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# CHANGELOG
## 1.3.1 - 2016-12-20
### Fixed
- `wait()` foreign promise compatibility
## 1.3.0 - 2016-11-18
### Added
- Adds support for custom task queues.
### Fixed
- Fixed coroutine promise memory leak.
## 1.2.0 - 2016-05-18
### Changed
- Update to now catch `\Throwable` on PHP 7+
## 1.1.0 - 2016-03-07
### Changed
- Update EachPromise to prevent recurring on a iterator when advancing, as this
could trigger fatal generator errors.
- Update Promise to allow recursive waiting without unwrapping exceptions.
## 1.0.3 - 2015-10-15
### Changed
- Update EachPromise to immediately resolve when the underlying promise iterator
is empty. Previously, such a promise would throw an exception when its `wait`
function was called.
## 1.0.2 - 2015-05-15
### Changed
- Conditionally require functions.php.
## 1.0.1 - 2015-06-24
### Changed
- Updating EachPromise to call next on the underlying promise iterator as late
as possible to ensure that generators that generate new requests based on
callbacks are not iterated until after callbacks are invoked.
## 1.0.0 - 2015-05-12
- Initial release

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Copyright (c) 2015-2016 Michael Dowling, https://github.com/mtdowling <mtdowling@gmail.com>
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

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all: clean test
test:
vendor/bin/phpunit
coverage:
vendor/bin/phpunit --coverage-html=artifacts/coverage
view-coverage:
open artifacts/coverage/index.html
clean:
rm -rf artifacts/*

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# Guzzle Promises
[Promises/A+](https://promisesaplus.com/) implementation that handles promise
chaining and resolution iteratively, allowing for "infinite" promise chaining
while keeping the stack size constant. Read [this blog post](https://blog.domenic.me/youre-missing-the-point-of-promises/)
for a general introduction to promises.
- [Features](#features)
- [Quick start](#quick-start)
- [Synchronous wait](#synchronous-wait)
- [Cancellation](#cancellation)
- [API](#api)
- [Promise](#promise)
- [FulfilledPromise](#fulfilledpromise)
- [RejectedPromise](#rejectedpromise)
- [Promise interop](#promise-interop)
- [Implementation notes](#implementation-notes)
# Features
- [Promises/A+](https://promisesaplus.com/) implementation.
- Promise resolution and chaining is handled iteratively, allowing for
"infinite" promise chaining.
- Promises have a synchronous `wait` method.
- Promises can be cancelled.
- Works with any object that has a `then` function.
- C# style async/await coroutine promises using
`GuzzleHttp\Promise\coroutine()`.
# Quick start
A *promise* represents the eventual result of an asynchronous operation. The
primary way of interacting with a promise is through its `then` method, which
registers callbacks to receive either a promise's eventual value or the reason
why the promise cannot be fulfilled.
## Callbacks
Callbacks are registered with the `then` method by providing an optional
`$onFulfilled` followed by an optional `$onRejected` function.
```php
use GuzzleHttp\Promise\Promise;
$promise = new Promise();
$promise->then(
// $onFulfilled
function ($value) {
echo 'The promise was fulfilled.';
},
// $onRejected
function ($reason) {
echo 'The promise was rejected.';
}
);
```
*Resolving* a promise means that you either fulfill a promise with a *value* or
reject a promise with a *reason*. Resolving a promises triggers callbacks
registered with the promises's `then` method. These callbacks are triggered
only once and in the order in which they were added.
## Resolving a promise
Promises are fulfilled using the `resolve($value)` method. Resolving a promise
with any value other than a `GuzzleHttp\Promise\RejectedPromise` will trigger
all of the onFulfilled callbacks (resolving a promise with a rejected promise
will reject the promise and trigger the `$onRejected` callbacks).
```php
use GuzzleHttp\Promise\Promise;
$promise = new Promise();
$promise
->then(function ($value) {
// Return a value and don't break the chain
return "Hello, " . $value;
})
// This then is executed after the first then and receives the value
// returned from the first then.
->then(function ($value) {
echo $value;
});
// Resolving the promise triggers the $onFulfilled callbacks and outputs
// "Hello, reader".
$promise->resolve('reader.');
```
## Promise forwarding
Promises can be chained one after the other. Each then in the chain is a new
promise. The return value of a promise is what's forwarded to the next
promise in the chain. Returning a promise in a `then` callback will cause the
subsequent promises in the chain to only be fulfilled when the returned promise
has been fulfilled. The next promise in the chain will be invoked with the
resolved value of the promise.
