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| <?php | |
| /** | |
| * @file | |
| * Contains \Drupal\Component\Diff\Engine\DiffEngine. | |
| */ | |
| namespace Drupal\Component\Diff\Engine; | |
| use Drupal\Component\Utility\Unicode; | |
| /** | |
| * Class used internally by Diff to actually compute the diffs. | |
| * | |
| * The algorithm used here is mostly lifted from the perl module | |
| * Algorithm::Diff (version 1.06) by Ned Konz, which is available at: | |
| * http://www.perl.com/CPAN/authors/id/N/NE/NEDKONZ/Algorithm-Diff-1.06.zip | |
| * | |
| * More ideas are taken from: | |
| * http://www.ics.uci.edu/~eppstein/161/960229.html | |
| * | |
| * Some ideas (and a bit of code) are from analyze.c, from GNU | |
| * diffutils-2.7, which can be found at: | |
| * ftp://gnudist.gnu.org/pub/gnu/diffutils/diffutils-2.7.tar.gz | |
| * | |
| * closingly, some ideas (subdivision by NCHUNKS > 2, and some optimizations) | |
| * are my own. | |
| * | |
| * Line length limits for robustness added by Tim Starling, 2005-08-31 | |
| * | |
| * @author Geoffrey T. Dairiki, Tim Starling | |
| * @private | |
| * @subpackage DifferenceEngine | |
| */ | |
| class DiffEngine { | |
| const USE_ASSERTS = FALSE; | |
| const MAX_XREF_LENGTH = 10000; | |
| public function diff($from_lines, $to_lines) { | |
| $n_from = sizeof($from_lines); | |
| $n_to = sizeof($to_lines); | |
| $this->xchanged = $this->ychanged = array(); | |
| $this->xv = $this->yv = array(); | |
| $this->xind = $this->yind = array(); | |
| unset($this->seq); | |
| unset($this->in_seq); | |
| unset($this->lcs); | |
| // Skip leading common lines. | |
| for ($skip = 0; $skip < $n_from && $skip < $n_to; $skip++) { | |
| if ($from_lines[$skip] !== $to_lines[$skip]) { | |
| break; | |
| } | |
| $this->xchanged[$skip] = $this->ychanged[$skip] = FALSE; | |
| } | |
| // Skip trailing common lines. | |
| $xi = $n_from; | |
| $yi = $n_to; | |
| for ($endskip = 0; --$xi > $skip && --$yi > $skip; $endskip++) { | |
| if ($from_lines[$xi] !== $to_lines[$yi]) { | |
| break; | |
| } | |
| $this->xchanged[$xi] = $this->ychanged[$yi] = FALSE; | |
| } | |
| // Ignore lines which do not exist in both files. | |
| for ($xi = $skip; $xi < $n_from - $endskip; $xi++) { | |
| $xhash[$this->_line_hash($from_lines[$xi])] = 1; | |
| } | |
| for ($yi = $skip; $yi < $n_to - $endskip; $yi++) { | |
| $line = $to_lines[$yi]; | |
| if ($this->ychanged[$yi] = empty($xhash[$this->_line_hash($line)])) { | |
| continue; | |
| } | |
| $yhash[$this->_line_hash($line)] = 1; | |
| $this->yv[] = $line; | |
| $this->yind[] = $yi; | |
| } | |
| for ($xi = $skip; $xi < $n_from - $endskip; $xi++) { | |
| $line = $from_lines[$xi]; | |
| if ($this->xchanged[$xi] = empty($yhash[$this->_line_hash($line)])) { | |
| continue; | |
| } | |
| $this->xv[] = $line; | |
| $this->xind[] = $xi; | |
| } | |
| // Find the LCS. | |
| $this->_compareseq(0, sizeof($this->xv), 0, sizeof($this->yv)); | |
| // Merge edits when possible | |
| $this->_shift_boundaries($from_lines, $this->xchanged, $this->ychanged); | |
| $this->_shift_boundaries($to_lines, $this->ychanged, $this->xchanged); | |
| // Compute the edit operations. | |
| $edits = array(); | |
| $xi = $yi = 0; | |
| while ($xi < $n_from || $yi < $n_to) { | |
| $this::USE_ASSERTS && assert($yi < $n_to || $this->xchanged[$xi]); | |
| $this::USE_ASSERTS && assert($xi < $n_from || $this->ychanged[$yi]); | |
| // Skip matching "snake". | |
| $copy = array(); | |
| while ( $xi < $n_from && $yi < $n_to && !$this->xchanged[$xi] && !$this->ychanged[$yi]) { | |
