'DerivativeResourceLoaderContext' => __DIR__ . '/includes/resourceloader/DerivativeResourceLoaderContext.php',
'DescribeFileOp' => __DIR__ . '/includes/filebackend/FileOp.php',
'Diff' => __DIR__ . '/includes/diff/DairikiDiff.php',
- 'DiffEngine' => __DIR__ . '/includes/diff/DairikiDiff.php',
+ 'DiffEngine' => __DIR__ . '/includes/diff/DiffEngine.php',
'DiffFormatter' => __DIR__ . '/includes/diff/DiffFormatter.php',
'DiffHistoryBlob' => __DIR__ . '/includes/HistoryBlob.php',
'DiffOp' => __DIR__ . '/includes/diff/DairikiDiff.php',
'RCFeedFormatter' => __DIR__ . '/includes/rcfeed/RCFeedFormatter.php',
'RSSFeed' => __DIR__ . '/includes/Feed.php',
'RandomPage' => __DIR__ . '/includes/specials/SpecialRandompage.php',
- 'RangeDifference' => __DIR__ . '/includes/diff/WikiDiff3.php',
+ 'RangeDifference' => __DIR__ . '/includes/diff/DiffEngine.php',
'RawAction' => __DIR__ . '/includes/actions/RawAction.php',
'RawMessage' => __DIR__ . '/includes/Message.php',
'ReadOnlyError' => __DIR__ . '/includes/exception/ReadOnlyError.php',
'WebRequestUpload' => __DIR__ . '/includes/WebRequestUpload.php',
'WebResponse' => __DIR__ . '/includes/WebResponse.php',
'WikiCategoryPage' => __DIR__ . '/includes/page/WikiCategoryPage.php',
- 'WikiDiff3' => __DIR__ . '/includes/diff/WikiDiff3.php',
'WikiExporter' => __DIR__ . '/includes/export/WikiExporter.php',
'WikiFilePage' => __DIR__ . '/includes/page/WikiFilePage.php',
'WikiImporter' => __DIR__ . '/includes/import/WikiImporter.php',
}
}
-/**
- * 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
- * Alternative implementation added by Guy Van den Broeck, 2008-07-30
- *
- * @author Geoffrey T. Dairiki, Tim Starling, Guy Van den Broeck
- * @private
- * @ingroup DifferenceEngine
- */
-class DiffEngine {
- protected $xchanged, $ychanged;
-
- /**
- * @param string[] $from_lines
- * @param string[] $to_lines
- *
- * @return DiffOp[]
- */
- public function diff( $from_lines, $to_lines ) {
-
- // Diff and store locally
- $this->diffLocal( $from_lines, $to_lines );
-
- // Merge edits when possible
- $this->shiftBoundaries( $from_lines, $this->xchanged, $this->ychanged );
- $this->shiftBoundaries( $to_lines, $this->ychanged, $this->xchanged );
-
- // Compute the edit operations.
- $n_from = count( $from_lines );
- $n_to = count( $to_lines );
-
- $edits = [];
- $xi = $yi = 0;
- while ( $xi < $n_from || $yi < $n_to ) {
- assert( $yi < $n_to || $this->xchanged[$xi] );
- 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;
- }
-
- /**
- * @param string[] $from_lines
- * @param string[] $to_lines
- */
- private function diffLocal( $from_lines, $to_lines ) {
- $wikidiff3 = new WikiDiff3();
- $wikidiff3->diff( $from_lines, $to_lines );
- $this->xchanged = $wikidiff3->removed;
- $this->ychanged = $wikidiff3->added;
- }
-
- /**
- * 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).
- */
- private function shiftBoundaries( $lines, &$changed, $other_changed ) {
- $i = 0;
- $j = 0;
-
- assert( count( $lines ) == count( $changed ) );
- $len = count( $lines );
- $other_len = count( $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] ) {
- 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--;
- }
- assert( $j > 0 );
- while ( $other_changed[--$j] ) {
- continue;
- }
- 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++;
- }
-
- 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;
- assert( $j > 0 );
- while ( $other_changed[--$j] ) {
- continue;
- }
- assert( $j >= 0 && !$other_changed[$j] );
- }
- }
- }
-}
-
/**
* Class representing a 'diff' between two sequences of strings.
* @todo document
--- /dev/null
+<?php
+/**
+ * New version of the difference engine
+ *
+ * Copyright © 2008 Guy Van den Broeck <guy@guyvdb.eu>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @ingroup DifferenceEngine
+ */
+
+/**
+ * This diff implementation is mainly lifted from the LCS algorithm of the Eclipse project which
+ * in turn is based on Myers' "An O(ND) difference algorithm and its variations"
+ * (http://citeseer.ist.psu.edu/myers86ond.html) with range compression (see Wu et al.'s
+ * "An O(NP) Sequence Comparison Algorithm").
+ *
+ * This implementation supports an upper bound on the execution time.
+ *
+ * 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
+ *
+ * Complexity: O((M + N)D) worst case time, O(M + N + D^2) expected time, O(M + N) space
+ *
+ * @author Guy Van den Broeck, Geoffrey T. Dairiki, Tim Starling
+ * @ingroup DifferenceEngine
+ */
+class DiffEngine {
+
+ // Input variables
+ private $from;
+ private $to;
+ private $m;
+ private $n;
+
+ private $tooLong;
+ private $powLimit;
+
+ // State variables
+ private $maxDifferences;
+ private $lcsLengthCorrectedForHeuristic = false;
+
+ // Output variables
+ public $length;
+ public $removed;
+ public $added;
+ public $heuristicUsed;
+
+ function __construct( $tooLong = 2000000, $powLimit = 1.45 ) {
+ $this->tooLong = $tooLong;
+ $this->powLimit = $powLimit;
+ }
+
+ /**
+ * @param string[] $from_lines
+ * @param string[] $to_lines
+ *
+ * @return DiffOp[]
+ */
+ public function diff( $from_lines, $to_lines ) {
+
+ // Diff and store locally
+ $this->diffInternal( $from_lines, $to_lines );
+
+ // Merge edits when possible
+ $this->shiftBoundaries( $from_lines, $this->removed, $this->added );
+ $this->shiftBoundaries( $to_lines, $this->added, $this->removed );
+
+ // Compute the edit operations.
