Verzeichnisstruktur phpBB-3.1.0
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engine.php
001 <?php
002 /**
003 *
004 * This file is part of the phpBB Forum Software package.
005 *
006 * @copyright (c) phpBB Limited <https://www.phpbb.com>
007 * @license GNU General Public License, version 2 (GPL-2.0)
008 *
009 * For full copyright and license information, please see
010 * the docs/CREDITS.txt file.
011 *
012 */
013
014 /**
015 * @ignore
016 */
017 if (!defined('IN_PHPBB'))
018 {
019 exit;
020 }
021
022 /**
023 * Code from pear.php.net, Text_Diff-1.1.0 package
024 * http://pear.php.net/package/Text_Diff/ (native engine)
025 *
026 * Modified by phpBB Limited to meet our coding standards
027 * and being able to integrate into phpBB
028 *
029 * Class used internally by Text_Diff to actually compute the diffs. This
030 * class is implemented using native PHP code.
031 *
032 * The algorithm used here is mostly lifted from the perl module
033 * Algorithm::Diff (version 1.06) by Ned Konz, which is available at:
034 * http://www.perl.com/CPAN/authors/id/N/NE/NEDKONZ/Algorithm-Diff-1.06.zip
035 *
036 * More ideas are taken from: http://www.ics.uci.edu/~eppstein/161/960229.html
037 *
038 * Some ideas (and a bit of code) are taken from analyze.c, of GNU
039 * diffutils-2.7, which can be found at:
040 * ftp://gnudist.gnu.org/pub/gnu/diffutils/diffutils-2.7.tar.gz
041 *
042 * Some ideas (subdivision by NCHUNKS > 2, and some optimizations) are from
043 * Geoffrey T. Dairiki <dairiki@dairiki.org>. The original PHP version of this
044 * code was written by him, and is used/adapted with his permission.
045 *
046 * Copyright 2004-2008 The Horde Project (http://www.horde.org/)
047 *
048 * @author Geoffrey T. Dairiki <dairiki@dairiki.org>
049 * @package diff
050 *
051 * @access private
052 */
053 class diff_engine
054 {
055 /**
056 * If set to true we trim all lines before we compare them. This ensures that sole space/tab changes do not trigger diffs.
057 */
058 var $skip_whitespace_changes = true;
059
060 function diff(&$from_lines, &$to_lines, $preserve_cr = true)
061 {
062 // Remove empty lines...
063 // If preserve_cr is true, we basically only change \r\n and bare \r to \n to get the same carriage returns for both files
064 // If it is false, we try to only use \n once per line and ommit all empty lines to be able to get a proper data diff
065
066 if (is_array($from_lines))
067 {
068 $from_lines = implode("\n", $from_lines);
069 }
070
071 if (is_array($to_lines))
072 {
073 $to_lines = implode("\n", $to_lines);
074 }
075
076 if ($preserve_cr)
077 {
078 $from_lines = explode("\n", str_replace("\r", "\n", str_replace("\r\n", "\n", $from_lines)));
079 $to_lines = explode("\n", str_replace("\r", "\n", str_replace("\r\n", "\n", $to_lines)));
080 }
081 else
082 {
083 $from_lines = explode("\n", preg_replace('#[\n\r]+#', "\n", $from_lines));
084 $to_lines = explode("\n", preg_replace('#[\n\r]+#', "\n", $to_lines));
085 }
086
087 $n_from = sizeof($from_lines);
088 $n_to = sizeof($to_lines);
089
090 $this->xchanged = $this->ychanged = $this->xv = $this->yv = $this->xind = $this->yind = array();
091 unset($this->seq, $this->in_seq, $this->lcs);
092
093 // Skip leading common lines.
094 for ($skip = 0; $skip < $n_from && $skip < $n_to; $skip++)
095 {
096 if (trim($from_lines[$skip]) !== trim($to_lines[$skip]))
097 {
098 break;
099 }
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 $this->_compareseq(0, sizeof($this->xv), 0, sizeof($this->yv));
149
150 // Merge edits when possible.