| $copy[] = $from_lines[$xi++]; | |
| ++$yi; | |
| } | |
| if ($copy) { | |
| $edits[] = new DiffOpCopy($copy); | |
| } | |
| // Find deletes & adds. | |
| $delete = array(); | |
| while ($xi < $n_from && $this->xchanged[$xi]) { | |
| $delete[] = $from_lines[$xi++]; | |
| } | |
| $add = array(); | |
| while ($yi < $n_to && $this->ychanged[$yi]) { | |
| $add[] = $to_lines[$yi++]; | |
| } | |
| if ($delete && $add) { | |
| $edits[] = new DiffOpChange($delete, $add); | |
| } | |
| elseif ($delete) { | |
| $edits[] = new DiffOpDelete($delete); | |
| } | |
| elseif ($add) { | |
| $edits[] = new DiffOpAdd($add); | |
| } | |
| } | |
| return $edits; | |
| } | |
| /** | |
| * Returns the whole line if it's small enough, or the MD5 hash otherwise. | |
| */ | |
| protected function _line_hash($line) { | |
| if (Unicode::strlen($line) > $this::MAX_XREF_LENGTH) { | |
| return md5($line); | |
| } | |
| else { | |
| return $line; | |
| } | |
| } | |
| /** | |
| * Divide the Largest Common Subsequence (LCS) of the sequences | |
| * [XOFF, XLIM) and [YOFF, YLIM) into NCHUNKS approximately equally | |
| * sized segments. | |
| * | |
| * Returns (LCS, PTS). LCS is the length of the LCS. PTS is an | |
| * array of NCHUNKS+1 (X, Y) indexes giving the diving points between | |
| * sub sequences. The first sub-sequence is contained in [X0, X1), | |
| * [Y0, Y1), the second in [X1, X2), [Y1, Y2) and so on. Note | |
| * that (X0, Y0) == (XOFF, YOFF) and | |
| * (X[NCHUNKS], Y[NCHUNKS]) == (XLIM, YLIM). | |
| * | |
| * This function assumes that the first lines of the specified portions | |
| * of the two files do not match, and likewise that the last lines do not | |
| * match. The caller must trim matching lines from the beginning and end | |
| * of the portions it is going to specify. | |
| */ | |
| protected function _diag($xoff, $xlim, $yoff, $ylim, $nchunks) { | |
| $flip = FALSE; | |
| if ($xlim - $xoff > $ylim - $yoff) { | |
| // Things seems faster (I'm not sure I understand why) | |
| // when the shortest sequence in X. | |
| $flip = TRUE; | |
| list($xoff, $xlim, $yoff, $ylim) = array($yoff, $ylim, $xoff, $xlim); | |
| } | |
| if ($flip) { | |
| for ($i = $ylim - 1; $i >= $yoff; $i--) { | |
| $ymatches[$this->xv[$i]][] = $i; | |
| } | |
| } | |
| else { | |
| for ($i = $ylim - 1; $i >= $yoff; $i--) { | |
| $ymatches[$this->yv[$i]][] = $i; | |
| } | |
| } | |
| $this->lcs = 0; | |
| $this->seq[0]= $yoff - 1; | |
| $this->in_seq = array(); | |
| $ymids[0] = array(); | |
| $numer = $xlim - $xoff + $nchunks - 1; | |
| $x = $xoff; | |
| for ($chunk = 0; $chunk < $nchunks; $chunk++) { | |
| if ($chunk > 0) { | |
| for ($i = 0; $i <= $this->lcs; $i++) { | |
| $ymids[$i][$chunk-1] = $this->seq[$i]; | |
| } | |
| } | |
| $x1 = $xoff + (int)(($numer + ($xlim-$xoff)*$chunk) / $nchunks); | |
| for ( ; $x < $x1; $x++) { | |
| $line = $flip ? $this->yv[$x] : $this->xv[$x]; | |
| if (empty($ymatches[$line])) { | |
| continue; | |
| } | |
| $matches = $ymatches[$line]; | |
| reset($matches); | |
| while (list ($junk, $y) = each($matches)) { | |
| if (empty($this->in_seq[$y])) { | |
| $k = $this->_lcs_pos($y); | |
| $this::USE_ASSERTS && assert($k > 0); | |
| $ymids[$k] = $ymids[$k-1]; | |
| break; | |
| } | |
| } | |
| while (list ($junk, $y) = each($matches)) { | |
| if ($y > $this->seq[$k-1]) { | |
| $this::USE_ASSERTS && assert($y < $this->seq[$k]); | |
| // Optimization: this is a common case: | |
| // next match is just replacing previous match. | |
| $this->in_seq[$this->seq[$k]] = FALSE; | |
| $this->seq[$k] = $y; | |
| $this->in_seq[$y] = 1; | |
