wikimedia/mediawiki-core

<?php

namespace MediaWiki\OutputTransform\Stages;

use MediaWiki\Html\Html;
use MediaWiki\OutputTransform\ContentTextTransformStage;
use MediaWiki\Parser\ParserOutput;
use MediaWiki\Parser\Sanitizer;
use ParserOptions;

/**
 * Generates a list of unique style links
 * @internal
 */
class DeduplicateStyles extends ContentTextTransformStage {

    public function shouldRun( ParserOutput $po, ?ParserOptions $popts, array $options = [] ): bool {
        return $options['deduplicateStyles'] ?? true;
    }

    protected function transformText( string $text, ParserOutput $po, ?ParserOptions $popts, array &$options ): string {
        $seen = [];
        return preg_replace_callback( '#<style\s+([^>]*data-mw-deduplicate\s*=[\'"][^>]*)>.*?</style>#s',
            static function ( $m ) use ( &$seen ) {
                $attr = Sanitizer::decodeTagAttributes( $m[1] );
                if ( !isset( $attr['data-mw-deduplicate'] ) ) {
                    return $m[0];
                }

                $key = $attr['data-mw-deduplicate'];
                if ( !isset( $seen[$key] ) ) {
                    $seen[$key] = true;

                    return $m[0];
                }

                // We were going to use an empty <style> here, but there
                // was concern that would be too much overhead for browsers.
                // So let's hope a <link> with a non-standard rel and href isn't
                // going to be misinterpreted or mangled by any subsequent processing.
                return Html::element( 'link', [
                    'rel' => 'mw-deduplicated-inline-style',
                    'href' => "mw-data:" . wfUrlencode( $key ),
                ] );
            }, $text );
    }
}