+ $n_from = count( $from_lines );
+ $n_to = count( $to_lines );
+
+ $edits = [];
+ $xi = $yi = 0;
+ while ( $xi < $n_from || $yi < $n_to ) {
+ assert( $yi < $n_to || $this->removed[$xi] );
+ assert( $xi < $n_from || $this->added[$yi] );
+
+ // Skip matching "snake".
+ $copy = [];
+ while ( $xi < $n_from && $yi < $n_to
+ && !$this->removed[$xi] && !$this->added[$yi]
+ ) {
+ $copy[] = $from_lines[$xi++];
+ ++$yi;
+ }
+ if ( $copy ) {
+ $edits[] = new DiffOpCopy( $copy );
+ }
+
+ // Find deletes & adds.
+ $delete = [];
+ while ( $xi < $n_from && $this->removed[$xi] ) {
+ $delete[] = $from_lines[$xi++];
+ }
+
+ $add = [];
+ while ( $yi < $n_to && $this->added[$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;
+ }
+
+ /**
+ * 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).
+ */
+ private function shiftBoundaries( $lines, &$changed, $other_changed ) {
+ $i = 0;
+ $j = 0;
+
+ assert( count( $lines ) == count( $changed ) );
+ $len = count( $lines );
+ $other_len = count( $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] ) {
+ 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--;
+ }
+ assert( $j > 0 );
+ while ( $other_changed[--$j] ) {
+ continue;
+ }
+ 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++;
+ }
+
+ 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;
+ assert( $j > 0 );
+ while ( $other_changed[--$j] ) {
+ continue;
+ }
+ assert( $j >= 0 && !$other_changed[$j] );
+ }
+ }
+ }
+
+ protected function diffInternal( /*array*/ $from, /*array*/ $to ) {
+ // remember initial lengths
+ $m = count( $from );
+ $n = count( $to );
+
+ $this->heuristicUsed = false;
+
+ // output
+ $removed = $m > 0 ? array_fill( 0, $m, true ) : [];
+ $added = $n > 0 ? array_fill( 0, $n, true ) : [];
+
+ // reduce the complexity for the next step (intentionally done twice)
+ // remove common tokens at the start
+ $i = 0;
+ while ( $i < $m && $i < $n && $from[$i] === $to[$i] ) {
+ $removed[$i] = $added[$i] = false;
+ unset( $from[$i], $to[$i] );
+ ++$i;
+ }
+
+ // remove common tokens at the end
+ $j = 1;
+ while ( $i + $j <= $m && $i + $j <= $n && $from[$m - $j] === $to[$n - $j] ) {
+ $removed[$m - $j] = $added[$n - $j] = false;
+ unset( $from[$m - $j], $to[$n - $j] );
+ ++$j;
+ }
+
+ $this->from = $newFromIndex = $this->to = $newToIndex = [];
+
+ // remove tokens not in both sequences
+ $shared = [];
+ foreach ( $from as $key ) {
+ $shared[$key] = false;
+ }
+
+ foreach ( $to as $index => &$el ) {
+ if ( array_key_exists( $el, $shared ) ) {
+ // keep it
+ $this->to[] = $el;
+ $shared[$el] = true;
+ $newToIndex[] = $index;
+ }
+ }
+ foreach ( $from as $index => &$el ) {
+ if ( $shared[$el] ) {
+ // keep it
+ $this->from[] = $el;
+ $newFromIndex[] = $index;
+ }
+ }
+
+ unset( $shared, $from, $to );
+
+ $this->m = count( $this->from );
+ $this->n = count( $this->to );
+
+ $this->removed = $this->m > 0 ? array_fill( 0, $this->m, true ) : [];
+ $this->added = $this->n > 0 ? array_fill( 0, $this->n, true ) : [];
+
+ if ( $this->m == 0 || $this->n == 0 ) {
+ $this->length = 0;
+ } else {
+ $this->maxDifferences = ceil( ( $this->m + $this->n ) / 2.0 );
+ if ( $this->m * $this->n > $this->tooLong ) {
+ // limit complexity to D^POW_LIMIT for long sequences
+ $this->maxDifferences = floor( pow( $this->maxDifferences, $this->powLimit - 1.0 ) );
+ wfDebug( "Limiting max number of differences to $this->maxDifferences\n" );
+ }
+
+ /*
+ * The common prefixes and suffixes are always part of some LCS, include
+ * them now to reduce our search space
+ */
+ $max = min( $this->m, $this->n );
+ for ( $forwardBound = 0; $forwardBound < $max
+ && $this->from[$forwardBound] === $this->to[$forwardBound];
+ ++$forwardBound
+ ) {
+ $this->removed[$forwardBound] = $this->added[$forwardBound] = false;
+ }
+
+ $backBoundL1 = $this->m - 1;
+ $backBoundL2 = $this->n - 1;
+
+ while ( $backBoundL1 >= $forwardBound && $backBoundL2 >= $forwardBound
+ && $this->from[$backBoundL1] === $this->to[$backBoundL2]
+ ) {
+ $this->removed[$backBoundL1--] = $this->added[$backBoundL2--] = false;
+ }
+
+ $temp = array_fill( 0, $this->m + $this->n + 1, 0 );
+ $V = [ $temp, $temp ];
+ $snake = [ 0, 0, 0 ];
+
+ $this->length = $forwardBound + $this->m - $backBoundL1 - 1
+ + $this->lcs_rec(
+ $forwardBound,
+ $backBoundL1,
+ $forwardBound,
+ $backBoundL2,
+ $V,
+ $snake
+ );
+ }
+
+ $this->m = $m;
+ $this->n = $n;
+
+ $this->length += $i + $j - 1;
+
+ foreach ( $this->removed as $key => &$removed_elem ) {
+ if ( !$removed_elem ) {
+ $removed[$newFromIndex[$key]] = false;
+ }
+ }
+ foreach ( $this->added as $key => &$added_elem ) {
+ if ( !$added_elem ) {
+ $added[$newToIndex[$key]] = false;
+ }
+ }
+ $this->removed = $removed;
+ $this->added = $added;
+ }
+
+ function diff_range( $from_lines, $to_lines ) {
+ // Diff and store locally
+ $this->diff( $from_lines, $to_lines );
+ unset( $from_lines, $to_lines );
+
+ $ranges = [];
+ $xi = $yi = 0;
+ while ( $xi < $this->m || $yi < $this->n ) {
+ // Matching "snake".
