WP-API/WP-API

<?php
/**
 * Integration points with WordPress core that won't ever be committed
 */

/**
 * Inject `parent__in` and `parent__not_in` vars to avoid bad cache
 *
 * @see https://core.trac.wordpress.org/ticket/35677
 */
function wp_api_comment_query_vars( $query ) {
    $query->query_var_defaults['parent__in'] = array();
    $query->query_var_defaults['parent__not_in'] = array();
}
add_action( 'pre_get_comments', 'wp_api_comment_query_vars' );

if ( ! function_exists( 'wp_parse_slug_list' ) ) {
    /**
     * Clean up an array, comma- or space-separated list of slugs.
     *
     * @since
     *
     * @param  array|string $list List of slugs.
     * @return array Sanitized array of slugs.
     */
    function wp_parse_slug_list( $list ) {
        if ( ! is_array( $list ) ) {
            $list = preg_split( '/[\s,]+/', $list );
        }

        return array_unique( array_map( 'sanitize_title', $list ) );
    }
}

if ( ! function_exists( 'rest_get_server' ) ) {
    /**
     * Retrieves the current REST server instance.
     *
     * Instantiates a new instance if none exists already.
     *
     * @since 4.5.0
     *
     * @global WP_REST_Server $wp_rest_server REST server instance.
     *
     * @return WP_REST_Server REST server instance.
     */
    function rest_get_server() {
        /* @var WP_REST_Server $wp_rest_server */
        global $wp_rest_server;

        if ( empty( $wp_rest_server ) ) {
            /**
             * Filter the REST Server Class.
             *
             * This filter allows you to adjust the server class used by the API, using a
             * different class to handle requests.
             *
             * @since 4.4.0
             *
             * @param string $class_name The name of the server class. Default 'WP_REST_Server'.
             */
            $wp_rest_server_class = apply_filters( 'wp_rest_server_class', 'WP_REST_Server' );
            $wp_rest_server = new $wp_rest_server_class;

            /**
             * Fires when preparing to serve an API request.
             *
             * Endpoint objects should be created and register their hooks on this action rather
             * than another action to ensure they're only loaded when needed.
             *
             * @since 4.4.0
             *
             * @param WP_REST_Server $wp_rest_server Server object.
             */
            do_action( 'rest_api_init', $wp_rest_server );
        }

        return $wp_rest_server;
    }
}