diff_common; 89 hunk->resolved_diff = NULL; 90 91 *position_list1 = position[0]; 92 *position_list2 = position[1]; 93 94 return; 95 } 96 97 hunk->type = svn_diff__type_conflict; 98 99 /* ### If we have a conflict we can try to find the 100 * ### common parts in it by getting an lcs between 101 * ### modified (start to start + length) and 102 * ### latest (start to start + length). 103 * ### We use this lcs to create a simple diff. Only 104 * ### where there is a diff between the two, we have 105 * ### a conflict. 106 * ### This raises a problem; several common diffs and 107 * ### conflicts can occur within the same original 108 * ### block. This needs some thought. 109 * ### 110 * ### NB: We can use the node _pointers_ to identify 111 * ### different tokens 112 */ 113 114 subpool = svn_pool_create(pool); 115 116 /* Calculate how much of the two sequences was 117 * actually the same. 118 */ 119 common_length = (modified_length < latest_length 120 ? modified_length : latest_length) 121 - common_length; 122 123 /* If there were matching symbols at the start of 124 * both sequences, record that fact. 125 */ 126 if (common_length > 0) 127 { 128 lcs = apr_palloc(subpool, sizeof(*lcs)); 129 lcs->next = NULL; 130 lcs->position[0] = start_position[0]; 131 lcs->position[1] = start_position[1]; 132 lcs->length = common_length; 133 134 lcs_ref = &lcs->next; 135 } 136 137 modified_length -= common_length; 138 latest_length -= common_length; 139 140 modified_start = start_position[0]->offset; 141 latest_start = start_position[1]->offset; 142 143 start_position[0] = position[0]; 144 start_position[1] = position[1]; 145 146 /* Create a new ring for svn_diff__lcs to grok. 147 * We can safely do this given we don't need the 148 * positions we processed anymore. 149 */ 150 if (modified_length == 0) 151 { 152 *position_list1 = position[0]; 153 position[0] = NULL; 154 } 155 else 156 { 157 while (--modified_length) 158 position[0] = position[0]->next; 159 160 *position_list1 = position[0]->next; 161 position[0]->next = start_position[0]; 162 } 163 164 if (latest_length == 0) 165 { 166 *position_list2 = position[1]; 167 position[1] = NULL; 168 } 169 else 170 { 171 while (--latest_length) 172 position[1] = position[1]->next; 173 174 *position_list2 = position[1]->next; 175 position[1]->next = start_position[1]; 176 } 177 178 token_counts[0] = svn_diff__get_token_counts(position[0], num_tokens, 179 subpool); 180 token_counts[1] = svn_diff__get_token_counts(position[1], num_tokens, 181 subpool); 182 183 *lcs_ref = svn_diff__lcs(position[0], position[1], token_counts[0], 184 token_counts[1], num_tokens, 0, 0, subpool); 185 186 /* Fix up the EOF lcs element in case one of 187 * the two sequences was NULL. 188 */ 189 if ((*lcs_ref)->position[0]->offset == 1) 190 (*lcs_ref)->position[0] = *position_list1; 191 192 if ((*lcs_ref)->position[1]->offset == 1) 193 (*lcs_ref)->position[1] = *position_list2; 194 195 /* Produce the resolved diff */ 196 while (1) 197 { 198 if (modified_start < lcs->position[0]->offset 199 || latest_start < lcs->position[1]->offset) 200 { 201 (*diff_ref) = apr_palloc(pool, sizeof(**diff_ref)); 202 203 (*diff_ref)->type = svn_diff__type_conflict; 204 (*diff_ref)->original_start = hunk->original_start; 