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| 1 | <?php |
| 2 | /** |
| 3 | * |
| 4 | * This file is part of the phpBB Forum Software package. |
| 5 | * |
| 6 | * @copyright (c) phpBB Limited <https://www.phpbb.com> |
| 7 | * @license GNU General Public License, version 2 (GPL-2.0) |
| 8 | * |
| 9 | * For full copyright and license information, please see |
| 10 | * the docs/CREDITS.txt file. |
| 11 | * |
| 12 | */ |
| 13 | |
| 14 | /** |
| 15 | * @ignore |
| 16 | */ |
| 17 | if (!defined('IN_PHPBB')) |
| 18 | { |
| 19 | exit; |
| 20 | } |
| 21 | |
| 22 | /** |
| 23 | * Code from pear.php.net, Text_Diff-1.1.0 package |
| 24 | * http://pear.php.net/package/Text_Diff/ (native engine) |
| 25 | * |
| 26 | * Modified by phpBB Limited to meet our coding standards |
| 27 | * and being able to integrate into phpBB |
| 28 | * |
| 29 | * Class used internally by Text_Diff to actually compute the diffs. This |
| 30 | * class is implemented using native PHP code. |
| 31 | * |
| 32 | * The algorithm used here is mostly lifted from the perl module |
| 33 | * Algorithm::Diff (version 1.06) by Ned Konz, which is available at: |
| 34 | * http://www.perl.com/CPAN/authors/id/N/NE/NEDKONZ/Algorithm-Diff-1.06.zip |
| 35 | * |
| 36 | * More ideas are taken from: http://www.ics.uci.edu/~eppstein/161/960229.html |
| 37 | * |
| 38 | * Some ideas (and a bit of code) are taken from analyze.c, of GNU |
| 39 | * diffutils-2.7, which can be found at: |
| 40 | * ftp://gnudist.gnu.org/pub/gnu/diffutils/diffutils-2.7.tar.gz |
| 41 | * |
| 42 | * Some ideas (subdivision by NCHUNKS > 2, and some optimizations) are from |
| 43 | * Geoffrey T. Dairiki <dairiki@dairiki.org>. The original PHP version of this |
| 44 | * code was written by him, and is used/adapted with his permission. |
| 45 | * |
| 46 | * Copyright 2004-2008 The Horde Project (http://www.horde.org/) |
| 47 | * |
| 48 | * @author Geoffrey T. Dairiki <dairiki@dairiki.org> |
| 49 | * @package diff |
| 50 | * |
| 51 | * @access private |
| 52 | */ |
| 53 | class diff_engine |
| 54 | { |
| 55 | /** |
| 56 | * If set to true we trim all lines before we compare them. This ensures that sole space/tab changes do not trigger diffs. |
| 57 | */ |
| 58 | var $skip_whitespace_changes = true; |
| 59 | |
| 60 | function diff(&$from_lines, &$to_lines, $preserve_cr = true) |
| 61 | { |
| 62 | // Remove empty lines... |
| 63 | // If preserve_cr is true, we basically only change \r\n and bare \r to \n to get the same carriage returns for both files |
| 64 | // If it is false, we try to only use \n once per line and ommit all empty lines to be able to get a proper data diff |
| 65 | |
| 66 | if (is_array($from_lines)) |
| 67 | { |
| 68 | $from_lines = implode("\n", $from_lines); |
| 69 | } |
| 70 | |
| 71 | if (is_array($to_lines)) |
| 72 | { |
| 73 | $to_lines = implode("\n", $to_lines); |
| 74 | } |
| 75 | |
| 76 | if ($preserve_cr) |
| 77 | { |
| 78 | $from_lines = explode("\n", str_replace("\r", "\n", str_replace("\r\n", "\n", $from_lines))); |
