| 1 | 5 | simandl | <?php |
| 2 | | | /** |
| 3 | | | * Class used internally by Text_Diff to actually compute the diffs. |
| 4 | | | * |
| 5 | | | * This class is implemented using native PHP code. |
| 6 | | | * |
| 7 | | | * The algorithm used here is mostly lifted from the perl module |
| 8 | | | * Algorithm::Diff (version 1.06) by Ned Konz, which is available at: |
| 9 | | | * http://www.perl.com/CPAN/authors/id/N/NE/NEDKONZ/Algorithm-Diff-1.06.zip |
| 10 | | | * |
| 11 | | | * More ideas are taken from: http://www.ics.uci.edu/~eppstein/161/960229.html |
| 12 | | | * |
| 13 | | | * Some ideas (and a bit of code) are taken from analyze.c, of GNU |
| 14 | | | * diffutils-2.7, which can be found at: |
| 15 | | | * ftp://gnudist.gnu.org/pub/gnu/diffutils/diffutils-2.7.tar.gz |
| 16 | | | * |
| 17 | | | * Some ideas (subdivision by NCHUNKS > 2, and some optimizations) are from |
| 18 | | | * Geoffrey T. Dairiki <dairiki@dairiki.org>. The original PHP version of this |
| 19 | | | * code was written by him, and is used/adapted with his permission. |
| 20 | | | * |
| 21 | | | * $Horde: framework/Text_Diff/Diff/Engine/native.php,v 1.7.2.4 2008/01/04 10:38:10 jan Exp $ |
| 22 | | | * |
| 23 | | | * Copyright 2004-2008 The Horde Project (http://www.horde.org/) |
| 24 | | | * |
| 25 | | | * See the enclosed file COPYING for license information (LGPL). If you did |
| 26 | | | * not receive this file, see http://opensource.org/licenses/lgpl-license.php. |
| 27 | | | * |
| 28 | | | * @author Geoffrey T. Dairiki <dairiki@dairiki.org> |
| 29 | | | * @package Text_Diff |
| 30 | | | */ |
| 31 | | | class Text_Diff_Engine_native { |
| 32 | | | |
| 33 | | | function diff($from_lines, $to_lines) |
| 34 | | | { |
| 35 | | | array_walk($from_lines, array('Text_Diff', 'trimNewlines')); |
| 36 | | | array_walk($to_lines, array('Text_Diff', 'trimNewlines')); |
| 37 | | | |
| 38 | | | $n_from = count($from_lines); |
| 39 | | | $n_to = count($to_lines); |
| 40 | | | |
| 41 | | | $this->xchanged = $this->ychanged = array(); |
| 42 | | | $this->xv = $this->yv = array(); |
| 43 | | | $this->xind = $this->yind = array(); |
| 44 | | | unset($this->seq); |
| 45 | | | unset($this->in_seq); |
| 46 | | | unset($this->lcs); |
| 47 | | | |
| 48 | | | // Skip leading common lines. |
| 49 | | | for ($skip = 0; $skip < $n_from && $skip < $n_to; $skip++) { |
| 50 | | | if ($from_lines[$skip] !== $to_lines[$skip]) { |
| 51 | | | break; |
| 52 | | | } |
| 53 | | | $this->xchanged[$skip] = $this->ychanged[$skip] = false; |
| 54 | | | } |
| 55 | | | |
| 56 | | | // Skip trailing common lines. |
| 57 | | | $xi = $n_from; $yi = $n_to; |
| 58 | | | for ($endskip = 0; --$xi > $skip && --$yi > $skip; $endskip++) { |
| 59 | | | if ($from_lines[$xi] !== $to_lines[$yi]) { |
| 60 | | | break; |
| 61 | | | } |
| 62 | | | $this->xchanged[$xi] = $this->ychanged[$yi] = false; |
| 63 | | | } |
| 64 | | | |