| } | |
| elseif (empty($this->in_seq[$y])) { | |
| $k = $this->_lcs_pos($y); | |
| $this::USE_ASSERTS && assert($k > 0); | |
| $ymids[$k] = $ymids[$k-1]; | |
| } | |
| } | |
| } | |
| } | |
| $seps[] = $flip ? array($yoff, $xoff) : array($xoff, $yoff); | |
| $ymid = $ymids[$this->lcs]; | |
| for ($n = 0; $n < $nchunks - 1; $n++) { | |
| $x1 = $xoff + (int)(($numer + ($xlim - $xoff) * $n) / $nchunks); | |
| $y1 = $ymid[$n] + 1; | |
| $seps[] = $flip ? array($y1, $x1) : array($x1, $y1); | |
| } | |
| $seps[] = $flip ? array($ylim, $xlim) : array($xlim, $ylim); | |
| return array($this->lcs, $seps); | |
| } | |
| protected function _lcs_pos($ypos) { | |
| $end = $this->lcs; | |
| if ($end == 0 || $ypos > $this->seq[$end]) { | |
| $this->seq[++$this->lcs] = $ypos; | |
| $this->in_seq[$ypos] = 1; | |
| return $this->lcs; | |
| } | |
| $beg = 1; | |
| while ($beg < $end) { | |
| $mid = (int)(($beg + $end) / 2); | |
| if ($ypos > $this->seq[$mid]) { | |
| $beg = $mid + 1; | |
| } | |
| else { | |
| $end = $mid; | |
| } | |
| } | |
| $this::USE_ASSERTS && assert($ypos != $this->seq[$end]); | |
| $this->in_seq[$this->seq[$end]] = FALSE; | |
| $this->seq[$end] = $ypos; | |
| $this->in_seq[$ypos] = 1; | |
| return $end; | |
| } | |
| /** | |
| * Find LCS of two sequences. | |
| * | |
| * The results are recorded in the vectors $this->{x,y}changed[], by | |
| * storing a 1 in the element for each line that is an insertion | |
| * or deletion (ie. is not in the LCS). | |
| * | |
| * The subsequence of file 0 is [XOFF, XLIM) and likewise for file 1. | |
| * | |
| * Note that XLIM, YLIM are exclusive bounds. | |
| * All line numbers are origin-0 and discarded lines are not counted. | |
| */ | |
| protected function _compareseq($xoff, $xlim, $yoff, $ylim) { | |
| // Slide down the bottom initial diagonal. | |
| while ($xoff < $xlim && $yoff < $ylim && $this->xv[$xoff] == $this->yv[$yoff]) { | |
| ++$xoff; | |
| ++$yoff; | |
| } | |
| // Slide up the top initial diagonal. | |
| while ($xlim > $xoff && $ylim > $yoff && $this->xv[$xlim - 1] == $this->yv[$ylim - 1]) { | |
| --$xlim; | |
| --$ylim; | |
| } | |
| if ($xoff == $xlim || $yoff == $ylim) { | |
| $lcs = 0; | |
| } | |
| else { | |
| // This is ad hoc but seems to work well. | |
| //$nchunks = sqrt(min($xlim - $xoff, $ylim - $yoff) / 2.5); | |
| //$nchunks = max(2, min(8, (int)$nchunks)); | |
| $nchunks = min(7, $xlim - $xoff, $ylim - $yoff) + 1; | |
| list($lcs, $seps) | |
| = $this->_diag($xoff, $xlim, $yoff, $ylim, $nchunks); | |
| } | |
| if ($lcs == 0) { | |
| // X and Y sequences have no common subsequence: | |
| // mark all changed. | |
| while ($yoff < $ylim) { | |
| $this->ychanged[$this->yind[$yoff++]] = 1; | |
| } | |
| while ($xoff < $xlim) { | |
| $this->xchanged[$this->xind[$xoff++]] = 1; | |
| } | |
| } | |
| else { | |
| // Use the partitions to split this problem into subproblems. | |
| reset($seps); | |
| $pt1 = $seps[0]; | |
| while ($pt2 = next($seps)) { | |
| $this->_compareseq ($pt1[0], $pt2[0], $pt1[1], $pt2[1]); | |
| $pt1 = $pt2; | |
| } | |
| } | |
| } | |
| /** | |
| * Adjust inserts/deletes of identical lines to join changes | |
| * as much as possible. | |
| * | |
| * We do something when a run of changed lines include a | |
| * line at one end and has an excluded, identical line at the other. | |
| * We are free to choose which identical line is included. | |
| * `compareseq' usually chooses the one at the beginning, | |
| * but usually it is cleaner to consider the following identical line | |
| * to be the "change". | |
| * | |