```php
use GuzzleHttp\Promise\Promise;
$promise = new Promise();
$nextPromise = new Promise();
$promise
->then(function ($value) use ($nextPromise) {
echo $value;
return $nextPromise;
})
->then(function ($value) {
echo $value;
});
// Triggers the first callback and outputs "A"
$promise->resolve('A');
// Triggers the second callback and outputs "B"
$nextPromise->resolve('B');
```
## Promise rejection
When a promise is rejected, the `$onRejected` callbacks are invoked with the
rejection reason.
```php
use GuzzleHttp\Promise\Promise;
$promise = new Promise();
$promise->then(null, function ($reason) {
echo $reason;
});
$promise->reject('Error!');
// Outputs "Error!"
```
## Rejection forwarding
If an exception is thrown in an `$onRejected` callback, subsequent
`$onRejected` callbacks are invoked with the thrown exception as the reason.
```php
use GuzzleHttp\Promise\Promise;
$promise = new Promise();
$promise->then(null, function ($reason) {
throw new \Exception($reason);
})->then(null, function ($reason) {
assert($reason->getMessage() === 'Error!');
});
$promise->reject('Error!');
```
You can also forward a rejection down the promise chain by returning a
`GuzzleHttp\Promise\RejectedPromise` in either an `$onFulfilled` or
`$onRejected` callback.
```php
use GuzzleHttp\Promise\Promise;
use GuzzleHttp\Promise\RejectedPromise;
$promise = new Promise();
$promise->then(null, function ($reason) {
return new RejectedPromise($reason);
})->then(null, function ($reason) {
assert($reason === 'Error!');
});
$promise->reject('Error!');
```
If an exception is not thrown in a `$onRejected` callback and the callback
does not return a rejected promise, downstream `$onFulfilled` callbacks are
invoked using the value returned from the `$onRejected` callback.
```php
use GuzzleHttp\Promise\Promise;
use GuzzleHttp\Promise\RejectedPromise;
$promise = new Promise();
$promise
->then(null, function ($reason) {
return "It's ok";
})
->then(function ($value) {
assert($value === "It's ok");
});
$promise->reject('Error!');
```
# Synchronous wait
You can synchronously force promises to complete using a promise's `wait`
method. When creating a promise, you can provide a wait function that is used
to synchronously force a promise to complete. When a wait function is invoked
it is expected to deliver a value to the promise or reject the promise. If the
wait function does not deliver a value, then an exception is thrown. The wait
function provided to a promise constructor is invoked when the `wait` function
of the promise is called.
```php
$promise = new Promise(function () use (&$promise) {
$promise->resolve('foo');
});
// Calling wait will return the value of the promise.
echo $promise->wait(); // outputs "foo"
```
If an exception is encountered while invoking the wait function of a promise,
the promise is rejected with the exception and the exception is thrown.
```php
$promise = new Promise(function () use (&$promise) {
throw new \Exception('foo');
});
$promise->wait(); // throws the exception.
```
Calling `wait` on a promise that has been fulfilled will not trigger the wait
function. It will simply return the previously resolved value.
```php
$promise = new Promise(function () { die('this is not called!'); });
$promise->resolve('foo');
echo $promise->wait(); // outputs "foo"
```
Calling `wait` on a promise that has been rejected will throw an exception. If
the rejection reason is an instance of `\Exception` the reason is thrown.
Otherwise, a `GuzzleHttp\Promise\RejectionException` is thrown and the reason
can be obtained by calling the `getReason` method of the exception.
```php
$promise = new Promise();
$promise->reject('foo');
$promise->wait();
```
> PHP Fatal error: Uncaught exception 'GuzzleHttp\Promise\RejectionException' with message 'The promise was rejected with value: foo'
## Unwrapping a promise
When synchronously waiting on a promise, you are joining the state of the
promise into the current state of execution (i.e., return the value of the
promise if it was fulfilled or throw an exception if it was rejected). This is
called "unwrapping" the promise. Waiting on a promise will by default unwrap
the promise state.
You can force a promise to resolve and *not* unwrap the state of the promise
by passing `false` to the first argument of the `wait` function:
```php
$promise = new Promise();
$promise->reject('foo');
// This will not throw an exception. It simply ensures the promise has
// been resolved.
$promise->wait(false);
```
When unwrapping a promise, the resolved value of the promise will be waited
upon until the unwrapped value is not a promise. This means that if you resolve
promise A with a promise B and unwrap promise A, the value returned by the
wait function will be the value delivered to promise B.
**Note**: when you do not unwrap the promise, no value is returned.
# Cancellation
You can cancel a promise that has not yet been fulfilled using the `cancel()`
method of a promise. When creating a promise you can provide an optional
cancel function that when invoked cancels the action of computing a resolution
of the promise.