| 65 | | | // Ignore lines which do not exist in both files. |
| 66 | | | for ($xi = $skip; $xi < $n_from - $endskip; $xi++) { |
| 67 | | | $xhash[$from_lines[$xi]] = 1; |
| 68 | | | } |
| 69 | | | for ($yi = $skip; $yi < $n_to - $endskip; $yi++) { |
| 70 | | | $line = $to_lines[$yi]; |
| 71 | | | if (($this->ychanged[$yi] = empty($xhash[$line]))) { |
| 72 | | | continue; |
| 73 | | | } |
| 74 | | | $yhash[$line] = 1; |
| 75 | | | $this->yv[] = $line; |
| 76 | | | $this->yind[] = $yi; |
| 77 | | | } |
| 78 | | | for ($xi = $skip; $xi < $n_from - $endskip; $xi++) { |
| 79 | | | $line = $from_lines[$xi]; |
| 80 | | | if (($this->xchanged[$xi] = empty($yhash[$line]))) { |
| 81 | | | continue; |
| 82 | | | } |
| 83 | | | $this->xv[] = $line; |
| 84 | | | $this->xind[] = $xi; |
| 85 | | | } |
| 86 | | | |
| 87 | | | // Find the LCS. |
| 88 | | | $this->_compareseq(0, count($this->xv), 0, count($this->yv)); |
| 89 | | | |
| 90 | | | // Merge edits when possible. |
| 91 | | | $this->_shiftBoundaries($from_lines, $this->xchanged, $this->ychanged); |
| 92 | | | $this->_shiftBoundaries($to_lines, $this->ychanged, $this->xchanged); |
| 93 | | | |
| 94 | | | // Compute the edit operations. |
| 95 | | | $edits = array(); |
| 96 | | | $xi = $yi = 0; |
| 97 | | | while ($xi < $n_from || $yi < $n_to) { |
| 98 | | | assert($yi < $n_to || $this->xchanged[$xi]); |
| 99 | | | assert($xi < $n_from || $this->ychanged[$yi]); |
| 100 | | | |
| 101 | | | // Skip matching "snake". |
| 102 | | | $copy = array(); |
| 103 | | | while ($xi < $n_from && $yi < $n_to |
| 104 | | | && !$this->xchanged[$xi] && !$this->ychanged[$yi]) { |
| 105 | | | $copy[] = $from_lines[$xi++]; |
| 106 | | | ++$yi; |
| 107 | | | } |
| 108 | | | if ($copy) { |
| 109 | | | $edits[] = &new Text_Diff_Op_copy($copy); |
| 110 | | | } |
| 111 | | | |
| 112 | | | // Find deletes & adds. |
| 113 | | | $delete = array(); |
| 114 | | | while ($xi < $n_from && $this->xchanged[$xi]) { |
| 115 | | | $delete[] = $from_lines[$xi++]; |
| 116 | | | } |
| 117 | | | |
| 118 | | | $add = array(); |
| 119 | | | while ($yi < $n_to && $this->ychanged[$yi]) { |
| 120 | | | $add[] = $to_lines[$yi++]; |
| 121 | | | } |
| 122 | | | |
| 123 | | | if ($delete && $add) { |
| 124 | | | $edits[] = &new Text_Diff_Op_change($delete, $add); |
| 125 | | | } elseif ($delete) { |
| 126 | | | $edits[] = &new Text_Diff_Op_delete($delete); |
| 127 | | | } elseif ($add) { |
| 128 | | | $edits[] = &new Text_Diff_Op_add($add); |
| 129 | | | } |
| 130 | | | } |
| 131 | | | |
| 132 | | | return $edits; |
| 133 | | | } |
| 134 | | | |
| 135 | | | /** |
| 136 | | | * Divides the Largest Common Subsequence (LCS) of the sequences (XOFF, |
| 137 | | | * XLIM) and (YOFF, YLIM) into NCHUNKS approximately equally sized |
| 138 | | | * segments. |
| 139 | | | * |
| 140 | | | * Returns (LCS, PTS). LCS is the length of the LCS. PTS is an array of |
| 141 | | | * NCHUNKS+1 (X, Y) indexes giving the diving points between sub |
