From ca32f08966f1b51fcb19460f0996bb0c4048e6fe Mon Sep 17 00:00:00 2001
From: Pierre Schmitz <pierre@archlinux.de>
Date: Sat, 3 Dec 2011 13:29:22 +0100
Subject: Update to MediaWiki 1.18.0

* also update ArchLinux skin to chagnes in MonoBook
* Use only css to hide our menu bar when printing
---
 includes/diff/DairikiDiff.php      | 1295 ++++++++++++++++++++++++++++++++++++
 includes/diff/DifferenceEngine.php |  259 +++++---
 includes/diff/WikiDiff.php         | 1241 ----------------------------------
 includes/diff/WikiDiff3.php        |   14 +-
 4 files changed, 1472 insertions(+), 1337 deletions(-)
 create mode 100644 includes/diff/DairikiDiff.php
 delete mode 100644 includes/diff/WikiDiff.php

(limited to 'includes/diff')

diff --git a/includes/diff/DairikiDiff.php b/includes/diff/DairikiDiff.php
new file mode 100644
index 00000000..8f19712b
--- /dev/null
+++ b/includes/diff/DairikiDiff.php
@@ -0,0 +1,1295 @@
+<?php
+/**
+ * A PHP diff engine for phpwiki. (Taken from phpwiki-1.3.3)
+ *
+ * Copyright © 2000, 2001 Geoffrey T. Dairiki <dairiki@dairiki.org>
+ * You may copy this code freely under the conditions of the GPL.
+ *
+ * @file
+ * @ingroup DifferenceEngine
+ * @defgroup DifferenceEngine DifferenceEngine
+ */
+
+/**
+ * @todo document
+ * @private
+ * @ingroup DifferenceEngine
+ */
+class _DiffOp {
+	var $type;
+	var $orig;
+	var $closing;
+
+	function reverse() {
+		trigger_error( 'pure virtual', E_USER_ERROR );
+	}
+
+	function norig() {
+		return $this->orig ? sizeof( $this->orig ) : 0;
+	}
+
+	function nclosing() {
+		return $this->closing ? sizeof( $this->closing ) : 0;
+	}
+}
+
+/**
+ * @todo document
+ * @private
+ * @ingroup DifferenceEngine
+ */
+class _DiffOp_Copy extends _DiffOp {
+	var $type = 'copy';
+
+	function __construct( $orig, $closing = false ) {
+		if ( !is_array( $closing ) ) {
+			$closing = $orig;
+		}
+		$this->orig = $orig;
+		$this->closing = $closing;
+	}
+
+	function reverse() {
+		return new _DiffOp_Copy( $this->closing, $this->orig );
+	}
+}
+
+/**
+ * @todo document
+ * @private
+ * @ingroup DifferenceEngine
+ */
+class _DiffOp_Delete extends _DiffOp {
+	var $type = 'delete';
+
+	function __construct( $lines ) {
+		$this->orig = $lines;
+		$this->closing = false;
+	}
+
+	function reverse() {
+		return new _DiffOp_Add( $this->orig );
+	}
+}
+
+/**
+ * @todo document
+ * @private
+ * @ingroup DifferenceEngine
+ */
+class _DiffOp_Add extends _DiffOp {
+	var $type = 'add';
+
+	function __construct( $lines ) {
+		$this->closing = $lines;
+		$this->orig = false;
+	}
+
+	function reverse() {
+		return new _DiffOp_Delete( $this->closing );
+	}
+}
+
+/**
+ * @todo document
+ * @private
+ * @ingroup DifferenceEngine
+ */
+class _DiffOp_Change extends _DiffOp {
+	var $type = 'change';
+
+	function __construct( $orig, $closing ) {
+		$this->orig = $orig;
+		$this->closing = $closing;
+	}
+
+	function reverse() {
+		return new _DiffOp_Change( $this->closing, $this->orig );
+	}
+}
+
+/**
+ * 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 are (and a bit of code) are from 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 {
+
+	const MAX_XREF_LENGTH =  10000;
+
+	protected $xchanged, $ychanged;
+
+	protected $xv = array(), $yv = array();
+	protected $xind = array(), $yind = array();
+
+	protected $seq = array(), $in_seq = array();
+
+	protected $lcs = 0;
+
+	function diff ( $from_lines, $to_lines ) {
+		wfProfileIn( __METHOD__ );
+
+		// Diff and store locally
+		$this->diff_local( $from_lines, $to_lines );
+
+		// 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.
+		$n_from = sizeof( $from_lines );
+		$n_to = sizeof( $to_lines );
+
+		$edits = array();
+		$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 = array();
+			while ( $xi < $n_from && $yi < $n_to
+			&& !$this->xchanged[$xi] && !$this->ychanged[$yi] ) {
+				$copy[] = $from_lines[$xi++];
+				++$yi;
+			}
+			if ( $copy ) {
+				$edits[] = new _DiffOp_Copy( $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 _DiffOp_Change( $delete, $add );
+			} elseif ( $delete ) {
+				$edits[] = new _DiffOp_Delete( $delete );
+			} elseif ( $add ) {
+				$edits[] = new _DiffOp_Add( $add );
+			}
+		}
+		wfProfileOut( __METHOD__ );
+		return $edits;
+	}
+
+	function diff_local ( $from_lines, $to_lines ) {
+		global $wgExternalDiffEngine;
+		wfProfileIn( __METHOD__ );
+
+		if ( $wgExternalDiffEngine == 'wikidiff3' ) {
+			// wikidiff3
+			$wikidiff3 = new WikiDiff3();
+			$wikidiff3->diff( $from_lines, $to_lines );
+			$this->xchanged = $wikidiff3->removed;
+			$this->ychanged = $wikidiff3->added;
+			unset( $wikidiff3 );
+		} else {
+			// old diff
+			$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 ) );
+		}
+		wfProfileOut( __METHOD__ );
+	}
+
+	/**
+	 * Returns the whole line if it's small enough, or the MD5 hash otherwise
+	 */
+	function _line_hash( $line ) {
+		if ( strlen( $line ) > self::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.
+	 */
+	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( , $y ) = each( $matches ) ) {
+					if ( empty( $this->in_seq[$y] ) ) {
+						$k = $this->_lcs_pos( $y );
+						assert( $k > 0 );
+						$ymids[$k] = $ymids[$k -1];
+						break;
+					}
+				}
+				while ( list ( , $y ) = each( $matches ) ) {
+					if ( $y > $this->seq[$k -1] ) {
+						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 );
+						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 );
+	}
+
+	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;
+			}
+		}
+
+		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.
+	 */
+	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).
+	 */
+	function _shift_boundaries( $lines, &$changed, $other_changed ) {
+		wfProfileIn( __METHOD__ );
+		$i = 0;
+		$j = 0;
+
+		assert( 'sizeof($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] ) {
+				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]' );
+			}
+		}
+		wfProfileOut( __METHOD__ );
+	}
+}
+
+/**
+ * Class representing a 'diff' between two sequences of strings.
+ * @todo document
+ * @private
+ * @ingroup DifferenceEngine
+ */
+class Diff {
+	var $edits;
+
+	/**
+	 * Constructor.
+	 * Computes diff between sequences of strings.
+	 *
+	 * @param $from_lines array An array of strings.
+	 *		  (Typically these are lines from a file.)
+	 * @param $to_lines array An array of strings.
+	 */
+	function __construct( $from_lines, $to_lines ) {
+		$eng = new _DiffEngine;
+		$this->edits = $eng->diff( $from_lines, $to_lines );
+		// $this->_check($from_lines, $to_lines);
+	}
+
+	/**
+	 * Compute reversed Diff.
+	 *
+	 * SYNOPSIS:
+	 *
+	 *	$diff = new Diff($lines1, $lines2);
+	 *	$rev = $diff->reverse();
+	 * @return object A Diff object representing the inverse of the
+	 *				  original diff.
+	 */
+	function reverse() {
+		$rev = $this;
+		$rev->edits = array();
+		foreach ( $this->edits as $edit ) {
+			$rev->edits[] = $edit->reverse();
+		}
+		return $rev;
+	}
+
+	/**
+	 * Check for empty diff.
+	 *
+	 * @return bool True iff two sequences were identical.
+	 */
+	function isEmpty() {
+		foreach ( $this->edits as $edit ) {
+			if ( $edit->type != 'copy' ) {
+				return false;
+			}
+		}
+		return true;
+	}
+
+	/**
+	 * Compute the length of the Longest Common Subsequence (LCS).
+	 *
+	 * This is mostly for diagnostic purposed.
+	 *
+	 * @return int The length of the LCS.
+	 */
+	function lcs() {
+		$lcs = 0;
+		foreach ( $this->edits as $edit ) {
+			if ( $edit->type == 'copy' ) {
+				$lcs += sizeof( $edit->orig );
+			}
+		}
+		return $lcs;
+	}
+
+	/**
+	 * Get the original set of lines.
+	 *
+	 * This reconstructs the $from_lines parameter passed to the
+	 * constructor.
+	 *
+	 * @return array The original sequence of strings.
+	 */
+	function orig() {
+		$lines = array();
+
+		foreach ( $this->edits as $edit ) {
+			if ( $edit->orig ) {
+				array_splice( $lines, sizeof( $lines ), 0, $edit->orig );
+			}
+		}
+		return $lines;
+	}
+
+	/**
+	 * Get the closing set of lines.
+	 *
+	 * This reconstructs the $to_lines parameter passed to the
+	 * constructor.
+	 *
+	 * @return array The sequence of strings.
+	 */
+	function closing() {
+		$lines = array();
+
+		foreach ( $this->edits as $edit ) {
+			if ( $edit->closing ) {
+				array_splice( $lines, sizeof( $lines ), 0, $edit->closing );
+			}
+		}
+		return $lines;
+	}
+
+	/**
+	 * Check a Diff for validity.
+	 *
+	 * This is here only for debugging purposes.
