awaitable-based-fiber.php

<?php

interface Awaitable
{
    /** Same as Amp\Promise */
    public function onResolve(callable $onResolve): void;
}

/**
 * This function returns an instance of Fiber as an implementation detail.
 *
 * @param callable $context
 * @param mixed ...$args
 *
 * @return Awaitable
 */
function async(callable $context, ...$args): Awaitable { }

/**
 * Suspend the current context until the given awaitable resolves. This method will add a callback to the given
 * awaitable to call Fiber::resume() or Fiber::throw().
 *
 * @param Awaitable $awaitable
 *
 * @return mixed Awaitable resolution value.
 */
function await(Awaitable $awaitable): mixed { }

final class Fiber implements Awaitable
{
    /**
     * @param callable $onResolve
     */
    public function onResolve(callable $onResolve): void { }

    /**
     * @internal Called by async() function.
     *
     * Initializes a fiber context.
     *
     * @param callable $context
     * @param mixed ...$args
     */
    private static function start(callable $context, ...$args): Fiber { }

    /**
     * @internal Called by await() function.
     *
     * Suspend the current task until the given awaitable resolves. This method will add a callback to the given
     * awaitable to call Fiber::resume() or Fiber::throw().
     *
     * @param Awaitable $awaitable
     *
     * @return mixed Awaitable resolution value.
     */
    private static function await(Awaitable $awaitable): mixed { }

    /**
     * @internal
     *
     * Resume the task, the given value is passed into the task as return value of await().
     */
    private function resume($v = null): void { }

    /**
     * @internal
     *
     * Resume the task with an error thrown from await().
     */
    private function throw(\Throwable $e): void { }
}