+ while ( $xi < $this->m && $yi < $this->n
+ && !$this->removed[$xi]
+ && !$this->added[$yi]
+ ) {
+ ++$xi;
+ ++$yi;
+ }
+ // Find deletes & adds.
+ $xstart = $xi;
+ while ( $xi < $this->m && $this->removed[$xi] ) {
+ ++$xi;
+ }
+
+ $ystart = $yi;
+ while ( $yi < $this->n && $this->added[$yi] ) {
+ ++$yi;
+ }
+
+ if ( $xi > $xstart || $yi > $ystart ) {
+ $ranges[] = new RangeDifference( $xstart, $xi, $ystart, $yi );
+ }
+ }
+
+ return $ranges;
+ }
+
+ private function lcs_rec( $bottoml1, $topl1, $bottoml2, $topl2, &$V, &$snake ) {
+ // check that both sequences are non-empty
+ if ( $bottoml1 > $topl1 || $bottoml2 > $topl2 ) {
+ return 0;
+ }
+
+ $d = $this->find_middle_snake( $bottoml1, $topl1, $bottoml2,
+ $topl2, $V, $snake );
+
+ // need to store these so we don't lose them when they're
+ // overwritten by the recursion
+ $len = $snake[2];
+ $startx = $snake[0];
+ $starty = $snake[1];
+
+ // the middle snake is part of the LCS, store it
+ for ( $i = 0; $i < $len; ++$i ) {
+ $this->removed[$startx + $i] = $this->added[$starty + $i] = false;
+ }
+
+ if ( $d > 1 ) {
+ return $len
+ + $this->lcs_rec( $bottoml1, $startx - 1, $bottoml2,
+ $starty - 1, $V, $snake )
+ + $this->lcs_rec( $startx + $len, $topl1, $starty + $len,
+ $topl2, $V, $snake );
+ } elseif ( $d == 1 ) {
+ /*
+ * In this case the sequences differ by exactly 1 line. We have
+ * already saved all the lines after the difference in the for loop
+ * above, now we need to save all the lines before the difference.
+ */
+ $max = min( $startx - $bottoml1, $starty - $bottoml2 );
+ for ( $i = 0; $i < $max; ++$i ) {
+ $this->removed[$bottoml1 + $i] =
+ $this->added[$bottoml2 + $i] = false;
+ }
+
+ return $max + $len;
+ }
+
+ return $len;
+ }
+
+ private function find_middle_snake( $bottoml1, $topl1, $bottoml2, $topl2, &$V, &$snake ) {
+ $from = &$this->from;
+ $to = &$this->to;
+ $V0 = &$V[0];
+ $V1 = &$V[1];
+ $snake0 = &$snake[0];
+ $snake1 = &$snake[1];
+ $snake2 = &$snake[2];
+ $bottoml1_min_1 = $bottoml1 - 1;
+ $bottoml2_min_1 = $bottoml2 - 1;
+ $N = $topl1 - $bottoml1_min_1;
+ $M = $topl2 - $bottoml2_min_1;
+ $delta = $N - $M;
+ $maxabsx = $N + $bottoml1;
+ $maxabsy = $M + $bottoml2;
+ $limit = min( $this->maxDifferences, ceil( ( $N + $M ) / 2 ) );
+
+ // value_to_add_forward: a 0 or 1 that we add to the start
+ // offset to make it odd/even
+ if ( ( $M & 1 ) == 1 ) {
+ $value_to_add_forward = 1;
+ } else {
+ $value_to_add_forward = 0;
+ }
+
+ if ( ( $N & 1 ) == 1 ) {
+ $value_to_add_backward = 1;
+ } else {
+ $value_to_add_backward = 0;
+ }
+
+ $start_forward = -$M;
+ $end_forward = $N;
+ $start_backward = -$N;
+ $end_backward = $M;
+
+ $limit_min_1 = $limit - 1;
+ $limit_plus_1 = $limit + 1;
+
+ $V0[$limit_plus_1] = 0;
+ $V1[$limit_min_1] = $N;
+ $limit = min( $this->maxDifferences, ceil( ( $N + $M ) / 2 ) );
+
+ if ( ( $delta & 1 ) == 1 ) {
+ for ( $d = 0; $d <= $limit; ++$d ) {
+ $start_diag = max( $value_to_add_forward + $start_forward, -$d );
+ $end_diag = min( $end_forward, $d );
+ $value_to_add_forward = 1 - $value_to_add_forward;
+
+ // compute forward furthest reaching paths
+ for ( $k = $start_diag; $k <= $end_diag; $k += 2 ) {
+ if ( $k == -$d || ( $k < $d
+ && $V0[$limit_min_1 + $k] < $V0[$limit_plus_1 + $k] )
+ ) {
+ $x = $V0[$limit_plus_1 + $k];
+ } else {
+ $x = $V0[$limit_min_1 + $k] + 1;
+ }
+
+ $absx = $snake0 = $x + $bottoml1;
+ $absy = $snake1 = $x - $k + $bottoml2;
+
+ while ( $absx < $maxabsx && $absy < $maxabsy && $from[$absx] === $to[$absy] ) {
+ ++$absx;