| 79 | $to_lines = explode("\n", str_replace("\r", "\n", str_replace("\r\n", "\n", $to_lines))); |
| 80 | } |
| 81 | else |
| 82 | { |
| 83 | $from_lines = explode("\n", preg_replace('#[\n\r]+#', "\n", $from_lines)); |
| 84 | $to_lines = explode("\n", preg_replace('#[\n\r]+#', "\n", $to_lines)); |
| 85 | } |
| 86 | |
| 87 | $n_from = count($from_lines); |
| 88 | $n_to = count($to_lines); |
| 89 | |
| 90 | $this->xchanged = $this->ychanged = $this->xv = $this->yv = $this->xind = $this->yind = array(); |
| 91 | unset($this->seq, $this->in_seq, $this->lcs); |
| 92 | |
| 93 | // Skip leading common lines. |
| 94 | for ($skip = 0; $skip < $n_from && $skip < $n_to; $skip++) |
| 95 | { |
| 96 | if (trim($from_lines[$skip]) !== trim($to_lines[$skip])) |
| 97 | { |
| 98 | break; |
| 99 | } |
| 100 | $this->xchanged[$skip] = $this->ychanged[$skip] = false; |
| 101 | } |
| 102 | |
| 103 | // Skip trailing common lines. |
| 104 | $xi = $n_from; |
| 105 | $yi = $n_to; |
| 106 | |
| 107 | for ($endskip = 0; --$xi > $skip && --$yi > $skip; $endskip++) |
| 108 | { |
| 109 | if (trim($from_lines[$xi]) !== trim($to_lines[$yi])) |
| 110 | { |
| 111 | break; |
| 112 | } |
| 113 | $this->xchanged[$xi] = $this->ychanged[$yi] = false; |
| 114 | } |
| 115 | |
| 116 | // Ignore lines which do not exist in both files. |
| 117 | for ($xi = $skip; $xi < $n_from - $endskip; $xi++) |
| 118 | { |
| 119 | if ($this->skip_whitespace_changes) $xhash[trim($from_lines[$xi])] = 1; else $xhash[$from_lines[$xi]] = 1; |
| 120 | } |
| 121 | |
| 122 | for ($yi = $skip; $yi < $n_to - $endskip; $yi++) |
| 123 | { |
| 124 | $line = ($this->skip_whitespace_changes) ? trim($to_lines[$yi]) : $to_lines[$yi]; |
| 125 | |
| 126 | if (($this->ychanged[$yi] = empty($xhash[$line]))) |
| 127 | { |
| 128 | continue; |
| 129 | } |
| 130 | $yhash[$line] = 1; |
| 131 | $this->yv[] = $line; |
| 132 | $this->yind[] = $yi; |
| 133 | } |
| 134 | |
| 135 | for ($xi = $skip; $xi < $n_from - $endskip; $xi++) |
| 136 | { |
| 137 | $line = ($this->skip_whitespace_changes) ? trim($from_lines[$xi]) : $from_lines[$xi]; |
| 138 | |
| 139 | if (($this->xchanged[$xi] = empty($yhash[$line]))) |
| 140 | { |
| 141 | continue; |
| 142 | } |
| 143 | $this->xv[] = $line; |
| 144 | $this->xind[] = $xi; |
| 145 | } |
| 146 | |
| 147 | // Find the LCS. |
| 148 | $this->_compareseq(0, count($this->xv), 0, count($this->yv)); |
| 149 | |
| 150 | // Merge edits when possible. |
| 151 | if ($this->skip_whitespace_changes) |
| 152 | { |
| 153 | $from_lines_clean = array_map('trim', $from_lines); |
| 154 | $to_lines_clean = array_map('trim', $to_lines); |
| 155 | |
| 156 | $this->_shift_boundaries($from_lines_clean, $this->xchanged, $this->ychanged); |
| 157 | $this->_shift_boundaries($to_lines_clean, $this->ychanged, $this->xchanged); |
| 158 | |
| 159 | unset($from_lines_clean, $to_lines_clean); |
| 160 | } |
| 161 | else |
| 162 | { |
| 163 | $this->_shift_boundaries($from_lines, $this->xchanged, $this->ychanged); |
| 164 | $this->_shift_boundaries($to_lines, $this->ychanged, $this->xchanged); |
