1 <?php
2 /**
3  * A PHP diff engine for phpwiki. (Taken from phpwiki-1.3.3)
4  *
5  * Additions by Axel Boldt for MediaWiki
6  *
7  * @copyright (C) 2000, 2001 Geoffrey T. Dairiki <dairiki@dairiki.org>
8  * @license  You may copy this code freely under the conditions of the GPL.
9  */
10 define('USE_ASSERTS', function_exists('assert'));
11 
12 class _DiffOp {
13     var $type;
14     var $orig;
15     var $closing;
16 
17     /**
18      * @return _DiffOp
19      */
20     function reverse() {
21         throw new \RuntimeException("pure virtual");
22     }
23 
24     function norig() {
25         return $this->orig ? count($this->orig) : 0;
26     }
27 
28     function nclosing() {
29         return $this->closing ? count($this->closing) : 0;
30     }
31 }
32 
33 class _DiffOp_Copy extends _DiffOp {
34     var $type = 'copy';
35 
36     function __construct($orig, $closing = false) {
37         if (!is_array($closing))
38             $closing = $orig;
39         $this->orig = $orig;
40         $this->closing = $closing;
41     }
42 
43     function reverse() {
44         return new _DiffOp_Copy($this->closing, $this->orig);
45     }
46 }
47 
48 class _DiffOp_Delete extends _DiffOp {
49     var $type = 'delete';
50 
51     function __construct($lines) {
52         $this->orig = $lines;
53         $this->closing = false;
54     }
55 
56     function reverse() {
57         return new _DiffOp_Add($this->orig);
58     }
59 }
60 
61 class _DiffOp_Add extends _DiffOp {
62     var $type = 'add';
63 
64     function __construct($lines) {
65         $this->closing = $lines;
66         $this->orig = false;
67     }
68 
69     function reverse() {
70         return new _DiffOp_Delete($this->closing);
71     }
72 }
73 
74 class _DiffOp_Change extends _DiffOp {
75     var $type = 'change';
76 
77     function __construct($orig, $closing) {
78         $this->orig = $orig;
79         $this->closing = $closing;
80     }
81 
82     function reverse() {
83         return new _DiffOp_Change($this->closing, $this->orig);
84     }
85 }
86 
87 
88 /**
89  * Class used internally by Diff to actually compute the diffs.
90  *
91  * The algorithm used here is mostly lifted from the perl module
92  * Algorithm::Diff (version 1.06) by Ned Konz, which is available at:
93  *   http://www.perl.com/CPAN/authors/id/N/NE/NEDKONZ/Algorithm-Diff-1.06.zip
94  *
95  * More ideas are taken from:
96  *   http://www.ics.uci.edu/~eppstein/161/960229.html
97  *
98  * Some ideas are (and a bit of code) are from from analyze.c, from GNU
99  * diffutils-2.7, which can be found at:
100  *   ftp://gnudist.gnu.org/pub/gnu/diffutils/diffutils-2.7.tar.gz
101  *
102  * closingly, some ideas (subdivision by NCHUNKS > 2, and some optimizations)
103  * are my own.
104  *
105  * @author Geoffrey T. Dairiki
106  * @access private
107  */
108 class _DiffEngine {
109 
110     var $xchanged = array();
111     var $ychanged = array();
112     var $xv = array();
113     var $yv = array();
114     var $xind = array();
115     var $yind = array();
116     var $seq;
117     var $in_seq;
118     var $lcs;
119 
120     /**
121      * @param array $from_lines
122      * @param array $to_lines
123      * @return _DiffOp[]
124      */
125     function diff($from_lines, $to_lines) {
126         $n_from = count($from_lines);
127         $n_to = count($to_lines);
128 
129         $this->xchanged = $this->ychanged = array();
130         $this->xv = $this->yv = array();
131         $this->xind = $this->yind = array();
132         unset($this->seq);
133         unset($this->in_seq);
134         unset($this->lcs);
135 
136         // Skip leading common lines.
137         for ($skip = 0; $skip < $n_from && $skip < $n_to; $skip++) {
138             if ($from_lines[$skip] != $to_lines[$skip])
139                 break;
140             $this->xchanged[$skip] = $this->ychanged[$skip] = false;
141         }
142         // Skip trailing common lines.
143         $xi = $n_from;
144         $yi = $n_to;
145         for ($endskip = 0; --$xi > $skip && --$yi > $skip; $endskip++) {
146             if ($from_lines[$xi] != $to_lines[$yi])
147                 break;
148             $this->xchanged[$xi] = $this->ychanged[$yi] = false;
149         }
150 
151         // Ignore lines which do not exist in both files.
152         for ($xi = $skip; $xi < $n_from - $endskip; $xi++)
153             $xhash[$from_lines[$xi]] = 1;
154         for ($yi = $skip; $yi < $n_to - $endskip; $yi++) {
155             $line = $to_lines[$yi];
156             if (($this->ychanged[$yi] = empty($xhash[$line])))
157                 continue;
158             $yhash[$line] = 1;
159             $this->yv[] = $line;
160             $this->yind[] = $yi;
161         }
162         for ($xi = $skip; $xi < $n_from - $endskip; $xi++) {
163             $line = $from_lines[$xi];
164             if (($this->xchanged[$xi] = empty($yhash[$line])))
165                 continue;
166             $this->xv[] = $line;
167             $this->xind[] = $xi;
168         }
169 
170         // Find the LCS.
171         $this->_compareseq(0, count($this->xv), 0, count($this->yv));
172 
173         // Merge edits when possible
174         $this->_shift_boundaries($from_lines, $this->xchanged, $this->ychanged);
175         $this->_shift_boundaries($to_lines, $this->ychanged, $this->xchanged);
176 
177         // Compute the edit operations.
178         $edits = array();
179         $xi = $yi = 0;
180         while ($xi < $n_from || $yi < $n_to) {
181             USE_ASSERTS && assert($yi < $n_to || $this->xchanged[$xi]);
182             USE_ASSERTS && assert($xi < $n_from || $this->ychanged[$yi]);
183 
184             // Skip matching "snake".
185             $copy = array();
186             while ($xi < $n_from && $yi < $n_to && !$this->xchanged[$xi] && !$this->ychanged[$yi]) {
187                 $copy[] = $from_lines[$xi++];
188                 ++$yi;
189             }
190             if ($copy)
191                 $edits[] = new _DiffOp_Copy($copy);
192 
193             // Find deletes & adds.