+	 */
+	function _check( $from_lines, $to_lines ) {
+		wfProfileIn( __METHOD__ );
+		if ( serialize( $from_lines ) != serialize( $this->orig() ) ) {
+			trigger_error( "Reconstructed original doesn't match", E_USER_ERROR );
+		}
+		if ( serialize( $to_lines ) != serialize( $this->closing() ) ) {
+			trigger_error( "Reconstructed closing doesn't match", E_USER_ERROR );
+		}
+
+		$rev = $this->reverse();
+		if ( serialize( $to_lines ) != serialize( $rev->orig() ) ) {
+			trigger_error( "Reversed original doesn't match", E_USER_ERROR );
+		}
+		if ( serialize( $from_lines ) != serialize( $rev->closing() ) ) {
+			trigger_error( "Reversed closing doesn't match", E_USER_ERROR );
+		}
+
+
+		$prevtype = 'none';
+		foreach ( $this->edits as $edit ) {
+			if ( $prevtype == $edit->type ) {
+				trigger_error( 'Edit sequence is non-optimal', E_USER_ERROR );
+			}
+			$prevtype = $edit->type;
+		}
+
+		$lcs = $this->lcs();
+		trigger_error( 'Diff okay: LCS = ' . $lcs, E_USER_NOTICE );
+		wfProfileOut( __METHOD__ );
+	}
+}
+
+/**
+ * @todo document, bad name.
+ * @private
+ * @ingroup DifferenceEngine
+ */
+class MappedDiff extends Diff {
+	/**
+	 * Constructor.
+	 *
+	 * Computes diff between sequences of strings.
+	 *
+	 * This can be used to compute things like
+	 * case-insensitve diffs, or diffs which ignore
+	 * changes in white-space.
+	 *
+	 * @param $from_lines array An array of strings.
+	 *	(Typically these are lines from a file.)
+	 *
+	 * @param $to_lines array An array of strings.
+	 *
+	 * @param $mapped_from_lines array This array should
+	 *	have the same size number of elements as $from_lines.
+	 *	The elements in $mapped_from_lines and
+	 *	$mapped_to_lines are what is actually compared
+	 *	when computing the diff.
+	 *
+	 * @param $mapped_to_lines array This array should
+	 *	have the same number of elements as $to_lines.
+	 */
+	function __construct( $from_lines, $to_lines,
+		$mapped_from_lines, $mapped_to_lines ) {
+		wfProfileIn( __METHOD__ );
+
+		assert( sizeof( $from_lines ) == sizeof( $mapped_from_lines ) );
+		assert( sizeof( $to_lines ) == sizeof( $mapped_to_lines ) );
+
+		parent::__construct( $mapped_from_lines, $mapped_to_lines );
+
+		$xi = $yi = 0;
+		for ( $i = 0; $i < sizeof( $this->edits ); $i++ ) {
+			$orig = &$this->edits[$i]->orig;
+			if ( is_array( $orig ) ) {
+				$orig = array_slice( $from_lines, $xi, sizeof( $orig ) );
+				$xi += sizeof( $orig );
+			}
+
+			$closing = &$this->edits[$i]->closing;
+			if ( is_array( $closing ) ) {
+				$closing = array_slice( $to_lines, $yi, sizeof( $closing ) );
+				$yi += sizeof( $closing );
+			}
+		}
+		wfProfileOut( __METHOD__ );
+	}
+}
+
+/**
+ * A class to format Diffs
+ *
+ * This class formats the diff in classic diff format.
+ * It is intended that this class be customized via inheritance,
+ * to obtain fancier outputs.
+ * @todo document
+ * @private
+ * @ingroup DifferenceEngine
+ */
+class DiffFormatter {
+	/**
+	 * Number of leading context "lines" to preserve.
+	 *
+	 * This should be left at zero for this class, but subclasses
+	 * may want to set this to other values.
+	 */
+	var $leading_context_lines = 0;
+
+	/**
+	 * Number of trailing context "lines" to preserve.
+	 *
+	 * This should be left at zero for this class, but subclasses
+	 * may want to set this to other values.
+	 */
+	var $trailing_context_lines = 0;
+
+	/**
+	 * Format a diff.
+	 *
+	 * @param $diff Diff A Diff object.
+	 * @return string The formatted output.
+	 */
+	function format( $diff ) {
+		wfProfileIn( __METHOD__ );
+
+		$xi = $yi = 1;
+		$block = false;
+		$context = array();
+
+		$nlead = $this->leading_context_lines;
+		$ntrail = $this->trailing_context_lines;
+
+		$this->_start_diff();
+
+		foreach ( $diff->edits as $edit ) {
+			if ( $edit->type == 'copy' ) {
+				if ( is_array( $block ) ) {
+					if ( sizeof( $edit->orig ) <= $nlead + $ntrail ) {
+						$block[] = $edit;
+					} else {
+						if ( $ntrail ) {
+							$context = array_slice( $edit->orig, 0, $ntrail );
+							$block[] = new _DiffOp_Copy( $context );
+						}
+						$this->_block( $x0, $ntrail + $xi - $x0,
+							$y0, $ntrail + $yi - $y0,
+							$block );
+						$block = false;
+					}
+				}
+				$context = $edit->orig;
+			} else {
+				if ( !is_array( $block ) ) {
+					$context = array_slice( $context, sizeof( $context ) - $nlead );
+					$x0 = $xi - sizeof( $context );
+					$y0 = $yi - sizeof( $context );
+					$block = array();
+					if ( $context ) {
+						$block[] = new _DiffOp_Copy( $context );
+					}
+				}
+				$block[] = $edit;
+			}
+
+			if ( $edit->orig ) {
+				$xi += sizeof( $edit->orig );
+			}
+			if ( $edit->closing ) {
+				$yi += sizeof( $edit->closing );
+			}
+		}
+
+		if ( is_array( $block ) ) {
+			$this->_block( $x0, $xi - $x0,
+				$y0, $yi - $y0,
+				$block );
+		}
+
+		$end = $this->_end_diff();
+		wfProfileOut( __METHOD__ );
+		return $end;
+	}
+
+	function _block( $xbeg, $xlen, $ybeg, $ylen, &$edits ) {
+		wfProfileIn( __METHOD__ );
+		$this->_start_block( $this->_block_header( $xbeg, $xlen, $ybeg, $ylen ) );
+		foreach ( $edits as $edit ) {
+			if ( $edit->type == 'copy' ) {
+				$this->_context( $edit->orig );
+			} elseif ( $edit->type == 'add' ) {
+				$this->_added( $edit->closing );
+			} elseif ( $edit->type == 'delete' ) {
+				$this->_deleted( $edit->orig );
+			} elseif ( $edit->type == 'change' ) {
+				$this->_changed( $edit->orig, $edit->closing );
+			} else {
+				trigger_error( 'Unknown edit type', E_USER_ERROR );
+			}
+		}
+		$this->_end_block();
+		wfProfileOut( __METHOD__ );
+	}
+
+	function _start_diff() {
+		ob_start();
+	}
+
+	function _end_diff() {
+		$val = ob_get_contents();
+		ob_end_clean();
+		return $val;
+	}
+
+	function _block_header( $xbeg, $xlen, $ybeg, $ylen ) {
+		if ( $xlen > 1 ) {
+			$xbeg .= ',' . ( $xbeg + $xlen - 1 );
+		}
+		if ( $ylen > 1 ) {
+			$ybeg .= ',' . ( $ybeg + $ylen - 1 );
+		}
+
+		return $xbeg . ( $xlen ? ( $ylen ? 'c' : 'd' ) : 'a' ) . $ybeg;
+	}
+
+	function _start_block( $header ) {
+		echo $header . "\n";
+	}
+
+	function _end_block() {
+	}
+
+	function _lines( $lines, $prefix = ' ' ) {
+		foreach ( $lines as $line ) {
+			echo "$prefix $line\n";
+		}
+	}
+
+	function _context( $lines ) {
+		$this->_lines( $lines );
+	}
+
+	function _added( $lines ) {
+		$this->_lines( $lines, '>' );
+	}
+	function _deleted( $lines ) {
+		$this->_lines( $lines, '<' );
+	}
+
+	function _changed( $orig, $closing ) {
+		$this->_deleted( $orig );
+		echo "---\n";
+		$this->_added( $closing );
+	}
+}
+
+/**
+ * A formatter that outputs unified diffs
+ * @ingroup DifferenceEngine
+ */
+class UnifiedDiffFormatter extends DiffFormatter {
+	var $leading_context_lines = 2;
+	var $trailing_context_lines = 2;
+
+	function _added( $lines ) {
+		$this->_lines( $lines, '+' );
+	}
+	function _deleted( $lines ) {
+		$this->_lines( $lines, '-' );
+	}
+	function _changed( $orig, $closing ) {
+		$this->_deleted( $orig );
+		$this->_added( $closing );
+	}
+	function _block_header( $xbeg, $xlen, $ybeg, $ylen ) {
+		return "@@ -$xbeg,$xlen +$ybeg,$ylen @@";
+	}
+}
+
+/**
+ * A pseudo-formatter that just passes along the Diff::$edits array
+ * @ingroup DifferenceEngine
+ */
+class ArrayDiffFormatter extends DiffFormatter {
+	function format( $diff ) {
+		$oldline = 1;
+		$newline = 1;
+		$retval = array();
+		foreach ( $diff->edits as $edit ) {
+			switch( $edit->type ) {
+				case 'add':
+					foreach ( $edit->closing as $l ) {
+						$retval[] = array(
+							'action' => 'add',
+							'new' => $l,
+							'newline' => $newline++
+						);
+					}
+					break;
+				case 'delete':
+					foreach ( $edit->orig as $l ) {
+						$retval[] = array(
+							'action' => 'delete',
+							'old' => $l,
+							'oldline' => $oldline++,
+						);
+					}
+					break;
+				case 'change':
+					foreach ( $edit->orig as $i => $l ) {
+						$retval[] = array(
+							'action' => 'change',
+							'old' => $l,
+							'new' => isset( $edit->closing[$i] ) ? $edit->closing[$i] : null,
+							'oldline' => $oldline++,
+							'newline' => $newline++,
+						);
+					}
+					break;
+				case 'copy':
+					$oldline += count( $edit->orig );
+					$newline += count( $edit->orig );
+			}
+		}
+		return $retval;
+	}
+}
+
+/**
+ * Additions by Axel Boldt follow, partly taken from diff.php, phpwiki-1.3.3
+ */
+
