556 lines
13 KiB
PHP
556 lines
13 KiB
PHP
<?php
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/**
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* A PHP diff engine for phpwiki. (Taken from phpwiki-1.3.3)
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*
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* Copyright © 2000, 2001 Geoffrey T. Dairiki <dairiki@dairiki.org>
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* You may copy this code freely under the conditions of the GPL.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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* http://www.gnu.org/copyleft/gpl.html
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*
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* @file
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* @ingroup DifferenceEngine
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* @defgroup DifferenceEngine DifferenceEngine
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*/
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/**
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* The base class for all other DiffOp classes.
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*
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* The classes that extend DiffOp are: DiffOpCopy, DiffOpDelete, DiffOpAdd and
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* DiffOpChange. FakeDiffOp also extends DiffOp, but it is not located in this file.
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*
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* @private
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* @ingroup DifferenceEngine
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*/
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abstract class DiffOp {
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/**
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* @var string
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*/
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public $type;
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/**
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* @var string[]
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*/
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public $orig;
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/**
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* @var string[]
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*/
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public $closing;
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/**
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* @return string
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*/
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public function getType() {
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return $this->type;
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}
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/**
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* @return string[]
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*/
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public function getOrig() {
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return $this->orig;
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}
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/**
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* @param int $i
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* @return string|null
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*/
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public function getClosing( $i = null ) {
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if ( $i === null ) {
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return $this->closing;
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}
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if ( array_key_exists( $i, $this->closing ) ) {
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return $this->closing[$i];
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}
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return null;
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}
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abstract public function reverse();
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/**
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* @return int
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*/
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public function norig() {
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return $this->orig ? count( $this->orig ) : 0;
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}
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/**
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* @return int
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*/
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public function nclosing() {
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return $this->closing ? count( $this->closing ) : 0;
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}
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}
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/**
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* Extends DiffOp. Used to mark strings that have been
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* copied from one string array to the other.
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*
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* @private
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* @ingroup DifferenceEngine
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*/
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class DiffOpCopy extends DiffOp {
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public $type = 'copy';
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public function __construct( $orig, $closing = false ) {
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if ( !is_array( $closing ) ) {
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$closing = $orig;
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}
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$this->orig = $orig;
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$this->closing = $closing;
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}
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/**
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* @return DiffOpCopy
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*/
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public function reverse() {
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return new DiffOpCopy( $this->closing, $this->orig );
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}
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}
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/**
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* Extends DiffOp. Used to mark strings that have been
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* deleted from the first string array.
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*
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* @private
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* @ingroup DifferenceEngine
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*/
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class DiffOpDelete extends DiffOp {
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public $type = 'delete';
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public function __construct( $lines ) {
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$this->orig = $lines;
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$this->closing = false;
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}
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/**
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* @return DiffOpAdd
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*/
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public function reverse() {
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return new DiffOpAdd( $this->orig );
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}
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}
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/**
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* Extends DiffOp. Used to mark strings that have been
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* added from the first string array.
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*
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* @private
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* @ingroup DifferenceEngine
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*/
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class DiffOpAdd extends DiffOp {
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public $type = 'add';
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public function __construct( $lines ) {
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$this->closing = $lines;
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$this->orig = false;
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}
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/**
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* @return DiffOpDelete
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*/
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public function reverse() {
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return new DiffOpDelete( $this->closing );
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}
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}
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/**
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* Extends DiffOp. Used to mark strings that have been
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* changed from the first string array (both added and subtracted).
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*
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* @private
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* @ingroup DifferenceEngine
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*/
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class DiffOpChange extends DiffOp {
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public $type = 'change';
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public function __construct( $orig, $closing ) {
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$this->orig = $orig;
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$this->closing = $closing;
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}
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/**
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* @return DiffOpChange
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*/
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public function reverse() {
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return new DiffOpChange( $this->closing, $this->orig );
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}
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}
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/**
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* Class used internally by Diff to actually compute the diffs.
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*
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* The algorithm used here is mostly lifted from the perl module
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* Algorithm::Diff (version 1.06) by Ned Konz, which is available at:
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* http://www.perl.com/CPAN/authors/id/N/NE/NEDKONZ/Algorithm-Diff-1.06.zip
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*
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* More ideas are taken from:
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* http://www.ics.uci.edu/~eppstein/161/960229.html
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*
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* Some ideas (and a bit of code) are from analyze.c, from GNU
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* diffutils-2.7, which can be found at:
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* ftp://gnudist.gnu.org/pub/gnu/diffutils/diffutils-2.7.tar.gz
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*
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* closingly, some ideas (subdivision by NCHUNKS > 2, and some optimizations)
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* are my own.
