--- /dev/null
+<?php
+
+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 = [];
+ $this->xv = $this->yv = [];
+ $this->xind = $this->yind = [];
+ unset($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 = [];
+ $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 = [];
+ 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.
+ $delete = [];
+ while ($xi < $n_from && $this->xchanged[$xi]) {
+ $delete[] = $from_lines[$xi++];
+ }
+ $add = [];
+ while ($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, $ylim) = [$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 = [];
+ $ymids[0] = [];
+
+ $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[] = $flip ? [$yoff, $xoff] : [$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[] = $flip ? [$y1, $x1] : [$x1, $y1];
+ }
+ $seps[] = $flip ? [$ylim, $xlim] : [$xlim, $ylim];
+
+ return [$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]');
+ }
+ }
+ }
+
+}
projects / yaffs-website / blobdiff