| 165 | } |
| 166 | |
| 167 | // Compute the edit operations. |
| 168 | $edits = array(); |
| 169 | $xi = $yi = 0; |
| 170 | |
| 171 | while ($xi < $n_from || $yi < $n_to) |
| 172 | { |
| 173 | // Skip matching "snake". |
| 174 | $copy = array(); |
| 175 | |
| 176 | while ($xi < $n_from && $yi < $n_to && !$this->xchanged[$xi] && !$this->ychanged[$yi]) |
| 177 | { |
| 178 | $copy[] = $from_lines[$xi++]; |
| 179 | $yi++; |
| 180 | } |
| 181 | |
| 182 | if ($copy) |
| 183 | { |
| 184 | $edits[] = new diff_op_copy($copy); |
| 185 | } |
| 186 | |
| 187 | // Find deletes & adds. |
| 188 | $delete = array(); |
| 189 | while ($xi < $n_from && $this->xchanged[$xi]) |
| 190 | { |
| 191 | $delete[] = $from_lines[$xi++]; |
| 192 | } |
| 193 | |
| 194 | $add = array(); |
| 195 | while ($yi < $n_to && $this->ychanged[$yi]) |
| 196 | { |
| 197 | $add[] = $to_lines[$yi++]; |
| 198 | } |
| 199 | |
| 200 | if ($delete && $add) |
| 201 | { |
| 202 | $edits[] = new diff_op_change($delete, $add); |
| 203 | } |
| 204 | else if ($delete) |
| 205 | { |
| 206 | $edits[] = new diff_op_delete($delete); |
| 207 | } |
| 208 | else if ($add) |
| 209 | { |
| 210 | $edits[] = new diff_op_add($add); |
| 211 | } |
| 212 | } |
| 213 | |
| 214 | return $edits; |
| 215 | } |
| 216 | |
| 217 | /** |
| 218 | * Divides the Largest Common Subsequence (LCS) of the sequences (XOFF, |
| 219 | * XLIM) and (YOFF, YLIM) into NCHUNKS approximately equally sized segments. |
| 220 | * |
| 221 | * Returns (LCS, PTS). LCS is the length of the LCS. PTS is an array of |
| 222 | * NCHUNKS+1 (X, Y) indexes giving the diving points between sub |
| 223 | * sequences. The first sub-sequence is contained in (X0, X1), (Y0, Y1), |
| 224 | * the second in (X1, X2), (Y1, Y2) and so on. Note that (X0, Y0) == |
| 225 | * (XOFF, YOFF) and (X[NCHUNKS], Y[NCHUNKS]) == (XLIM, YLIM). |
| 226 | * |
| 227 | * This function assumes that the first lines of the specified portions of |
| 228 | * the two files do not match, and likewise that the last lines do not |
| 229 | * match. The caller must trim matching lines from the beginning and end |
| 230 | * of the portions it is going to specify. |
| 231 | */ |
| 232 | function _diag($xoff, $xlim, $yoff, $ylim, $nchunks) |
| 233 | { |
| 234 | $flip = false; |
| 235 | |
| 236 | if ($xlim - $xoff > $ylim - $yoff) |
| 237 | { |
| 238 | // Things seems faster (I'm not sure I understand why) when the shortest sequence is in X. |
| 239 | $flip = true; |
| 240 | list($xoff, $xlim, $yoff, $ylim) = array($yoff, $ylim, $xoff, $xlim); |
| 241 | } |
| 242 | |
| 243 | if ($flip) |
| 244 | { |
| 245 | for ($i = $ylim - 1; $i >= $yoff; $i--) |
| 246 | { |
| 247 | $ymatches[$this->xv[$i]][] = $i; |
| 248 | } |
| 249 | } |
| 250 | else |
| 251 | { |
| 252 | for ($i = $ylim - 1; $i >= $yoff; $i--) |
| 253 | { |
| 254 | $ymatches[$this->yv[$i]][] = $i; |
| 255 | } |
| 256 | } |
| 257 | |
| 258 | $this->lcs = 0; |
| 259 | $this->seq[0]= $yoff - 1; |
| 260 | $this->in_seq = array(); |
| 261 | $ymids[0] = array(); |