205 (*diff_ref)->original_length = hunk->original_length; 206 (*diff_ref)->modified_start = modified_start - 1; 207 (*diff_ref)->modified_length = lcs->position[0]->offset 208 - modified_start; 209 (*diff_ref)->latest_start = latest_start - 1; 210 (*diff_ref)->latest_length = lcs->position[1]->offset 211 - latest_start; 212 (*diff_ref)->resolved_diff = NULL; 213 214 diff_ref = &(*diff_ref)->next; 215 } 216 217 /* Detect the EOF */ 218 if (lcs->length == 0) 219 break; 220 221 modified_start = lcs->position[0]->offset; 222 latest_start = lcs->position[1]->offset; 223 224 (*diff_ref) = apr_palloc(pool, sizeof(**diff_ref)); 225 226 (*diff_ref)->type = svn_diff__type_diff_common; 227 (*diff_ref)->original_start = hunk->original_start; 228 (*diff_ref)->original_length = hunk->original_length; 229 (*diff_ref)->modified_start = modified_start - 1; 230 (*diff_ref)->modified_length = lcs->length; 231 (*diff_ref)->latest_start = latest_start - 1; 232 (*diff_ref)->latest_length = lcs->length; 233 (*diff_ref)->resolved_diff = NULL; 234 235 diff_ref = &(*diff_ref)->next; 236 237 modified_start += lcs->length; 238 latest_start += lcs->length; 239 240 lcs = lcs->next; 241 } 242 243 *diff_ref = NULL; 244 245 svn_pool_destroy(subpool); 246} 247 248 249svn_error_t * 250svn_diff_diff3_2(svn_diff_t **diff, 251 void *diff_baton, 252 const svn_diff_fns2_t *vtable, 253 apr_pool_t *pool) 254{ 255 svn_diff__tree_t *tree; 256 svn_diff__position_t *position_list[3]; 257 svn_diff__token_index_t num_tokens; 258 svn_diff__token_index_t *token_counts[3]; 259 svn_diff_datasource_e datasource[] = {svn_diff_datasource_original, 260 svn_diff_datasource_modified, 261 svn_diff_datasource_latest}; 262 svn_diff__lcs_t *lcs_om; 263 svn_diff__lcs_t *lcs_ol; 264 apr_pool_t *subpool; 265 apr_pool_t *treepool; 266 apr_off_t prefix_lines = 0; 267 apr_off_t suffix_lines = 0; 268 269 *diff = NULL; 270 271 subpool = svn_pool_create(pool); 272 treepool = svn_pool_create(pool); 273 274 svn_diff__tree_create(&tree, treepool); 275 276 SVN_ERR(vtable->datasources_open(diff_baton, &prefix_lines, &suffix_lines, 277 datasource, 3)); 278 279 SVN_ERR(svn_diff__get_tokens(&position_list[0], 280 tree, 281 diff_baton, vtable, 282 svn_diff_datasource_original, 283 prefix_lines, 284 subpool)); 285 286 SVN_ERR(svn_diff__get_tokens(&position_list[1], 287 tree, 288 diff_baton, vtable, 289 svn_diff_datasource_modified, 290 prefix_lines, 291 subpool)); 292 293 SVN_ERR(svn_diff__get_tokens(&position_list[2], 294 tree, 295 diff_baton, vtable, 296 svn_diff_datasource_latest, 297 prefix_lines, 298 subpool)); 299 300 num_tokens = svn_diff__get_node_count(tree); 301 302 /* Get rid of the tokens, we don't need them to calc the diff */ 303 if (vtable->token_discard_all != NULL) 304 vtable->token_discard_all(diff_baton); 305 306 /* We don't need the nodes in the tree either anymore, nor the tree itself */ 307 svn_pool_destroy(treepool); 308 309 token_counts[0] = svn_diff__get_token_counts(position_list[0], num_tokens, 310 subpool); 311 token_counts[1] = svn_diff__get_token_counts(position_list[1], num_tokens, 312 subpool); 313 token_counts[2] = svn_diff__get_token_counts(position_list[2], num_tokens, 314 subpool); 315 316 /* Get the lcs for original-modified