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Eine auf WordPress spezialiserte Suchmaschine für Entwickler und Theme-Autoren

function wp_get_feed_namespaces( string $type ): array {
	$defaults = array();

	switch ( $type ) {
		case 'rss2':
			$defaults = array(
				'content' => 'http://purl.org/rss/1.0/modules/content/',
				'wfw'     => 'http://wellformedweb.org/CommentAPI/',
				'dc'      => 'http://purl.org/dc/elements/1.1/',
				'atom'    => 'http://www.w3.org/2005/Atom',
				'sy'      => 'http://purl.org/rss/1.0/modules/syndication/',
				'slash'   => 'http://purl.org/rss/1.0/modules/slash/',
			);
			break;

		case 'rss2-comments':
			$defaults = array(
				'content' => 'http://purl.org/rss/1.0/modules/content/',
				'dc'      => 'http://purl.org/dc/elements/1.1/',
				'atom'    => 'http://www.w3.org/2005/Atom',
				'sy'      => 'http://purl.org/rss/1.0/modules/syndication/',
			);
			break;

		case 'rdf':
			$defaults = array(
				'rdf'     => 'http://www.w3.org/1999/02/22-rdf-syntax-ns#',
				'dc'      => 'http://purl.org/dc/elements/1.1/',
				'sy'      => 'http://purl.org/rss/1.0/modules/syndication/',
				'admin'   => 'http://webns.net/mvcb/',
				'content' => 'http://purl.org/rss/1.0/modules/content/',
			);
			break;

		case 'atom':
		case 'atom-comments':
			$defaults = array(
				'thr' => 'http://purl.org/syndication/thread/1.0',
			);
			break;
	}

	/**
	 * Filters the XML namespaces of a feed's root element.
	 *
	 * Namespaces are keyed by their prefix, which makes duplicate `xmlns`
	 * attributes impossible.
	 *
	 * @since 7.2.0
	 *
	 * @param array<string, string> $namespaces Array of namespace URIs, keyed by their prefix.
	 * @param string                $type       Type of feed. Possible values include 'rss2',
	 *                                          'rss2-comments', 'rdf', 'atom', and 'atom-comments'.
	 */
	$namespaces = apply_filters( 'wp_feed_namespaces', $defaults, $type );

	if ( ! is_array( $namespaces ) ) {
		$namespaces = array();
	}

	// The bundled feed templates use the default namespaces, so they cannot be removed.
	$namespaces = array_merge( $namespaces, $defaults );

	$sanitized = array();

	foreach ( $namespaces as $prefix => $uri ) {
		$prefix = (string) $prefix;

		// Prefixes must be valid XML names, and the `xml` and `xmlns` prefixes are reserved.
		if ( ! preg_match( '/^[\p{L}_][\p{L}\p{M}\p{N}._\-\x{B7}]*\z/u', $prefix )
			|| in_array( strtolower( $prefix ), array( 'xml', 'xmlns' ), true )
		) {
			continue;
		}

		if ( ! is_string( $uri ) || empty( $uri ) ) {
			continue;
		}

		$sanitized[ $prefix ] = $uri;
	}

	return $sanitized;
}