+define( 'NBSP', '&#160;' ); // iso-8859-x non-breaking space.
+
+/**
+ * @todo document
+ * @private
+ * @ingroup DifferenceEngine
+ */
+class _HWLDF_WordAccumulator {
+	function __construct() {
+		$this->_lines = array();
+		$this->_line = '';
+		$this->_group = '';
+		$this->_tag = '';
+	}
+
+	function _flushGroup( $new_tag ) {
+		if ( $this->_group !== '' ) {
+			if ( $this->_tag == 'ins' ) {
+				$this->_line .= '<ins class="diffchange diffchange-inline">' .
+						htmlspecialchars( $this->_group ) . '</ins>';
+			} elseif ( $this->_tag == 'del' ) {
+				$this->_line .= '<del class="diffchange diffchange-inline">' .
+						htmlspecialchars( $this->_group ) . '</del>';
+			} else {
+				$this->_line .= htmlspecialchars( $this->_group );
+			}
+		}
+		$this->_group = '';
+		$this->_tag = $new_tag;
+	}
+
+	function _flushLine( $new_tag ) {
+		$this->_flushGroup( $new_tag );
+		if ( $this->_line != '' ) {
+			array_push( $this->_lines, $this->_line );
+		} else {
+			# make empty lines visible by inserting an NBSP
+			array_push( $this->_lines, NBSP );
+		}
+		$this->_line = '';
+	}
+
+	function addWords ( $words, $tag = '' ) {
+		if ( $tag != $this->_tag ) {
+			$this->_flushGroup( $tag );
+		}
+
+		foreach ( $words as $word ) {
+			// new-line should only come as first char of word.
+			if ( $word == '' ) {
+				continue;
+			}
+			if ( $word[0] == "\n" ) {
+				$this->_flushLine( $tag );
+				$word = substr( $word, 1 );
+			}
+			assert( !strstr( $word, "\n" ) );
+			$this->_group .= $word;
+		}
+	}
+
+	function getLines() {
+		$this->_flushLine( '~done' );
+		return $this->_lines;
+	}
+}
+
+/**
+ * @todo document
+ * @private
+ * @ingroup DifferenceEngine
+ */
+class WordLevelDiff extends MappedDiff {
+	const MAX_LINE_LENGTH = 10000;
+
+	function __construct ( $orig_lines, $closing_lines ) {
+		wfProfileIn( __METHOD__ );
+
+		list( $orig_words, $orig_stripped ) = $this->_split( $orig_lines );
+		list( $closing_words, $closing_stripped ) = $this->_split( $closing_lines );
+
+		parent::__construct( $orig_words, $closing_words,
+		$orig_stripped, $closing_stripped );
+		wfProfileOut( __METHOD__ );
+	}
+
+	function _split( $lines ) {
+		wfProfileIn( __METHOD__ );
+
+		$words = array();
+		$stripped = array();
+		$first = true;
+		foreach ( $lines as $line ) {
+			# If the line is too long, just pretend the entire line is one big word
+			# This prevents resource exhaustion problems
+			if ( $first ) {
+				$first = false;
+			} else {
+				$words[] = "\n";
+				$stripped[] = "\n";
+			}
+			if ( strlen( $line ) > self::MAX_LINE_LENGTH ) {
+				$words[] = $line;
+				$stripped[] = $line;
+			} else {
+				$m = array();
+				if ( preg_match_all( '/ ( [^\S\n]+ | [0-9_A-Za-z\x80-\xff]+ | . ) (?: (?!< \n) [^\S\n])? /xs',
+					$line, $m ) )
+				{
+					$words = array_merge( $words, $m[0] );
+					$stripped = array_merge( $stripped, $m[1] );
+				}
+			}
+		}
+		wfProfileOut( __METHOD__ );
+		return array( $words, $stripped );
+	}
+
+	function orig() {
+		wfProfileIn( __METHOD__ );
+		$orig = new _HWLDF_WordAccumulator;
+
+		foreach ( $this->edits as $edit ) {
+			if ( $edit->type == 'copy' ) {
+				$orig->addWords( $edit->orig );
+			} elseif ( $edit->orig ) {
+				$orig->addWords( $edit->orig, 'del' );
+			}
+		}
+		$lines = $orig->getLines();
+		wfProfileOut( __METHOD__ );
+		return $lines;
+	}
+
+	function closing() {
+		wfProfileIn( __METHOD__ );
+		$closing = new _HWLDF_WordAccumulator;
+
+		foreach ( $this->edits as $edit ) {
+			if ( $edit->type == 'copy' ) {
+				$closing->addWords( $edit->closing );
+			} elseif ( $edit->closing ) {
+				$closing->addWords( $edit->closing, 'ins' );
+			}
+		}
+		$lines = $closing->getLines();
+		wfProfileOut( __METHOD__ );
+		return $lines;
+	}
+}
+
+/**
+ * Wikipedia Table style diff formatter.
+ * @todo document
+ * @private
+ * @ingroup DifferenceEngine
+ */
+class TableDiffFormatter extends DiffFormatter {
+	function __construct() {
+		$this->leading_context_lines = 2;
+		$this->trailing_context_lines = 2;
+	}
+
+	public static function escapeWhiteSpace( $msg ) {
+		$msg = preg_replace( '/^ /m', '&#160; ', $msg );
+		$msg = preg_replace( '/ $/m', ' &#160;', $msg );
+		$msg = preg_replace( '/  /', '&#160; ', $msg );
+		return $msg;
+	}
+
+	function _block_header( $xbeg, $xlen, $ybeg, $ylen ) {
+		$r = '<tr><td colspan="2" class="diff-lineno"><!--LINE ' . $xbeg . "--></td>\n" .
+		  '<td colspan="2" class="diff-lineno"><!--LINE ' . $ybeg . "--></td></tr>\n";
+		return $r;
+	}
+
+	function _start_block( $header ) {
+		echo $header;
+	}
+
+	function _end_block() {
+	}
+
+	function _lines( $lines, $prefix = ' ', $color = 'white' ) {
+	}
+
+	# HTML-escape parameter before calling this
+	function addedLine( $line ) {
+		return $this->wrapLine( '+', 'diff-addedline', $line );
+	}
+
+	# HTML-escape parameter before calling this
+	function deletedLine( $line ) {
+		return $this->wrapLine( '−', 'diff-deletedline', $line );
+	}
+
+	# HTML-escape parameter before calling this
+	function contextLine( $line ) {
+		return $this->wrapLine( '&#160;', 'diff-context', $line );
+	}
+
+	private function wrapLine( $marker, $class, $line ) {
+		if ( $line !== '' ) {
+			// The <div> wrapper is needed for 'overflow: auto' style to scroll properly
+			$line = Xml::tags( 'div', null, $this->escapeWhiteSpace( $line ) );
+		}
+		return "<td class='diff-marker'>$marker</td><td class='$class'>$line</td>";
+	}
+
+	function emptyLine() {
+		return '<td colspan="2">&#160;</td>';
+	}
+
+	function _added( $lines ) {
+		foreach ( $lines as $line ) {
+			echo '<tr>' . $this->emptyLine() .
+			$this->addedLine( '<ins class="diffchange">' .
+			htmlspecialchars( $line ) . '</ins>' ) . "</tr>\n";
+		}
+	}
+
+	function _deleted( $lines ) {
+		foreach ( $lines as $line ) {
+			echo '<tr>' . $this->deletedLine( '<del class="diffchange">' .
+			htmlspecialchars( $line ) . '</del>' ) .
+			$this->emptyLine() . "</tr>\n";
+		}
+	}
+
+	function _context( $lines ) {
+		foreach ( $lines as $line ) {
+			echo '<tr>' .
+			$this->contextLine( htmlspecialchars( $line ) ) .
+			$this->contextLine( htmlspecialchars( $line ) ) . "</tr>\n";
+		}
+	}
+
+	function _changed( $orig, $closing ) {
+		wfProfileIn( __METHOD__ );
+
+		$diff = new WordLevelDiff( $orig, $closing );
+		$del = $diff->orig();
+		$add = $diff->closing();
+
+		# Notice that WordLevelDiff returns HTML-escaped output.
+		# Hence, we will be calling addedLine/deletedLine without HTML-escaping.
+
+		while ( $line = array_shift( $del ) ) {
+			$aline = array_shift( $add );
+			echo '<tr>' . $this->deletedLine( $line ) .
+			$this->addedLine( $aline ) . "</tr>\n";
+		}
+		foreach ( $add as $line ) {	# If any leftovers
+			echo '<tr>' . $this->emptyLine() .
+			$this->addedLine( $line ) . "</tr>\n";
+		}
+		wfProfileOut( __METHOD__ );
+	}
+}
diff --git a/includes/diff/DifferenceEngine.php b/includes/diff/DifferenceEngine.php
index edf35a92..5902461b 100644
--- a/includes/diff/DifferenceEngine.php
+++ b/includes/diff/DifferenceEngine.php
@@ -22,11 +22,19 @@ class DifferenceEngine {
 	/**#@+
 	 * @private
 	 */
-	var $mOldid, $mNewid, $mTitle;
+	var $mOldid, $mNewid;
 	var $mOldtitle, $mNewtitle, $mPagetitle;
 	var $mOldtext, $mNewtext;
-	var $mOldPage, $mNewPage;
+
+	/**
+	 * @var Title
+	 */
+	var $mOldPage, $mNewPage, $mTitle;
 	var $mRcidMarkPatrolled;
+
+	/**
+	 * @var Revision
+	 */
 	var $mOldRev, $mNewRev;
 	var $mRevisionsLoaded = false; // Have the revisions been loaded
 	var $mTextLoaded = 0; // How many text blobs have been loaded, 0, 1 or 2?
@@ -49,9 +57,9 @@ class DifferenceEngine {
 	/**
 	 * Constructor
 	 * @param $titleObj Title object that the diff is associated with
-	 * @param $old Integer: old ID we want to show and diff with.
-	 * @param $new String: either 'prev' or 'next'.
-	 * @param $rcid Integer: ??? FIXME (default 0)
+	 * @param $old Integer old ID we want to show and diff with.
+	 * @param $new String either 'prev' or 'next'.
+	 * @param $rcid Integer ??? FIXME (default 0)
 	 * @param $refreshCache boolean If set, refreshes the diff cache
 	 * @param $unhide boolean If set, allow viewing deleted revs
 	 */
@@ -62,7 +70,7 @@ class DifferenceEngine {
 			$this->mTitle = $titleObj;
 		} else {
 			global $wgTitle;
-			$this->mTitle = $wgTitle;
+			$this->mTitle = $wgTitle; // @TODO: get rid of this
 		}
 		wfDebug( "DifferenceEngine old '$old' new '$new' rcid '$rcid'\n" );
 
