CallableResolver.php

<?php

namespace Drupal\Core\Utility;

use Drupal\Core\DependencyInjection\ClassResolverInterface;

/**
 * Resolves PHP callables.
 *
 * The callable resolver service aims to provide a standardized approach to how
 * callables are resolved and invoked from various subsystems. The callable
 * resolver will return or invoke a callable defined in any of the following
 * definition formats:
 *
 * - Service notation:
 * @code
 * 'some.service:method'
 * @endcode
 * - Static methods:
 * @code
 * '\FooClass::staticMethod'
 * @endcode
 * - Non-static methods, instantiated with the class resolver:
 * @code
 * '\DependencyInjectedClass::method'
 * @endcode
 * - Object calls:
 * @code
 * [$object, 'method']
 * @endcode
 * - Classes with an __invoke method:
 * @code
 * '\ClassWithInvoke'
 * @endcode
 * - Closures.
 */
class CallableResolver {
    
    /**
     * Constructs a CallableResolver object.
     *
     * @param \Drupal\Core\DependencyInjection\ClassResolverInterface $classResolver
     *   The class resolver.
     */
    public function __construct(ClassResolverInterface $classResolver) {
    }
    
    /**
     * Gets a callable from a definition.
     *
     * @param callable|array|string $definition
     *   A callable definition.
     *
     * @return callable
     *   A callable.
     *
     * @throws \InvalidArgumentException
     *   Thrown when no valid callable could be resolved from the definition.
     */
    public function getCallableFromDefinition(callable|array|string $definition) : callable {
        // If the definition is natively a callable, we can return it immediately.
        if (is_callable($definition)) {
            return $definition;
        }
        if (is_array($definition)) {
            throw new \InvalidArgumentException(sprintf('The callable definition provided "[%s]" is not a valid callable.', implode(",", $definition)));
        }
        if (!is_string($definition)) {
            throw new \InvalidArgumentException(sprintf('The callable definition provided was invalid. Illegal format of type: %s', gettype($definition)));
        }
        // Callable with __invoke().
        if (!str_contains($definition, ':')) {
            $instance = $this->classResolver
                ->getInstanceFromDefinition($definition);
            if (!is_callable($instance)) {
                throw new \InvalidArgumentException(sprintf('The callable definition provided was invalid. Class "%s" does not have a method "__invoke" and is not callable.', $instance::class));
            }
            return $instance;
        }
        // Callable in the service:method notation.
        $class_or_service = NULL;
        $method = NULL;
        $count = substr_count($definition, ':');
        if ($count == 1) {
            [
                $class_or_service,
                $method,
            ] = explode(':', $definition, 2);
        }
        // Callable in the class::method notation.
        if (str_contains($definition, '::')) {
            [
                $class_or_service,
                $method,
            ] = explode('::', $definition, 2);
        }
        if (empty($class_or_service) || empty($method)) {
            throw new \InvalidArgumentException(sprintf('The callable definition provided was invalid. Could not get class and method from definition "%s".', $definition));
        }
        $instance = $this->classResolver
            ->getInstanceFromDefinition($class_or_service);
        if (!is_callable([
            $instance,
            $method,
        ])) {
            throw new \InvalidArgumentException(sprintf('The callable definition provided was invalid. Either class "%s" does not have a method "%s", or it is not callable.', $instance::class, $method));
        }
        return [
            $instance,
            $method,
        ];
    }

}