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Merge Wikidiff3 into DiffEngine

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Change-Id: Ib4d083a5200824e4d032de6921c375e455e77fb2
This commit is contained in:
Max Semenik 2016-04-26 15:59:21 -07:00 committed by MaxSem
parent 7e60f670bf
commit 20f066e971
3 changed files with 199 additions and 235 deletions
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5
autoload.php
View file

@ -352,7 +352,7 @@ $wgAutoloadLocalClasses = [
'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',
@ -1087,7 +1087,7 @@ $wgAutoloadLocalClasses = [
'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',
@ -1505,7 +1505,6 @@ $wgAutoloadLocalClasses = [
'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',

229
includes/diff/DairikiDiff.php
View file

@ -191,235 +191,6 @@ class DiffOpChange extends DiffOp {
}
}
/**
* 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

200
includes/diff/WikiDiff3.php → includes/diff/DiffEngine.php
View file

@ -31,12 +31,16 @@
*
* 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
* @author Guy Van den Broeck, Geoffrey T. Dairiki, Tim Starling
* @ingroup DifferenceEngine
*/
class WikiDiff3 {
class DiffEngine {
// Input variables
private $from;
@ -62,7 +66,197 @@ class WikiDiff3 {
$this->powLimit = $powLimit;
}
public function diff( /*array*/ $from, /*array*/ $to ) {
/**
* @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 );