# API
## Promise
When creating a promise object, you can provide an optional `$waitFn` and
`$cancelFn`. `$waitFn` is a function that is invoked with no arguments and is
expected to resolve the promise. `$cancelFn` is a function with no arguments
that is expected to cancel the computation of a promise. It is invoked when the
`cancel()` method of a promise is called.
```php
use GuzzleHttp\Promise\Promise;
$promise = new Promise(
function () use (&$promise) {
$promise->resolve('waited');
},
function () {
// do something that will cancel the promise computation (e.g., close
// a socket, cancel a database query, etc...)
}
);
assert('waited' === $promise->wait());
```
A promise has the following methods:
- `then(callable $onFulfilled, callable $onRejected) : PromiseInterface`
Appends fulfillment and rejection handlers to the promise, and returns a new promise resolving to the return value of the called handler.
- `otherwise(callable $onRejected) : PromiseInterface`
Appends a rejection handler callback to the promise, and returns a new promise resolving to the return value of the callback if it is called, or to its original fulfillment value if the promise is instead fulfilled.
- `wait($unwrap = true) : mixed`
Synchronously waits on the promise to complete.
`$unwrap` controls whether or not the value of the promise is returned for a
fulfilled promise or if an exception is thrown if the promise is rejected.
This is set to `true` by default.
- `cancel()`
Attempts to cancel the promise if possible. The promise being cancelled and
the parent most ancestor that has not yet been resolved will also be
cancelled. Any promises waiting on the cancelled promise to resolve will also
be cancelled.
- `getState() : string`
Returns the state of the promise. One of `pending`, `fulfilled`, or
`rejected`.
- `resolve($value)`
Fulfills the promise with the given `$value`.
- `reject($reason)`
Rejects the promise with the given `$reason`.
## FulfilledPromise
A fulfilled promise can be created to represent a promise that has been
fulfilled.
```php
use GuzzleHttp\Promise\FulfilledPromise;
$promise = new FulfilledPromise('value');
// Fulfilled callbacks are immediately invoked.
$promise->then(function ($value) {
echo $value;
});
```
## RejectedPromise
A rejected promise can be created to represent a promise that has been
rejected.
```php
use GuzzleHttp\Promise\RejectedPromise;
$promise = new RejectedPromise('Error');
// Rejected callbacks are immediately invoked.
$promise->then(null, function ($reason) {
echo $reason;
});
```
# Promise interop
This library works with foreign promises that have a `then` method. This means
you can use Guzzle promises with [React promises](https://github.com/reactphp/promise)
for example. When a foreign promise is returned inside of a then method
callback, promise resolution will occur recursively.
```php
// Create a React promise
$deferred = new React\Promise\Deferred();
$reactPromise = $deferred->promise();
// Create a Guzzle promise that is fulfilled with a React promise.
$guzzlePromise = new \GuzzleHttp\Promise\Promise();
$guzzlePromise->then(function ($value) use ($reactPromise) {
// Do something something with the value...
// Return the React promise
return $reactPromise;
});
```
Please note that wait and cancel chaining is no longer possible when forwarding
a foreign promise. You will need to wrap a third-party promise with a Guzzle
promise in order to utilize wait and cancel functions with foreign promises.
## Event Loop Integration
In order to keep the stack size constant, Guzzle promises are resolved
asynchronously using a task queue. When waiting on promises synchronously, the
task queue will be automatically run to ensure that the blocking promise and
any forwarded promises are resolved. When using promises asynchronously in an
event loop, you will need to run the task queue on each tick of the loop. If
you do not run the task queue, then promises will not be resolved.
You can run the task queue using the `run()` method of the global task queue
instance.
```php
// Get the global task queue
$queue = \GuzzleHttp\Promise\queue();
$queue->run();
```
For example, you could use Guzzle promises with React using a periodic timer:
```php
$loop = React\EventLoop\Factory::create();
$loop->addPeriodicTimer(0, [$queue, 'run']);
```
*TODO*: Perhaps adding a `futureTick()` on each tick would be faster?
# Implementation notes
## Promise resolution and chaining is handled iteratively
By shuffling pending handlers from one owner to another, promises are
resolved iteratively, allowing for "infinite" then chaining.
```php
<?php
require 'vendor/autoload.php';
use GuzzleHttp\Promise\Promise;
$parent = new Promise();
$p = $parent;
for ($i = 0; $i < 1000; $i++) {
$p = $p->then(function ($v) {
// The stack size remains constant (a good thing)
echo xdebug_get_stack_depth() . ', ';
return $v + 1;
});
}
$parent->resolve(0);
var_dump($p->wait()); // int(1000)
```
When a promise is fulfilled or rejected with a non-promise value, the promise
then takes ownership of the handlers of each child promise and delivers values
down the chain without using recursion.