@@ -91,26 +99,82 @@ class DifferenceEngine {
 		$this->unhide = $unhide;
 	}
 
+	/**
+	 * @param $value bool
+	 */
 	function setReducedLineNumbers( $value = true ) {
 		$this->mReducedLineNumbers = $value;
 	}
 
+	/**
+	 * @return Title
+	 */
 	function getTitle() {
 		return $this->mTitle;
 	}
 
+	/**
+	 * @return bool
+	 */
 	function wasCacheHit() {
 		return $this->mCacheHit;
 	}
 
+	/**
+	 * @return int
+	 */
 	function getOldid() {
 		return $this->mOldid;
 	}
 
+	/**
+	 * @return Bool|int
+	 */
 	function getNewid() {
 		return $this->mNewid;
 	}
 
+	/**
+	 * Look up a special:Undelete link to the given deleted revision id,
+	 * as a workaround for being unable to load deleted diffs in currently.
+	 *
+	 * @param int $id revision ID
+	 * @return mixed URL or false
+	 */
+	function deletedLink( $id ) {
+		global $wgUser;
+		if ( $wgUser->isAllowed( 'deletedhistory' ) ) {
+			$dbr = wfGetDB( DB_SLAVE );
+			$row = $dbr->selectRow('archive', '*',
+				array( 'ar_rev_id' => $id ),
+				__METHOD__ );
+			if ( $row ) {
+				$rev = Revision::newFromArchiveRow( $row );
+				$title = Title::makeTitleSafe( $row->ar_namespace, $row->ar_title );
+				return SpecialPage::getTitleFor( 'Undelete' )->getFullURL( array(
+					'target' => $title->getPrefixedText(),
+					'timestamp' => $rev->getTimestamp()
+				));
+			}
+		}
+		return false;
+	}
+
+	/**
+	 * Build a wikitext link toward a deleted revision, if viewable.
+	 *
+	 * @param int $id revision ID
+	 * @return string wikitext fragment
+	 */
+	function deletedIdMarker( $id ) {
+		$link = $this->deletedLink( $id );
+		if ( $link ) {
+			return "[$link $id]";
+		} else {
+			return $id;
+		}
+	}
+
 	function showDiffPage( $diffOnly = false ) {
 		global $wgUser, $wgOut, $wgUseExternalEditor, $wgUseRCPatrol;
 		wfProfileIn( __METHOD__ );
@@ -122,14 +186,14 @@ class DifferenceEngine {
 		# we'll use the application/x-external-editor interface to call
 		# an external diff tool like kompare, kdiff3, etc.
 		if ( $wgUseExternalEditor && $wgUser->getOption( 'externaldiff' ) ) {
-			global $wgInputEncoding, $wgServer, $wgScript, $wgLang;
+			global $wgCanonicalServer, $wgScript, $wgLang;
 			$wgOut->disable();
-			header ( "Content-type: application/x-external-editor; charset=" . $wgInputEncoding );
-			$url1 = $this->mTitle->getFullURL( array(
+			header ( "Content-type: application/x-external-editor; charset=UTF-8" );
+			$url1 = $this->mTitle->getCanonical( array(
 				'action' => 'raw',
 				'oldid' => $this->mOldid
 			) );
-			$url2 = $this->mTitle->getFullURL( array(
+			$url2 = $this->mTitle->getCanonical( array(
 				'action' => 'raw',
 				'oldid' => $this->mNewid
 			) );
@@ -138,7 +202,7 @@ class DifferenceEngine {
 			[Process]
 			Type=Diff text
 			Engine=MediaWiki
-			Script={$wgServer}{$wgScript}
+			Script={$wgCanonicalServer}{$wgScript}
 			Special namespace={$special}
 
 			[File]
@@ -157,10 +221,13 @@ CONTROL;
 
 		$wgOut->setArticleFlag( false );
 		if ( !$this->loadRevisionData() ) {
+			// Sounds like a deleted revision... Let's see what we can do.
 			$t = $this->mTitle->getPrefixedText();
-			$d = wfMsgExt( 'missingarticle-diff', array( 'escape' ), $this->mOldid, $this->mNewid );
+			$d = wfMsgExt( 'missingarticle-diff', array( 'escape' ),
+				$this->deletedIdMarker( $this->mOldid ),
+				$this->deletedIdMarker( $this->mNewid ) );
 			$wgOut->setPagetitle( wfMsg( 'errorpagetitle' ) );
-			$wgOut->addWikiMsg( 'missing-article', "<nowiki>$t</nowiki>", $d );
+			$wgOut->addWikiMsg( 'missing-article', "<nowiki>$t</nowiki>", "<span class='plainlinks'>$d</span>" );
 			wfProfileOut( __METHOD__ );
 			return;
 		}
@@ -181,8 +248,6 @@ CONTROL;
 			return;
 		}
 
-		$wgOut->suppressQuickbar();
-
 		$oldTitle = $this->mOldPage->getPrefixedText();
 		$newTitle = $this->mNewPage->getPrefixedText();
 		if ( $oldTitle == $newTitle ) {
@@ -206,6 +271,9 @@ CONTROL;
 		}
 
 		$sk = $wgUser->getSkin();
+		if ( method_exists( $sk, 'suppressQuickbar' ) ) {
+			$sk->suppressQuickbar();
+		}
 
 		// Check if page is editable
 		$editable = $this->mNewRev->getTitle()->userCan( 'edit' );
@@ -372,7 +440,7 @@ CONTROL;
 			if ( !$allowed ) {
 				$msg = $suppressed ? 'rev-suppressed-no-diff' : 'rev-deleted-no-diff';
 				# Give explanation for why revision is not visible
-				$wgOut->wrapWikiMsg( "<div class='mw-warning plainlinks'>\n$1\n</div>\n",
+				$wgOut->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n",
 					array( $msg ) );
 			} else {
 				# Give explanation and add a link to view the diff...
@@ -382,7 +450,7 @@ CONTROL;
 					'unhide' => 1
 				) );
 				$msg = $suppressed ? 'rev-suppressed-unhide-diff' : 'rev-deleted-unhide-diff';
-				$wgOut->wrapWikiMsg( "<div class='mw-warning plainlinks'>\n$1\n</div>\n", array( $msg, $link ) );
+				$wgOut->wrapWikiMsg( "<div id='mw-$msg' class='mw-warning plainlinks'>\n$1\n</div>\n", array( $msg, $link ) );
 			}
 		# Otherwise, output a regular diff...
 		} else {
@@ -390,7 +458,7 @@ CONTROL;
 			$notice = '';
 			if ( $deleted ) {
 				$msg = $suppressed ? 'rev-suppressed-diff-view' : 'rev-deleted-diff-view';
-				$notice = "<div class='mw-warning plainlinks'>\n" . wfMsgExt( $msg, 'parseinline' ) . "</div>\n";
+				$notice = "<div id='mw-$msg' class='mw-warning plainlinks'>\n" . wfMsgExt( $msg, 'parseinline' ) . "</div>\n";
 			}
 			$this->showDiff( $oldHeader, $newHeader, $notice );
 			if ( !$diffOnly ) {
@@ -400,6 +468,10 @@ CONTROL;
 		wfProfileOut( __METHOD__ );
 	}
 
+	/**
+	 * @param $rev Revision
+	 * @return String
+	 */
 	protected function revisionDeleteLink( $rev ) {
 		global $wgUser;
 		$link = '';
@@ -431,42 +503,37 @@ CONTROL;
 	function renderNewRevision() {
 		global $wgOut, $wgUser;
 		wfProfileIn( __METHOD__ );
+		# Add "current version as of X" title
+		$wgOut->addHTML( "<hr class='diff-hr' />
+		<h2 class='diff-currentversion-title'>{$this->mPagetitle}</h2>\n" );
+		# Page content may be handled by a hooked call instead...
+		if ( wfRunHooks( 'ArticleContentOnDiff', array( $this, $wgOut ) ) ) {
+			# Use the current version parser cache if applicable
+			$pCache = true;
+			if ( !$this->mNewRev->isCurrent() ) {
+				$oldEditSectionSetting = $wgOut->parserOptions()->setEditSection( false );
+				$pCache = false;
+			}
 
-		$wgOut->addHTML( "<hr /><h2>{$this->mPagetitle}</h2>\n" );
-		# Add deleted rev tag if needed
-		if ( !$this->mNewRev->userCan( Revision::DELETED_TEXT ) ) {
-			$wgOut->wrapWikiMsg( "<div class='mw-warning plainlinks'>\n$1\n</div>\n", 'rev-deleted-text-permission' );
-		} else if ( $this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
-			$wgOut->wrapWikiMsg( "<div class='mw-warning plainlinks'>\n$1\n</div>\n", 'rev-deleted-text-view' );
-		}
-
-		$pCache = true;
-		if ( !$this->mNewRev->isCurrent() ) {
-			$oldEditSectionSetting = $wgOut->parserOptions()->setEditSection( false );
-			$pCache = false;
-		}
-
-		$this->loadNewText();
-		if ( is_object( $this->mNewRev ) ) {
+			$this->loadNewText();
 			$wgOut->setRevisionId( $this->mNewRev->getId() );
-		}
 
-		if ( $this->mTitle->isCssJsSubpage() || $this->mTitle->isCssOrJsPage() ) {
-			// Stolen from Article::view --AG 2007-10-11
-			// Give hooks a chance to customise the output
-			if ( wfRunHooks( 'ShowRawCssJs', array( $this->mNewtext, $this->mTitle, $wgOut ) ) ) {
-				// Wrap the whole lot in a <pre> and don't parse
-				$m = array();
-				preg_match( '!\.(css|js)$!u', $this->mTitle->getText(), $m );
-				$wgOut->addHTML( "<pre class=\"mw-code mw-{$m[1]}\" dir=\"ltr\">\n" );
-				$wgOut->addHTML( htmlspecialchars( $this->mNewtext ) );
-				$wgOut->addHTML( "\n</pre>\n" );
-			}
-		} elseif ( wfRunHooks( 'ArticleContentOnDiff', array( $this, $wgOut ) ) ) {
-			if ( $pCache ) {
+			if ( $this->mTitle->isCssJsSubpage() || $this->mTitle->isCssOrJsPage() ) {
+				// Stolen from Article::view --AG 2007-10-11
+				// Give hooks a chance to customise the output
+				// @TODO: standardize this crap into one function
+				if ( wfRunHooks( 'ShowRawCssJs', array( $this->mNewtext, $this->mTitle, $wgOut ) ) ) {
+					// Wrap the whole lot in a <pre> and don't parse
+					$m = array();
+					preg_match( '!\.(css|js)$!u', $this->mTitle->getText(), $m );
+					$wgOut->addHTML( "<pre class=\"mw-code mw-{$m[1]}\" dir=\"ltr\">\n" );
+					$wgOut->addHTML( htmlspecialchars( $this->mNewtext ) );
+					$wgOut->addHTML( "\n</pre>\n" );
+				}
+			} elseif ( $pCache ) {
 				$article = new Article( $this->mTitle, 0 );
 				$pOutput = ParserCache::singleton()->get( $article, $wgOut->parserOptions() );
-				if ( $pOutput ) {
+				if( $pOutput ) {
 					$wgOut->addParserOutput( $pOutput );
 				} else {
 					$article->doViewParse();
@@ -474,12 +541,11 @@ CONTROL;
 			} else {
 				$wgOut->addWikiTextTidy( $this->mNewtext );
 			}
-		}
 