| 262 | |
| 263 | $numer = $xlim - $xoff + $nchunks - 1; |
| 264 | $x = $xoff; |
| 265 | |
| 266 | for ($chunk = 0; $chunk < $nchunks; $chunk++) |
| 267 | { |
| 268 | if ($chunk > 0) |
| 269 | { |
| 270 | for ($i = 0; $i <= $this->lcs; $i++) |
| 271 | { |
| 272 | $ymids[$i][$chunk - 1] = $this->seq[$i]; |
| 273 | } |
| 274 | } |
| 275 | |
| 276 | $x1 = $xoff + (int)(($numer + ($xlim - $xoff) * $chunk) / $nchunks); |
| 277 | |
| 278 | for (; $x < $x1; $x++) |
| 279 | { |
| 280 | $line = $flip ? $this->yv[$x] : $this->xv[$x]; |
| 281 | if (empty($ymatches[$line])) |
| 282 | { |
| 283 | continue; |
| 284 | } |
| 285 | $matches = $ymatches[$line]; |
| 286 | |
| 287 | reset($matches); |
| 288 | while ($y = current($matches)) |
| 289 | { |
| 290 | next($matches); |
| 291 | if (empty($this->in_seq[$y])) |
| 292 | { |
| 293 | $k = $this->_lcs_pos($y); |
| 294 | $ymids[$k] = $ymids[$k - 1]; |
| 295 | break; |
| 296 | } |
| 297 | } |
| 298 | |
| 299 | // no reset() here |
| 300 | while ($y = current($matches)) |
| 301 | { |
| 302 | next($matches); |
| 303 | if ($y > $this->seq[$k - 1]) |
| 304 | { |
| 305 | // Optimization: this is a common case: next match is just replacing previous match. |
| 306 | $this->in_seq[$this->seq[$k]] = false; |
| 307 | $this->seq[$k] = $y; |
| 308 | $this->in_seq[$y] = 1; |
| 309 | } |
| 310 | else if (empty($this->in_seq[$y])) |
| 311 | { |
| 312 | $k = $this->_lcs_pos($y); |
| 313 | $ymids[$k] = $ymids[$k - 1]; |
| 314 | } |
| 315 | } |
| 316 | } |
| 317 | } |
| 318 | |
| 319 | $seps[] = $flip ? array($yoff, $xoff) : array($xoff, $yoff); |
| 320 | $ymid = $ymids[$this->lcs]; |
| 321 | |
| 322 | for ($n = 0; $n < $nchunks - 1; $n++) |
| 323 | { |
| 324 | $x1 = $xoff + (int)(($numer + ($xlim - $xoff) * $n) / $nchunks); |
| 325 | $y1 = $ymid[$n] + 1; |
| 326 | $seps[] = $flip ? array($y1, $x1) : array($x1, $y1); |
| 327 | } |
| 328 | $seps[] = $flip ? array($ylim, $xlim) : array($xlim, $ylim); |
| 329 | |
| 330 | return array($this->lcs, $seps); |
| 331 | } |
| 332 | |
| 333 | function _lcs_pos($ypos) |
| 334 | { |
| 335 | $end = $this->lcs; |
| 336 | |
| 337 | if ($end == 0 || $ypos > $this->seq[$end]) |
| 338 | { |
| 339 | $this->seq[++$this->lcs] = $ypos; |
| 340 | $this->in_seq[$ypos] = 1; |
| 341 | return $this->lcs; |
| 342 | } |
| 343 | |
| 344 | $beg = 1; |
| 345 | while ($beg < $end) |
| 346 | { |
| 347 | $mid = (int)(($beg + $end) / 2); |
| 348 | if ($ypos > $this->seq[$mid]) |
| 349 | { |
| 350 | $beg = $mid + 1; |
| 351 | } |
| 352 | else |
| 353 | { |
| 354 | $end = $mid; |
| 355 | } |
| 356 | } |
| 357 | |
| 358 | $this->in_seq[$this->seq[$end]] = false; |
| 359 | $this->seq[$end] = $ypos; |
| 360 | $this->in_seq[$ypos] = 1; |
| 361 | |
| 362 | return $end; |
| 363 | } |
| 364 | |
| 365 | /** |
| 366 | * Finds LCS of two sequences. |
| 367 | * |
| 368 | * The results are recorded in the vectors $this->{x,y}changed[], by |
| 369 | * storing a 1 in the element for each line that is an insertion or |
| 370 | * deletion (ie. is not in the LCS). |
