Method loadExtension

/**
 * Loads the extension.
 *
 * @param   string  $type           The extension type
 * @param   string  $extensionName  The extension name
 * @param   string  $extensionPath  The path of the extension
 *
 * @return  ComponentInterface|ModuleInterface|PluginInterface
 *
 * @since   4.0.0
 */
private function loadExtension($type, $extensionName, $extensionPath)
{
    // Check if the extension is already loaded
    if (!empty(ExtensionHelper::$extensions[$type][$extensionName])) {
        return ExtensionHelper::$extensions[$type][$extensionName];
    }
    // The container to get the services from
    $container = $this->getContainer()->createChild();
    $container->get(DispatcherInterface::class)->dispatch('onBeforeExtensionBoot', AbstractEvent::create('onBeforeExtensionBoot', ['subject' => $this, 'type' => $type, 'extensionName' => $extensionName, 'container' => $container]));
    // The path of the loader file
    $path = $extensionPath . '/services/provider.php';
    if (is_file($path)) {
        // Load the file
        $provider = (require_once $path);
        // Check if the extension supports the service provider interface
        if ($provider instanceof ServiceProviderInterface) {
            $provider->register($container);
        }
    }
    // Fallback to legacy
    if (!$container->has($type)) {
        switch ($type) {
            case ComponentInterface::class:
                $container->set($type, new LegacyComponent('com_' . $extensionName));
                break;
            case ModuleInterface::class:
                $container->set($type, new Module(new ModuleDispatcherFactory(''), new HelperFactory('')));
                break;
            case PluginInterface::class:
                list($pluginName, $pluginType) = explode(':', $extensionName);
                $container->set($type, $this->loadPluginFromFilesystem($pluginName, $pluginType));
        }
    }
    $container->get(DispatcherInterface::class)->dispatch('onAfterExtensionBoot', AbstractEvent::create('onAfterExtensionBoot', ['subject' => $this, 'type' => $type, 'extensionName' => $extensionName, 'container' => $container]));
    $extension = $container->get($type);
    if ($extension instanceof BootableExtensionInterface) {
        $extension->boot($container);
    }
    // Cache the extension
    ExtensionHelper::$extensions[$type][$extensionName] = $extension;
    return $extension;
}