-		if ( is_object( $this->mNewRev ) && !$this->mNewRev->isCurrent() ) {
-			$wgOut->parserOptions()->setEditSection( $oldEditSectionSetting );
+			if ( !$this->mNewRev->isCurrent() ) {
+				$wgOut->parserOptions()->setEditSection( $oldEditSectionSetting );
+			}
 		}
-
 		# Add redundant patrol link on bottom...
 		if ( $this->mRcidMarkPatrolled && $this->mTitle->quickUserCan( 'patrol' ) ) {
 			$sk = $wgUser->getSkin();
@@ -491,9 +557,9 @@ CONTROL;
 					wfMsgHtml( 'markaspatrolleddiff' ),
 					array(),
 					array(
-						'action' => 'markpatrolled',
-						'rcid' => $this->mRcidMarkPatrolled,
-						'token' => $token,
+						'action'	=> 'markpatrolled',
+						'rcid'		=> $this->mRcidMarkPatrolled,
+						'token' 	=> $token,
 					)
 				) . ']</div>'
 			 );
@@ -514,9 +580,11 @@ CONTROL;
 		#
 		if ( ! $this->loadNewText() ) {
 			$t = $this->mTitle->getPrefixedText();
-			$d = wfMsgExt( 'missingarticle-diff', array( 'escape' ), $this->mOldid, $this->mNewid );
+			$d = wfMsgExt( 'missingarticle-diff', array( 'escape' ),
+					$this->deletedIdMarker( $this->mOldid ),
+					$this->deletedIdMarker( $this->mNewid ) );
 			$wgOut->setPagetitle( wfMsg( 'errorpagetitle' ) );
-			$wgOut->addWikiMsg( 'missing-article', "<nowiki>$t</nowiki>", $d );
+			$wgOut->addWikiMsg( 'missing-article', "<nowiki>$t</nowiki>", "<span class='plainlinks'>$d</span>" );
 			wfProfileOut( __METHOD__ );
 			return;
 		}
@@ -571,6 +639,8 @@ CONTROL;
 	/**
 	 * Get the diff text, send it to $wgOut
 	 * Returns false if the diff could not be generated, otherwise returns true
+	 *
+	 * @return bool
 	 */
 	function showDiff( $otitle, $ntitle, $notice = '' ) {
 		global $wgOut;
@@ -590,8 +660,7 @@ CONTROL;
 	 */
 	function showDiffStyle() {
 		global $wgOut;
-		$wgOut->addModuleStyles( 'mediawiki.legacy.diff' );
-		$wgOut->addModuleScripts( 'mediawiki.legacy.diff' );
+		$wgOut->addModuleStyles( 'mediawiki.action.history.diff' );
 	}
 
 	/**
@@ -691,16 +760,12 @@ CONTROL;
 		global $wgExternalDiffEngine;
 		if ( $wgExternalDiffEngine == 'wikidiff' && !function_exists( 'wikidiff_do_diff' ) ) {
 			wfProfileIn( __METHOD__ . '-php_wikidiff.so' );
-			wfSuppressWarnings();
-			dl( 'php_wikidiff.so' );
-			wfRestoreWarnings();
+			wfDl( 'php_wikidiff' );
 			wfProfileOut( __METHOD__ . '-php_wikidiff.so' );
 		}
-		else if ( $wgExternalDiffEngine == 'wikidiff2' && !function_exists( 'wikidiff2_do_diff' ) ) {
+		elseif ( $wgExternalDiffEngine == 'wikidiff2' && !function_exists( 'wikidiff2_do_diff' ) ) {
 			wfProfileIn( __METHOD__ . '-php_wikidiff2.so' );
-			wfSuppressWarnings();
 			wfDl( 'wikidiff2' );
-			wfRestoreWarnings();
 			wfProfileOut( __METHOD__ . '-php_wikidiff2.so' );
 		}
 	}
@@ -714,6 +779,8 @@ CONTROL;
 	function generateDiffBody( $otext, $ntext ) {
 		global $wgExternalDiffEngine, $wgContLang;
 
+		wfProfileIn( __METHOD__ );
+
 		$otext = str_replace( "\r\n", "\n", $otext );
 		$ntext = str_replace( "\r\n", "\n", $ntext );
 
@@ -724,6 +791,7 @@ CONTROL;
 			# input text to be HTML-escaped already
 			$otext = htmlspecialchars ( $wgContLang->segmentForDiff( $otext ) );
 			$ntext = htmlspecialchars ( $wgContLang->segmentForDiff( $ntext ) );
+			wfProfileOut( __METHOD__ );
 			return $wgContLang->unsegmentForDiff( wikidiff_do_diff( $otext, $ntext, 2 ) ) .
 			$this->debug( 'wikidiff1' );
 		}
@@ -735,6 +803,7 @@ CONTROL;
 			$text = wikidiff2_do_diff( $otext, $ntext, 2 );
 			$text .= $this->debug( 'wikidiff2' );
 			wfProfileOut( 'wikidiff2_do_diff' );
+			wfProfileOut( __METHOD__ );
 			return $text;
 		}
 		if ( $wgExternalDiffEngine != 'wikidiff3' && $wgExternalDiffEngine !== false ) {
@@ -776,7 +845,6 @@ CONTROL;
 		$difftext = $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) ) .
 		wfProfileOut( __METHOD__ );
 		return $difftext;
-		$this->debug();
 	}
 
 	/**
@@ -828,18 +896,18 @@ CONTROL;
 			return '';
 		}
 
-		$oldid = $this->mOldRev->getId();
-		$newid = $this->mNewRev->getId();
-		if ( $oldid > $newid ) {
-			$tmp = $oldid; $oldid = $newid; $newid = $tmp;
+		if ( $this->mOldRev->getTimestamp() > $this->mNewRev->getTimestamp() ) {
+			$oldRev = $this->mNewRev; // flip
+			$newRev = $this->mOldRev; // flip
+		} else { // normal case
+			$oldRev = $this->mOldRev;
+			$newRev = $this->mNewRev;
 		}
 
-		$nEdits = $this->mTitle->countRevisionsBetween( $oldid, $newid );
+		$nEdits = $this->mTitle->countRevisionsBetween( $oldRev, $newRev );
 		if ( $nEdits > 0 ) {
-			$limit = 100;
-			// We use ($limit + 1) so we can detect if there are > 100 authors
-			// in a given revision range. In that case, diff-multi-manyusers is used.
-			$numUsers = $this->mTitle->countAuthorsBetween( $oldid, $newid, $limit + 1 );
+			$limit = 100; // use diff-multi-manyusers if too many users
+			$numUsers = $this->mTitle->countAuthorsBetween( $oldRev, $newRev, $limit );
 			return self::intermediateEditsMsg( $nEdits, $numUsers, $limit );
 		}
 		return ''; // nothing
@@ -866,9 +934,15 @@ CONTROL;
 
 	/**
 	 * Add the header to a diff body
+	 *
+	 * @return string
 	 */
-	static function addHeader( $diff, $otitle, $ntitle, $multi = '', $notice = '' ) {
-		$header = "<table class='diff'>";
+	function addHeader( $diff, $otitle, $ntitle, $multi = '', $notice = '' ) {
+		// shared.css sets diff in interface language/dir,
+		// but the actual content should be in the page language/dir
+		$pageLang = $this->mTitle->getPageLanguage();
+		$tableClass = 'diff diff-contentalign-' . htmlspecialchars( $pageLang->alignStart() );
+		$header = "<table class='$tableClass'>";
 		if ( $diff ) { // Safari/Chrome show broken output if cols not used
 			$header .= "
 			<col class='diff-marker' />
@@ -916,6 +990,8 @@ CONTROL;
 	 * If oldid is false, leave the corresponding revision object set
 	 * to false. This is impossible via ordinary user input, and is provided for
 	 * API convenience.
+	 *
+	 * @return bool
 	 */
 	function loadRevisionData() {
 		global $wgLang, $wgUser;
@@ -930,8 +1006,9 @@ CONTROL;
 		$this->mNewRev = $this->mNewid
 			? Revision::newFromId( $this->mNewid )
 			: Revision::newFromTitle( $this->mTitle );
-		if ( !$this->mNewRev instanceof Revision )
+		if ( !$this->mNewRev instanceof Revision ) {
 			return false;
+		}
 
 		// Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
 		$this->mNewid = $this->mNewRev->getId();
@@ -980,7 +1057,7 @@ CONTROL;
 		}
 		if ( !$this->mNewRev->userCan( Revision::DELETED_TEXT ) ) {
 			$this->mNewtitle = "<span class='history-deleted'>{$this->mPagetitle}</span>";
-		} else if ( $this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
+		} elseif ( $this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
 			$this->mNewtitle = "<span class='history-deleted'>{$this->mNewtitle}</span>";
 		}
 
@@ -1022,20 +1099,20 @@ CONTROL;
 			$this->mOldtitle = "<a href='$oldLink'>{$this->mOldPagetitle}</a>"
 			. " (<a href='$oldEdit'>" . wfMsgHtml( $editable ? 'editold' : 'viewsourceold' ) . "</a>)";
 			// Add an "undo" link
-			$newUndo = $this->mNewPage->escapeLocalUrl( array(
-				'action' => 'edit',
-				'undoafter' => $this->mOldid,
-				'undo' => $this->mNewid
-			) );
-			$htmlLink = htmlspecialchars( wfMsg( 'editundo' ) );
-			$htmlTitle = Xml::expandAttributes( array( 'title' => $wgUser->getSkin()->titleAttrib( 'undo' ) ) );
 			if ( $editable && !$this->mOldRev->isDeleted( Revision::DELETED_TEXT ) && !$this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
-				$this->mNewtitle .= " (<a href='$newUndo' $htmlTitle>" . $htmlLink . "</a>)";
+				$undoLink = Html::element( 'a', array(
+					'href' => $this->mNewPage->getLocalUrl( array(
+						'action' => 'edit',
+						'undoafter' => $this->mOldid,
+						'undo' => $this->mNewid ) ),
+					'title' => $wgUser->getSkin()->titleAttrib( 'undo' )
+				), wfMsg( 'editundo' ) );
+				$this->mNewtitle .= ' (' . $undoLink . ')';
 			}
 
 			if ( !$this->mOldRev->userCan( Revision::DELETED_TEXT ) ) {
 				$this->mOldtitle = '<span class="history-deleted">' . $this->mOldPagetitle . '</span>';
-			} else if ( $this->mOldRev->isDeleted( Revision::DELETED_TEXT ) ) {
+			} elseif ( $this->mOldRev->isDeleted( Revision::DELETED_TEXT ) ) {
 				$this->mOldtitle = '<span class="history-deleted">' . $this->mOldtitle . '</span>';
 			}
 		}
@@ -1045,6 +1122,8 @@ CONTROL;
 