194             $delete = array();
195             while ($xi < $n_from && $this->xchanged[$xi])
196                 $delete[] = $from_lines[$xi++];
197 
198             $add = array();
199             while ($yi < $n_to && $this->ychanged[$yi])
200                 $add[] = $to_lines[$yi++];
201 
202             if ($delete && $add)
203                 $edits[] = new _DiffOp_Change($delete, $add);
204             elseif ($delete)
205                 $edits[] = new _DiffOp_Delete($delete);
206             elseif ($add)
207                 $edits[] = new _DiffOp_Add($add);
208         }
209         return $edits;
210     }
211 
212 
213     /**
214      * Divide the Largest Common Subsequence (LCS) of the sequences
215      * [XOFF, XLIM) and [YOFF, YLIM) into NCHUNKS approximately equally
216      * sized segments.
217      *
218      * Returns (LCS, PTS).  LCS is the length of the LCS. PTS is an
219      * array of NCHUNKS+1 (X, Y) indexes giving the diving points between
220      * sub sequences.  The first sub-sequence is contained in [X0, X1),
221      * [Y0, Y1), the second in [X1, X2), [Y1, Y2) and so on.  Note
222      * that (X0, Y0) == (XOFF, YOFF) and
223      * (X[NCHUNKS], Y[NCHUNKS]) == (XLIM, YLIM).
224      *
225      * This function assumes that the first lines of the specified portions
226      * of the two files do not match, and likewise that the last lines do not
227      * match.  The caller must trim matching lines from the beginning and end
228      * of the portions it is going to specify.
229      *
230      * @param integer $xoff
231      * @param integer $xlim
232      * @param integer $yoff
233      * @param integer $ylim
234      * @param integer $nchunks
235      *
236      * @return array
237      */
238     function _diag($xoff, $xlim, $yoff, $ylim, $nchunks) {
239         $flip = false;
240 
241         if ($xlim - $xoff > $ylim - $yoff) {
242             // Things seems faster (I'm not sure I understand why)
243             // when the shortest sequence in X.
244             $flip = true;
245             list ($xoff, $xlim, $yoff, $ylim) = array($yoff, $ylim, $xoff, $xlim);
246         }
247 
248         if ($flip)
249             for ($i = $ylim - 1; $i >= $yoff; $i--)
250                 $ymatches[$this->xv[$i]][] = $i;
251         else
252             for ($i = $ylim - 1; $i >= $yoff; $i--)
253                 $ymatches[$this->yv[$i]][] = $i;
254 
255         $this->lcs = 0;
256         $this->seq[0]= $yoff - 1;
257         $this->in_seq = array();
258         $ymids[0] = array();
259 
260         $numer = $xlim - $xoff + $nchunks - 1;
261         $x = $xoff;
262         for ($chunk = 0; $chunk < $nchunks; $chunk++) {
263             if ($chunk > 0)
264                 for ($i = 0; $i <= $this->lcs; $i++)
265                     $ymids[$i][$chunk-1] = $this->seq[$i];
266 
267             $x1 = $xoff + (int)(($numer + ($xlim-$xoff)*$chunk) / $nchunks);
268             for ( ; $x < $x1; $x++) {
269                 $line = $flip ? $this->yv[$x] : $this->xv[$x];
270                 if (empty($ymatches[$line]))
271                     continue;
272                 $matches = $ymatches[$line];
273                 $switch = false;
274                 foreach ($matches as $y) {
275                     if ($switch && $y > $this->seq[$k-1]) {
276                         USE_ASSERTS && assert($y < $this->seq[$k]);
277                         // Optimization: this is a common case:
278                         //  next match is just replacing previous match.
279                         $this->in_seq[$this->seq[$k]] = false;
280                         $this->seq[$k] = $y;
281                         $this->in_seq[$y] = 1;
282                     }
283                     else if (empty($this->in_seq[$y])) {
284                         $k = $this->_lcs_pos($y);
285                         USE_ASSERTS && assert($k > 0);
286                         $ymids[$k] = $ymids[$k-1];
287                         $switch = true;
288                     }
289                 }
290             }
291         }
292 
293         $seps[] = $flip ? array($yoff, $xoff) : array($xoff, $yoff);
294         $ymid = $ymids[$this->lcs];
295         for ($n = 0; $n < $nchunks - 1; $n++) {
296             $x1 = $xoff + (int)(($numer + ($xlim - $xoff) * $n) / $nchunks);
297             $y1 = $ymid[$n] + 1;
298             $seps[] = $flip ? array($y1, $x1) : array($x1, $y1);
299         }
300         $seps[] = $flip ? array($ylim, $xlim) : array($xlim, $ylim);
301 
302         return array($this->lcs, $seps);
303     }
304 
305     function _lcs_pos($ypos) {
306         $end = $this->lcs;
307         if ($end == 0 || $ypos > $this->seq[$end]) {
308             $this->seq[++$this->lcs] = $ypos;
309             $this->in_seq[$ypos] = 1;
310             return $this->lcs;
311         }
312 
313         $beg = 1;
314         while ($beg < $end) {
315             $mid = (int)(($beg + $end) / 2);
316             if ($ypos > $this->seq[$mid])
317                 $beg = $mid + 1;
318             else
319                 $end = $mid;
320         }
321 
322         USE_ASSERTS && assert($ypos != $this->seq[$end]);
323 
324         $this->in_seq[$this->seq[$end]] = false;
325         $this->seq[$end] = $ypos;
326         $this->in_seq[$ypos] = 1;
327         return $end;
328     }
329 
330     /**
331      * Find LCS of two sequences.
332      *
333      * The results are recorded in the vectors $this->{x,y}changed[], by
334      * storing a 1 in the element for each line that is an insertion
335      * or deletion (ie. is not in the LCS).
336      *
337      * The subsequence of file 0 is [XOFF, XLIM) and likewise for file 1.
338      *
339      * Note that XLIM, YLIM are exclusive bounds.
340      * All line numbers are origin-0 and discarded lines are not counted.
341      *
342      * @param integer $xoff
343      * @param integer $xlim
344      * @param integer $yoff
345      * @param integer $ylim
346      */
347     function _compareseq($xoff, $xlim, $yoff, $ylim) {
348         // Slide down the bottom initial diagonal.
349         while ($xoff < $xlim && $yoff < $ylim && $this->xv[$xoff] == $this->yv[$yoff]) {
350             ++$xoff;
351             ++$yoff;
352         }
353 
354         // Slide up the top initial diagonal.
355         while ($xlim > $xoff && $ylim > $yoff && $this->xv[$xlim - 1] == $this->yv[$ylim - 1]) {
356             --$xlim;
357             --$ylim;
358         }
359 
360         if ($xoff == $xlim || $yoff == $ylim)
361             $lcs = 0;
362         else {
363             // This is ad hoc but seems to work well.