When a promise is resolved with another promise, the original promise transfers
all of its pending handlers to the new promise. When the new promise is
eventually resolved, all of the pending handlers are delivered the forwarded
value.
## A promise is the deferred.
Some promise libraries implement promises using a deferred object to represent
a computation and a promise object to represent the delivery of the result of
the computation. This is a nice separation of computation and delivery because
consumers of the promise cannot modify the value that will be eventually
delivered.
One side effect of being able to implement promise resolution and chaining
iteratively is that you need to be able for one promise to reach into the state
of another promise to shuffle around ownership of handlers. In order to achieve
this without making the handlers of a promise publicly mutable, a promise is
also the deferred value, allowing promises of the same parent class to reach
into and modify the private properties of promises of the same type. While this
does allow consumers of the value to modify the resolution or rejection of the
deferred, it is a small price to pay for keeping the stack size constant.
```php
$promise = new Promise();
$promise->then(function ($value) { echo $value; });
// The promise is the deferred value, so you can deliver a value to it.
$promise->resolve('foo');
// prints "foo"
```

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{
"name": "guzzlehttp/promises",
"description": "Guzzle promises library",
"keywords": ["promise"],
"license": "MIT",
"authors": [
{
"name": "Michael Dowling",
"email": "mtdowling@gmail.com",
"homepage": "https://github.com/mtdowling"
}
],
"require": {
"php": ">=5.5.0"
},
"require-dev": {
"phpunit/phpunit": "^4.0"
},
"autoload": {
"psr-4": {
"GuzzleHttp\\Promise\\": "src/"
},
"files": ["src/functions_include.php"]
},
"scripts": {
"test": "vendor/bin/phpunit",
"test-ci": "vendor/bin/phpunit --coverage-text"
},
"extra": {
"branch-alias": {
"dev-master": "1.4-dev"
}
}
}

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<?php
namespace GuzzleHttp\Promise;
/**
* Exception thrown when too many errors occur in the some() or any() methods.
*/
class AggregateException extends RejectionException
{
public function __construct($msg, array $reasons)
{
parent::__construct(
$reasons,
sprintf('%s; %d rejected promises', $msg, count($reasons))
);
}
}

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<?php
namespace GuzzleHttp\Promise;
/**
* Exception that is set as the reason for a promise that has been cancelled.
*/
class CancellationException extends RejectionException
{
}

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<?php
namespace GuzzleHttp\Promise;
use Exception;
use Generator;
use Throwable;
/**
* Creates a promise that is resolved using a generator that yields values or
* promises (somewhat similar to C#'s async keyword).
*
* When called, the coroutine function will start an instance of the generator
* and returns a promise that is fulfilled with its final yielded value.
*
* Control is returned back to the generator when the yielded promise settles.
* This can lead to less verbose code when doing lots of sequential async calls
* with minimal processing in between.
*
* use GuzzleHttp\Promise;
*
* function createPromise($value) {
* return new Promise\FulfilledPromise($value);
* }
*
* $promise = Promise\coroutine(function () {
* $value = (yield createPromise('a'));
* try {
* $value = (yield createPromise($value . 'b'));
* } catch (\Exception $e) {
* // The promise was rejected.
* }
* yield $value . 'c';
* });
*
* // Outputs "abc"
* $promise->then(function ($v) { echo $v; });
*
* @param callable $generatorFn Generator function to wrap into a promise.