+ ++$absy;
+ }
+ $x = $absx - $bottoml1;
+
+ $snake2 = $absx - $snake0;
+ $V0[$limit + $k] = $x;
+ if ( $k >= $delta - $d + 1 && $k <= $delta + $d - 1
+ && $x >= $V1[$limit + $k - $delta]
+ ) {
+ return 2 * $d - 1;
+ }
+
+ // check to see if we can cut down the diagonal range
+ if ( $x >= $N && $end_forward > $k - 1 ) {
+ $end_forward = $k - 1;
+ } elseif ( $absy - $bottoml2 >= $M ) {
+ $start_forward = $k + 1;
+ $value_to_add_forward = 0;
+ }
+ }
+
+ $start_diag = max( $value_to_add_backward + $start_backward, -$d );
+ $end_diag = min( $end_backward, $d );
+ $value_to_add_backward = 1 - $value_to_add_backward;
+
+ // compute backward furthest reaching paths
+ for ( $k = $start_diag; $k <= $end_diag; $k += 2 ) {
+ if ( $k == $d
+ || ( $k != -$d && $V1[$limit_min_1 + $k] < $V1[$limit_plus_1 + $k] )
+ ) {
+ $x = $V1[$limit_min_1 + $k];
+ } else {
+ $x = $V1[$limit_plus_1 + $k] - 1;
+ }
+
+ $y = $x - $k - $delta;
+
+ $snake2 = 0;
+ while ( $x > 0 && $y > 0
+ && $from[$x + $bottoml1_min_1] === $to[$y + $bottoml2_min_1]
+ ) {
+ --$x;
+ --$y;
+ ++$snake2;
+ }
+ $V1[$limit + $k] = $x;
+
+ // check to see if we can cut down our diagonal range
+ if ( $x <= 0 ) {
+ $start_backward = $k + 1;
+ $value_to_add_backward = 0;
+ } elseif ( $y <= 0 && $end_backward > $k - 1 ) {
+ $end_backward = $k - 1;
+ }
+ }
+ }
+ } else {
+ for ( $d = 0; $d <= $limit; ++$d ) {
+ $start_diag = max( $value_to_add_forward + $start_forward, -$d );
+ $end_diag = min( $end_forward, $d );
+ $value_to_add_forward = 1 - $value_to_add_forward;
+
+ // compute forward furthest reaching paths
+ for ( $k = $start_diag; $k <= $end_diag; $k += 2 ) {
+ if ( $k == -$d
+ || ( $k < $d && $V0[$limit_min_1 + $k] < $V0[$limit_plus_1 + $k] )
+ ) {
+ $x = $V0[$limit_plus_1 + $k];
+ } else {
+ $x = $V0[$limit_min_1 + $k] + 1;
+ }
+
+ $absx = $snake0 = $x + $bottoml1;
+ $absy = $snake1 = $x - $k + $bottoml2;
+
+ while ( $absx < $maxabsx && $absy < $maxabsy && $from[$absx] === $to[$absy] ) {
+ ++$absx;
+ ++$absy;
+ }
+ $x = $absx - $bottoml1;
+ $snake2 = $absx - $snake0;
+ $V0[$limit + $k] = $x;
+
+ // check to see if we can cut down the diagonal range
+ if ( $x >= $N && $end_forward > $k - 1 ) {
+ $end_forward = $k - 1;
+ } elseif ( $absy - $bottoml2 >= $M ) {
+ $start_forward = $k + 1;
+ $value_to_add_forward = 0;
+ }
+ }
+
+ $start_diag = max( $value_to_add_backward + $start_backward, -$d );
+ $end_diag = min( $end_backward, $d );
+ $value_to_add_backward = 1 - $value_to_add_backward;
+
+ // compute backward furthest reaching paths
+ for ( $k = $start_diag; $k <= $end_diag; $k += 2 ) {
+ if ( $k == $d
+ || ( $k != -$d && $V1[$limit_min_1 + $k] < $V1[$limit_plus_1 + $k] )
+ ) {
+ $x = $V1[$limit_min_1 + $k];
+ } else {
+ $x = $V1[$limit_plus_1 + $k] - 1;
+ }
+
+ $y = $x - $k - $delta;
+
+ $snake2 = 0;
+ while ( $x > 0 && $y > 0
+ && $from[$x + $bottoml1_min_1] === $to[$y + $bottoml2_min_1]
+ ) {
+ --$x;
+ --$y;
+ ++$snake2;
+ }
+ $V1[$limit + $k] = $x;
+
+ if ( $k >= -$delta - $d && $k <= $d - $delta
+ && $x <= $V0[$limit + $k + $delta]
+ ) {
+ $snake0 = $bottoml1 + $x;
+ $snake1 = $bottoml2 + $y;
+
+ return 2 * $d;
+ }
+
+ // check to see if we can cut down our diagonal range
+ if ( $x <= 0 ) {
+ $start_backward = $k + 1;
+ $value_to_add_backward = 0;
+ } elseif ( $y <= 0 && $end_backward > $k - 1 ) {
+ $end_backward = $k - 1;
+ }
+ }
+ }
+ }
+ /*
+ * computing the true LCS is too expensive, instead find the diagonal
+ * with the most progress and pretend a midle snake of length 0 occurs
+ * there.