151 if ($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 (list(, $y) = each($matches))
289 {
290 if (empty($this->in_seq[$y]))
291 {
292 $k = $this->_lcs_pos($y);
293 $ymids[$k] = $ymids[$k - 1];
294 break;
295 }
296 }
297
298 // no reset() here
299 while (list(, $y) = each($matches))
300 {
301 if ($y > $this->seq[$k - 1])
302 {
303 // Optimization: this is a common case: next match is just replacing previous match.
304 $this->in_seq[$this->seq[$k]] = false;
305 $this->seq[$k] = $y;
306 $this->in_seq[$y] = 1;
307 }
308 else if (empty($this->in_seq[$y]))
309 {
310 $k = $this->_lcs_pos($y);
311 $ymids[$k] = $ymids[$k - 1];
312 }
313 }
314 }
315 }
316
317 $seps[] = $flip ? array($yoff, $xoff) : array($xoff, $yoff);
318 $ymid = $ymids[$this->lcs];
319
320 for ($n = 0; $n < $nchunks - 1; $n++)
321 {
322 $x1 = $xoff + (int)(($numer + ($xlim - $xoff) * $n) / $nchunks);
323 $y1 = $ymid[$n] + 1;
324 $seps[] = $flip ? array($y1, $x1) : array($x1, $y1);
325 }
326 $seps[] = $flip ? array($ylim, $xlim) : array($xlim, $ylim);
327
328 return array($this->lcs, $seps);
329 }
330
331 function _lcs_pos($ypos)
332 {
333 $end = $this->lcs;
334
335 if ($end == 0 || $ypos > $this->seq[$end])
336 {
337 $this->seq[++$this->lcs] = $ypos;
338 $this->in_seq[$ypos] = 1;
339 return $this->lcs;
340 }
341
342 $beg = 1;
343 while ($beg < $end)
344 {
345 $mid = (int)(($beg + $end) / 2);
346 if ($ypos > $this->seq[$mid])
347 {
348 $beg = $mid + 1;
349 }
350 else
351 {
352 $end = $mid;
353 }
354 }
355
356 $this->in_seq[$this->seq[$end]] = false;
357 $this->seq[$end] = $ypos;
358 $this->in_seq[$ypos] = 1;
359
360 return $end;
361 }
362
363 /**
364 * Finds LCS of two sequences.
365 *
366 * The results are recorded in the vectors $this->{x,y}changed[], by
367 * storing a 1 in the element for each line that is an insertion or
368 * deletion (ie. is not in the LCS).
369 *
370 * The subsequence of file 0 is (XOFF, XLIM) and likewise for file 1.
371 *
372 * Note that XLIM, YLIM are exclusive bounds. All line numbers are
373 * origin-0 and discarded lines are not counted.
374 */
375 function _compareseq($xoff, $xlim, $yoff, $ylim)
376 {
377 // Slide down the bottom initial diagonal.
378 while ($xoff < $xlim && $yoff < $ylim && $this->xv[$xoff] == $this->yv[$yoff])
379 {
380 ++$xoff;
381 ++$yoff;
382 }
383
384 // Slide up the top initial diagonal.
385 while ($xlim > $xoff && $ylim > $yoff && $this->xv[$xlim - 1] == $this->yv[$ylim - 1])
386 {
387 --$xlim;
388 --$ylim;
389 }
390
391 if ($xoff == $xlim || $yoff == $ylim)
392 {
393 $lcs = 0;
394 }
395 else
396 {
397 // This is ad hoc but seems to work well.
398 // $nchunks = sqrt(min($xlim - $xoff, $ylim - $yoff) / 2.5);
399 // $nchunks = max(2,min(8,(int)$nchunks));
400 $nchunks = min(7, $xlim - $xoff, $ylim - $yoff) + 1;
401 list($lcs, $seps) = $this->_diag($xoff, $xlim, $yoff, $ylim, $nchunks);
402 }
403
404 if ($lcs == 0)
405 {
406 // X and Y sequences have no common subsequence: mark all changed.
