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mirror of https://github.com/danog/amp.git synced 2024-11-27 04:24:42 +01:00
amp/lib/functions.php
2017-04-13 18:49:32 +02:00

661 lines
21 KiB
PHP

<?php
namespace Amp {
use React\Promise\PromiseInterface as ReactPromise;
/**
* Wraps the callback in a promise/coroutine-aware function that automatically upgrades Generators to coroutines and
* calls rethrow() on the returned promises (or the coroutine created).
*
* @param callable (...$args): \Generator|\Amp\Promise|mixed $callback
*
* @return callable(...$args): void
*/
function wrap(callable $callback): callable {
return function (...$args) use ($callback) {
$result = $callback(...$args);
if ($result instanceof \Generator) {
$result = new Coroutine($result);
}
if ($result instanceof Promise || $result instanceof ReactPromise) {
Promise\rethrow($result);
}
};
}
/**
* Returns a new function that wraps $worker in a promise/coroutine-aware function that automatically upgrades
* Generators to coroutines. The returned function always returns a promise when invoked. If $worker throws,
* a failed promise is returned.
*
* @param callable (mixed ...$args): mixed $worker
*
* @return callable(mixed ...$args): \Amp\Promise
*/
function coroutine(callable $worker): callable {
return function (...$args) use ($worker): Promise {
try {
$result = $worker(...$args);
} catch (\Throwable $exception) {
return new Failure($exception);
}
if ($result instanceof \Generator) {
return new Coroutine($result);
}
if ($result instanceof Promise) {
return $result;
}
if ($result instanceof ReactPromise) {
return Promise\adapt($result);
}
return new Success($result);
};
}
/**
* Calls the given function, always returning a promise. If the function returns a Generator, it will be run as a
* coroutine. If the function throws, a failed promise will be returned.
*
* @param callable (mixed ...$args): mixed $functor
* @param array ...$args Arguments to pass to the function.
*
* @return \Amp\Promise
*/
function call(callable $functor, ...$args): Promise {
try {
$result = $functor(...$args);
} catch (\Throwable $exception) {
return new Failure($exception);
}
if ($result instanceof \Generator) {
return new Coroutine($result);
}
if ($result instanceof Promise) {
return $result;
}
if ($result instanceof ReactPromise) {
return Promise\adapt($result);
}
return new Success($result);
}
}
namespace Amp\Promise {
use Amp\Loop;
use Amp\Deferred;
use Amp\MultiReasonException;
use Amp\Promise;
use Amp\Success;
use Amp\TimeoutException;
use Amp\UnionTypeError;
use React\Promise\PromiseInterface as ReactPromise;
/**
* Registers a callback that will forward the failure reason to the Loop error handler if the promise fails.
*
* @param \Amp\Promise|\React\Promise\PromiseInterface $promise
*
* @throws \TypeError If $promise is not an instance of \Amp\Promise or \React\Promise\PromiseInterface.
*/
function rethrow($promise) {
if (!$promise instanceof Promise) {
if ($promise instanceof ReactPromise) {
$promise = adapt($promise);
} else {
throw new UnionTypeError([Promise::class, ReactPromise::class], $promise);
}
}
$promise->onResolve(function ($exception) {
if ($exception) {
throw $exception;
}
});
}
/**
* Runs the event loop until the promise is resolved. Should not be called within a running event loop.
*
* @param \Amp\Promise|\React\Promise\PromiseInterface $promise
*
* @return mixed Promise success value.
*
* @throws \TypeError If $promise is not an instance of \Amp\Promise or \React\Promise\PromiseInterface.
* @throws \Throwable Promise failure reason.
*/
function wait($promise) {
if (!$promise instanceof Promise) {
if ($promise instanceof ReactPromise) {
$promise = adapt($promise);
} else {
throw new UnionTypeError([Promise::class, ReactPromise::class], $promise);
}
}
$resolved = false;
Loop::run(function () use (&$resolved, &$value, &$exception, $promise) {
$promise->onResolve(function ($e, $v) use (&$resolved, &$value, &$exception) {
Loop::stop();
$resolved = true;
$exception = $e;
$value = $v;
});
});
if (!$resolved) {
throw new \Error("Loop stopped without resolving promise");
}
if ($exception) {
throw $exception;
}
return $value;
}
/**
* Pipe the promised value through the specified functor once it resolves.