| * This is extracted verbatim from analyze.c (GNU diffutils-2.7). | |
| */ | |
| protected function _shift_boundaries($lines, &$changed, $other_changed) { | |
| $i = 0; | |
| $j = 0; | |
| $this::USE_ASSERTS && assert('sizeof($lines) == sizeof($changed)'); | |
| $len = sizeof($lines); | |
| $other_len = sizeof($other_changed); | |
| while (1) { | |
| /* | |
| * Scan forwards to find beginning of another run of changes. | |
| * Also keep track of the corresponding point in the other file. | |
| * | |
| * Throughout this code, $i and $j are adjusted together so that | |
| * the first $i elements of $changed and the first $j elements | |
| * of $other_changed both contain the same number of zeros | |
| * (unchanged lines). | |
| * Furthermore, $j is always kept so that $j == $other_len or | |
| * $other_changed[$j] == FALSE. | |
| */ | |
| while ($j < $other_len && $other_changed[$j]) { | |
| $j++; | |
| } | |
| while ($i < $len && ! $changed[$i]) { | |
| $this::USE_ASSERTS && assert('$j < $other_len && ! $other_changed[$j]'); | |
| $i++; | |
| $j++; | |
| while ($j < $other_len && $other_changed[$j]) { | |
| $j++; | |
| } | |
| } | |
| if ($i == $len) { | |
| break; | |
| } | |
| $start = $i; | |
| // Find the end of this run of changes. | |
| while (++$i < $len && $changed[$i]) { | |
| continue; | |
| } | |
| do { | |
| /* | |
| * Record the length of this run of changes, so that | |
| * we can later determine whether the run has grown. | |
| */ | |
| $runlength = $i - $start; | |
| /* | |
| * Move the changed region back, so long as the | |
| * previous unchanged line matches the last changed one. | |
| * This merges with previous changed regions. | |
| */ | |
| while ($start > 0 && $lines[$start - 1] == $lines[$i - 1]) { | |
| $changed[--$start] = 1; | |
| $changed[--$i] = FALSE; | |
| while ($start > 0 && $changed[$start - 1]) { | |
| $start--; | |
| } | |
| $this::USE_ASSERTS && assert('$j > 0'); | |
| while ($other_changed[--$j]) { | |
| continue; | |
| } | |
| $this::USE_ASSERTS && assert('$j >= 0 && !$other_changed[$j]'); | |
| } | |
| /* | |
| * Set CORRESPONDING to the end of the changed run, at the last | |
| * point where it corresponds to a changed run in the other file. | |
| * CORRESPONDING == LEN means no such point has been found. | |
| */ | |
| $corresponding = $j < $other_len ? $i : $len; | |
| /* | |
| * Move the changed region forward, so long as the | |
| * first changed line matches the following unchanged one. | |
| * This merges with following changed regions. | |
| * Do this second, so that if there are no merges, | |
| * the changed region is moved forward as far as possible. | |
| */ | |
| while ($i < $len && $lines[$start] == $lines[$i]) { | |
| $changed[$start++] = FALSE; | |
| $changed[$i++] = 1; | |
| while ($i < $len && $changed[$i]) { | |
| $i++; | |
| } | |
| $this::USE_ASSERTS && assert('$j < $other_len && ! $other_changed[$j]'); | |
| $j++; | |
| if ($j < $other_len && $other_changed[$j]) { | |
| $corresponding = $i; | |
| while ($j < $other_len && $other_changed[$j]) { | |
| $j++; | |
| } | |
| } | |
| } | |
| } while ($runlength != $i - $start); | |
| /* | |
| * If possible, move the fully-merged run of changes | |
| * back to a corresponding run in the other file. | |
| */ | |
| while ($corresponding < $i) { | |
| $changed[--$start] = 1; | |
| $changed[--$i] = 0; | |
| $this::USE_ASSERTS && assert('$j > 0'); | |
| while ($other_changed[--$j]) { | |
| continue; | |
| } | |
| $this::USE_ASSERTS && assert('$j >= 0 && !$other_changed[$j]'); | |
| } | |
| } | |
| } | |
| } |