| 142 | | | * sequences. The first sub-sequence is contained in (X0, X1), (Y0, Y1), |
| 143 | | | * the second in (X1, X2), (Y1, Y2) and so on. Note that (X0, Y0) == |
| 144 | | | * (XOFF, YOFF) and (X[NCHUNKS], Y[NCHUNKS]) == (XLIM, YLIM). |
| 145 | | | * |
| 146 | | | * This function assumes that the first lines of the specified portions of |
| 147 | | | * the two files do not match, and likewise that the last lines do not |
| 148 | | | * match. The caller must trim matching lines from the beginning and end |
| 149 | | | * of the portions it is going to specify. |
| 150 | | | */ |
| 151 | | | function _diag ($xoff, $xlim, $yoff, $ylim, $nchunks) |
| 152 | | | { |
| 153 | | | $flip = false; |
| 154 | | | |
| 155 | | | if ($xlim - $xoff > $ylim - $yoff) { |
| 156 | | | /* Things seems faster (I'm not sure I understand why) when the |
| 157 | | | * shortest sequence is in X. */ |
| 158 | | | $flip = true; |
| 159 | | | list ($xoff, $xlim, $yoff, $ylim) |
| 160 | | | = array($yoff, $ylim, $xoff, $xlim); |
| 161 | | | } |
| 162 | | | |
| 163 | | | if ($flip) { |
| 164 | | | for ($i = $ylim - 1; $i >= $yoff; $i--) { |
| 165 | | | $ymatches[$this->xv[$i]][] = $i; |
| 166 | | | } |
| 167 | | | } else { |
| 168 | | | for ($i = $ylim - 1; $i >= $yoff; $i--) { |
| 169 | | | $ymatches[$this->yv[$i]][] = $i; |
| 170 | | | } |
| 171 | | | } |
| 172 | | | |
| 173 | | | $this->lcs = 0; |
| 174 | | | $this->seq[0]= $yoff - 1; |
| 175 | | | $this->in_seq = array(); |
| 176 | | | $ymids[0] = array(); |
| 177 | | | |
| 178 | | | $numer = $xlim - $xoff + $nchunks - 1; |
| 179 | | | $x = $xoff; |
| 180 | | | for ($chunk = 0; $chunk < $nchunks; $chunk++) { |
| 181 | | | if ($chunk > 0) { |
| 182 | | | for ($i = 0; $i <= $this->lcs; $i++) { |
| 183 | | | $ymids[$i][$chunk - 1] = $this->seq[$i]; |
| 184 | | | } |
| 185 | | | } |
| 186 | | | |
| 187 | | | $x1 = $xoff + (int)(($numer + ($xlim - $xoff) * $chunk) / $nchunks); |
| 188 | | | for (; $x < $x1; $x++) { |
| 189 | | | $line = $flip ? $this->yv[$x] : $this->xv[$x]; |
| 190 | | | if (empty($ymatches[$line])) { |
| 191 | | | continue; |
| 192 | | | } |
| 193 | | | $matches = $ymatches[$line]; |
| 194 | | | reset($matches); |
| 195 | | | while (list(, $y) = each($matches)) { |
| 196 | | | if (empty($this->in_seq[$y])) { |
| 197 | | | $k = $this->_lcsPos($y); |
| 198 | | | assert($k > 0); |
| 199 | | | $ymids[$k] = $ymids[$k - 1]; |
| 200 | | | break; |
| 201 | | | } |
| 202 | | | } |
| 203 | | | while (list(, $y) = each($matches)) { |
| 204 | | | if ($y > $this->seq[$k - 1]) { |
| 205 | | | assert($y <= $this->seq[$k]); |
| 206 | | | /* Optimization: this is a common case: next match is |
| 207 | | | * just replacing previous match. */ |
| 208 | | | $this->in_seq[$this->seq[$k]] = false; |
| 209 | | | $this->seq[$k] = $y; |
| 210 | | | $this->in_seq[$y] = 1; |
| 211 | | | } elseif (empty($this->in_seq[$y])) { |