 	/**
 	 * Load the text of the revisions, as well as revision data.
+	 *
+	 * @return bool
 	 */
 	function loadText() {
 		if ( $this->mTextLoaded == 2 ) {
@@ -1074,6 +1153,8 @@ CONTROL;
 
 	/**
 	 * Load the text of the new revision, not the old one
+	 *
+	 * @return bool
 	 */
 	function loadNewText() {
 		if ( $this->mTextLoaded >= 1 ) {
diff --git a/includes/diff/WikiDiff.php b/includes/diff/WikiDiff.php
deleted file mode 100644
index 2d904c96..00000000
--- a/includes/diff/WikiDiff.php
+++ /dev/null
@@ -1,1241 +0,0 @@
-<?php
-/**
- * A PHP diff engine for phpwiki. (Taken from phpwiki-1.3.3)
- *
- * Copyright © 2000, 2001 Geoffrey T. Dairiki <dairiki@dairiki.org>
- * You may copy this code freely under the conditions of the GPL.
- *
- * @file
- * @ingroup DifferenceEngine
- * @defgroup DifferenceEngine DifferenceEngine
- */
-
-/**
- * @todo document
- * @private
- * @ingroup DifferenceEngine
- */
-class _DiffOp {
-	var $type;
-	var $orig;
-	var $closing;
-
-	function reverse() {
-		trigger_error( 'pure virtual', E_USER_ERROR );
-	}
-
-	function norig() {
-		return $this->orig ? sizeof( $this->orig ) : 0;
-	}
-
-	function nclosing() {
-		return $this->closing ? sizeof( $this->closing ) : 0;
-	}
-}
-
-/**
- * @todo document
- * @private
- * @ingroup DifferenceEngine
- */
-class _DiffOp_Copy extends _DiffOp {
-	var $type = 'copy';
-
-	function __construct ( $orig, $closing = false ) {
-		if ( !is_array( $closing ) )
-		$closing = $orig;
-		$this->orig = $orig;
-		$this->closing = $closing;
-	}
-
-	function reverse() {
-		return new _DiffOp_Copy( $this->closing, $this->orig );
-	}
-}
-
-/**
- * @todo document
- * @private
- * @ingroup DifferenceEngine
- */
-class _DiffOp_Delete extends _DiffOp {
-	var $type = 'delete';
-
-	function __construct ( $lines ) {
-		$this->orig = $lines;
-		$this->closing = false;
-	}
-
-	function reverse() {
-		return new _DiffOp_Add( $this->orig );
-	}
-}
-
-/**
- * @todo document
- * @private
- * @ingroup DifferenceEngine
- */
-class _DiffOp_Add extends _DiffOp {
-	var $type = 'add';
-
-	function __construct ( $lines ) {
-		$this->closing = $lines;
-		$this->orig = false;
-	}
-
-	function reverse() {
-		return new _DiffOp_Delete( $this->closing );
-	}
-}
-
-/**
- * @todo document
- * @private
- * @ingroup DifferenceEngine
- */
-class _DiffOp_Change extends _DiffOp {
-	var $type = 'change';
-
-	function __construct ( $orig, $closing ) {
-		$this->orig = $orig;
-		$this->closing = $closing;
-	}
-
-	function reverse() {
-		return new _DiffOp_Change( $this->closing, $this->orig );
-	}
-}
-
-/**
- * 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 are (and a bit of code) are from 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 {
-
-	const MAX_XREF_LENGTH =  10000;
-
-	function diff ( $from_lines, $to_lines ) {
-		wfProfileIn( __METHOD__ );
-
-		// Diff and store locally
-		$this->diff_local( $from_lines, $to_lines );
-
-		// 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.
-		$n_from = sizeof( $from_lines );
-		$n_to = sizeof( $to_lines );
-
-		$edits = array();
-		$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 = array();
-			while ( $xi < $n_from && $yi < $n_to
-			&& !$this->xchanged[$xi] && !$this->ychanged[$yi] ) {
-				$copy[] = $from_lines[$xi++];
-				++$yi;
-			}
-			if ( $copy )
-			$edits[] = new _DiffOp_Copy( $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 _DiffOp_Change( $delete, $add );
-			elseif ( $delete )
-			$edits[] = new _DiffOp_Delete( $delete );
-			elseif ( $add )
-			$edits[] = new _DiffOp_Add( $add );
-		}
-		wfProfileOut( __METHOD__ );
-		return $edits;
-	}
-
-	function diff_local ( $from_lines, $to_lines ) {
-		global $wgExternalDiffEngine;
-		wfProfileIn( __METHOD__ );
-
-		if ( $wgExternalDiffEngine == 'wikidiff3' ) {
-			// wikidiff3
-			$wikidiff3 = new WikiDiff3();
-			$wikidiff3->diff( $from_lines, $to_lines );
-			$this->xchanged = $wikidiff3->removed;
-			$this->ychanged = $wikidiff3->added;
-			unset( $wikidiff3 );
-		} else {
-			// old diff
-			$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 ) );
-		}
-		wfProfileOut( __METHOD__ );
-	}
-
-	/**
-	 * Returns the whole line if it's small enough, or the MD5 hash otherwise
-	 */
-	function _line_hash( $line ) {
-		if ( strlen( $line ) > self::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.
-	 */
-	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( , $y ) = each( $matches ) ) {
-					if ( empty( $this->in_seq[$y] ) ) {
-						$k = $this->_lcs_pos( $y );
-						assert( $k > 0 );
-						$ymids[$k] = $ymids[$k -1];
-						break;
-					}
-				}
-				while ( list ( , $y ) = each( $matches ) ) {
-					if ( $y > $this->seq[$k -1] ) {
-						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;
-					} else if ( empty( $this->in_seq[$y] ) ) {
-						$k = $this->_lcs_pos( $y );
-						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 );
-	}
-
-	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;
-		}
-
-		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.
-	 */
-	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).
-	 */
-	function _shift_boundaries ( $lines, &$changed, $other_changed ) {
-		wfProfileIn( __METHOD__ );
-		$i = 0;
-		$j = 0;
-
-		assert( 'sizeof($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] ) {
-				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]' );
-			}
-		}
-		wfProfileOut( __METHOD__ );
-	}
-}
-
-/**
- * Class representing a 'diff' between two sequences of strings.
- * @todo document
- * @private
- * @ingroup DifferenceEngine
- */
-class Diff
-{
-	var $edits;
-
-	/**
-	 * Constructor.
-	 * Computes diff between sequences of strings.
-	 *
-	 * @param $from_lines array An array of strings.
-	 *		  (Typically these are lines from a file.)
-	 * @param $to_lines array An array of strings.
-	 */
-	function __construct( $from_lines, $to_lines ) {
-		$eng = new _DiffEngine;
-		$this->edits = $eng->diff( $from_lines, $to_lines );
-		// $this->_check($from_lines, $to_lines);
-	}
-
-	/**
-	 * Compute reversed Diff.
-	 *
-	 * SYNOPSIS:
-	 *
-	 *	$diff = new Diff($lines1, $lines2);
-	 *	$rev = $diff->reverse();
-	 * @return object A Diff object representing the inverse of the
-	 *				  original diff.
-	 */
-	function reverse () {
-		$rev = $this;
-		$rev->edits = array();
-		foreach ( $this->edits as $edit ) {
-			$rev->edits[] = $edit->reverse();
-		}
-		return $rev;
-	}
-
-	/**
-	 * Check for empty diff.
-	 *
-	 * @return bool True iff two sequences were identical.
-	 */
-	function isEmpty () {
-		foreach ( $this->edits as $edit ) {
-			if ( $edit->type != 'copy' )
-			return false;
-		}
-		return true;
-	}
-
-	/**
-	 * Compute the length of the Longest Common Subsequence (LCS).
-	 *
-	 * This is mostly for diagnostic purposed.
-	 *
-	 * @return int The length of the LCS.
-	 */
-	function lcs () {
-		$lcs = 0;
-		foreach ( $this->edits as $edit ) {
-			if ( $edit->type == 'copy' )
-			$lcs += sizeof( $edit->orig );
-		}
-		return $lcs;
-	}
-
-	/**
-	 * Get the original set of lines.
-	 *
-	 * This reconstructs the $from_lines parameter passed to the
-	 * constructor.
-	 *
-	 * @return array The original sequence of strings.
-	 */
-	function orig() {
-		$lines = array();
-
-		foreach ( $this->edits as $edit ) {
-			if ( $edit->orig )
-			array_splice( $lines, sizeof( $lines ), 0, $edit->orig );
-		}
-		return $lines;
-	}
-
-	/**
-	 * Get the closing set of lines.
-	 *
-	 * This reconstructs the $to_lines parameter passed to the
-	 * constructor.
-	 *
-	 * @return array The sequence of strings.
-	 */
-	function closing() {
-		$lines = array();
-
-		foreach ( $this->edits as $edit ) {
-			if ( $edit->closing )
-			array_splice( $lines, sizeof( $lines ), 0, $edit->closing );
-		}
-		return $lines;
-	}
-
-	/**
-	 * Check a Diff for validity.
-	 *
-	 * This is here only for debugging purposes.
-	 */
-	function _check ( $from_lines, $to_lines ) {
-		wfProfileIn( __METHOD__ );
-		if ( serialize( $from_lines ) != serialize( $this->orig() ) )
-		trigger_error( "Reconstructed original doesn't match", E_USER_ERROR );
-		if ( serialize( $to_lines ) != serialize( $this->closing() ) )
-		trigger_error( "Reconstructed closing doesn't match", E_USER_ERROR );
-
-		$rev = $this->reverse();
-		if ( serialize( $to_lines ) != serialize( $rev->orig() ) )
-		trigger_error( "Reversed original doesn't match", E_USER_ERROR );
-		if ( serialize( $from_lines ) != serialize( $rev->closing() ) )