*
* @param \Amp\Promise|\React\Promise\PromiseInterface $promise
* @param callable (mixed $value): mixed $functor
*
* @return \Amp\Promise
*
* @throws \TypeError If $promise is not an instance of \Amp\Promise or \React\Promise\PromiseInterface.
*/
function pipe($promise, callable $functor): Promise {
if (!$promise instanceof Promise) {
if ($promise instanceof ReactPromise) {
$promise = adapt($promise);
} else {
throw new UnionTypeError([Promise::class, ReactPromise::class], $promise);
}
}
$deferred = new Deferred;
$promise->onResolve(function ($exception, $value) use ($deferred, $functor) {
if ($exception) {
$deferred->fail($exception);
return;
}
try {
$deferred->resolve($functor($value));
} catch (\Throwable $exception) {
$deferred->fail($exception);
}
});
return $deferred->promise();
}
/**
* @param \Amp\Promise|\React\Promise\PromiseInterface $promise
* @param string $className Throwable class name to capture. Given callback will only be invoked if the failure
* reason is an instance of the given throwable class name.
* @param callable (\Throwable $exception): mixed $functor
*
* @return \Amp\Promise
*
* @throws \TypeError If $promise is not an instance of \Amp\Promise or \React\Promise\PromiseInterface.
*/
function capture($promise, string $className, callable $functor): Promise {
if (!$promise instanceof Promise) {
if ($promise instanceof ReactPromise) {
$promise = adapt($promise);
} else {
throw new UnionTypeError([Promise::class, ReactPromise::class], $promise);
}
}
$deferred = new Deferred;
$promise->onResolve(function ($exception, $value) use ($deferred, $className, $functor) {
if (!$exception) {
$deferred->resolve($value);
return;
}
if (!$exception instanceof $className) {
$deferred->fail($exception);
return;
}
try {
$deferred->resolve($functor($exception));
} catch (\Throwable $exception) {
$deferred->fail($exception);
}
});
return $deferred->promise();
}
/**
* Create an artificial timeout for any Promise.
*
* If the timeout expires before the promise is resolved, the returned promise fails with an instance of
* \Amp\TimeoutException.
*
* @param \Amp\Promise|\React\Promise\PromiseInterface $promise
* @param int $timeout Timeout in milliseconds.
*
* @return \Amp\Promise
*
* @throws \TypeError If $promise is not an instance of \Amp\Promise or \React\Promise\PromiseInterface.
*/
function timeout($promise, int $timeout): Promise {
if (!$promise instanceof Promise) {
if ($promise instanceof ReactPromise) {
$promise = adapt($promise);
} else {
throw new UnionTypeError([Promise::class, ReactPromise::class], $promise);
}
}
$deferred = new Deferred;
$watcher = Loop::delay($timeout, function () use (&$deferred) {
$temp = $deferred; // prevent double resolve
$deferred = null;
$temp->fail(new TimeoutException);
});
Loop::unreference($watcher);
$promise->onResolve(function () use (&$deferred, $promise, $watcher) {
if ($deferred !== null) {
Loop::cancel($watcher);
$deferred->resolve($promise);
}
});
return $deferred->promise();
}
/**
* Adapts any object with a done(callable $onFulfilled, callable $onRejected) or then(callable $onFulfilled,
* callable $onRejected) method to a promise usable by components depending on placeholders implementing
* \AsyncInterop\Promise.
*
* @param object $promise Object with a done() or then() method.
*
* @return \Amp\Promise Promise resolved by the $thenable object.
*
* @throws \Error If the provided object does not have a then() method.
*/
function adapt($promise): Promise {
$deferred = new Deferred;
if (\method_exists($promise, 'done')) {
$promise->done([$deferred, 'resolve'], [$deferred, 'fail']);
} elseif (\method_exists($promise, 'then')) {
$promise->then([$deferred, 'resolve'], [$deferred, 'fail']);
} else {
throw new \Error("Object must have a 'then' or 'done' method");
}
return $deferred->promise();
}
/**
* Returns a promise that is resolved when all promises are resolved. The returned promise will not fail.