| 212 | | | $k = $this->_lcsPos($y); |
| 213 | | | assert($k > 0); |
| 214 | | | $ymids[$k] = $ymids[$k - 1]; |
| 215 | | | } |
| 216 | | | } |
| 217 | | | } |
| 218 | | | } |
| 219 | | | |
| 220 | | | $seps[] = $flip ? array($yoff, $xoff) : array($xoff, $yoff); |
| 221 | | | $ymid = $ymids[$this->lcs]; |
| 222 | | | for ($n = 0; $n < $nchunks - 1; $n++) { |
| 223 | | | $x1 = $xoff + (int)(($numer + ($xlim - $xoff) * $n) / $nchunks); |
| 224 | | | $y1 = $ymid[$n] + 1; |
| 225 | | | $seps[] = $flip ? array($y1, $x1) : array($x1, $y1); |
| 226 | | | } |
| 227 | | | $seps[] = $flip ? array($ylim, $xlim) : array($xlim, $ylim); |
| 228 | | | |
| 229 | | | return array($this->lcs, $seps); |
| 230 | | | } |
| 231 | | | |
| 232 | | | function _lcsPos($ypos) |
| 233 | | | { |
| 234 | | | $end = $this->lcs; |
| 235 | | | if ($end == 0 || $ypos > $this->seq[$end]) { |
| 236 | | | $this->seq[++$this->lcs] = $ypos; |
| 237 | | | $this->in_seq[$ypos] = 1; |
| 238 | | | return $this->lcs; |
| 239 | | | } |
| 240 | | | |
| 241 | | | $beg = 1; |
| 242 | | | while ($beg < $end) { |
| 243 | | | $mid = (int)(($beg + $end) / 2); |
| 244 | | | if ($ypos > $this->seq[$mid]) { |
| 245 | | | $beg = $mid + 1; |
| 246 | | | } else { |
| 247 | | | $end = $mid; |
| 248 | | | } |
| 249 | | | } |
| 250 | | | |
| 251 | | | assert($ypos != $this->seq[$end]); |
| 252 | | | |
| 253 | | | $this->in_seq[$this->seq[$end]] = false; |
| 254 | | | $this->seq[$end] = $ypos; |
| 255 | | | $this->in_seq[$ypos] = 1; |
| 256 | | | return $end; |
| 257 | | | } |
| 258 | | | |
| 259 | | | /** |
| 260 | | | * Finds LCS of two sequences. |
| 261 | | | * |
| 262 | | | * The results are recorded in the vectors $this->{x,y}changed[], by |
| 263 | | | * storing a 1 in the element for each line that is an insertion or |
| 264 | | | * deletion (ie. is not in the LCS). |
| 265 | | | * |
| 266 | | | * The subsequence of file 0 is (XOFF, XLIM) and likewise for file 1. |
| 267 | | | * |
| 268 | | | * Note that XLIM, YLIM are exclusive bounds. All line numbers are |
| 269 | | | * origin-0 and discarded lines are not counted. |
| 270 | | | */ |
| 271 | | | function _compareseq ($xoff, $xlim, $yoff, $ylim) |
| 272 | | | { |
| 273 | | | /* Slide down the bottom initial diagonal. */ |
| 274 | | | while ($xoff < $xlim && $yoff < $ylim |
| 275 | | | && $this->xv[$xoff] == $this->yv[$yoff]) { |
| 276 | | | ++$xoff; |
| 277 | | | ++$yoff; |
| 278 | | | } |
| 279 | | | |
| 280 | | | /* Slide up the top initial diagonal. */ |
| 281 | | | while ($xlim > $xoff && $ylim > $yoff |
| 282 | | | && $this->xv[$xlim - 1] == $this->yv[$ylim - 1]) { |
| 283 | | | --$xlim; |
| 284 | | | --$ylim; |
| 285 | | | } |
| 286 | | | |
| 287 | | | if ($xoff == $xlim || $yoff == $ylim) { |
| 288 | | | $lcs = 0; |
| 289 | | | } else { |
| 290 | | | /* This is ad hoc but seems to work well. $nchunks = |
| 291 | | | * sqrt(min($xlim - $xoff, $ylim - $yoff) / 2.5); $nchunks = |