407 while ($yoff < $ylim)
408 {
409 $this->ychanged[$this->yind[$yoff++]] = 1;
410 }
411
412 while ($xoff < $xlim)
413 {
414 $this->xchanged[$this->xind[$xoff++]] = 1;
415 }
416 }
417 else
418 {
419 // Use the partitions to split this problem into subproblems.
420 reset($seps);
421 $pt1 = $seps[0];
422
423 while ($pt2 = next($seps))
424 {
425 $this->_compareseq($pt1[0], $pt2[0], $pt1[1], $pt2[1]);
426 $pt1 = $pt2;
427 }
428 }
429 }
430
431 /**
432 * Adjusts inserts/deletes of identical lines to join changes as much as possible.
433 *
434 * We do something when a run of changed lines include a line at one end
435 * and has an excluded, identical line at the other. We are free to
436 * choose which identical line is included. 'compareseq' usually chooses
437 * the one at the beginning, but usually it is cleaner to consider the
438 * following identical line to be the "change".
439 *
440 * This is extracted verbatim from analyze.c (GNU diffutils-2.7).
441 */
442 function _shift_boundaries($lines, &$changed, $other_changed)
443 {
444 $i = 0;
445 $j = 0;
446
447 $len = sizeof($lines);
448 $other_len = sizeof($other_changed);
449
450 while (1)
451 {
452 // Scan forward to find the beginning of another run of
453 // changes. Also keep track of the corresponding point in the other file.
454 //
455 // Throughout this code, $i and $j are adjusted together so that
456 // the first $i elements of $changed and the first $j elements of
457 // $other_changed both contain the same number of zeros (unchanged lines).
458 //
459 // Furthermore, $j is always kept so that $j == $other_len or $other_changed[$j] == false.
460 while ($j < $other_len && $other_changed[$j])
461 {
462 $j++;
463 }
464
465 while ($i < $len && ! $changed[$i])
466 {
467 $i++;
468 $j++;
469
470 while ($j < $other_len && $other_changed[$j])
471 {
472 $j++;
473 }
474 }
475
476 if ($i == $len)
477 {
478 break;
479 }
480
481 $start = $i;
482
483 // Find the end of this run of changes.
484 while (++$i < $len && $changed[$i])
485 {
486 continue;
487 }
488
489 do
490 {
491 // Record the length of this run of changes, so that we can later determine whether the run has grown.
492 $runlength = $i - $start;
493
494 // Move the changed region back, so long as the previous unchanged line matches the last changed one.
495 // This merges with previous changed regions.
496 while ($start > 0 && $lines[$start - 1] == $lines[$i - 1])
497 {
498 $changed[--$start] = 1;
499 $changed[--$i] = false;
500
501 while ($start > 0 && $changed[$start - 1])
502 {
503 $start--;
504 }
505
506 while ($other_changed[--$j])
507 {
508 continue;
509 }
510 }
511
512 // Set CORRESPONDING to the end of the changed run, at the last point where it corresponds to a changed run in the
513 // other file. CORRESPONDING == LEN means no such point has been found.
514 $corresponding = $j < $other_len ? $i : $len;
515
516 // Move the changed region forward, so long as the first changed line matches the following unchanged one.
517 // This merges with following changed regions.
518 // Do this second, so that if there are no merges, the changed region is moved forward as far as possible.
519 while ($i < $len && $lines[$start] == $lines[$i])
520 {
521 $changed[$start++] = false;
522 $changed[$i++] = 1;
523
524 while ($i < $len && $changed[$i])
525 {
526 $i++;
527 }
528
529 $j++;
530 if ($j < $other_len && $other_changed[$j])
531 {
532 $corresponding = $i;
533 while ($j < $other_len && $other_changed[$j])
534 {
535 $j++;
536 }
537 }
538 }
539 }
540 while ($runlength != $i - $start);
541
542 // If possible, move the fully-merged run of changes back to a corresponding run in the other file.
543 while ($corresponding < $i)
544 {
545 $changed[--$start] = 1;
546 $changed[--$i] = 0;
547
548 while ($other_changed[--$j])
549 {
550 continue;
551 }
552 }
553 }
554 }
555 }
556