protected function getDependencies($class)
    {
        if (isset($this->_reflections[$class])) {
            return [$this->_reflections[$class], $this->_dependencies[$class]];
        }

        $dependencies = [];
        try {
            $reflection = new ReflectionClass($class);
        } catch (\ReflectionException $e) {
            throw new InvalidConfigException('Failed to instantiate component or class "' . $class . '".', 0, $e);
        }

        $constructor = $reflection->getConstructor();
        if ($constructor !== null) {
            foreach ($constructor->getParameters() as $param) {
                if (version_compare(PHP_VERSION, '5.6.0', '>=') && $param->isVariadic()) {
                    break;
                } elseif ($param->isDefaultValueAvailable()) {
                    $dependencies[] = $param->getDefaultValue();
                } else {
                    $c = $param->getClass();
                    $dependencies[] = Instance::of($c === null ? null : $c->getName());
                }
            }
        }

        $this->_reflections[$class] = $reflection;
        $this->_dependencies[$class] = $dependencies;

        return [$reflection, $dependencies];
    }