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*
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* Line length limits for robustness added by Tim Starling, 2005-08-31
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* Alternative implementation added by Guy Van den Broeck, 2008-07-30
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*
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* @author Geoffrey T. Dairiki, Tim Starling, Guy Van den Broeck
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* @private
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* @ingroup DifferenceEngine
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*/
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class DiffEngine {
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protected $xchanged, $ychanged;
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/**
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* @param string[] $from_lines
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* @param string[] $to_lines
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*
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* @return DiffOp[]
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*/
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public function diff( $from_lines, $to_lines ) {
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// Diff and store locally
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$this->diffLocal( $from_lines, $to_lines );
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// Merge edits when possible
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$this->shiftBoundaries( $from_lines, $this->xchanged, $this->ychanged );
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$this->shiftBoundaries( $to_lines, $this->ychanged, $this->xchanged );
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// Compute the edit operations.
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$n_from = count( $from_lines );
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$n_to = count( $to_lines );
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$edits = [];
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$xi = $yi = 0;
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while ( $xi < $n_from || $yi < $n_to ) {
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assert( $yi < $n_to || $this->xchanged[$xi] );
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assert( $xi < $n_from || $this->ychanged[$yi] );
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// Skip matching "snake".
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$copy = [];
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while ( $xi < $n_from && $yi < $n_to
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&& !$this->xchanged[$xi] && !$this->ychanged[$yi]
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) {
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$copy[] = $from_lines[$xi++];
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++$yi;
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}
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if ( $copy ) {
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$edits[] = new DiffOpCopy( $copy );
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}
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// Find deletes & adds.
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$delete = [];
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while ( $xi < $n_from && $this->xchanged[$xi] ) {
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$delete[] = $from_lines[$xi++];
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}
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$add = [];
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while ( $yi < $n_to && $this->ychanged[$yi] ) {
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$add[] = $to_lines[$yi++];
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}
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if ( $delete && $add ) {
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$edits[] = new DiffOpChange( $delete, $add );
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} elseif ( $delete ) {
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$edits[] = new DiffOpDelete( $delete );
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} elseif ( $add ) {
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$edits[] = new DiffOpAdd( $add );
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}
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}
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return $edits;
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}
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/**
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* @param string[] $from_lines
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* @param string[] $to_lines
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*/
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private function diffLocal( $from_lines, $to_lines ) {
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$wikidiff3 = new WikiDiff3();
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$wikidiff3->diff( $from_lines, $to_lines );
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$this->xchanged = $wikidiff3->removed;
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$this->ychanged = $wikidiff3->added;
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}
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/**
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* Adjust inserts/deletes of identical lines to join changes
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* as much as possible.
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*
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* We do something when a run of changed lines include a
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* line at one end and has an excluded, identical line at the other.
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* We are free to choose which identical line is included.
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* `compareseq' usually chooses the one at the beginning,
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* but usually it is cleaner to consider the following identical line
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* to be the "change".
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*
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* This is extracted verbatim from analyze.c (GNU diffutils-2.7).
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*/
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private function shiftBoundaries( $lines, &$changed, $other_changed ) {
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$i = 0;
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$j = 0;
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assert( count( $lines ) == count( $changed ) );
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$len = count( $lines );
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$other_len = count( $other_changed );
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while ( 1 ) {
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/*
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* Scan forwards to find beginning of another run of changes.
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* Also keep track of the corresponding point in the other file.
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*
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* Throughout this code, $i and $j are adjusted together so that
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* the first $i elements of $changed and the first $j elements
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* of $other_changed both contain the same number of zeros
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* (unchanged lines).
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* Furthermore, $j is always kept so that $j == $other_len or
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* $other_changed[$j] == false.
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*/
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while ( $j < $other_len && $other_changed[$j] ) {
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$j++;
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}
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while ( $i < $len && !$changed[$i] ) {
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assert( $j < $other_len && ! $other_changed[$j] );
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$i++;
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$j++;
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while ( $j < $other_len && $other_changed[$j] ) {
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$j++;
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}
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}
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if ( $i == $len ) {
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break;
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}
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$start = $i;
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// Find the end of this run of changes.
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while ( ++$i < $len && $changed[$i] ) {
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continue;
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}
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do {
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/*
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* Record the length of this run of changes, so that
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* we can later determine whether the run has grown.
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*/
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$runlength = $i - $start;
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/*
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* Move the changed region back, so long as the
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* previous unchanged line matches the last changed one.
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* This merges with previous changed regions.