* Returned promise succeeds with a two-item array delineating successful and failed promise results,
* with keys identical and corresponding to the original given array.
*
* This function is the same as some() with the notable exception that it will never fail even
* if all promises in the array resolve unsuccessfully.
*
* @param Promise[] $promises
*
* @return \Amp\Promise
*
* @throws \Error If a non-Promise is in the array.
*/
function any(array $promises): Promise {
return some($promises, 0);
}
/**
* Returns a promise that succeeds when all promises succeed, and fails if any promise fails. Returned
* promise succeeds with an array of values used to succeed each contained promise, with keys corresponding to
* the array of promises.
*
* @param \Amp\Promise[] $promises Array of only promises.
*
* @return \Amp\Promise
*
* @throws \Error If a non-Promise is in the array.
*/
function all(array $promises): Promise {
if (empty($promises)) {
return new Success([]);
}
$deferred = new Deferred;
$result = $deferred->promise();
$pending = \count($promises);
$values = [];
foreach ($promises as $key => $promise) {
if ($promise instanceof ReactPromise) {
$promise = adapt($promise);
} elseif (!$promise instanceof Promise) {
throw new UnionTypeError([Promise::class, ReactPromise::class], $promise);
}
$promise->onResolve(function ($exception, $value) use (&$deferred, &$values, &$pending, $key) {
if ($pending === 0) {
return;
}
if ($exception) {
$pending = 0;
$deferred->fail($exception);
$deferred = null;
return;
}
$values[$key] = $value;
if (0 === --$pending) {
$deferred->resolve($values);
}
});
}
return $result;
}
/**
* Returns a promise that succeeds when the first promise succeeds, and fails only if all promises fail.
*
* @param \Amp\Promise[] $promises Array of only promises.
*
* @return \Amp\Promise
*
* @throws \Error If the array is empty or a non-Promise is in the array.
*/
function first(array $promises): Promise {
if (empty($promises)) {
throw new \Error("No promises provided");
}
$deferred = new Deferred;
$result = $deferred->promise();
$pending = \count($promises);
$exceptions = [];
foreach ($promises as $key => $promise) {
if ($promise instanceof ReactPromise) {
$promise = adapt($promise);
} elseif (!$promise instanceof Promise) {
throw new UnionTypeError([Promise::class, ReactPromise::class], $promise);
}
$promise->onResolve(function ($error, $value) use (&$deferred, &$exceptions, &$pending, &$resolved, $key) {
if ($pending === 0) {
return;
}
if (!$error) {
$pending = 0;
$deferred->resolve($value);
$deferred = null;
return;
}
$exceptions[$key] = $error;
if (0 === --$pending) {
$deferred->fail(new MultiReasonException($exceptions));
}
});
}
return $result;
}
/**
* Resolves with a two-item array delineating successful and failed Promise results.
*
* The returned promise will only fail if the given number of required promises fail.
*
* @param \Amp\Promise[] $promises Array of only promises.
* @param int $required Number of promises that must succeed for the returned promise to succeed.
*
* @return \Amp\Promise
*
* @throws \Error If a non-Promise is in the array.
*/
function some(array $promises, int $required = 1): Promise {
if ($required < 0) {
throw new \Error("Number of promises required must be non-negative");
}
$pending = \count($promises);
if ($required > $pending) {
throw new \Error("Too few promises provided");
}
if (empty($promises)) {
return new Success([[], []]);
}
$deferred = new Deferred;
$result = $deferred->promise();
$values = [];
$exceptions = [];
foreach ($promises as $key => $promise) {
if ($promise instanceof ReactPromise) {
$promise = adapt($promise);
} elseif (!$promise instanceof Promise) {
throw new UnionTypeError([Promise::class, ReactPromise::class], $promise);
}
$promise->onResolve(function ($exception, $value) use (
&$values, &$exceptions, &$pending, $key, $required, $deferred
) {
if ($exception) {
$exceptions[$key] = $exception;
} else {
$values[$key] = $value;
}
if (0 === --$pending) {
if (\count($values) < $required) {
$deferred->fail(new MultiReasonException($exceptions));
} else {
$deferred->resolve([$exceptions, $values]);
}
}
});
}
return $result;
}
}
namespace Amp\Stream {
use Amp\Coroutine;
use Amp\Emitter;
use Amp\StreamIterator;
use Amp\Loop;
use Amp\Pause;
use Amp\Producer;
use Amp\Promise;
use Amp\Stream;
use Amp\UnionTypeError;
/**
* Creates a stream from the given iterable, emitting the each value. The iterable may contain promises. If any
* promise fails, the stream will fail with the same reason.
