MediaWiki 1.30.2

[autoinstalls/mediawiki.git] / includes / diff / WordLevelDiff.php

<?php
/**
 * Copyright © 2000, 2001 Geoffrey T. Dairiki <dairiki@dairiki.org>
 * You may copy this code freely under the conditions of the GPL.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 * @ingroup DifferenceEngine
 * @defgroup DifferenceEngine DifferenceEngine
 */

use MediaWiki\Diff\ComplexityException;
use MediaWiki\Diff\WordAccumulator;

/**
 * Performs a word-level diff on several lines
 *
 * @ingroup DifferenceEngine
 */
class WordLevelDiff extends \Diff {
        /**
         * @inheritDoc
         */
        protected $bailoutComplexity = 40000000; // Roughly 6K x 6K words changed

        /**
         * @param string[] $linesBefore
         * @param string[] $linesAfter
         */
        public function __construct( $linesBefore, $linesAfter ) {
                list( $wordsBefore, $wordsBeforeStripped ) = $this->split( $linesBefore );
                list( $wordsAfter, $wordsAfterStripped ) = $this->split( $linesAfter );

                try {
                        parent::__construct( $wordsBeforeStripped, $wordsAfterStripped );
                } catch ( ComplexityException $ex ) {
                        // Too hard to diff, just show whole paragraph(s) as changed
                        $this->edits = [ new DiffOpChange( $linesBefore, $linesAfter ) ];
                }

                $xi = $yi = 0;
                $editCount = count( $this->edits );
                for ( $i = 0; $i < $editCount; $i++ ) {
                        $orig = &$this->edits[$i]->orig;
                        if ( is_array( $orig ) ) {
                                $orig = array_slice( $wordsBefore, $xi, count( $orig ) );
                                $xi += count( $orig );
                        }

                        $closing = &$this->edits[$i]->closing;
                        if ( is_array( $closing ) ) {
                                $closing = array_slice( $wordsAfter, $yi, count( $closing ) );
                                $yi += count( $closing );
                        }
                }
        }

        /**
         * @param string[] $lines
         *
         * @return array[]
         */
        private function split( $lines ) {
                $words = [];
                $stripped = [];
                $first = true;
                foreach ( $lines as $line ) {
                        if ( $first ) {
                                $first = false;
                        } else {
                                $words[] = "\n";
                                $stripped[] = "\n";
                        }
                        $m = [];
                        if ( preg_match_all( '/ ( [^\S\n]+ | [0-9_A-Za-z\x80-\xff]+ | . ) (?: (?!< \n) [^\S\n])? /xs',
                                $line, $m ) ) {
                                foreach ( $m[0] as $word ) {
                                        $words[] = $word;
                                }
                                foreach ( $m[1] as $stripped_word ) {
                                        $stripped[] = $stripped_word;
                                }
                        }
                }

                return [ $words, $stripped ];
        }

        /**
         * @return string[]
         */
        public function orig() {
                $orig = new 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();

                return $lines;
        }

        /**
         * @return string[]
         */
        public function closing() {
                $closing = new 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();

                return $lines;
        }

}