* @final */ class EmitterStack extends SplStack implements EmitterInterface { /** * Emit a response * * Loops through the stack, calling emit() on each; any that return a * boolean true value will short-circuit, skipping any remaining emitters * in the stack. * * As such, return a boolean false value from an emitter to indicate it * cannot emit the response, allowing the next emitter to try. */ public function emit(ResponseInterface $response): bool { foreach ($this as $emitter) { if (false !== $emitter->emit($response)) { return true; } } return false; } /** * Set an emitter on the stack by index. * * @param int $offset * @param EmitterInterface $value * @return void * @throws Exception\InvalidEmitterException If not an EmitterInterface instance. */ #[ReturnTypeWillChange] public function offsetSet($offset, $value) { $this->validateEmitter($value); parent::offsetSet($offset, $value); } /** * Push an emitter to the stack. * * @param EmitterInterface $value * @return void * @throws Exception\InvalidEmitterException If not an EmitterInterface instance. */ #[ReturnTypeWillChange] public function push($value) { $this->validateEmitter($value); parent::push($value); } /** * Unshift an emitter to the stack. * * @param EmitterInterface $value * @return void * @throws Exception\InvalidEmitterException If not an EmitterInterface instance. */ #[ReturnTypeWillChange] public function unshift($value) { $this->validateEmitter($value); parent::unshift($value); } /** * Validate that an emitter implements EmitterInterface. * * @throws Exception\InvalidEmitterException For non-emitter instances. * @psalm-assert EmitterInterface $emitter */ private function validateEmitter(mixed $emitter): void { if (! $emitter instanceof EmitterInterface) { throw Exception\InvalidEmitterException::forEmitter($emitter); } } }