fiber_to_generator.php

<?php 
/**
 * @template TArgStart
 * @template TArgResume
 * @template TArgReturn
 * @template TArgSuspend
 *
 * @param \Fiber<TArgStart, TArgResume, TArgReturn, TArgSuspend> $fiber
 * @param TArgStart ...$args
 * @return \Generator<array-key, TArgResume, TArgReturn, TArgSuspend>
 * @throws \Throwable
 *
 * @psalm-suppress TooManyTemplateParams
 * @psalm-suppress MixedAssignment
 */
function fiber_to_generator(\Fiber $fiber, mixed ...$args): \Generator
{
    $index = -1; // Note: Pre-increment is faster than post-increment.
    $value = null;

    // Allow an already running fiber.
    if (!$fiber->isStarted()) {
        $value = $fiber->start(...$args);

        if (!$fiber->isTerminated()) {
            $value = yield ++$index => $value;
        }
    }

    // A Fiber without suspends should return the result immediately.
    if (!$fiber->isTerminated()) {
        while (true) {
            $value = $fiber->resume($value);

            // The last call to "resume()" moves the execution of the
            // Fiber to the "return" stmt.
            //
            // So the "yield" is not needed. Skip this step and return
            // the result.
            if ($fiber->isTerminated()) {
                break;
            }

            $value = yield ++$index => $value;
        }
    }

    return $fiber->getReturn();
}