364             //$nchunks = sqrt(min($xlim - $xoff, $ylim - $yoff) / 2.5);
365             //$nchunks = max(2,min(8,(int)$nchunks));
366             $nchunks = min(7, $xlim - $xoff, $ylim - $yoff) + 1;
367             list ($lcs, $seps)
368                 = $this->_diag($xoff,$xlim,$yoff, $ylim,$nchunks);
369         }
370 
371         if ($lcs == 0) {
372             // X and Y sequences have no common subsequence:
373             // mark all changed.
374             while ($yoff < $ylim)
375                 $this->ychanged[$this->yind[$yoff++]] = 1;
376             while ($xoff < $xlim)
377                 $this->xchanged[$this->xind[$xoff++]] = 1;
378         }
379         else {
380             // Use the partitions to split this problem into subproblems.
381             reset($seps);
382             $pt1 = $seps[0];
383             while ($pt2 = next($seps)) {
384                 $this->_compareseq ($pt1[0], $pt2[0], $pt1[1], $pt2[1]);
385                 $pt1 = $pt2;
386             }
387         }
388     }
389 
390     /**
391      * Adjust inserts/deletes of identical lines to join changes
392      * as much as possible.
393      *
394      * We do something when a run of changed lines include a
395      * line at one end and has an excluded, identical line at the other.
396      * We are free to choose which identical line is included.
397      * `compareseq' usually chooses the one at the beginning,
398      * but usually it is cleaner to consider the following identical line
399      * to be the "change".
400      *
401      * This is extracted verbatim from analyze.c (GNU diffutils-2.7).
402      *
403      * @param array $lines
404      * @param array $changed
405      * @param array $other_changed
406      */
407     function _shift_boundaries($lines, &$changed, $other_changed) {
408         $i = 0;
409         $j = 0;
410 
411         USE_ASSERTS && assert(count($lines) == count($changed));
412         $len = count($lines);
413         $other_len = count($other_changed);
414 
415         while (1) {
416             /*
417              * Scan forwards to find beginning of another run of changes.
418              * Also keep track of the corresponding point in the other file.
419              *
420              * Throughout this code, $i and $j are adjusted together so that
421              * the first $i elements of $changed and the first $j elements
422              * of $other_changed both contain the same number of zeros
423              * (unchanged lines).
424              * Furthermore, $j is always kept so that $j == $other_len or
425              * $other_changed[$j] == false.
426              */
427             while ($j < $other_len && $other_changed[$j])
428                 $j++;
429 
430             while ($i < $len && ! $changed[$i]) {
431                 USE_ASSERTS && assert($j < $other_len && ! $other_changed[$j]);
432                 $i++;
433                 $j++;
434                 while ($j < $other_len && $other_changed[$j])
435                     $j++;
436             }
437 
438             if ($i == $len)
439                 break;
440 
441             $start = $i;
442 
443             // Find the end of this run of changes.
444             while (++$i < $len && $changed[$i])
445                 continue;
446 
447             do {
448                 /*
449                  * Record the length of this run of changes, so that
450                  * we can later determine whether the run has grown.
451                  */
452                 $runlength = $i - $start;
453 
454                 /*
455                  * Move the changed region back, so long as the
456                  * previous unchanged line matches the last changed one.
457                  * This merges with previous changed regions.
458                  */
459                 while ($start > 0 && $lines[$start - 1] == $lines[$i - 1]) {
460                     $changed[--$start] = 1;
461                     $changed[--$i] = false;
462                     while ($start > 0 && $changed[$start - 1])
463                         $start--;
464                     USE_ASSERTS && assert($j > 0);
465                     while ($other_changed[--$j])
466                         continue;
467                     USE_ASSERTS && assert($j >= 0 && !$other_changed[$j]);
468                 }
469 
470                 /*
471                  * Set CORRESPONDING to the end of the changed run, at the last
472                  * point where it corresponds to a changed run in the other file.
473                  * CORRESPONDING == LEN means no such point has been found.
474                  */
475                 $corresponding = $j < $other_len ? $i : $len;
476 
477                 /*
478                  * Move the changed region forward, so long as the
479                  * first changed line matches the following unchanged one.
480                  * This merges with following changed regions.
481                  * Do this second, so that if there are no merges,
482                  * the changed region is moved forward as far as possible.
483                  */
484                 while ($i < $len && $lines[$start] == $lines[$i]) {
485                     $changed[$start++] = false;
486                     $changed[$i++] = 1;
487                     while ($i < $len && $changed[$i])
488                         $i++;
489 
490                     USE_ASSERTS && assert($j < $other_len && ! $other_changed[$j]);
491                     $j++;
492                     if ($j < $other_len && $other_changed[$j]) {
493                         $corresponding = $i;
494                         while ($j < $other_len && $other_changed[$j])
495                             $j++;
496                     }
497                 }
498             } while ($runlength != $i - $start);
499 
500             /*
501              * If possible, move the fully-merged run of changes
502              * back to a corresponding run in the other file.
503              */
504             while ($corresponding < $i) {
505                 $changed[--$start] = 1;
506                 $changed[--$i] = 0;
507                 USE_ASSERTS && assert($j > 0);
508                 while ($other_changed[--$j])
509                     continue;
510                 USE_ASSERTS && assert($j >= 0 && !$other_changed[$j]);
511             }
512         }
513     }
514 }
515 
516 /**
517  * Class representing a 'diff' between two sequences of strings.
518  */
519 class Diff {
520 
521     var $edits;
522 
523     /**
524      * Constructor.
525      * Computes diff between sequences of strings.
526      *
527      * @param array $from_lines An array of strings.
528      *                          (Typically these are lines from a file.)
529      * @param array $to_lines   An array of strings.
530      */
531     function __construct($from_lines, $to_lines) {
532         $eng = new _DiffEngine;
533         $this->edits = $eng->diff($from_lines, $to_lines);
534         //$this->_check($from_lines, $to_lines);
535     }
536 
537     /**
538      * Compute reversed Diff.
539      *
540      * SYNOPSIS:
541      *
542      *  $diff = new Diff($lines1, $lines2);
543      *  $rev = $diff->reverse();
544      *
545      * @return Diff  A Diff object representing the inverse of the
546      *               original diff.
547      */
548     function reverse() {
549         $rev = $this;
550         $rev->edits = array();
551         foreach ($this->edits as $edit) {
552             $rev->edits[] = $edit->reverse();
553         }
554         return $rev;
555     }
556 
557     /**
558      * Check for empty diff.