-		trigger_error( "Reversed closing doesn't match", E_USER_ERROR );
-
-
-		$prevtype = 'none';
-		foreach ( $this->edits as $edit ) {
-			if ( $prevtype == $edit->type )
-			trigger_error( "Edit sequence is non-optimal", E_USER_ERROR );
-			$prevtype = $edit->type;
-		}
-
-		$lcs = $this->lcs();
-		trigger_error( 'Diff okay: LCS = ' . $lcs, E_USER_NOTICE );
-		wfProfileOut( __METHOD__ );
-	}
-}
-
-/**
- * @todo document, bad name.
- * @private
- * @ingroup DifferenceEngine
- */
-class MappedDiff extends Diff
-{
-	/**
-	 * Constructor.
-	 *
-	 * Computes diff between sequences of strings.
-	 *
-	 * This can be used to compute things like
-	 * case-insensitve diffs, or diffs which ignore
-	 * changes in white-space.
-	 *
-	 * @param $from_lines array An array of strings.
-	 *	(Typically these are lines from a file.)
-	 *
-	 * @param $to_lines array An array of strings.
-	 *
-	 * @param $mapped_from_lines array This array should
-	 *	have the same size number of elements as $from_lines.
-	 *	The elements in $mapped_from_lines and
-	 *	$mapped_to_lines are what is actually compared
-	 *	when computing the diff.
-	 *
-	 * @param $mapped_to_lines array This array should
-	 *	have the same number of elements as $to_lines.
-	 */
-	function __construct( $from_lines, $to_lines,
-	$mapped_from_lines, $mapped_to_lines ) {
-		wfProfileIn( __METHOD__ );
-
-		assert( sizeof( $from_lines ) == sizeof( $mapped_from_lines ) );
-		assert( sizeof( $to_lines ) == sizeof( $mapped_to_lines ) );
-
-		parent::__construct( $mapped_from_lines, $mapped_to_lines );
-
-		$xi = $yi = 0;
-		for ( $i = 0; $i < sizeof( $this->edits ); $i++ ) {
-			$orig = &$this->edits[$i]->orig;
-			if ( is_array( $orig ) ) {
-				$orig = array_slice( $from_lines, $xi, sizeof( $orig ) );
-				$xi += sizeof( $orig );
-			}
-
-			$closing = &$this->edits[$i]->closing;
-			if ( is_array( $closing ) ) {
-				$closing = array_slice( $to_lines, $yi, sizeof( $closing ) );
-				$yi += sizeof( $closing );
-			}
-		}
-		wfProfileOut( __METHOD__ );
-	}
-}
-
-/**
- * A class to format Diffs
- *
- * This class formats the diff in classic diff format.
- * It is intended that this class be customized via inheritance,
- * to obtain fancier outputs.
- * @todo document
- * @private
- * @ingroup DifferenceEngine
- */
-class DiffFormatter {
-	/**
-	 * Number of leading context "lines" to preserve.
-	 *
-	 * This should be left at zero for this class, but subclasses
-	 * may want to set this to other values.
-	 */
-	var $leading_context_lines = 0;
-
-	/**
-	 * Number of trailing context "lines" to preserve.
-	 *
-	 * This should be left at zero for this class, but subclasses
-	 * may want to set this to other values.
-	 */
-	var $trailing_context_lines = 0;
-
-	/**
-	 * Format a diff.
-	 *
-	 * @param $diff object A Diff object.
-	 * @return string The formatted output.
-	 */
-	function format( $diff ) {
-		wfProfileIn( __METHOD__ );
-
-		$xi = $yi = 1;
-		$block = false;
-		$context = array();
-
-		$nlead = $this->leading_context_lines;
-		$ntrail = $this->trailing_context_lines;
-
-		$this->_start_diff();
-
-		foreach ( $diff->edits as $edit ) {
-			if ( $edit->type == 'copy' ) {
-				if ( is_array( $block ) ) {
-					if ( sizeof( $edit->orig ) <= $nlead + $ntrail ) {
-						$block[] = $edit;
-					}
-					else {
-						if ( $ntrail ) {
-							$context = array_slice( $edit->orig, 0, $ntrail );
-							$block[] = new _DiffOp_Copy( $context );
-						}
-						$this->_block( $x0, $ntrail + $xi - $x0,
-						$y0, $ntrail + $yi - $y0,
-						$block );
-						$block = false;
-					}
-				}
-				$context = $edit->orig;
-			}
-			else {
-				if ( ! is_array( $block ) ) {
-					$context = array_slice( $context, sizeof( $context ) - $nlead );
-					$x0 = $xi - sizeof( $context );
-					$y0 = $yi - sizeof( $context );
-					$block = array();
-					if ( $context )
-					$block[] = new _DiffOp_Copy( $context );
-				}
-				$block[] = $edit;
-			}
-
-			if ( $edit->orig )
-			$xi += sizeof( $edit->orig );
-			if ( $edit->closing )
-			$yi += sizeof( $edit->closing );
-		}
-
-		if ( is_array( $block ) )
-		$this->_block( $x0, $xi - $x0,
-		$y0, $yi - $y0,
-		$block );
-
-		$end = $this->_end_diff();
-		wfProfileOut( __METHOD__ );
-		return $end;
-	}
-
-	function _block( $xbeg, $xlen, $ybeg, $ylen, &$edits ) {
-		wfProfileIn( __METHOD__ );
-		$this->_start_block( $this->_block_header( $xbeg, $xlen, $ybeg, $ylen ) );
-		foreach ( $edits as $edit ) {
-			if ( $edit->type == 'copy' )
-			$this->_context( $edit->orig );
-			elseif ( $edit->type == 'add' )
-			$this->_added( $edit->closing );
-			elseif ( $edit->type == 'delete' )
-			$this->_deleted( $edit->orig );
-			elseif ( $edit->type == 'change' )
-			$this->_changed( $edit->orig, $edit->closing );
-			else
-			trigger_error( 'Unknown edit type', E_USER_ERROR );
-		}
-		$this->_end_block();
-		wfProfileOut( __METHOD__ );
-	}
-
-	function _start_diff() {
-		ob_start();
-	}
-
-	function _end_diff() {
-		$val = ob_get_contents();
-		ob_end_clean();
-		return $val;
-	}
-
-	function _block_header( $xbeg, $xlen, $ybeg, $ylen ) {
-		if ( $xlen > 1 )
-		$xbeg .= "," . ( $xbeg + $xlen - 1 );
-		if ( $ylen > 1 )
-		$ybeg .= "," . ( $ybeg + $ylen - 1 );
-
-		return $xbeg . ( $xlen ? ( $ylen ? 'c' : 'd' ) : 'a' ) . $ybeg;
-	}
-
-	function _start_block( $header ) {
-		echo $header . "\n";
-	}
-
-	function _end_block() {
-	}
-
-	function _lines( $lines, $prefix = ' ' ) {
-		foreach ( $lines as $line )
-		echo "$prefix $line\n";
-	}
-
-	function _context( $lines ) {
-		$this->_lines( $lines );
-	}
-
-	function _added( $lines ) {
-		$this->_lines( $lines, '>' );
-	}
-	function _deleted( $lines ) {
-		$this->_lines( $lines, '<' );
-	}
-
-	function _changed( $orig, $closing ) {
-		$this->_deleted( $orig );
-		echo "---\n";
-		$this->_added( $closing );
-	}
-}
-
-/**
- * A formatter that outputs unified diffs
- * @ingroup DifferenceEngine
- */
-
-class UnifiedDiffFormatter extends DiffFormatter {
-	var $leading_context_lines = 2;
-	var $trailing_context_lines = 2;
-
-	function _added( $lines ) {
-		$this->_lines( $lines, '+' );
-	}
-	function _deleted( $lines ) {
-		$this->_lines( $lines, '-' );
-	}
-	function _changed( $orig, $closing ) {
-		$this->_deleted( $orig );
-		$this->_added( $closing );
-	}
-	function _block_header( $xbeg, $xlen, $ybeg, $ylen ) {
-		return "@@ -$xbeg,$xlen +$ybeg,$ylen @@";
-	}
-}
-
-/**
- * A pseudo-formatter that just passes along the Diff::$edits array
- * @ingroup DifferenceEngine
- */
-class ArrayDiffFormatter extends DiffFormatter {
-	function format( $diff ) {
-		$oldline = 1;
-		$newline = 1;
-		$retval = array();
-		foreach ( $diff->edits as $edit )
-		switch( $edit->type ) {
-			case 'add':
-				foreach ( $edit->closing as $l ) {
-					$retval[] = array(
-							'action' => 'add',
-							'new' => $l,
-							'newline' => $newline++
-					);
-				}
-				break;
-			case 'delete':
-				foreach ( $edit->orig as $l ) {
-					$retval[] = array(
-							'action' => 'delete',
-							'old' => $l,
-							'oldline' => $oldline++,
-					);
-				}
-				break;
-			case 'change':
-				foreach ( $edit->orig as $i => $l ) {
-					$retval[] = array(
-							'action' => 'change',
-							'old' => $l,
-							'new' => @$edit->closing[$i],
-							'oldline' => $oldline++,
-							'newline' => $newline++,
-					);
-				}
-				break;
-			case 'copy':
-				$oldline += count( $edit->orig );
-				$newline += count( $edit->orig );
-		}
-		return $retval;
-	}
-}
-
-/**
- *	Additions by Axel Boldt follow, partly taken from diff.php, phpwiki-1.3.3
- *
- */
-
-define( 'NBSP', '&#160;' ); // iso-8859-x non-breaking space.
-
-/**
- * @todo document
- * @private
- * @ingroup DifferenceEngine
- */
-class _HWLDF_WordAccumulator {
-	function __construct () {
-		$this->_lines = array();
-		$this->_line = '';
-		$this->_group = '';
-		$this->_tag = '';
-	}
-
-	function _flushGroup ( $new_tag ) {
-		if ( $this->_group !== '' ) {
-			if ( $this->_tag == 'ins' )
-			$this->_line .= '<ins class="diffchange diffchange-inline">' .
-			htmlspecialchars ( $this->_group ) . '</ins>';
-			elseif ( $this->_tag == 'del' )
-			$this->_line .= '<del class="diffchange diffchange-inline">' .
-			htmlspecialchars ( $this->_group ) . '</del>';
-			else
-			$this->_line .= htmlspecialchars ( $this->_group );
-		}
-		$this->_group = '';
-		$this->_tag = $new_tag;
-	}
-