| 292 | | | * max(2,min(8,(int)$nchunks)); */ |
| 293 | | | $nchunks = min(7, $xlim - $xoff, $ylim - $yoff) + 1; |
| 294 | | | list($lcs, $seps) |
| 295 | | | = $this->_diag($xoff, $xlim, $yoff, $ylim, $nchunks); |
| 296 | | | } |
| 297 | | | |
| 298 | | | if ($lcs == 0) { |
| 299 | | | /* X and Y sequences have no common subsequence: mark all |
| 300 | | | * changed. */ |
| 301 | | | while ($yoff < $ylim) { |
| 302 | | | $this->ychanged[$this->yind[$yoff++]] = 1; |
| 303 | | | } |
| 304 | | | while ($xoff < $xlim) { |
| 305 | | | $this->xchanged[$this->xind[$xoff++]] = 1; |
| 306 | | | } |
| 307 | | | } else { |
| 308 | | | /* Use the partitions to split this problem into subproblems. */ |
| 309 | | | reset($seps); |
| 310 | | | $pt1 = $seps[0]; |
| 311 | | | while ($pt2 = next($seps)) { |
| 312 | | | $this->_compareseq ($pt1[0], $pt2[0], $pt1[1], $pt2[1]); |
| 313 | | | $pt1 = $pt2; |
| 314 | | | } |
| 315 | | | } |
| 316 | | | } |
| 317 | | | |
| 318 | | | /** |
| 319 | | | * Adjusts inserts/deletes of identical lines to join changes as much as |
| 320 | | | * possible. |
| 321 | | | * |
| 322 | | | * We do something when a run of changed lines include a line at one end |
| 323 | | | * and has an excluded, identical line at the other. We are free to |
| 324 | | | * choose which identical line is included. `compareseq' usually chooses |
| 325 | | | * the one at the beginning, but usually it is cleaner to consider the |
| 326 | | | * following identical line to be the "change". |
| 327 | | | * |
| 328 | | | * This is extracted verbatim from analyze.c (GNU diffutils-2.7). |
| 329 | | | */ |
| 330 | | | function _shiftBoundaries($lines, &$changed, $other_changed) |
| 331 | | | { |
| 332 | | | $i = 0; |
| 333 | | | $j = 0; |
| 334 | | | |
| 335 | | | assert('count($lines) == count($changed)'); |
| 336 | | | $len = count($lines); |
| 337 | | | $other_len = count($other_changed); |
| 338 | | | |
| 339 | | | while (1) { |
| 340 | | | /* Scan forward to find the beginning of another run of |
| 341 | | | * changes. Also keep track of the corresponding point in the |
| 342 | | | * other file. |
| 343 | | | * |
| 344 | | | * Throughout this code, $i and $j are adjusted together so that |
| 345 | | | * the first $i elements of $changed and the first $j elements of |
| 346 | | | * $other_changed both contain the same number of zeros (unchanged |
| 347 | | | * lines). |
| 348 | | | * |
| 349 | | | * Furthermore, $j is always kept so that $j == $other_len or |
| 350 | | | * $other_changed[$j] == false. */ |
| 351 | | | while ($j < $other_len && $other_changed[$j]) { |
| 352 | | | $j++; |
| 353 | | | } |
| 354 | | | |
| 355 | | | while ($i < $len && ! $changed[$i]) { |
| 356 | | | assert('$j < $other_len && ! $other_changed[$j]'); |
| 357 | | | $i++; $j++; |
| 358 | | | while ($j < $other_len && $other_changed[$j]) { |
| 359 | | | $j++; |
| 360 | | | } |
| 361 | | | } |
| 362 | | | |