559      *
560      * @return bool True iff two sequences were identical.
561      */
562     function isEmpty() {
563         foreach ($this->edits as $edit) {
564             if ($edit->type != 'copy')
565                 return false;
566         }
567         return true;
568     }
569 
570     /**
571      * Compute the length of the Longest Common Subsequence (LCS).
572      *
573      * This is mostly for diagnostic purposed.
574      *
575      * @return int The length of the LCS.
576      */
577     function lcs() {
578         $lcs = 0;
579         foreach ($this->edits as $edit) {
580             if ($edit->type == 'copy')
581                 $lcs += count($edit->orig);
582         }
583         return $lcs;
584     }
585 
586     /**
587      * Get the original set of lines.
588      *
589      * This reconstructs the $from_lines parameter passed to the
590      * constructor.
591      *
592      * @return array The original sequence of strings.
593      */
594     function orig() {
595         $lines = array();
596 
597         foreach ($this->edits as $edit) {
598             if ($edit->orig)
599                 array_splice($lines, count($lines), 0, $edit->orig);
600         }
601         return $lines;
602     }
603 
604     /**
605      * Get the closing set of lines.
606      *
607      * This reconstructs the $to_lines parameter passed to the
608      * constructor.
609      *
610      * @return array The sequence of strings.
611      */
612     function closing() {
613         $lines = array();
614 
615         foreach ($this->edits as $edit) {
616             if ($edit->closing)
617                 array_splice($lines, count($lines), 0, $edit->closing);
618         }
619         return $lines;
620     }
621 
622     /**
623      * Check a Diff for validity.
624      *
625      * This is here only for debugging purposes.
626      *
627      * @param mixed $from_lines
628      * @param mixed $to_lines
629      */
630     function _check($from_lines, $to_lines) {
631         if (serialize($from_lines) != serialize($this->orig()))
632             throw new \RuntimeException("Reconstructed original doesn't match");
633         if (serialize($to_lines) != serialize($this->closing()))
634             throw new \RuntimeException("Reconstructed closing doesn't match");
635 
636         $rev = $this->reverse();
637         if (serialize($to_lines) != serialize($rev->orig()))
638             throw new \RuntimeException("Reversed original doesn't match");
639         if (serialize($from_lines) != serialize($rev->closing()))
640             throw new \RuntimeException("Reversed closing doesn't match");
641 
642         $prevtype = 'none';
643         foreach ($this->edits as $edit) {
644             if ($prevtype == $edit->type)
645                 throw new \RuntimeException("Edit sequence is non-optimal");
646             $prevtype = $edit->type;
647         }
648 
649         $lcs = $this->lcs();
650         trigger_error("Diff okay: LCS = $lcs", E_USER_NOTICE);
651     }
652 }
653 
654 /**
655  * FIXME: bad name.
656  */
657 class MappedDiff extends Diff {
658     /**
659      * Constructor.
660      *
661      * Computes diff between sequences of strings.
662      *
663      * This can be used to compute things like
664      * case-insensitve diffs, or diffs which ignore
665      * changes in white-space.
666      *
667      * @param string[] $from_lines         An array of strings.
668      *                                     (Typically these are lines from a file.)
669      *
670      * @param string[] $to_lines           An array of strings.
671      *
672      * @param string[] $mapped_from_lines  This array should
673      *                                     have the same size number of elements as $from_lines.
674      *                                     The elements in $mapped_from_lines and
675      *                                     $mapped_to_lines are what is actually compared
676      *                                     when computing the diff.
677      *
678      * @param string[] $mapped_to_lines    This array should
679      *                                     have the same number of elements as $to_lines.
680      */
681     function __construct($from_lines, $to_lines, $mapped_from_lines, $mapped_to_lines) {
682 
683         assert(count($from_lines) == count($mapped_from_lines));
684         assert(count($to_lines) == count($mapped_to_lines));
685 
686         parent::__construct($mapped_from_lines, $mapped_to_lines);
687 
688         $xi = $yi = 0;
689         $ecnt = count($this->edits);
690         for ($i = 0; $i < $ecnt; $i++) {
691             $orig = &$this->edits[$i]->orig;
692             if (is_array($orig)) {
693                 $orig = array_slice($from_lines, $xi, count($orig));
694                 $xi += count($orig);
695             }
696 
697             $closing = &$this->edits[$i]->closing;
698             if (is_array($closing)) {
699                 $closing = array_slice($to_lines, $yi, count($closing));
700                 $yi += count($closing);
701             }
702         }
703     }
704 }
705 
706 /**
707  * A class to format Diffs
708  *
709  * This class formats the diff in classic diff format.
710  * It is intended that this class be customized via inheritance,
711  * to obtain fancier outputs.
712  */
713 class DiffFormatter {
714     /**
715      * Number of leading context "lines" to preserve.
716      *
717      * This should be left at zero for this class, but subclasses
718      * may want to set this to other values.
719      */
720     var $leading_context_lines = 0;
721 
722     /**
723      * Number of trailing context "lines" to preserve.
724      *
725      * This should be left at zero for this class, but subclasses
726      * may want to set this to other values.
727      */
728     var $trailing_context_lines = 0;
729 
730     /**
731      * Format a diff.
732      *
733      * @param Diff $diff A Diff object.
734      * @return string The formatted output.