and original-latest */ 317 lcs_om = svn_diff__lcs(position_list[0], position_list[1], token_counts[0], 318 token_counts[1], num_tokens, prefix_lines, 319 suffix_lines, subpool); 320 lcs_ol = svn_diff__lcs(position_list[0], position_list[2], token_counts[0], 321 token_counts[2], num_tokens, prefix_lines, 322 suffix_lines, subpool); 323 324 /* Produce a merged diff */ 325 { 326 svn_diff_t **diff_ref = diff; 327 328 apr_off_t original_start = 1; 329 apr_off_t modified_start = 1; 330 apr_off_t latest_start = 1; 331 apr_off_t original_sync; 332 apr_off_t modified_sync; 333 apr_off_t latest_sync; 334 apr_off_t common_length; 335 apr_off_t modified_length; 336 apr_off_t latest_length; 337 svn_boolean_t is_modified; 338 svn_boolean_t is_latest; 339 svn_diff__position_t sentinel_position[2]; 340 341 /* Point the position lists to the start of the list 342 * so that common_diff/conflict detection actually is 343 * able to work. 344 */ 345 if (position_list[1]) 346 { 347 sentinel_position[0].next = position_list[1]->next; 348 sentinel_position[0].offset = position_list[1]->offset + 1; 349 position_list[1]->next = &sentinel_position[0]; 350 position_list[1] = sentinel_position[0].next; 351 } 352 else 353 { 354 sentinel_position[0].offset = prefix_lines + 1; 355 sentinel_position[0].next = NULL; 356 position_list[1] = &sentinel_position[0]; 357 } 358 359 if (position_list[2]) 360 { 361 sentinel_position[1].next = position_list[2]->next; 362 sentinel_position[1].offset = position_list[2]->offset + 1; 363 position_list[2]->next = &sentinel_position[1]; 364 position_list[2] = sentinel_position[1].next; 365 } 366 else 367 { 368 sentinel_position[1].offset = prefix_lines + 1; 369 sentinel_position[1].next = NULL; 370 position_list[2] = &sentinel_position[1]; 371 } 372 373 while (1) 374 { 375 /* Find the sync points */ 376 while (1) 377 { 378 if (lcs_om->position[0]->offset > lcs_ol->position[0]->offset) 379 { 380 original_sync = lcs_om->position[0]->offset; 381 382 while (lcs_ol->position[0]->offset + lcs_ol->length 383 < original_sync) 384 lcs_ol = lcs_ol->next; 385 386 /* If the sync point is the EOF, and our current lcs segment 387 * doesn't reach as far as EOF, we need to skip this segment. 388 */ 389 if (lcs_om->length == 0 && lcs_ol->length > 0 390 && lcs_ol->position[0]->offset + lcs_ol->length 391 == original_sync 392 && lcs_ol->position[1]->offset + lcs_ol->length 393 != lcs_ol->next->position[1]->offset) 394 lcs_ol = lcs_ol->next; 395 396 if (lcs_ol->position[0]->offset <= original_sync) 397 break; 398 } 399 else 400 { 401 original_sync = lcs_ol->position[0]->offset; 402 403 while (lcs_om->position[0]->offset + lcs_om->length 404 < original_sync) 405 lcs_om = lcs_om->next; 406 407 /* If the sync point is the EOF, and our current lcs segment 408 * doesn't reach as far as EOF, we need to skip this segment. 