| 363 | | | if ($i == $len) { |
| 364 | | | break; |
| 365 | | | } |
| 366 | | | |
| 367 | | | $start = $i; |
| 368 | | | |
| 369 | | | /* Find the end of this run of changes. */ |
| 370 | | | while (++$i < $len && $changed[$i]) { |
| 371 | | | continue; |
| 372 | | | } |
| 373 | | | |
| 374 | | | do { |
| 375 | | | /* Record the length of this run of changes, so that we can |
| 376 | | | * later determine whether the run has grown. */ |
| 377 | | | $runlength = $i - $start; |
| 378 | | | |
| 379 | | | /* Move the changed region back, so long as the previous |
| 380 | | | * unchanged line matches the last changed one. This merges |
| 381 | | | * with previous changed regions. */ |
| 382 | | | while ($start > 0 && $lines[$start - 1] == $lines[$i - 1]) { |
| 383 | | | $changed[--$start] = 1; |
| 384 | | | $changed[--$i] = false; |
| 385 | | | while ($start > 0 && $changed[$start - 1]) { |
| 386 | | | $start--; |
| 387 | | | } |
| 388 | | | assert('$j > 0'); |
| 389 | | | while ($other_changed[--$j]) { |
| 390 | | | continue; |
| 391 | | | } |
| 392 | | | assert('$j >= 0 && !$other_changed[$j]'); |
| 393 | | | } |
| 394 | | | |
| 395 | | | /* Set CORRESPONDING to the end of the changed run, at the |
| 396 | | | * last point where it corresponds to a changed run in the |
| 397 | | | * other file. CORRESPONDING == LEN means no such point has |
| 398 | | | * been found. */ |
| 399 | | | $corresponding = $j < $other_len ? $i : $len; |
| 400 | | | |
| 401 | | | /* Move the changed region forward, so long as the first |
| 402 | | | * changed line matches the following unchanged one. This |
| 403 | | | * merges with following changed regions. Do this second, so |
| 404 | | | * that if there are no merges, the changed region is moved |
| 405 | | | * forward as far as possible. */ |
| 406 | | | while ($i < $len && $lines[$start] == $lines[$i]) { |
| 407 | | | $changed[$start++] = false; |
| 408 | | | $changed[$i++] = 1; |
| 409 | | | while ($i < $len && $changed[$i]) { |
| 410 | | | $i++; |
| 411 | | | } |
| 412 | | | |
| 413 | | | assert('$j < $other_len && ! $other_changed[$j]'); |
| 414 | | | $j++; |
| 415 | | | if ($j < $other_len && $other_changed[$j]) { |
| 416 | | | $corresponding = $i; |
| 417 | | | while ($j < $other_len && $other_changed[$j]) { |
| 418 | | | $j++; |
| 419 | | | } |
| 420 | | | } |
| 421 | | | } |
| 422 | | | } while ($runlength != $i - $start); |
| 423 | | | |
| 424 | | | /* If possible, move the fully-merged run of changes back to a |
| 425 | | | * corresponding run in the other file. */ |
| 426 | | | while ($corresponding < $i) { |
| 427 | | | $changed[--$start] = 1; |
| 428 | | | $changed[--$i] = 0; |
| 429 | | | assert('$j > 0'); |
| 430 | | | while ($other_changed[--$j]) { |
| 431 | | | continue; |
| 432 | | | } |
| 433 | | | assert('$j >= 0 && !$other_changed[$j]'); |
| 434 | | | } |
| 435 | | | } |
| 436 | | | } |
| 437 | | | |
| 438 | | | } |