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*/
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while ( $start > 0 && $lines[$start - 1] == $lines[$i - 1] ) {
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$changed[--$start] = 1;
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$changed[--$i] = false;
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while ( $start > 0 && $changed[$start - 1] ) {
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$start--;
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}
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assert( $j > 0 );
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while ( $other_changed[--$j] ) {
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continue;
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}
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assert( $j >= 0 && !$other_changed[$j] );
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}
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/*
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* Set CORRESPONDING to the end of the changed run, at the last
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* point where it corresponds to a changed run in the other file.
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* CORRESPONDING == LEN means no such point has been found.
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*/
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$corresponding = $j < $other_len ? $i : $len;
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/*
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* Move the changed region forward, so long as the
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* first changed line matches the following unchanged one.
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* This merges with following changed regions.
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* Do this second, so that if there are no merges,
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* the changed region is moved forward as far as possible.
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*/
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while ( $i < $len && $lines[$start] == $lines[$i] ) {
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$changed[$start++] = false;
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$changed[$i++] = 1;
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while ( $i < $len && $changed[$i] ) {
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$i++;
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}
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assert( $j < $other_len && ! $other_changed[$j] );
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$j++;
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if ( $j < $other_len && $other_changed[$j] ) {
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$corresponding = $i;
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while ( $j < $other_len && $other_changed[$j] ) {
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$j++;
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}
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}
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}
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} while ( $runlength != $i - $start );
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/*
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* If possible, move the fully-merged run of changes
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* back to a corresponding run in the other file.
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*/
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while ( $corresponding < $i ) {
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$changed[--$start] = 1;
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$changed[--$i] = 0;
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assert( $j > 0 );
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while ( $other_changed[--$j] ) {
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continue;
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}
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assert( $j >= 0 && !$other_changed[$j] );
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}
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}
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}
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}
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/**
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* Class representing a 'diff' between two sequences of strings.
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* @todo document
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* @private
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* @ingroup DifferenceEngine
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*/
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class Diff {
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/**
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* @var DiffOp[]
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*/
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public $edits;
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/**
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* Constructor.
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* Computes diff between sequences of strings.
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*
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* @param string[] $from_lines An array of strings.
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* Typically these are lines from a file.
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* @param string[] $to_lines An array of strings.
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*/
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public function __construct( $from_lines, $to_lines ) {
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$eng = new DiffEngine;
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$this->edits = $eng->diff( $from_lines, $to_lines );
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}
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/**
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* @return DiffOp[]
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*/
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public function getEdits() {
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return $this->edits;
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}
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/**
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* Compute reversed Diff.
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*
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* SYNOPSIS:
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*
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* $diff = new Diff($lines1, $lines2);
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* $rev = $diff->reverse();
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*
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* @return Object A Diff object representing the inverse of the
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* original diff.
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*/
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public function reverse() {
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$rev = $this;
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$rev->edits = [];
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/** @var DiffOp $edit */
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foreach ( $this->edits as $edit ) {
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$rev->edits[] = $edit->reverse();
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}
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return $rev;
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}
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/**
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* Check for empty diff.
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*
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* @return bool True if two sequences were identical.
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*/
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public function isEmpty() {
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foreach ( $this->edits as $edit ) {
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if ( $edit->type != 'copy' ) {
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return false;
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}
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}
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return true;
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}
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/**
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* Compute the length of the Longest Common Subsequence (LCS).
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*
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* This is mostly for diagnostic purposed.
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*
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* @return int The length of the LCS.
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*/
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public function lcs() {
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$lcs = 0;
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foreach ( $this->edits as $edit ) {
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if ( $edit->type == 'copy' ) {
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$lcs += count( $edit->orig );
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}
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}
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return $lcs;
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}
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/**
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* Get the original set of lines.
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*
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* This reconstructs the $from_lines parameter passed to the
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* constructor.
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*
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* @return string[] The original sequence of strings.
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*/
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public function orig() {
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$lines = [];
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foreach ( $this->edits as $edit ) {
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if ( $edit->orig ) {
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array_splice( $lines, count( $lines ), 0, $edit->orig );
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}
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}
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return $lines;
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}
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/**
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* Get the closing set of lines.
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*
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* This reconstructs the $to_lines parameter passed to the
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* constructor.
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*
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* @return string[] The sequence of strings.
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*/
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public function closing() {
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$lines = [];
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foreach ( $this->edits as $edit ) {
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if ( $edit->closing ) {
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array_splice( $lines, count( $lines ), 0, $edit->closing );
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}
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}
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return $lines;
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}
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}
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/**
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* @deprecated Alias for WordAccumulator, to be soon removed
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*/
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class HWLDFWordAccumulator extends MediaWiki\Diff\WordAccumulator {
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}
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