| 371 | * |
| 372 | * The subsequence of file 0 is (XOFF, XLIM) and likewise for file 1. |
| 373 | * |
| 374 | * Note that XLIM, YLIM are exclusive bounds. All line numbers are |
| 375 | * origin-0 and discarded lines are not counted. |
| 376 | */ |
| 377 | function _compareseq($xoff, $xlim, $yoff, $ylim) |
| 378 | { |
| 379 | // Slide down the bottom initial diagonal. |
| 380 | while ($xoff < $xlim && $yoff < $ylim && $this->xv[$xoff] == $this->yv[$yoff]) |
| 381 | { |
| 382 | ++$xoff; |
| 383 | ++$yoff; |
| 384 | } |
| 385 | |
| 386 | // Slide up the top initial diagonal. |
| 387 | while ($xlim > $xoff && $ylim > $yoff && $this->xv[$xlim - 1] == $this->yv[$ylim - 1]) |
| 388 | { |
| 389 | --$xlim; |
| 390 | --$ylim; |
| 391 | } |
| 392 | |
| 393 | if ($xoff == $xlim || $yoff == $ylim) |
| 394 | { |
| 395 | $lcs = 0; |
| 396 | } |
| 397 | else |
| 398 | { |
| 399 | // This is ad hoc but seems to work well. |
| 400 | // $nchunks = sqrt(min($xlim - $xoff, $ylim - $yoff) / 2.5); |
| 401 | // $nchunks = max(2,min(8,(int)$nchunks)); |
| 402 | $nchunks = min(7, $xlim - $xoff, $ylim - $yoff) + 1; |
| 403 | list($lcs, $seps) = $this->_diag($xoff, $xlim, $yoff, $ylim, $nchunks); |
| 404 | } |
| 405 | |
| 406 | if ($lcs == 0) |
| 407 | { |
| 408 | // X and Y sequences have no common subsequence: mark all changed. |
| 409 | while ($yoff < $ylim) |
| 410 | { |
| 411 | $this->ychanged[$this->yind[$yoff++]] = 1; |
| 412 | } |
| 413 | |
| 414 | while ($xoff < $xlim) |
| 415 | { |
| 416 | $this->xchanged[$this->xind[$xoff++]] = 1; |
| 417 | } |
| 418 | } |
| 419 | else |
| 420 | { |
| 421 | // Use the partitions to split this problem into subproblems. |
| 422 | reset($seps); |
| 423 | $pt1 = $seps[0]; |
| 424 | |
| 425 | while ($pt2 = next($seps)) |
| 426 | { |
| 427 | $this->_compareseq($pt1[0], $pt2[0], $pt1[1], $pt2[1]); |
| 428 | $pt1 = $pt2; |
| 429 | } |
| 430 | } |
| 431 | } |
| 432 | |
| 433 | /** |
| 434 | * Adjusts inserts/deletes of identical lines to join changes as much as possible. |
| 435 | * |
| 436 | * We do something when a run of changed lines include a line at one end |
| 437 | * and has an excluded, identical line at the other. We are free to |
| 438 | * choose which identical line is included. 'compareseq' usually chooses |
| 439 | * the one at the beginning, but usually it is cleaner to consider the |
| 440 | * following identical line to be the "change". |
| 441 | * |
| 442 | * This is extracted verbatim from analyze.c (GNU diffutils-2.7). |
| 443 | */ |
| 444 | function _shift_boundaries($lines, &$changed, $other_changed) |
| 445 | { |
| 446 | $i = 0; |
| 447 | $j = 0; |
| 448 | |
| 449 | $len = count($lines); |
| 450 | $other_len = count($other_changed); |
| 451 | |
| 452 | while (1) |
| 453 | { |
| 454 | // Scan forward to find the beginning of another run of |
| 455 | // changes. Also keep track of the corresponding point in the other file. |
| 456 | // |
| 457 | // Throughout this code, $i and $j are adjusted together so that |