+ */
+
+ $most_progress = self::findMostProgress( $M, $N, $limit, $V );
+
+ $snake0 = $bottoml1 + $most_progress[0];
+ $snake1 = $bottoml2 + $most_progress[1];
+ $snake2 = 0;
+ wfDebug( "Computing the LCS is too expensive. Using a heuristic.\n" );
+ $this->heuristicUsed = true;
+
+ return 5; /*
+ * HACK: since we didn't really finish the LCS computation
+ * we don't really know the length of the SES. We don't do
+ * anything with the result anyway, unless it's <=1. We know
+ * for a fact SES > 1 so 5 is as good a number as any to
+ * return here
+ */
+ }
+
+ private static function findMostProgress( $M, $N, $limit, $V ) {
+ $delta = $N - $M;
+
+ if ( ( $M & 1 ) == ( $limit & 1 ) ) {
+ $forward_start_diag = max( -$M, -$limit );
+ } else {
+ $forward_start_diag = max( 1 - $M, -$limit );
+ }
+
+ $forward_end_diag = min( $N, $limit );
+
+ if ( ( $N & 1 ) == ( $limit & 1 ) ) {
+ $backward_start_diag = max( -$N, -$limit );
+ } else {
+ $backward_start_diag = max( 1 - $N, -$limit );
+ }
+
+ $backward_end_diag = -min( $M, $limit );
+
+ $temp = [ 0, 0, 0 ];
+
+ $max_progress = array_fill( 0, ceil( max( $forward_end_diag - $forward_start_diag,
+ $backward_end_diag - $backward_start_diag ) / 2 ), $temp );
+ $num_progress = 0; // the 1st entry is current, it is initialized
+ // with 0s
+
+ // first search the forward diagonals
+ for ( $k = $forward_start_diag; $k <= $forward_end_diag; $k += 2 ) {
+ $x = $V[0][$limit + $k];
+ $y = $x - $k;
+ if ( $x > $N || $y > $M ) {
+ continue;
+ }
+
+ $progress = $x + $y;
+ if ( $progress > $max_progress[0][2] ) {
+ $num_progress = 0;
+ $max_progress[0][0] = $x;
+ $max_progress[0][1] = $y;
+ $max_progress[0][2] = $progress;
+ } elseif ( $progress == $max_progress[0][2] ) {
+ ++$num_progress;
+ $max_progress[$num_progress][0] = $x;
+ $max_progress[$num_progress][1] = $y;
+ $max_progress[$num_progress][2] = $progress;
+ }
+ }
+
+ $max_progress_forward = true; // initially the maximum
+ // progress is in the forward
+ // direction
+
+ // now search the backward diagonals
+ for ( $k = $backward_start_diag; $k <= $backward_end_diag; $k += 2 ) {
+ $x = $V[1][$limit + $k];
+ $y = $x - $k - $delta;
+ if ( $x < 0 || $y < 0 ) {
+ continue;
+ }
+
+ $progress = $N - $x + $M - $y;
+ if ( $progress > $max_progress[0][2] ) {
+ $num_progress = 0;
+ $max_progress_forward = false;
+ $max_progress[0][0] = $x;
+ $max_progress[0][1] = $y;
+ $max_progress[0][2] = $progress;
+ } elseif ( $progress == $max_progress[0][2] && !$max_progress_forward ) {
+ ++$num_progress;
+ $max_progress[$num_progress][0] = $x;
+ $max_progress[$num_progress][1] = $y;
+ $max_progress[$num_progress][2] = $progress;
+ }
+ }
+
+ // return the middle diagonal with maximal progress.
+ return $max_progress[(int)floor( $num_progress / 2 )];
+ }
+
+ /**
+ * @return mixed
+ */
+ public function getLcsLength() {
+ if ( $this->heuristicUsed && !$this->lcsLengthCorrectedForHeuristic ) {
+ $this->lcsLengthCorrectedForHeuristic = true;
+ $this->length = $this->m - array_sum( $this->added );
+ }
+
+ return $this->length;
+ }
+
+}
+
+/**
+ * Alternative representation of a set of changes, by the index
+ * ranges that are changed.
+ *
+ * @ingroup DifferenceEngine
+ */
+class RangeDifference {
+
+ /** @var int */
+ public $leftstart;
+
+ /** @var int */
+ public $leftend;
+
+ /** @var int */
+ public $leftlength;
+
+ /** @var int */
+ public $rightstart;
+
+ /** @var int */
+ public $rightend;
+
+ /** @var int */
+ public $rightlength;
+
+ function __construct( $leftstart, $leftend, $rightstart, $rightend ) {
+ $this->leftstart = $leftstart;
+ $this->leftend = $leftend;
+ $this->leftlength = $leftend - $leftstart;
+ $this->rightstart = $rightstart;
+ $this->rightend = $rightend;
+ $this->rightlength = $rightend - $rightstart;
+ }
+
+}
+++ /dev/null
-<?php
-/**
- * New version of the difference engine
- *
- * Copyright © 2008 Guy Van den Broeck <guy@guyvdb.eu>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
- * http://www.gnu.org/copyleft/gpl.html
- *
- * @file
- * @ingroup DifferenceEngine
- */
-
-/**
- * This diff implementation is mainly lifted from the LCS algorithm of the Eclipse project which
- * in turn is based on Myers' "An O(ND) difference algorithm and its variations"
- * (http://citeseer.ist.psu.edu/myers86ond.html) with range compression (see Wu et al.'s
- * "An O(NP) Sequence Comparison Algorithm").
- *
- * This implementation supports an upper bound on the execution time.
