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<?php
namespace Laminas\EventManager;
use Psr\Container\ContainerInterface;
use function is_string;
use function method_exists;
/**
* Lazy listener instance.
*
* Used to allow lazy creation of listeners via a dependency injection
* container.
*
* Lazy listener definitions have the following members:
*
* - listener: the service name of the listener to use.
* - method: the method name of the listener to invoke for the specified event.
*
* If desired, you can pass $env at instantiation; this will be passed to the
* container's `build()` method, if it has one, when creating the listener
* instance.
*
* Pass instances directly to the event manager's `attach()` method as the
* listener argument.
*/
class LazyListener
{
/** @var ContainerInterface Container from which to pull listener. */
private $container;
/** @var array Variables/options to use during service creation, if any. */
private $env;
/** @var callable Marshaled listener callback. */
private $listener;
/** @var string Method name to invoke on listener. */
private $method;
/** @var string Service name of listener. */
private $service;
/**
* @param array $definition
* @param array $env
*/
public function __construct(array $definition, ContainerInterface $container, array $env = [])
{
if (
! isset($definition['listener'])
|| ! is_string($definition['listener'])
|| empty($definition['listener'])
) {
throw new Exception\InvalidArgumentException(
'Lazy listener definition is missing a valid "listener" member; cannot create LazyListener'
);
}
if (
! isset($definition['method'])
|| ! is_string($definition['method'])
|| empty($definition['method'])
) {
throw new Exception\InvalidArgumentException(
'Lazy listener definition is missing a valid "method" member; cannot create LazyListener'
);
}
$this->service = $definition['listener'];
$this->method = $definition['method'];
$this->container = $container;
$this->env = $env;
}
/**
* Use the listener as an invokable, allowing direct attachment to an event manager.
*
* @return callable
*/
public function __invoke(EventInterface $event)
{
$listener = $this->fetchListener();
$method = $this->method;
return $listener->{$method}($event);
}
/**
* @return callable
*/
private function fetchListener()
{
if ($this->listener) {
return $this->listener;
}
// In the future, typehint against Laminas\ServiceManager\ServiceLocatorInterface,
// which defines this message starting in v3.
if (method_exists($this->container, 'build') && ! empty($this->env)) {
$this->listener = $this->container->build($this->service, $this->env);
return $this->listener;
}
$this->listener = $this->container->get($this->service);
return $this->listener;
}
}