source: embed-optimizer/trunk/load.php

<?php
/**
 * Plugin Name: Embed Optimizer
 * Plugin URI: https://github.com/WordPress/performance/tree/trunk/plugins/embed-optimizer
 * Description: Optimizes the performance of embeds through lazy-loading, adding dns-prefetch links, and reserving space to reduce layout shifts.
 * Requires at least: 6.6
 * Requires PHP: 7.2
 * Version: 1.0.0-beta5
 * Author: WordPress Performance Team
 * Author URI: https://make.wordpress.org/performance/
 * License: GPLv2 or later
 * License URI: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
 * Text Domain: embed-optimizer
 *
 * @package embed-optimizer
 */

// @codeCoverageIgnoreStart
if ( ! defined( 'ABSPATH' ) ) {
        exit; // Exit if accessed directly.
}
// @codeCoverageIgnoreEnd

(
        /**
         * Register this copy of the plugin among other potential copies embedded in plugins or themes.
         *
         * @param string  $global_var_name Global variable name for storing the plugin pending loading.
         * @param string  $version         Version.
         * @param Closure $load            Callback that loads the plugin.
         */
        static function ( string $global_var_name, string $version, Closure $load ): void {
                if ( ! isset( $GLOBALS[ $global_var_name ] ) ) {
                        $bootstrap = static function () use ( $global_var_name ): void {
                                if (
                                        isset( $GLOBALS[ $global_var_name ]['load'], $GLOBALS[ $global_var_name ]['version'] )
                                        &&
                                        $GLOBALS[ $global_var_name ]['load'] instanceof Closure
                                        &&
                                        is_string( $GLOBALS[ $global_var_name ]['version'] )
                                ) {
                                        call_user_func( $GLOBALS[ $global_var_name ]['load'], $GLOBALS[ $global_var_name ]['version'] );
                                        unset( $GLOBALS[ $global_var_name ] );
                                }
                        };

                        /*
                         * Wait until after the plugins have loaded and the theme has loaded. The after_setup_theme action could be
                         * used since it is the first action that fires once the theme is loaded. However, plugins may embed this
                         * logic inside a module which initializes even later at the init action. The earliest action that this
                         * plugin has hooks for is the init action at the default priority of 10 (which includes the rest_api_init
                         * action), so this is why it gets initialized at priority 9.
                         */
                        add_action( 'init', $bootstrap, 9 );
                }

                // Register this copy of the plugin.
                if (
                        // Register this copy if none has been registered yet.
                        ! isset( $GLOBALS[ $global_var_name ]['version'] )
                        ||
                        // Or register this copy if the version greater than what is currently registered.
                        version_compare( $version, $GLOBALS[ $global_var_name ]['version'], '>' )
                        ||
                        // Otherwise, register this copy if it is actually the one installed in the directory for plugins.
                        rtrim( WP_PLUGIN_DIR, '/' ) === dirname( __DIR__ )
                ) {
                        $GLOBALS[ $global_var_name ]['version'] = $version; // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedVariableFound -- It is prefixed.
                        $GLOBALS[ $global_var_name ]['load']    = $load; // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedVariableFound -- It is prefixed.
                }
        }
)(
        'embed_optimizer_pending_plugin',
        '1.0.0-beta5',
        static function ( string $version ): void {
                if ( defined( 'EMBED_OPTIMIZER_VERSION' ) ) {
                        return;
                }

                define( 'EMBED_OPTIMIZER_VERSION', $version );

                require_once __DIR__ . '/helper.php';
                require_once __DIR__ . '/hooks.php';
        }
);