class WP_URL_Pattern_Prefixer {}

In this article

This class’s access is marked private. This means it is not intended for use by plugin or theme developers, only by core. It is listed here for completeness.

Class for prefixing URL patterns.

Description

This class is intended primarily for use as part of the speculative loading feature.

Methods

NameDescription
WP_URL_Pattern_Prefixer::__constructConstructor.
WP_URL_Pattern_Prefixer::escape_pattern_stringEscapes a string for use in a URL pattern component.
WP_URL_Pattern_Prefixer::get_default_contextsReturns the default contexts used by the class.
WP_URL_Pattern_Prefixer::prefix_path_patternPrefixes the given URL path pattern with the base path for the given context.

Source

class WP_URL_Pattern_Prefixer {

	/**
	 * Map of `$context_string => $base_path` pairs.
	 *
	 * @since 6.8.0
	 * @var array<string, string>
	 */
	private $contexts;

	/**
	 * Constructor.
	 *
	 * @since 6.8.0
	 *
	 * @param array<string, string> $contexts Optional. Map of `$context_string => $base_path` pairs. Default is the
	 *                                        contexts returned by the
	 *                                        WP_URL_Pattern_Prefixer::get_default_contexts() method.
	 */
	public function __construct( array $contexts = array() ) {
		if ( count( $contexts ) > 0 ) {
			$this->contexts = array_map(
				static function ( string $str ): string {
					return self::escape_pattern_string( trailingslashit( $str ) );
				},
				$contexts
			);
		} else {
			$this->contexts = self::get_default_contexts();
		}
	}

	/**
	 * Prefixes the given URL path pattern with the base path for the given context.
	 *
	 * This ensures that these path patterns work correctly on WordPress subdirectory sites, for example in a multisite
	 * network, or when WordPress itself is installed in a subdirectory of the hostname.
	 *
	 * The given URL path pattern is only prefixed if it does not already include the expected prefix.
	 *
	 * @since 6.8.0
	 *
	 * @param string $path_pattern URL pattern starting with the path segment.
	 * @param string $context      Optional. Context to use for prefixing the path pattern. Default 'home'.
	 * @return string URL pattern, prefixed as necessary.
	 */
	public function prefix_path_pattern( string $path_pattern, string $context = 'home' ): string {
		// If context path does not exist, the context is invalid.
		if ( ! isset( $this->contexts[ $context ] ) ) {
			_doing_it_wrong(
				__FUNCTION__,
				esc_html(
					sprintf(
						/* translators: %s: context string */
						__( 'Invalid URL pattern context %s.' ),
						$context
					)
				),
				'6.8.0'
			);
			return $path_pattern;
		}

		/*
		 * In the event that the context path contains a :, ? or # (which can cause the URL pattern parser to switch to
		 * another state, though only the latter two should be percent encoded anyway), it additionally needs to be
		 * enclosed in grouping braces. The final forward slash (trailingslashit ensures there is one) affects the
		 * meaning of the * wildcard, so is left outside the braces.
		 */
		$context_path         = $this->contexts[ $context ];
		$escaped_context_path = $context_path;
		if ( strcspn( $context_path, ':?#' ) !== strlen( $context_path ) ) {
			$escaped_context_path = '{' . substr( $context_path, 0, -1 ) . '}/';
		}

		/*
		 * If the path already starts with the context path (including '/'), remove it first
		 * since it is about to be added back.
		 */
		if ( str_starts_with( $path_pattern, $context_path ) ) {
			$path_pattern = substr( $path_pattern, strlen( $context_path ) );
		}

		return $escaped_context_path . ltrim( $path_pattern, '/' );
	}

	/**
	 * Returns the default contexts used by the class.
	 *
	 * @since 6.8.0
	 *
	 * @return array<string, string> Map of `$context_string => $base_path` pairs.
	 */
	public static function get_default_contexts(): array {
		return array(
			'home'       => self::escape_pattern_string( trailingslashit( (string) wp_parse_url( home_url( '/' ), PHP_URL_PATH ) ) ),
			'site'       => self::escape_pattern_string( trailingslashit( (string) wp_parse_url( site_url( '/' ), PHP_URL_PATH ) ) ),
			'uploads'    => self::escape_pattern_string( trailingslashit( (string) wp_parse_url( wp_upload_dir( null, false )['baseurl'], PHP_URL_PATH ) ) ),
			'content'    => self::escape_pattern_string( trailingslashit( (string) wp_parse_url( content_url(), PHP_URL_PATH ) ) ),
			'plugins'    => self::escape_pattern_string( trailingslashit( (string) wp_parse_url( plugins_url(), PHP_URL_PATH ) ) ),
			'template'   => self::escape_pattern_string( trailingslashit( (string) wp_parse_url( get_stylesheet_directory_uri(), PHP_URL_PATH ) ) ),
			'stylesheet' => self::escape_pattern_string( trailingslashit( (string) wp_parse_url( get_template_directory_uri(), PHP_URL_PATH ) ) ),
		);
	}

	/**
	 * Escapes a string for use in a URL pattern component.
	 *
	 * @since 6.8.0
	 * @see https://urlpattern.spec.whatwg.org/#escape-a-pattern-string
	 *
	 * @param string $str String to be escaped.
	 * @return string String with backslashes added where required.
	 */
	private static function escape_pattern_string( string $str ): string {
		return addcslashes( $str, '+*?:{}()\\' );
	}
}

Changelog

VersionDescription
6.8.0Introduced.

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