includes/diff/WordLevelDiff.php

   1 <?php
   2 /**
   3  * Copyright © 2000, 2001 Geoffrey T. Dairiki <dairiki@dairiki.org>
   4  * You may copy this code freely under the conditions of the GPL.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License along
  17  * with this program; if not, write to the Free Software Foundation, Inc.,
  18  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  19  * http://www.gnu.org/copyleft/gpl.html
  20  *
  21  * @file
  22  * @ingroup DifferenceEngine
  23  * @defgroup DifferenceEngine DifferenceEngine
  24  */
  25
  26 use MediaWiki\Diff\WordAccumulator;
  27
  28 /**
  29  * Performs a word-level diff on several lines
  30  *
  31  * @ingroup DifferenceEngine
  32  */
  33 class WordLevelDiff extends \Diff {
  34         const MAX_LINE_LENGTH = 10000;
  35
  36         /**
  37          * @param string[] $linesBefore
  38          * @param string[] $linesAfter
  39          */
  40         public function __construct( $linesBefore, $linesAfter ) {
  41
  42                 list( $wordsBefore, $wordsBeforeStripped ) = $this->split( $linesBefore );
  43                 list( $wordsAfter, $wordsAfterStripped ) = $this->split( $linesAfter );
  44
  45                 parent::__construct( $wordsBeforeStripped, $wordsAfterStripped );
  46
  47                 $xi = $yi = 0;
  48                 $editCount = count( $this->edits );
  49                 for ( $i = 0; $i < $editCount; $i++ ) {
  50                         $orig = &$this->edits[$i]->orig;
  51                         if ( is_array( $orig ) ) {
  52                                 $orig = array_slice( $wordsBefore, $xi, count( $orig ) );
  53                                 $xi += count( $orig );
  54                         }
  55
  56                         $closing = &$this->edits[$i]->closing;
  57                         if ( is_array( $closing ) ) {
  58                                 $closing = array_slice( $wordsAfter, $yi, count( $closing ) );
  59                                 $yi += count( $closing );
  60                         }
  61                 }
  62
  63         }
  64
  65         /**
  66          * @param string[] $lines
  67          *
  68          * @return array[]
  69          */
  70         private function split( $lines ) {
  71
  72                 $words = [];
  73                 $stripped = [];
  74                 $first = true;
  75                 foreach ( $lines as $line ) {
  76                         # If the line is too long, just pretend the entire line is one big word
  77                         # This prevents resource exhaustion problems
  78                         if ( $first ) {
  79                                 $first = false;
  80                         } else {
  81                                 $words[] = "\n";
  82                                 $stripped[] = "\n";
  83                         }
  84                         if ( strlen( $line ) > self::MAX_LINE_LENGTH ) {
  85                                 $words[] = $line;
  86                                 $stripped[] = $line;
  87                         } else {
  88                                 $m = [];
  89                                 if ( preg_match_all( '/ ( [^\S\n]+ | [0-9_A-Za-z\x80-\xff]+ | . ) (?: (?!< \n) [^\S\n])? /xs',
  90                                         $line, $m )
  91                                 ) {
  92                                         foreach ( $m[0] as $word ) {
  93                                                 $words[] = $word;
  94                                         }
  95                                         foreach ( $m[1] as $stripped_word ) {
  96                                                 $stripped[] = $stripped_word;
  97                                         }
  98                                 }
  99                         }
 100                 }
 101
 102                 return [ $words, $stripped ];
 103         }
 104
 105         /**
 106          * @return string[]
 107          */
 108         public function orig() {
 109                 $orig = new WordAccumulator;
 110
 111                 foreach ( $this->edits as $edit ) {
 112                         if ( $edit->type == 'copy' ) {
 113                                 $orig->addWords( $edit->orig );
 114                         } elseif ( $edit->orig ) {
 115                                 $orig->addWords( $edit->orig, 'del' );
 116                         }
 117                 }
 118                 $lines = $orig->getLines();
 119
 120                 return $lines;
 121         }
 122
 123         /**
 124          * @return string[]
 125          */
 126         public function closing() {
 127                 $closing = new WordAccumulator;
 128
 129                 foreach ( $this->edits as $edit ) {
 130                         if ( $edit->type == 'copy' ) {
 131                                 $closing->addWords( $edit->closing );
 132                         } elseif ( $edit->closing ) {
 133                                 $closing->addWords( $edit->closing, 'ins' );
 134                         }
 135                 }
 136                 $lines = $closing->getLines();
 137
 138                 return $lines;
 139         }
 140
 141 }