wikimedia/mediawiki-core

<?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
 */

namespace Wikimedia\Diff;

/**
 * Performs a word-level diff on several lines
 *
 * @newable
 * @ingroup DifferenceEngine
 */
class WordLevelDiff extends Diff {
    /**
     * @inheritDoc
     */
    protected $bailoutComplexity = 40_000_000; // Roughly 6K x 6K words changed

    /**
     * @stable to call
     * @todo Don't do work in the constructor, use a service to create diffs instead (T257472).
     *
     * @param string[] $linesBefore
     * @param string[] $linesAfter
     */
    public function __construct( $linesBefore, $linesAfter ) {
        [ $wordsBefore, $wordsBeforeStripped ] = $this->split( $linesBefore );
        [ $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;
    }

}

/** @deprecated class alias since 1.41 */
class_alias( WordLevelDiff::class, 'WordLevelDiff' );