735      */
736     function format($diff) {
737 
738         $xi = $yi = 1;
739         $x0 = $y0 = 0;
740         $block = false;
741         $context = array();
742 
743         $nlead = $this->leading_context_lines;
744         $ntrail = $this->trailing_context_lines;
745 
746         $this->_start_diff();
747 
748         foreach ($diff->edits as $edit) {
749             if ($edit->type == 'copy') {
750                 if (is_array($block)) {
751                     if (count($edit->orig) <= $nlead + $ntrail) {
752                         $block[] = $edit;
753                     }
754                     else{
755                         if ($ntrail) {
756                             $context = array_slice($edit->orig, 0, $ntrail);
757                             $block[] = new _DiffOp_Copy($context);
758                         }
759                         $this->_block($x0, $ntrail + $xi - $x0, $y0, $ntrail + $yi - $y0, $block);
760                         $block = false;
761                     }
762                 }
763                 $context = $edit->orig;
764             }
765             else {
766                 if (! is_array($block)) {
767                     $context = array_slice($context, count($context) - $nlead);
768                     $x0 = $xi - count($context);
769                     $y0 = $yi - count($context);
770                     $block = array();
771                     if ($context)
772                         $block[] = new _DiffOp_Copy($context);
773                 }
774                 $block[] = $edit;
775             }
776 
777             if ($edit->orig)
778                 $xi += count($edit->orig);
779             if ($edit->closing)
780                 $yi += count($edit->closing);
781         }
782 
783         if (is_array($block))
784             $this->_block($x0, $xi - $x0, $y0, $yi - $y0, $block);
785 
786         return $this->_end_diff();
787     }
788 
789     /**
790      * @param int $xbeg
791      * @param int $xlen
792      * @param int $ybeg
793      * @param int $ylen
794      * @param array $edits
795      */
796     function _block($xbeg, $xlen, $ybeg, $ylen, &$edits) {
797         $this->_start_block($this->_block_header($xbeg, $xlen, $ybeg, $ylen));
798         foreach ($edits as $edit) {
799             if ($edit->type == 'copy')
800                 $this->_context($edit->orig);
801             elseif ($edit->type == 'add')
802                 $this->_added($edit->closing);
803             elseif ($edit->type == 'delete')
804                 $this->_deleted($edit->orig);
805             elseif ($edit->type == 'change')
806                 $this->_changed($edit->orig, $edit->closing);
807             else
808                 throw new \RuntimeException("Unknown edit type");
809         }
810         $this->_end_block();
811     }
812 
813     function _start_diff() {
814         ob_start();
815     }
816 
817     function _end_diff() {
818         $val = ob_get_contents();
819         ob_end_clean();
820         return $val;
821     }
822 
823     /**
824      * @param int $xbeg
825      * @param int $xlen
826      * @param int $ybeg
827      * @param int $ylen
828      * @return string
829      */
830     function _block_header($xbeg, $xlen, $ybeg, $ylen) {
831         if ($xlen > 1)
832             $xbeg .= "," . ($xbeg + $xlen - 1);
833         if ($ylen > 1)
834             $ybeg .= "," . ($ybeg + $ylen - 1);
835 
836         return $xbeg . ($xlen ? ($ylen ? 'c' : 'd') : 'a') . $ybeg;
837     }
838 
839     /**
840      * @param string $header
841      */
842     function _start_block($header) {
843         echo $header;
844     }
845 
846     function _end_block() {
847     }
848 
849     function _lines($lines, $prefix = ' ') {
850         foreach ($lines as $line)
851             echo "$prefix ".$this->_escape($line)."\n";
852     }
853 
854     function _context($lines) {
855         $this->_lines($lines);
856     }
857 
858     function _added($lines) {
859         $this->_lines($lines, ">");
860     }
861     function _deleted($lines) {
862         $this->_lines($lines, "<");
863     }
864 
865     function _changed($orig, $closing) {
866         $this->_deleted($orig);
867         echo "---\n";
868         $this->_added($closing);
869     }
870 
871     /**
872      * Escape string
873      *
874      * Override this method within other formatters if escaping required.
875      * Base class requires $str to be returned WITHOUT escaping.
876      *
877      * @param $str string Text string to escape
878      * @return string The escaped string.
879      */
880     function _escape($str){
881         return $str;
882     }
883 }
884 
885 /**
886  * Utilityclass for styling HTML formatted diffs
887  *
888  * Depends on global var $DIFF_INLINESTYLES, if true some minimal predefined
889  * inline styles are used. Useful for HTML mails and RSS feeds
890  *
891  * @author Andreas Gohr <andi@splitbrain.org>
892  */
893 class HTMLDiff {
894     /**
895      * Holds the style names and basic CSS
896      */
897     static public $styles = array(
898             'diff-addedline'    => 'background-color: #ddffdd;',
899             'diff-deletedline'  => 'background-color: #ffdddd;',
900             'diff-context'      => 'background-color: #f5f5f5;',
901             'diff-mark'         => 'color: #ff0000;',
902         );
903 
904     /**
905      * Return a class or style parameter
906      *
907      * @param string $classname
908      *
909      * @return string
910      */
911     static function css($classname){
912         global $DIFF_INLINESTYLES;
913 
914         if($DIFF_INLINESTYLES){
915             if(!isset(self::$styles[$classname])) return '';
916             return 'style="'.self::$styles[$classname].'"';
917         }else{
918             return 'class="'.$classname.'"';
919         }
920     }
921 }
922 
923 /**
924  *  Additions by Axel Boldt follow, partly taken from diff.php, phpwiki-1.3.3
925  *
926  */
927 
928 define('NBSP', "\xC2\xA0");     // utf-8 non-breaking space.
929 
930 class _HWLDF_WordAccumulator {
931 
932     /** @var array */
933     protected $_lines;
934 
935     /** @var string */
936     protected $_line;
937 
938     /** @var string */
939     protected $_group;
940 
941     /** @var string */
942     protected $_tag;
943 
944     function __construct() {
945         $this->_lines = array();
946         $this->_line = '';
947         $this->_group = '';
948         $this->_tag = '';
949     }
950 
951     function _flushGroup($new_tag) {
952         if ($this->_group !== '') {
953             if ($this->_tag == 'mark')
954                 $this->_line .= '<strong '.HTMLDiff::css('diff-mark').'>'.$this->_escape($this->_group).'</strong>';
955             elseif ($this->_tag == 'add')
956                 $this->_line .= '<span '.HTMLDiff::css('diff-addedline').'>'.$this->_escape($this->_group).'</span>';
957             elseif ($this->_tag == 'del')
958                 $this->_line .= '<span '.HTMLDiff::css('diff-deletedline').'><del>'.$this->_escape($this->_group).'</del></span>';
959             else
960                 $this->_line .= $this->_escape($this->_group);
961         }
962         $this->_group = '';
963         $this->_tag = $new_tag;
964     }
965 
966     /**
967      * @param string $new_tag
968      */
969     function _flushLine($new_tag) {
970         $this->_flushGroup($new_tag);
971         if ($this->_line != '')
972             $this->_lines[] = $this->_line;
973         $this->_line = '';
974     }
975 
976     function addWords($words, $tag = '') {
977         if ($tag != $this->_tag)
978             $this->_flushGroup($tag);
979 
980         foreach ($words as $word) {
981             // new-line should only come as first char of word.
