WordLevelDiff.php

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<?php
namespace Wikimedia\Diff;
 
class WordLevelDiff extends Diff {
    protected $bailoutComplexity = 40000000; // Roughly 6K x 6K words changed
 
    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 );
            }
        }
    }
 
    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 ];
    }
 
    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;
    }
 
    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;
    }
 
}
 
class_alias( WordLevelDiff::class, 'WordLevelDiff' );