- *
- * Complexity: O((M + N)D) worst case time, O(M + N + D^2) expected time, O(M + N) space
- *
- * @author Guy Van den Broeck
- * @ingroup DifferenceEngine
- */
-class WikiDiff3 {
-
- // Input variables
- private $from;
- private $to;
- private $m;
- private $n;
-
- private $tooLong;
- private $powLimit;
-
- // State variables
- private $maxDifferences;
- private $lcsLengthCorrectedForHeuristic = false;
-
- // Output variables
- public $length;
- public $removed;
- public $added;
- public $heuristicUsed;
-
- function __construct( $tooLong = 2000000, $powLimit = 1.45 ) {
- $this->tooLong = $tooLong;
- $this->powLimit = $powLimit;
- }
-
- public function diff( /*array*/ $from, /*array*/ $to ) {
- // remember initial lengths
- $m = count( $from );
- $n = count( $to );
-
- $this->heuristicUsed = false;
-
- // output
- $removed = $m > 0 ? array_fill( 0, $m, true ) : [];
- $added = $n > 0 ? array_fill( 0, $n, true ) : [];
-
- // reduce the complexity for the next step (intentionally done twice)
- // remove common tokens at the start
- $i = 0;
- while ( $i < $m && $i < $n && $from[$i] === $to[$i] ) {
- $removed[$i] = $added[$i] = false;
- unset( $from[$i], $to[$i] );
- ++$i;
- }
-
- // remove common tokens at the end
- $j = 1;
- while ( $i + $j <= $m && $i + $j <= $n && $from[$m - $j] === $to[$n - $j] ) {
- $removed[$m - $j] = $added[$n - $j] = false;
- unset( $from[$m - $j], $to[$n - $j] );
- ++$j;
- }
-
- $this->from = $newFromIndex = $this->to = $newToIndex = [];
-
- // remove tokens not in both sequences
- $shared = [];
- foreach ( $from as $key ) {
- $shared[$key] = false;
- }
-
- foreach ( $to as $index => &$el ) {
- if ( array_key_exists( $el, $shared ) ) {
- // keep it
- $this->to[] = $el;
- $shared[$el] = true;
- $newToIndex[] = $index;
- }
- }
- foreach ( $from as $index => &$el ) {
- if ( $shared[$el] ) {
- // keep it
- $this->from[] = $el;
- $newFromIndex[] = $index;
- }
- }
-
- unset( $shared, $from, $to );
-
- $this->m = count( $this->from );
- $this->n = count( $this->to );
-
- $this->removed = $this->m > 0 ? array_fill( 0, $this->m, true ) : [];
- $this->added = $this->n > 0 ? array_fill( 0, $this->n, true ) : [];
-
- if ( $this->m == 0 || $this->n == 0 ) {
- $this->length = 0;
- } else {
- $this->maxDifferences = ceil( ( $this->m + $this->n ) / 2.0 );
- if ( $this->m * $this->n > $this->tooLong ) {
- // limit complexity to D^POW_LIMIT for long sequences
- $this->maxDifferences = floor( pow( $this->maxDifferences, $this->powLimit - 1.0 ) );
- wfDebug( "Limiting max number of differences to $this->maxDifferences\n" );
- }
-
- /*
- * The common prefixes and suffixes are always part of some LCS, include
- * them now to reduce our search space
- */
- $max = min( $this->m, $this->n );
- for ( $forwardBound = 0; $forwardBound < $max
- && $this->from[$forwardBound] === $this->to[$forwardBound];
- ++$forwardBound
- ) {
- $this->removed[$forwardBound] = $this->added[$forwardBound] = false;
- }
-
- $backBoundL1 = $this->m - 1;
- $backBoundL2 = $this->n - 1;
-
- while ( $backBoundL1 >= $forwardBound && $backBoundL2 >= $forwardBound
- && $this->from[$backBoundL1] === $this->to[$backBoundL2]
- ) {
- $this->removed[$backBoundL1--] = $this->added[$backBoundL2--] = false;
- }
-
- $temp = array_fill( 0, $this->m + $this->n + 1, 0 );
- $V = [ $temp, $temp ];
- $snake = [ 0, 0, 0 ];
-
- $this->length = $forwardBound + $this->m - $backBoundL1 - 1
- + $this->lcs_rec(
- $forwardBound,
- $backBoundL1,
- $forwardBound,
- $backBoundL2,
- $V,
- $snake
- );
- }
-
- $this->m = $m;
- $this->n = $n;
-
- $this->length += $i + $j - 1;
-
- foreach ( $this->removed as $key => &$removed_elem ) {
- if ( !$removed_elem ) {
- $removed[$newFromIndex[$key]] = false;
- }
- }
- foreach ( $this->added as $key => &$added_elem ) {
- if ( !$added_elem ) {
- $added[$newToIndex[$key]] = false;
- }
- }
- $this->removed = $removed;
- $this->added = $added;
- }
-
- function diff_range( $from_lines, $to_lines ) {
- // Diff and store locally
- $this->diff( $from_lines, $to_lines );
- unset( $from_lines, $to_lines );
-
- $ranges = [];
- $xi = $yi = 0;
- while ( $xi < $this->m || $yi < $this->n ) {
- // Matching "snake".
- while ( $xi < $this->m && $yi < $this->n
- && !$this->removed[$xi]
- && !$this->added[$yi]
- ) {
- ++$xi;
- ++$yi;
- }
- // Find deletes & adds.
- $xstart = $xi;
- while ( $xi < $this->m && $this->removed[$xi] ) {
- ++$xi;
- }
-
- $ystart = $yi;
- while ( $yi < $this->n && $this->added[$yi] ) {
- ++$yi;
- }
-
- if ( $xi > $xstart || $yi > $ystart ) {
- $ranges[] = new RangeDifference( $xstart, $xi, $ystart, $yi );
- }
- }
-
- return $ranges;
- }
-
- private function lcs_rec( $bottoml1, $topl1, $bottoml2, $topl2, &$V, &$snake ) {
- // check that both sequences are non-empty
- if ( $bottoml1 > $topl1 || $bottoml2 > $topl2 ) {
- return 0;
- }
-
- $d = $this->find_middle_snake( $bottoml1, $topl1, $bottoml2,
- $topl2, $V, $snake );
-
- // need to store these so we don't lose them when they're
- // overwritten by the recursion
- $len = $snake[2];
- $startx = $snake[0];
- $starty = $snake[1];
-
- // the middle snake is part of the LCS, store it
- for ( $i = 0; $i < $len; ++$i ) {
- $this->removed[$startx + $i] = $this->added[$starty + $i] = false;
- }
-
- if ( $d > 1 ) {
- return $len
- + $this->lcs_rec( $bottoml1, $startx - 1, $bottoml2,
- $starty - 1, $V, $snake )
- + $this->lcs_rec( $startx + $len, $topl1, $starty + $len,
- $topl2, $V, $snake );
- } elseif ( $d == 1 ) {
- /*
- * In this case the sequences differ by exactly 1 line. We have
- * already saved all the lines after the difference in the for loop
- * above, now we need to save all the lines before the difference.
