RequestHandler.php

<?php

namespace Phpactor\LanguageServer\Core\Middleware;

use Amp\Promise;
use Phpactor\LanguageServer\Core\Middleware\Exception\MiddlewareTerminated;
use Phpactor\LanguageServer\Core\Rpc\Message;
use Phpactor\LanguageServer\Core\Rpc\ResponseMessage;

final class RequestHandler
{
    public function __construct(
        /** @var array<Middleware> */
        private array $queue = []
    ) {
    }

    /**
     * @return Promise<ResponseMessage|null>
     */
    public function handle(Message $request): Promise
    {
        $middleware = array_shift($this->queue);

        if (!$middleware) {
            throw new MiddlewareTerminated(
                'Middleware terminated (no middleware handled the request)'
            );
        }

        assert($middleware instanceof Middleware);

        return $middleware->process($request, $this);
    }
}