982             if ($word == '')
983                 continue;
984             if ($word[0] == "\n") {
985                 $this->_group .= NBSP;
986                 $this->_flushLine($tag);
987                 $word = substr($word, 1);
988             }
989             assert(!strstr($word, "\n"));
990             $this->_group .= $word;
991         }
992     }
993 
994     function getLines() {
995         $this->_flushLine('~done');
996         return $this->_lines;
997     }
998 
999     function _escape($str){
1000         return hsc($str);
1001     }
1002 }
1003 
1004 class WordLevelDiff extends MappedDiff {
1005 
1006     function __construct($orig_lines, $closing_lines) {
1007         list ($orig_words, $orig_stripped) = $this->_split($orig_lines);
1008         list ($closing_words, $closing_stripped) = $this->_split($closing_lines);
1009 
1010         parent::__construct($orig_words, $closing_words, $orig_stripped, $closing_stripped);
1011     }
1012 
1013     function _split($lines) {
1014         if (!preg_match_all('/ ( [^\S\n]+ | [0-9_A-Za-z\x80-\xff]+ | . ) (?: (?!< \n) [^\S\n])? /xsu',
1015              implode("\n", $lines), $m)) {
1016             return array(array(''), array(''));
1017         }
1018         return array($m[0], $m[1]);
1019     }
1020 
1021     function orig() {
1022         $orig = new _HWLDF_WordAccumulator;
1023 
1024         foreach ($this->edits as $edit) {
1025             if ($edit->type == 'copy')
1026                 $orig->addWords($edit->orig);
1027             elseif ($edit->orig)
1028                 $orig->addWords($edit->orig, 'mark');
1029         }
1030         return $orig->getLines();
1031     }
1032 
1033     function closing() {
1034         $closing = new _HWLDF_WordAccumulator;
1035 
1036         foreach ($this->edits as $edit) {
1037             if ($edit->type == 'copy')
1038                 $closing->addWords($edit->closing);
1039             elseif ($edit->closing)
1040                 $closing->addWords($edit->closing, 'mark');
1041         }
1042         return $closing->getLines();
1043     }
1044 }
1045 
1046 class InlineWordLevelDiff extends MappedDiff {
1047 
1048     function __construct($orig_lines, $closing_lines) {
1049         list ($orig_words, $orig_stripped) = $this->_split($orig_lines);
1050         list ($closing_words, $closing_stripped) = $this->_split($closing_lines);
1051 
1052         parent::__construct($orig_words, $closing_words, $orig_stripped, $closing_stripped);
1053     }
1054 
1055     function _split($lines) {
1056         if (!preg_match_all('/ ( [^\S\n]+ | [0-9_A-Za-z\x80-\xff]+ | . ) (?: (?!< \n) [^\S\n])? /xsu',
1057              implode("\n", $lines), $m)) {
1058             return array(array(''), array(''));
1059         }
1060         return array($m[0], $m[1]);
1061     }
1062 
1063     function inline() {
1064         $orig = new _HWLDF_WordAccumulator;
1065         foreach ($this->edits as $edit) {
1066             if ($edit->type == 'copy')
1067                 $orig->addWords($edit->closing);
1068             elseif ($edit->type == 'change'){
1069                 $orig->addWords($edit->orig, 'del');
1070                 $orig->addWords($edit->closing, 'add');
1071             } elseif ($edit->type == 'delete')
1072                 $orig->addWords($edit->orig, 'del');
1073             elseif ($edit->type == 'add')
1074                 $orig->addWords($edit->closing, 'add');
1075             elseif ($edit->orig)
1076                 $orig->addWords($edit->orig, 'del');
1077         }
1078         return $orig->getLines();
1079     }
1080 }
1081 
1082 /**
1083  * "Unified" diff formatter.
1084  *
1085  * This class formats the diff in classic "unified diff" format.
1086  *
1087  * NOTE: output is plain text and unsafe for use in HTML without escaping.
1088  */
1089 class UnifiedDiffFormatter extends DiffFormatter {
1090 
1091     function __construct($context_lines = 4) {
1092         $this->leading_context_lines = $context_lines;
1093         $this->trailing_context_lines = $context_lines;
1094     }
1095 
1096     function _block_header($xbeg, $xlen, $ybeg, $ylen) {
1097         if ($xlen != 1)
1098             $xbeg .= "," . $xlen;
1099         if ($ylen != 1)
1100             $ybeg .= "," . $ylen;
1101         return "@@ -$xbeg +$ybeg @@\n";
1102     }
1103 
1104     function _added($lines) {
1105         $this->_lines($lines, "+");
1106     }
1107     function _deleted($lines) {
1108         $this->_lines($lines, "-");
1109     }
1110     function _changed($orig, $final) {
1111         $this->_deleted($orig);
1112         $this->_added($final);
1113     }
1114 }
1115 
1116 /**
1117  *  Wikipedia Table style diff formatter.
1118  *
1119  */
1120 class TableDiffFormatter extends DiffFormatter {
1121     var $colspan = 2;
1122 
1123     function __construct() {
1124         $this->leading_context_lines = 2;
1125         $this->trailing_context_lines = 2;
1126     }
1127 
1128     /**
1129      * @param Diff $diff
1130      * @return string
1131      */
1132     function format($diff) {
1133         // Preserve whitespaces by converting some to non-breaking spaces.
1134         // Do not convert all of them to allow word-wrap.
1135         $val = parent::format($diff);
1136         $val = str_replace('  ','&#160; ', $val);
1137         $val = preg_replace('/ (?=<)|(?<=[ >]) /', '&#160;', $val);
1138         return $val;
1139     }
1140 
1141     function _pre($text){
1142         $text = htmlspecialchars($text);
1143         return $text;
1144     }
1145 
1146     function _block_header($xbeg, $xlen, $ybeg, $ylen) {
1147         global $lang;
1148         $l1 = $lang['line'].' '.$xbeg;
1149         $l2 = $lang['line'].' '.$ybeg;
1150         $r = '<tr><td '.HTMLDiff::css('diff-blockheader').' colspan="'.$this->colspan.'">'.$l1.":</td>\n".
1151              '<td '.HTMLDiff::css('diff-blockheader').' colspan="'.$this->colspan.'">'.$l2.":</td>\n".
1152              "</tr>\n";
1153         return $r;
1154     }
1155 
1156     function _start_block($header) {
1157         print($header);
1158     }
1159 
1160     function _end_block() {
1161     }
1162 
1163     function _lines($lines, $prefix=' ', $color="white") {
1164     }
1165 
1166     function addedLine($line,$escaped=false) {
1167         if (!$escaped){
1168             $line = $this->_escape($line);
1169         }
1170         return '<td '.HTMLDiff::css('diff-lineheader').'>+</td>'.
1171                '<td '.HTMLDiff::css('diff-addedline').'>' .  $line.'</td>';
1172     }
1173 
1174     function deletedLine($line,$escaped=false) {
1175         if (!$escaped){
1176             $line = $this->_escape($line);
1177         }
1178         return '<td '.HTMLDiff::css('diff-lineheader').'>-</td>'.