-	function _flushLine ( $new_tag ) {
-		$this->_flushGroup( $new_tag );
-		if ( $this->_line != '' )
-		array_push ( $this->_lines, $this->_line );
-		else
-		# make empty lines visible by inserting an NBSP
-		array_push ( $this->_lines, NBSP );
-		$this->_line = '';
-	}
-
-	function addWords ( $words, $tag = '' ) {
-		if ( $tag != $this->_tag )
-		$this->_flushGroup( $tag );
-
-		foreach ( $words as $word ) {
-			// new-line should only come as first char of word.
-			if ( $word == '' )
-			continue;
-			if ( $word[0] == "\n" ) {
-				$this->_flushLine( $tag );
-				$word = substr( $word, 1 );
-			}
-			assert( !strstr( $word, "\n" ) );
-			$this->_group .= $word;
-		}
-	}
-
-	function getLines() {
-		$this->_flushLine( '~done' );
-		return $this->_lines;
-	}
-}
-
-/**
- * @todo document
- * @private
- * @ingroup DifferenceEngine
- */
-class WordLevelDiff extends MappedDiff {
-	const MAX_LINE_LENGTH = 10000;
-
-	function __construct ( $orig_lines, $closing_lines ) {
-		wfProfileIn( __METHOD__ );
-
-		list ( $orig_words, $orig_stripped ) = $this->_split( $orig_lines );
-		list ( $closing_words, $closing_stripped ) = $this->_split( $closing_lines );
-
-		parent::__construct( $orig_words, $closing_words,
-		$orig_stripped, $closing_stripped );
-		wfProfileOut( __METHOD__ );
-	}
-
-	function _split( $lines ) {
-		wfProfileIn( __METHOD__ );
-
-		$words = array();
-		$stripped = array();
-		$first = true;
-		foreach ( $lines as $line ) {
-			# If the line is too long, just pretend the entire line is one big word
-			# This prevents resource exhaustion problems
-			if ( $first ) {
-				$first = false;
-			} else {
-				$words[] = "\n";
-				$stripped[] = "\n";
-			}
-			if ( strlen( $line ) > self::MAX_LINE_LENGTH ) {
-				$words[] = $line;
-				$stripped[] = $line;
-			} else {
-				$m = array();
-				if ( preg_match_all( '/ ( [^\S\n]+ | [0-9_A-Za-z\x80-\xff]+ | . ) (?: (?!< \n) [^\S\n])? /xs',
-				$line, $m ) )
-				{
-					$words = array_merge( $words, $m[0] );
-					$stripped = array_merge( $stripped, $m[1] );
-				}
-			}
-		}
-		wfProfileOut( __METHOD__ );
-		return array( $words, $stripped );
-	}
-
-	function orig () {
-		wfProfileIn( __METHOD__ );
-		$orig = new _HWLDF_WordAccumulator;
-
-		foreach ( $this->edits as $edit ) {
-			if ( $edit->type == 'copy' )
-			$orig->addWords( $edit->orig );
-			elseif ( $edit->orig )
-			$orig->addWords( $edit->orig, 'del' );
-		}
-		$lines = $orig->getLines();
-		wfProfileOut( __METHOD__ );
-		return $lines;
-	}
-
-	function closing () {
-		wfProfileIn( __METHOD__ );
-		$closing = new _HWLDF_WordAccumulator;
-
-		foreach ( $this->edits as $edit ) {
-			if ( $edit->type == 'copy' )
-			$closing->addWords( $edit->closing );
-			elseif ( $edit->closing )
-			$closing->addWords( $edit->closing, 'ins' );
-		}
-		$lines = $closing->getLines();
-		wfProfileOut( __METHOD__ );
-		return $lines;
-	}
-}
-
-/**
- * Wikipedia Table style diff formatter.
- * @todo document
- * @private
- * @ingroup DifferenceEngine
- */
-class TableDiffFormatter extends DiffFormatter {
-	function __construct() {
-		$this->leading_context_lines = 2;
-		$this->trailing_context_lines = 2;
-	}
-
-	public static function escapeWhiteSpace( $msg ) {
-		$msg = preg_replace( '/^ /m', '&#160; ', $msg );
-		$msg = preg_replace( '/ $/m', ' &#160;', $msg );
-		$msg = preg_replace( '/  /', '&#160; ', $msg );
-		return $msg;
-	}
-
-	function _block_header( $xbeg, $xlen, $ybeg, $ylen ) {
-		$r = '<tr><td colspan="2" class="diff-lineno"><!--LINE ' . $xbeg . "--></td>\n" .
-		  '<td colspan="2" class="diff-lineno"><!--LINE ' . $ybeg . "--></td></tr>\n";
-		return $r;
-	}
-
-	function _start_block( $header ) {
-		echo $header;
-	}
-
-	function _end_block() {
-	}
-
-	function _lines( $lines, $prefix = ' ', $color = 'white' ) {
-	}
-
-	# HTML-escape parameter before calling this
-	function addedLine( $line ) {
-		return $this->wrapLine( '+', 'diff-addedline', $line );
-	}
-
-	# HTML-escape parameter before calling this
-	function deletedLine( $line ) {
-		return $this->wrapLine( '&minus;', 'diff-deletedline', $line );
-	}
-
-	# HTML-escape parameter before calling this
-	function contextLine( $line ) {
-		return $this->wrapLine( '&#160;', 'diff-context', $line );
-	}
-
-	private function wrapLine( $marker, $class, $line ) {
-		if ( $line !== '' ) {
-			// The <div> wrapper is needed for 'overflow: auto' style to scroll properly
-			$line = Xml::tags( 'div', null, $this->escapeWhiteSpace( $line ) );
-		}
-		return "<td class='diff-marker'>$marker</td><td class='$class'>$line</td>";
-	}
-
-	function emptyLine() {
-		return '<td colspan="2">&#160;</td>';
-	}
-
-	function _added( $lines ) {
-		foreach ( $lines as $line ) {
-			echo '<tr>' . $this->emptyLine() .
-			$this->addedLine( '<ins class="diffchange">' .
-			htmlspecialchars ( $line ) . '</ins>' ) . "</tr>\n";
-		}
-	}
-
-	function _deleted( $lines ) {
-		foreach ( $lines as $line ) {
-			echo '<tr>' . $this->deletedLine( '<del class="diffchange">' .
-			htmlspecialchars ( $line ) . '</del>' ) .
-			$this->emptyLine() . "</tr>\n";
-		}
-	}
-
-	function _context( $lines ) {
-		foreach ( $lines as $line ) {
-			echo '<tr>' .
-			$this->contextLine( htmlspecialchars ( $line ) ) .
-			$this->contextLine( htmlspecialchars ( $line ) ) . "</tr>\n";
-		}
-	}
-
-	function _changed( $orig, $closing ) {
-		wfProfileIn( __METHOD__ );
-
-		$diff = new WordLevelDiff( $orig, $closing );
-		$del = $diff->orig();
-		$add = $diff->closing();
-
-		# Notice that WordLevelDiff returns HTML-escaped output.
-		# Hence, we will be calling addedLine/deletedLine without HTML-escaping.
-
-		while ( $line = array_shift( $del ) ) {
-			$aline = array_shift( $add );
-			echo '<tr>' . $this->deletedLine( $line ) .
-			$this->addedLine( $aline ) . "</tr>\n";
-		}
-		foreach ( $add as $line ) {	# If any leftovers
-			echo '<tr>' . $this->emptyLine() .
-			$this->addedLine( $line ) . "</tr>\n";
-		}
-		wfProfileOut( __METHOD__ );
-	}
-}
diff --git a/includes/diff/WikiDiff3.php b/includes/diff/WikiDiff3.php
index 8def296d..27d3d5b8 100644
--- a/includes/diff/WikiDiff3.php
+++ b/includes/diff/WikiDiff3.php
@@ -239,7 +239,7 @@ class WikiDiff3 {
 							$starty - 1, $V, $snake )
 			+ $this->lcs_rec( $startx + $len, $topl1, $starty + $len,
 							$topl2, $V, $snake );
-		} else if ( $d == 1 ) {
+		} 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
@@ -332,7 +332,7 @@ class WikiDiff3 {
 					// check to see if we can cut down the diagonal range
 					if ( $x >= $N && $end_forward > $k - 1 ) {
 						$end_forward = $k - 1;
-					} else if ( $absy - $bottoml2 >= $M ) {
+					} elseif ( $absy - $bottoml2 >= $M ) {
 						$start_forward = $k + 1;
 						$value_to_add_forward = 0;
 					}
@@ -366,7 +366,7 @@ class WikiDiff3 {
 					if ( $x <= 0 ) {
 						$start_backward = $k + 1;
 						$value_to_add_backward = 0;
-					} else if ( $y <= 0 && $end_backward > $k - 1 ) {
+					} elseif ( $y <= 0 && $end_backward > $k - 1 ) {
 						$end_backward = $k - 1;
 					}
 				}
@@ -400,7 +400,7 @@ class WikiDiff3 {
 					// check to see if we can cut down the diagonal range
 					if ( $x >= $N && $end_forward > $k - 1 ) {
 						$end_forward = $k - 1;
-					} else if ( $absy -$bottoml2 >= $M ) {
+					} elseif ( $absy -$bottoml2 >= $M ) {
 						$start_forward = $k + 1;
 						$value_to_add_forward = 0;
 					}
@@ -441,7 +441,7 @@ class WikiDiff3 {
 					if ( $x <= 0 ) {
 						$start_backward = $k + 1;
 						$value_to_add_backward = 0;
-					} else if ( $y <= 0 && $end_backward > $k - 1 ) {
+					} elseif ( $y <= 0 && $end_backward > $k - 1 ) {
 						$end_backward = $k - 1;
 					}
 				}
@@ -510,7 +510,7 @@ class WikiDiff3 {
 				$max_progress[0][0] = $x;
 				$max_progress[0][1] = $y;
 				$max_progress[0][2] = $progress;
-			} else if ( $progress == $max_progress[0][2] ) {
+			} elseif ( $progress == $max_progress[0][2] ) {
 				++$num_progress;
 				$max_progress[$num_progress][0] = $x;
 				$max_progress[$num_progress][1] = $y;
@@ -537,7 +537,7 @@ class WikiDiff3 {
 				$max_progress[0][0] = $x;
 				$max_progress[0][1] = $y;
 				$max_progress[0][2] = $progress;
-			} else if ( $progress == $max_progress[0][2] && !$max_progress_forward ) {
+			} elseif ( $progress == $max_progress[0][2] && !$max_progress_forward ) {
 				++$num_progress;
 				$max_progress[$num_progress][0] = $x;
 				$max_progress[$num_progress][1] = $y;
-- 
cgit v1.2.2