- */
- $max = min( $startx - $bottoml1, $starty - $bottoml2 );
- for ( $i = 0; $i < $max; ++$i ) {
- $this->removed[$bottoml1 + $i] =
- $this->added[$bottoml2 + $i] = false;
- }
-
- return $max + $len;
- }
-
- return $len;
- }
-
- private function find_middle_snake( $bottoml1, $topl1, $bottoml2, $topl2, &$V, &$snake ) {
- $from = &$this->from;
- $to = &$this->to;
- $V0 = &$V[0];
- $V1 = &$V[1];
- $snake0 = &$snake[0];
- $snake1 = &$snake[1];
- $snake2 = &$snake[2];
- $bottoml1_min_1 = $bottoml1 - 1;
- $bottoml2_min_1 = $bottoml2 - 1;
- $N = $topl1 - $bottoml1_min_1;
- $M = $topl2 - $bottoml2_min_1;
- $delta = $N - $M;
- $maxabsx = $N + $bottoml1;
- $maxabsy = $M + $bottoml2;
- $limit = min( $this->maxDifferences, ceil( ( $N + $M ) / 2 ) );
-
- // value_to_add_forward: a 0 or 1 that we add to the start
- // offset to make it odd/even
- if ( ( $M & 1 ) == 1 ) {
- $value_to_add_forward = 1;
- } else {
- $value_to_add_forward = 0;
- }
-
- if ( ( $N & 1 ) == 1 ) {
- $value_to_add_backward = 1;
- } else {
- $value_to_add_backward = 0;
- }
-
- $start_forward = -$M;
- $end_forward = $N;
- $start_backward = -$N;
- $end_backward = $M;
-
- $limit_min_1 = $limit - 1;
- $limit_plus_1 = $limit + 1;
-
- $V0[$limit_plus_1] = 0;
- $V1[$limit_min_1] = $N;
- $limit = min( $this->maxDifferences, ceil( ( $N + $M ) / 2 ) );
-
- if ( ( $delta & 1 ) == 1 ) {
- for ( $d = 0; $d <= $limit; ++$d ) {
- $start_diag = max( $value_to_add_forward + $start_forward, -$d );
- $end_diag = min( $end_forward, $d );
- $value_to_add_forward = 1 - $value_to_add_forward;
-
- // compute forward furthest reaching paths
- for ( $k = $start_diag; $k <= $end_diag; $k += 2 ) {
- if ( $k == -$d || ( $k < $d
- && $V0[$limit_min_1 + $k] < $V0[$limit_plus_1 + $k] )
- ) {
- $x = $V0[$limit_plus_1 + $k];
- } else {
- $x = $V0[$limit_min_1 + $k] + 1;
- }
-
- $absx = $snake0 = $x + $bottoml1;
- $absy = $snake1 = $x - $k + $bottoml2;
-
- while ( $absx < $maxabsx && $absy < $maxabsy && $from[$absx] === $to[$absy] ) {
- ++$absx;
- ++$absy;
- }
- $x = $absx - $bottoml1;
-
- $snake2 = $absx - $snake0;
- $V0[$limit + $k] = $x;
- if ( $k >= $delta - $d + 1 && $k <= $delta + $d - 1
- && $x >= $V1[$limit + $k - $delta]
- ) {
- return 2 * $d - 1;
- }
-
- // check to see if we can cut down the diagonal range
- if ( $x >= $N && $end_forward > $k - 1 ) {
- $end_forward = $k - 1;
- } elseif ( $absy - $bottoml2 >= $M ) {
- $start_forward = $k + 1;
- $value_to_add_forward = 0;
- }
- }
-
- $start_diag = max( $value_to_add_backward + $start_backward, -$d );
- $end_diag = min( $end_backward, $d );
- $value_to_add_backward = 1 - $value_to_add_backward;
-
- // compute backward furthest reaching paths
- for ( $k = $start_diag; $k <= $end_diag; $k += 2 ) {
- if ( $k == $d
- || ( $k != -$d && $V1[$limit_min_1 + $k] < $V1[$limit_plus_1 + $k] )
- ) {
- $x = $V1[$limit_min_1 + $k];
- } else {
- $x = $V1[$limit_plus_1 + $k] - 1;
- }
-
- $y = $x - $k - $delta;
-
- $snake2 = 0;
- while ( $x > 0 && $y > 0
- && $from[$x + $bottoml1_min_1] === $to[$y + $bottoml2_min_1]
- ) {
- --$x;
- --$y;
- ++$snake2;
- }
- $V1[$limit + $k] = $x;
-
- // check to see if we can cut down our diagonal range
- if ( $x <= 0 ) {
- $start_backward = $k + 1;
- $value_to_add_backward = 0;
- } elseif ( $y <= 0 && $end_backward > $k - 1 ) {
- $end_backward = $k - 1;
- }
- }
- }
- } else {
- for ( $d = 0; $d <= $limit; ++$d ) {
- $start_diag = max( $value_to_add_forward + $start_forward, -$d );
- $end_diag = min( $end_forward, $d );
- $value_to_add_forward = 1 - $value_to_add_forward;
-
- // compute forward furthest reaching paths
- for ( $k = $start_diag; $k <= $end_diag; $k += 2 ) {
- if ( $k == -$d
- || ( $k < $d && $V0[$limit_min_1 + $k] < $V0[$limit_plus_1 + $k] )
- ) {
- $x = $V0[$limit_plus_1 + $k];
- } else {
- $x = $V0[$limit_min_1 + $k] + 1;
- }
-
- $absx = $snake0 = $x + $bottoml1;
- $absy = $snake1 = $x - $k + $bottoml2;
-
- while ( $absx < $maxabsx && $absy < $maxabsy && $from[$absx] === $to[$absy] ) {
- ++$absx;
- ++$absy;
- }
- $x = $absx - $bottoml1;
- $snake2 = $absx - $snake0;
- $V0[$limit + $k] = $x;
-
- // check to see if we can cut down the diagonal range
- if ( $x >= $N && $end_forward > $k - 1 ) {
- $end_forward = $k - 1;
- } elseif ( $absy - $bottoml2 >= $M ) {
- $start_forward = $k + 1;
- $value_to_add_forward = 0;
- }
- }
-
- $start_diag = max( $value_to_add_backward + $start_backward, -$d );
- $end_diag = min( $end_backward, $d );
- $value_to_add_backward = 1 - $value_to_add_backward;
-
- // compute backward furthest reaching paths
- for ( $k = $start_diag; $k <= $end_diag; $k += 2 ) {
- if ( $k == $d
- || ( $k != -$d && $V1[$limit_min_1 + $k] < $V1[$limit_plus_1 + $k] )
- ) {
- $x = $V1[$limit_min_1 + $k];
- } else {
- $x = $V1[$limit_plus_1 + $k] - 1;
- }
-
- $y = $x - $k - $delta;
-
- $snake2 = 0;
- while ( $x > 0 && $y > 0
- && $from[$x + $bottoml1_min_1] === $to[$y + $bottoml2_min_1]
- ) {
- --$x;
- --$y;
- ++$snake2;
- }
- $V1[$limit + $k] = $x;
-
- if ( $k >= -$delta - $d && $k <= $d - $delta
- && $x <= $V0[$limit + $k + $delta]
- ) {
- $snake0 = $bottoml1 + $x;
- $snake1 = $bottoml2 + $y;
-
- return 2 * $d;
- }
-
- // check to see if we can cut down our diagonal range
- if ( $x <= 0 ) {
- $start_backward = $k + 1;
- $value_to_add_backward = 0;
- } elseif ( $y <= 0 && $end_backward > $k - 1 ) {
- $end_backward = $k - 1;
- }
- }
- }
- }
- /*
- * computing the true LCS is too expensive, instead find the diagonal
- * with the most progress and pretend a midle snake of length 0 occurs
- * there.