1179                '<td '.HTMLDiff::css('diff-deletedline').'>' .  $line.'</td>';
1180     }
1181 
1182     function emptyLine() {
1183         return '<td colspan="'.$this->colspan.'">&#160;</td>';
1184     }
1185 
1186     function contextLine($line) {
1187         return '<td '.HTMLDiff::css('diff-lineheader').'>&#160;</td>'.
1188                '<td '.HTMLDiff::css('diff-context').'>'.$this->_escape($line).'</td>';
1189     }
1190 
1191     function _added($lines) {
1192         $this->_addedLines($lines,false);
1193     }
1194 
1195     function _addedLines($lines,$escaped=false){
1196         foreach ($lines as $line) {
1197             print('<tr>' . $this->emptyLine() . $this->addedLine($line,$escaped) . "</tr>\n");
1198         }
1199     }
1200 
1201     function _deleted($lines) {
1202         foreach ($lines as $line) {
1203             print('<tr>' . $this->deletedLine($line) . $this->emptyLine() . "</tr>\n");
1204         }
1205     }
1206 
1207     function _context($lines) {
1208         foreach ($lines as $line) {
1209             print('<tr>' . $this->contextLine($line) .  $this->contextLine($line) . "</tr>\n");
1210         }
1211     }
1212 
1213     function _changed($orig, $closing) {
1214         $diff = new WordLevelDiff($orig, $closing);  // this escapes the diff data
1215         $del = $diff->orig();
1216         $add = $diff->closing();
1217 
1218         while ($line = array_shift($del)) {
1219             $aline = array_shift($add);
1220             print('<tr>' . $this->deletedLine($line,true) . $this->addedLine($aline,true) . "</tr>\n");
1221         }
1222         $this->_addedLines($add,true); # If any leftovers
1223     }
1224 
1225     function _escape($str) {
1226         return hsc($str);
1227     }
1228 }
1229 
1230 /**
1231  *  Inline style diff formatter.
1232  *
1233  */
1234 class InlineDiffFormatter extends DiffFormatter {
1235     var $colspan = 2;
1236 
1237     function __construct() {
1238         $this->leading_context_lines = 2;
1239         $this->trailing_context_lines = 2;
1240     }
1241 
1242     /**
1243      * @param Diff $diff
1244      * @return string
1245      */
1246     function format($diff) {
1247         // Preserve whitespaces by converting some to non-breaking spaces.
1248         // Do not convert all of them to allow word-wrap.
1249         $val = parent::format($diff);
1250         $val = str_replace('  ','&#160; ', $val);
1251         $val = preg_replace('/ (?=<)|(?<=[ >]) /', '&#160;', $val);
1252         return $val;
1253     }
1254 
1255     function _pre($text){
1256         $text = htmlspecialchars($text);
1257         return $text;
1258     }
1259 
1260     function _block_header($xbeg, $xlen, $ybeg, $ylen) {
1261         global $lang;
1262         if ($xlen != 1)
1263             $xbeg .= "," . $xlen;
1264         if ($ylen != 1)
1265             $ybeg .= "," . $ylen;
1266         $r = '<tr><td colspan="'.$this->colspan.'" '.HTMLDiff::css('diff-blockheader').'>@@ '.$lang['line']." -$xbeg +$ybeg @@";
1267         $r .= ' <span '.HTMLDiff::css('diff-deletedline').'><del>'.$lang['deleted'].'</del></span>';
1268         $r .= ' <span '.HTMLDiff::css('diff-addedline').'>'.$lang['created'].'</span>';
1269         $r .= "</td></tr>\n";
1270         return $r;
1271     }
1272 
1273     function _start_block($header) {
1274         print($header."\n");
1275     }
1276 
1277     function _end_block() {
1278     }
1279 
1280     function _lines($lines, $prefix=' ', $color="white") {
1281     }
1282 
1283     function _added($lines) {
1284         foreach ($lines as $line) {
1285             print('<tr><td '.HTMLDiff::css('diff-lineheader').'>&#160;</td><td '.HTMLDiff::css('diff-addedline').'>'. $this->_escape($line) . "</td></tr>\n");
1286         }
1287     }
1288 
1289     function _deleted($lines) {
1290         foreach ($lines as $line) {
1291             print('<tr><td '.HTMLDiff::css('diff-lineheader').'>&#160;</td><td '.HTMLDiff::css('diff-deletedline').'><del>' . $this->_escape($line) . "</del></td></tr>\n");
1292         }
1293     }
1294 
1295     function _context($lines) {
1296         foreach ($lines as $line) {
1297             print('<tr><td '.HTMLDiff::css('diff-lineheader').'>&#160;</td><td '.HTMLDiff::css('diff-context').'>'. $this->_escape($line) ."</td></tr>\n");
1298         }
1299     }
1300 
1301     function _changed($orig, $closing) {
1302         $diff = new InlineWordLevelDiff($orig, $closing);  // this escapes the diff data
1303         $add = $diff->inline();
1304 
1305         foreach ($add as $line)
1306             print('<tr><td '.HTMLDiff::css('diff-lineheader').'>&#160;</td><td>'.$line."</td></tr>\n");
1307     }
1308 
1309     function _escape($str) {
1310         return hsc($str);
1311     }
1312 }
1313 
1314 /**
1315  * A class for computing three way diffs.
1316  *
1317  * @author  Geoffrey T. Dairiki <dairiki@dairiki.org>
1318  */
1319 class Diff3 extends Diff {
1320 
1321     /**
1322      * Conflict counter.
1323      *
1324      * @var integer
1325      */
1326     var $_conflictingBlocks = 0;
1327 
1328     /**
1329      * Computes diff between 3 sequences of strings.
1330      *
1331      * @param array $orig    The original lines to use.
1332      * @param array $final1  The first version to compare to.
1333      * @param array $final2  The second version to compare to.