*
* @param array|\Traversable $iterable Elements to emit.
* @param int $delay Delay between element emissions.
*
* @return \Amp\Stream
*
* @throws \TypeError If the argument is not an array or instance of \Traversable.
*/
function fromIterable(/* iterable */ $iterable, int $delay = 0): Stream {
if (!$iterable instanceof \Traversable && !\is_array($iterable)) {
throw new UnionTypeError(["array", "Traversable"], $iterable);
}
return new Producer(function (callable $emit) use ($iterable, $delay) {
foreach ($iterable as $value) {
if ($delay) {
yield new Pause($delay);
}
yield $emit($value);
}
});
}
/**
* @param \Amp\Stream $stream
* @param callable (mixed $value): mixed $onEmit
* @param callable (mixed $value): mixed|null $onResolve
*
* @return \Amp\Stream
*/
function map(Stream $stream, callable $onEmit, callable $onResolve = null): Stream {
$streamIterator = new StreamIterator($stream);
return new Producer(function (callable $emit) use ($streamIterator, $onEmit, $onResolve) {
while (yield $streamIterator->advance()) {
yield $emit($onEmit($streamIterator->getCurrent()));
}
if ($onResolve === null) {
return $streamIterator->getResult();
}
return $onResolve($streamIterator->getResult());
});
}
/**
* @param \Amp\Stream $stream
* @param callable (mixed $value): bool $filter
*
* @return \Amp\Stream
*/
function filter(Stream $stream, callable $filter): Stream {
$streamIterator = new StreamIterator($stream);
return new Producer(function (callable $emit) use ($streamIterator, $filter) {
while (yield $streamIterator->advance()) {
if ($filter($streamIterator->getCurrent())) {
yield $emit($streamIterator->getCurrent());
}
}
return $streamIterator->getResult();
});
}
/**
* Creates a stream that emits values emitted from any stream in the array of streams.
*
* @param \Amp\Stream[] $streams
*
* @return \Amp\Stream
*/
function merge(array $streams): Stream {
$emitter = new Emitter;
$result = $emitter->stream();
foreach ($streams as $stream) {
if (!$stream instanceof Stream) {
throw new UnionTypeError([Stream::class], $stream);
}
$stream->onEmit(function ($value) use (&$emitter) {
if ($emitter !== null) {
return $emitter->emit($value);
}
});
}
Promise\all($streams)->onResolve(function ($exception, array $values = null) use (&$emitter) {
if ($exception) {
$emitter->fail($exception);
$emitter = null;
} else {
$emitter->resolve($values);
}
});
return $result;
}
/**
* Concatenates the given streams into a single stream, emitting values from a single stream at a time. The
* prior stream must complete before values are emitted from any subsequent stream. Streams are concatenated
* in the order given (iteration order of the array).
*
* @param array $streams
*
* @return \Amp\Stream
*/
function concat(array $streams): Stream {
foreach ($streams as $stream) {
if (!$stream instanceof Stream) {
throw new UnionTypeError([Stream::class], $stream);
}
}
$emitter = new Emitter;
$subscriptions = [];
$previous = [];
$promise = Promise\all($previous);
foreach ($streams as $stream) {
$generator = function ($value) use ($emitter, $promise) {
static $pending = true, $failed = false;
if ($failed) {
return;
}
if ($pending) {
try {
yield $promise;
$pending = false;
} catch (\Throwable $exception) {
$failed = true;
return; // Prior stream failed.
}
}
yield $emitter->emit($value);
};
$subscriptions[] = $stream->onEmit(function ($value) use ($generator) {
return new Coroutine($generator($value));
});
$previous[] = $stream;
$promise = Promise\all($previous);
}
$promise->onResolve(function ($exception, array $values = null) use ($emitter) {
if ($exception) {
$emitter->fail($exception);
return;
}
$emitter->resolve($values);
});
return $emitter->stream();
}
}