- */
-
- $most_progress = self::findMostProgress( $M, $N, $limit, $V );
-
- $snake0 = $bottoml1 + $most_progress[0];
- $snake1 = $bottoml2 + $most_progress[1];
- $snake2 = 0;
- wfDebug( "Computing the LCS is too expensive. Using a heuristic.\n" );
- $this->heuristicUsed = true;
-
- return 5; /*
- * HACK: since we didn't really finish the LCS computation
- * we don't really know the length of the SES. We don't do
- * anything with the result anyway, unless it's <=1. We know
- * for a fact SES > 1 so 5 is as good a number as any to
- * return here
- */
- }
-
- private static function findMostProgress( $M, $N, $limit, $V ) {
- $delta = $N - $M;
-
- if ( ( $M & 1 ) == ( $limit & 1 ) ) {
- $forward_start_diag = max( -$M, -$limit );
- } else {
- $forward_start_diag = max( 1 - $M, -$limit );
- }
-
- $forward_end_diag = min( $N, $limit );
-
- if ( ( $N & 1 ) == ( $limit & 1 ) ) {
- $backward_start_diag = max( -$N, -$limit );
- } else {
- $backward_start_diag = max( 1 - $N, -$limit );
- }
-
- $backward_end_diag = -min( $M, $limit );
-
- $temp = [ 0, 0, 0 ];
-
- $max_progress = array_fill( 0, ceil( max( $forward_end_diag - $forward_start_diag,
- $backward_end_diag - $backward_start_diag ) / 2 ), $temp );
- $num_progress = 0; // the 1st entry is current, it is initialized
- // with 0s
-
- // first search the forward diagonals
- for ( $k = $forward_start_diag; $k <= $forward_end_diag; $k += 2 ) {
- $x = $V[0][$limit + $k];
- $y = $x - $k;
- if ( $x > $N || $y > $M ) {
- continue;
- }
-
- $progress = $x + $y;
- if ( $progress > $max_progress[0][2] ) {
- $num_progress = 0;
- $max_progress[0][0] = $x;
- $max_progress[0][1] = $y;
- $max_progress[0][2] = $progress;
- } elseif ( $progress == $max_progress[0][2] ) {
- ++$num_progress;
- $max_progress[$num_progress][0] = $x;
- $max_progress[$num_progress][1] = $y;
- $max_progress[$num_progress][2] = $progress;
- }
- }
-
- $max_progress_forward = true; // initially the maximum
- // progress is in the forward
- // direction
-
- // now search the backward diagonals
- for ( $k = $backward_start_diag; $k <= $backward_end_diag; $k += 2 ) {
- $x = $V[1][$limit + $k];
- $y = $x - $k - $delta;
- if ( $x < 0 || $y < 0 ) {
- continue;
- }
-
- $progress = $N - $x + $M - $y;
- if ( $progress > $max_progress[0][2] ) {
- $num_progress = 0;
- $max_progress_forward = false;
- $max_progress[0][0] = $x;
- $max_progress[0][1] = $y;
- $max_progress[0][2] = $progress;
- } elseif ( $progress == $max_progress[0][2] && !$max_progress_forward ) {
- ++$num_progress;
- $max_progress[$num_progress][0] = $x;
- $max_progress[$num_progress][1] = $y;
- $max_progress[$num_progress][2] = $progress;
- }
- }
-
- // return the middle diagonal with maximal progress.
- return $max_progress[(int)floor( $num_progress / 2 )];
- }
-
- /**
- * @return mixed
- */
- public function getLcsLength() {
- if ( $this->heuristicUsed && !$this->lcsLengthCorrectedForHeuristic ) {
- $this->lcsLengthCorrectedForHeuristic = true;
- $this->length = $this->m - array_sum( $this->added );
- }
-
- return $this->length;
- }
-
-}
-
-/**
- * Alternative representation of a set of changes, by the index
- * ranges that are changed.
- *
- * @ingroup DifferenceEngine
- */
-class RangeDifference {
-
- /** @var int */
- public $leftstart;
-
- /** @var int */
- public $leftend;
-
- /** @var int */
- public $leftlength;
-
- /** @var int */
- public $rightstart;
-
- /** @var int */
- public $rightend;
-
- /** @var int */
- public $rightlength;
-
- function __construct( $leftstart, $leftend, $rightstart, $rightend ) {
- $this->leftstart = $leftstart;
- $this->leftend = $leftend;
- $this->leftlength = $leftend - $leftstart;
- $this->rightstart = $rightstart;
- $this->rightend = $rightend;
- $this->rightlength = $rightend - $rightstart;
- }
-
-}
dépôts / lhc / web / wiklou.git / commitdiff