| 458 | // the first $i elements of $changed and the first $j elements of |
| 459 | // $other_changed both contain the same number of zeros (unchanged lines). |
| 460 | // |
| 461 | // Furthermore, $j is always kept so that $j == $other_len or $other_changed[$j] == false. |
| 462 | while ($j < $other_len && $other_changed[$j]) |
| 463 | { |
| 464 | $j++; |
| 465 | } |
| 466 | |
| 467 | while ($i < $len && ! $changed[$i]) |
| 468 | { |
| 469 | $i++; |
| 470 | $j++; |
| 471 | |
| 472 | while ($j < $other_len && $other_changed[$j]) |
| 473 | { |
| 474 | $j++; |
| 475 | } |
| 476 | } |
| 477 | |
| 478 | if ($i == $len) |
| 479 | { |
| 480 | break; |
| 481 | } |
| 482 | |
| 483 | $start = $i; |
| 484 | |
| 485 | // Find the end of this run of changes. |
| 486 | while (++$i < $len && $changed[$i]) |
| 487 | { |
| 488 | continue; |
| 489 | } |
| 490 | |
| 491 | do |
| 492 | { |
| 493 | // Record the length of this run of changes, so that we can later determine whether the run has grown. |
| 494 | $runlength = $i - $start; |
| 495 | |
| 496 | // Move the changed region back, so long as the previous unchanged line matches the last changed one. |
| 497 | // This merges with previous changed regions. |
| 498 | while ($start > 0 && $lines[$start - 1] == $lines[$i - 1]) |
| 499 | { |
| 500 | $changed[--$start] = 1; |
| 501 | $changed[--$i] = false; |
| 502 | |
| 503 | while ($start > 0 && $changed[$start - 1]) |
| 504 | { |
| 505 | $start--; |
| 506 | } |
| 507 | |
| 508 | while ($other_changed[--$j]) |
| 509 | { |
| 510 | continue; |
| 511 | } |
| 512 | } |
| 513 | |
| 514 | // Set CORRESPONDING to the end of the changed run, at the last point where it corresponds to a changed run in the |
| 515 | // other file. CORRESPONDING == LEN means no such point has been found. |
| 516 | $corresponding = $j < $other_len ? $i : $len; |
| 517 | |
| 518 | // Move the changed region forward, so long as the first changed line matches the following unchanged one. |
| 519 | // This merges with following changed regions. |
| 520 | // Do this second, so that if there are no merges, the changed region is moved forward as far as possible. |
| 521 | while ($i < $len && $lines[$start] == $lines[$i]) |
| 522 | { |
| 523 | $changed[$start++] = false; |
| 524 | $changed[$i++] = 1; |
| 525 | |
| 526 | while ($i < $len && $changed[$i]) |
| 527 | { |
| 528 | $i++; |
| 529 | } |
| 530 | |
| 531 | $j++; |
| 532 | if ($j < $other_len && $other_changed[$j]) |
| 533 | { |
| 534 | $corresponding = $i; |
| 535 | while ($j < $other_len && $other_changed[$j]) |
| 536 | { |
| 537 | $j++; |
| 538 | } |
| 539 | } |
| 540 | } |
| 541 | } |
| 542 | while ($runlength != $i - $start); |
| 543 | |
| 544 | // If possible, move the fully-merged run of changes back to a corresponding run in the other file. |
| 545 | while ($corresponding < $i) |
| 546 | { |
| 547 | $changed[--$start] = 1; |
| 548 | $changed[--$i] = 0; |
| 549 | |
| 550 | while ($other_changed[--$j]) |
| 551 | { |
| 552 | continue; |
| 553 | } |
| 554 | } |
| 555 | } |
| 556 | } |
| 557 | } |