TableDiffFormatter.php

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<?php
class TableDiffFormatter extends DiffFormatter {
 
    private const SIDE_DELETED = 'deleted';
    private const SIDE_ADDED = 'added';
    private const SIDE_CLASSES = [
        self::SIDE_DELETED => 'diff-side-deleted',
        self::SIDE_ADDED => 'diff-side-added'
    ];
 
    public function __construct() {
        $this->leadingContextLines = 2;
        $this->trailingContextLines = 2;
    }
 
    public static function escapeWhiteSpace( $msg ) {
        $msg = preg_replace( '/^ /m', "\u{00A0} ", $msg );
        $msg = preg_replace( '/ $/m', " \u{00A0}", $msg );
        $msg = preg_replace( '/  /', "\u{00A0} ", $msg );
 
        return $msg;
    }
 
    protected function blockHeader( $xbeg, $xlen, $ybeg, $ylen ) {
        // '<!--LINE \d+ -->' get replaced by a localised line number
        // in DifferenceEngine::localiseLineNumbers
        return Html::rawElement(
            'tr',
            [],
            Html::rawElement(
                'td',
                [ 'colspan' => '2', 'class' => 'diff-lineno', 'id' => 'mw-diff-left-l' . $xbeg ],
                '<!--LINE ' . $xbeg . '-->'
            ) .
            "\n" .
            Html::rawElement(
                'td',
                [ 'colspan' => '2', 'class' => 'diff-lineno' ],
                '<!--LINE ' . $ybeg . '-->'
            )
        ) . "\n";
    }
 
    protected function startBlock( $header ) {
        $this->writeOutput( $header );
    }
 
    protected function endBlock() {
    }
 
    protected function lines( $lines, $prefix = ' ', $color = 'white' ) {
    }
 
    protected function addedLine( $line ) {
        return $this->wrapLine( '+', [ 'diff-addedline', $this->getClassForSide( self::SIDE_ADDED ) ], $line );
    }
 
    protected function deletedLine( $line ) {
        return $this->wrapLine( '−', [ 'diff-deletedline', $this->getClassForSide( self::SIDE_DELETED ) ], $line );
    }
 
    protected function contextLine( $line, string $side ) {
        return $this->wrapLine( '', [ 'diff-context', $this->getClassForSide( $side ) ], $line );
    }
 
    protected function wrapLine( $marker, $class, $line ) {
        if ( $line !== '' ) {
            // The <div> wrapper is needed for 'overflow: auto' style to scroll properly
            $line = Html::rawElement( 'div', [], $this->escapeWhiteSpace( $line ) );
        } else {
            $line = Html::element( 'br' );
        }
 
        $markerAttrs = [ 'class' => 'diff-marker' ];
        if ( $marker ) {
            $markerAttrs['data-marker'] = $marker;
        }
 
        return Html::element( 'td', $markerAttrs ) .
            Html::rawElement( 'td', [ 'class' => $class ], $line );
    }
 
    protected function emptyLine( string $side ) {
        return Html::element( 'td', [ 'colspan' => '2', 'class' => $this->getClassForSide( $side ) ] );
    }
 
    protected function added( $lines ) {
        foreach ( $lines as $line ) {
            $this->writeOutput(
                Html::rawElement(
                    'tr',
                    [],
                    $this->emptyLine( self::SIDE_DELETED ) .
                    $this->addedLine(
                        Html::element(
                            'ins',
                            [ 'class' => 'diffchange' ],
                            $line
                        )
                    )
                ) .
                "\n"
            );
        }
    }
 
    protected function deleted( $lines ) {
        foreach ( $lines as $line ) {
            $this->writeOutput(
                Html::rawElement(
                    'tr',
                    [],
                    $this->deletedLine(
                        Html::element(
                            'del',
                            [ 'class' => 'diffchange' ],
                            $line
                        )
                    ) .
                    $this->emptyLine( self::SIDE_ADDED )
                ) .
                "\n"
            );
        }
    }
 
    protected function context( $lines ) {
        foreach ( $lines as $line ) {
            $this->writeOutput(
                Html::rawElement(
                    'tr',
                    [],
                    $this->contextLine( htmlspecialchars( $line ), self::SIDE_DELETED ) .
                    $this->contextLine( htmlspecialchars( $line ), self::SIDE_ADDED )
                ) .
                "\n"
            );
        }
    }
 
    protected function changed( $orig, $closing ) {
        $diff = new WordLevelDiff( $orig, $closing );
        $del = $diff->orig();
        $add = $diff->closing();
 
        # Notice that WordLevelDiff returns HTML-escaped output.
        # Hence, we will be calling addedLine/deletedLine without HTML-escaping.
 
        $ndel = count( $del );
        $nadd = count( $add );
        $n = max( $ndel, $nadd );
        for ( $i = 0; $i < $n; $i++ ) {
            $delLine = $i < $ndel ? $this->deletedLine( $del[$i] ) : $this->emptyLine( self::SIDE_DELETED );
            $addLine = $i < $nadd ? $this->addedLine( $add[$i] ) : $this->emptyLine( self::SIDE_ADDED );
            $this->writeOutput(
                Html::rawElement(
                    'tr',
                    [],
                    $delLine . $addLine
                ) .
                "\n"
            );
        }
    }
 
    private function getClassForSide( string $side ): string {
        if ( !isset( self::SIDE_CLASSES[$side] ) ) {
            throw new InvalidArgumentException( "Invalid diff side: $side" );
        }
        return self::SIDE_CLASSES[$side];
    }
}