409 */ 410 if (lcs_ol->length == 0 && lcs_om->length > 0 411 && lcs_om->position[0]->offset + lcs_om->length 412 == original_sync 413 && lcs_om->position[1]->offset + lcs_om->length 414 != lcs_om->next->position[1]->offset) 415 lcs_om = lcs_om->next; 416 417 if (lcs_om->position[0]->offset <= original_sync) 418 break; 419 } 420 } 421 422 modified_sync = lcs_om->position[1]->offset 423 + (original_sync - lcs_om->position[0]->offset); 424 latest_sync = lcs_ol->position[1]->offset 425 + (original_sync - lcs_ol->position[0]->offset); 426 427 /* Determine what is modified, if anything */ 428 is_modified = lcs_om->position[0]->offset - original_start > 0 429 || lcs_om->position[1]->offset - modified_start > 0; 430 431 is_latest = lcs_ol->position[0]->offset - original_start > 0 432 || lcs_ol->position[1]->offset - latest_start > 0; 433 434 if (is_modified || is_latest) 435 { 436 modified_length = modified_sync - modified_start; 437 latest_length = latest_sync - latest_start; 438 439 (*diff_ref) = apr_palloc(pool, sizeof(**diff_ref)); 440 441 (*diff_ref)->original_start = original_start - 1; 442 (*diff_ref)->original_length = original_sync - original_start; 443 (*diff_ref)->modified_start = modified_start - 1; 444 (*diff_ref)->modified_length = modified_length; 445 (*diff_ref)->latest_start = latest_start - 1; 446 (*diff_ref)->latest_length = latest_length; 447 (*diff_ref)->resolved_diff = NULL; 448 449 if (is_modified && is_latest) 450 { 451 svn_diff__resolve_conflict(*diff_ref, 452 &position_list[1], 453 &position_list[2], 454 num_tokens, 455 pool); 456 } 457 else if (is_modified) 458 { 459 (*diff_ref)->type = svn_diff__type_diff_modified; 460 } 461 else 462 { 463 (*diff_ref)->type = svn_diff__type_diff_latest; 464 } 465 466 diff_ref = &(*diff_ref)->next; 467 } 468 469 /* Detect EOF */ 470 if (lcs_om->length == 0 || lcs_ol->length == 0) 471 break; 472 473 modified_length = lcs_om->length 474 - (original_sync - lcs_om->position[0]->offset); 475 latest_length = lcs_ol->length 476 - (original_sync - lcs_ol->position[0]->offset); 477 common_length = modified_length < latest_length 478 ? modified_length : latest_length; 479 480 (*diff_ref) = apr_palloc(pool, sizeof(**diff_ref)); 481 482 (*diff_ref)->type = svn_diff__type_common; 483 (*diff_ref)->original_start = original_sync - 1; 484 (*diff_ref)->original_length = common_length; 485 (*diff_ref)->modified_start = modified_sync - 1; 486 (*diff_ref)->modified_length = common_length; 487 (*diff_ref)->latest_start = latest_sync - 1; 488 (*diff_ref)->latest_length = common_length; 489 (*diff_ref)->resolved_diff = NULL; 490 491 diff_ref = &(*diff_ref)->next; 492 493 /* Set the new offsets */ 494 original_start = original_sync + common_length; 495 modified_start = modified_sync + common_length; 496 latest_start = latest_sync + common_length; 497 498 /* Make it easier for diff_common/conflict detection 499 by recording last lcs start positions 500 */ 501 if (position_list[1]->offset < lcs_om->position[1]->offset) 502 position_list[1] = lcs_om->position[1]; 503 504 if (position_list[2]->offset < lcs_ol->position[1]->offset) 505 position_list[2] = lcs_ol->position[1]; 506 507 /* Make sure we are pointing to lcs entries beyond 508 * the range we just processed 509 */ 510 while (original_start >= lcs_om->position[0]->offset + lcs_om->length 511 && lcs_om->length > 0) 512 { 513 lcs_om = lcs_om->next; 514 } 515 516 while (original_start >= lcs_ol->position[0]->offset + lcs_ol->length 517 && lcs_ol->length > 0) 518 { 519 lcs_ol = lcs_ol->next; 520 } 521 } 522 523 *diff_ref = NULL; 524 } 525 526 svn_pool_destroy(subpool); 527 528 return SVN_NO_ERROR; 529} 530