1334      */
1335     function __construct($orig, $final1, $final2) {
1336         $engine = new _DiffEngine();
1337 
1338         $this->_edits = $this->_diff3($engine->diff($orig, $final1),
1339                                       $engine->diff($orig, $final2));
1340     }
1341 
1342     /**
1343      * Returns the merged lines
1344      *
1345      * @param string $label1  label for first version
1346      * @param string $label2  label for second version
1347      * @param string $label3  separator between versions
1348      * @return array          lines of the merged text
1349      */
1350     function mergedOutput($label1='<<<<<<<',$label2='>>>>>>>',$label3='=======') {
1351         $lines = array();
1352         foreach ($this->_edits as $edit) {
1353             if ($edit->isConflict()) {
1354                 /* FIXME: this should probably be moved somewhere else. */
1355                 $lines = array_merge($lines,
1356                                      array($label1),
1357                                      $edit->final1,
1358                                      array($label3),
1359                                      $edit->final2,
1360                                      array($label2));
1361                 $this->_conflictingBlocks++;
1362             } else {
1363                 $lines = array_merge($lines, $edit->merged());
1364             }
1365         }
1366 
1367         return $lines;
1368     }
1369 
1370     /**
1371      * @access private
1372      *
1373      * @param array $edits1
1374      * @param array $edits2
1375      *
1376      * @return array
1377      */
1378     function _diff3($edits1, $edits2) {
1379         $edits = array();
1380         $bb = new _Diff3_BlockBuilder();
1381 
1382         $e1 = current($edits1);
1383         $e2 = current($edits2);
1384         while ($e1 || $e2) {
1385             if ($e1 && $e2 && is_a($e1, '_DiffOp_copy') && is_a($e2, '_DiffOp_copy')) {
1386                 /* We have copy blocks from both diffs. This is the (only)
1387                  * time we want to emit a diff3 copy block.  Flush current
1388                  * diff3 diff block, if any. */
1389                 if ($edit = $bb->finish()) {
1390                     $edits[] = $edit;
1391                 }
1392 
1393                 $ncopy = min($e1->norig(), $e2->norig());
1394                 assert($ncopy > 0);
1395                 $edits[] = new _Diff3_Op_copy(array_slice($e1->orig, 0, $ncopy));
1396 
1397                 if ($e1->norig() > $ncopy) {
1398                     array_splice($e1->orig, 0, $ncopy);
1399                     array_splice($e1->closing, 0, $ncopy);
1400                 } else {
1401                     $e1 = next($edits1);
1402                 }
1403 
1404                 if ($e2->norig() > $ncopy) {
1405                     array_splice($e2->orig, 0, $ncopy);
1406                     array_splice($e2->closing, 0, $ncopy);
1407                 } else {
1408                     $e2 = next($edits2);
1409                 }
1410             } else {
1411                 if ($e1 && $e2) {
1412                     if ($e1->orig && $e2->orig) {
1413                         $norig = min($e1->norig(), $e2->norig());
1414                         $orig = array_splice($e1->orig, 0, $norig);
1415                         array_splice($e2->orig, 0, $norig);
1416                         $bb->input($orig);
1417                     }
1418 
1419                     if (is_a($e1, '_DiffOp_copy')) {
1420                         $bb->out1(array_splice($e1->closing, 0, $norig));
1421                     }
1422 
1423                     if (is_a($e2, '_DiffOp_copy')) {
1424                         $bb->out2(array_splice($e2->closing, 0, $norig));
1425                     }
1426                 }
1427 
1428                 if ($e1 && ! $e1->orig) {
1429                     $bb->out1($e1->closing);
1430                     $e1 = next($edits1);
1431                 }
1432                 if ($e2 && ! $e2->orig) {
1433                     $bb->out2($e2->closing);
1434                     $e2 = next($edits2);
1435                 }
1436             }
1437         }
1438 
1439         if ($edit = $bb->finish()) {
1440             $edits[] = $edit;
1441         }
1442 
1443         return $edits;
1444     }
1445 }
1446 
1447 /**
1448  * @author  Geoffrey T. Dairiki <dairiki@dairiki.org>
1449  *
1450  * @access private
1451  */
1452 class _Diff3_Op {
1453 
1454     /** @var array|mixed */
1455     protected $orig;
1456 
1457     /** @var array|mixed */
1458     protected $final1;
1459 
1460     /** @var array|mixed */
1461     protected $final2;
1462 
1463     /** @var array|mixed|false */
1464     protected $_merged;
1465 
1466     function __construct($orig = false, $final1 = false, $final2 = false) {
1467         $this->orig = $orig ? $orig : array();
1468         $this->final1 = $final1 ? $final1 : array();
1469         $this->final2 = $final2 ? $final2 : array();
1470     }
1471 
1472     function merged() {
1473         if (!isset($this->_merged)) {
1474             if ($this->final1 === $this->final2) {
1475                 $this->_merged = &$this->final1;
1476             } elseif ($this->final1 === $this->orig) {
1477                 $this->_merged = &$this->final2;
1478             } elseif ($this->final2 === $this->orig) {
1479                 $this->_merged = &$this->final1;
1480             } else {
1481                 $this->_merged = false;
1482             }
1483         }
1484 
1485         return $this->_merged;
1486     }
1487 
1488     function isConflict() {
1489         return $this->merged() === false;
1490     }
1491 
1492 }
1493 
1494 /**
1495  * @author  Geoffrey T. Dairiki <dairiki@dairiki.org>
1496  *
1497  * @access private
1498  */
1499 class _Diff3_Op_copy extends _Diff3_Op {
1500 
1501     function __construct($lines = false) {
1502         $this->orig = $lines ? $lines : array();
1503         $this->final1 = &$this->orig;
1504         $this->final2 = &$this->orig;
1505     }
1506 
1507     function merged() {
1508         return $this->orig;
1509     }
1510 
1511     function isConflict() {
1512         return false;
1513     }
1514 }
1515 
1516 /**
1517  * @author  Geoffrey T. Dairiki <dairiki@dairiki.org>
1518  *
1519  * @access private
1520  */
1521 class _Diff3_BlockBuilder {
1522 
1523     function __construct() {
1524         $this->_init();
1525     }
1526 
1527     function input($lines) {
1528         if ($lines) {
1529             $this->_append($this->orig, $lines);
1530         }
1531     }
1532 
1533     function out1($lines) {
1534         if ($lines) {
1535             $this->_append($this->final1, $lines);
1536         }
1537     }
1538 
1539     function out2($lines) {
1540         if ($lines) {
1541             $this->_append($this->final2, $lines);
1542         }
1543     }
1544 
1545     function isEmpty() {
1546         return !$this->orig && !$this->final1 && !$this->final2;
1547     }
1548 
1549     function finish() {
1550         if ($this->isEmpty()) {
1551             return false;
1552         } else {
1553             $edit = new _Diff3_Op($this->orig, $this->final1, $this->final2);
1554             $this->_init();
1555             return $edit;
1556         }
1557     }
1558 
1559     function _init() {
1560         $this->orig = $this->final1 = $this->final2 = array();
1561     }
1562 
1563     function _append(&$array, $lines) {
1564         array_splice($array, sizeof($array), 0, $lines);
1565     }
1566 }
1567 
1568 //Setup VIM: ex: et ts=4 :
1569