+ if ( $options['deduplicateStyles'] ) {
+ $seen = [];
+ $text = preg_replace_callback(
+ '#<style\s+([^>]*data-mw-deduplicate\s*=[^>]*)>.*?</style>#s',
+ 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
+ );
+ }
+