*
* @return Promise
* @link https://github.com/petkaantonov/bluebird/blob/master/API.md#generators inspiration
*/
final class Coroutine implements PromiseInterface
{
/**
* @var PromiseInterface|null
*/
private $currentPromise;
/**
* @var Generator
*/
private $generator;
/**
* @var Promise
*/
private $result;
public function __construct(callable $generatorFn)
{
$this->generator = $generatorFn();
$this->result = new Promise(function () {
while (isset($this->currentPromise)) {
$this->currentPromise->wait();
}
});
$this->nextCoroutine($this->generator->current());
}
public function then(
callable $onFulfilled = null,
callable $onRejected = null
) {
return $this->result->then($onFulfilled, $onRejected);
}
public function otherwise(callable $onRejected)
{
return $this->result->otherwise($onRejected);
}
public function wait($unwrap = true)
{
return $this->result->wait($unwrap);
}
public function getState()
{
return $this->result->getState();
}
public function resolve($value)
{
$this->result->resolve($value);
}
public function reject($reason)
{
$this->result->reject($reason);
}
public function cancel()
{
$this->currentPromise->cancel();
$this->result->cancel();
}
private function nextCoroutine($yielded)
{
$this->currentPromise = promise_for($yielded)
->then([$this, '_handleSuccess'], [$this, '_handleFailure']);
}
/**
* @internal
*/
public function _handleSuccess($value)
{
unset($this->currentPromise);
try {
$next = $this->generator->send($value);
if ($this->generator->valid()) {
$this->nextCoroutine($next);
} else {
$this->result->resolve($value);
}
} catch (Exception $exception) {
$this->result->reject($exception);
} catch (Throwable $throwable) {
$this->result->reject($throwable);
}
}
/**
* @internal
*/
public function _handleFailure($reason)
{
unset($this->currentPromise);
try {
$nextYield = $this->generator->throw(exception_for($reason));
// The throw was caught, so keep iterating on the coroutine
$this->nextCoroutine($nextYield);
} catch (Exception $exception) {
$this->result->reject($exception);
} catch (Throwable $throwable) {
$this->result->reject($throwable);
}
}
}

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<?php
namespace GuzzleHttp\Promise;
/**
* Represents a promise that iterates over many promises and invokes
* side-effect functions in the process.
*/
class EachPromise implements PromisorInterface
{
private $pending = [];
/** @var \Iterator */
private $iterable;
/** @var callable|int */
private $concurrency;
/** @var callable */
private $onFulfilled;
/** @var callable */
private $onRejected;
/** @var Promise */
private $aggregate;
/** @var bool */
private $mutex;
/**
* Configuration hash can include the following key value pairs:
*
* - fulfilled: (callable) Invoked when a promise fulfills. The function
* is invoked with three arguments: the fulfillment value, the index
* position from the iterable list of the promise, and the aggregate
* promise that manages all of the promises. The aggregate promise may
* be resolved from within the callback to short-circuit the promise.
* - rejected: (callable) Invoked when a promise is rejected. The
* function is invoked with three arguments: the rejection reason, the
* index position from the iterable list of the promise, and the
* aggregate promise that manages all of the promises. The aggregate
* promise may be resolved from within the callback to short-circuit
* the promise.
* - concurrency: (integer) Pass this configuration option to limit the
* allowed number of outstanding concurrently executing promises,
* creating a capped pool of promises. There is no limit by default.
*
* @param mixed $iterable Promises or values to iterate.
* @param array $config Configuration options
*/
public function __construct($iterable, array $config = [])
{
$this->iterable = iter_for($iterable);
if (isset($config['concurrency'])) {
$this->concurrency = $config['concurrency'];
}
if (isset($config['fulfilled'])) {
$this->onFulfilled = $config['fulfilled'];
}
if (isset($config['rejected'])) {
$this->onRejected = $config['rejected'];
}
}
public function promise()
{
if ($this->aggregate) {
return $this->aggregate;
}
try {
$this->createPromise();
$this->iterable->rewind();
$this->refillPending();
} catch (\Throwable $e) {
$this->aggregate->reject($e);
} catch (\Exception $e) {
$this->aggregate->reject($e);
}
return $this->aggregate;
}
private function createPromise()
{
$this->mutex = false;
$this->aggregate = new Promise(function () {
reset($this->pending);
if (empty($this->pending) && !$this->iterable->valid()) {
$this->aggregate->resolve(null);
return;
}
// Consume a potentially fluctuating list of promises while
// ensuring that indexes are maintained (precluding array_shift).
while ($promise = current($this->pending)) {
next($this->pending);
$promise->wait();
if ($this->aggregate->getState() !== PromiseInterface::PENDING) {
return;
}
}
});
// Clear the references when the promise is resolved.
$clearFn = function () {
$this->iterable = $this->concurrency = $this->pending = null;
$this->onFulfilled = $this->onRejected = null;
};
$this->aggregate->then($clearFn, $clearFn);
}
private function refillPending()
{
if (!$this->concurrency) {
// Add all pending promises.
while ($this->addPending() && $this->advanceIterator());
return;
}
// Add only up to N pending promises.
$concurrency = is_callable($this->concurrency)
? call_user_func($this->concurrency, count($this->pending))
: $this->concurrency;
$concurrency = max($concurrency - count($this->pending), 0);
// Concurrency may be set to 0 to disallow new promises.
if (!$concurrency) {
return;
}
// Add the first pending promise.
$this->addPending();
// Note this is special handling for concurrency=1 so that we do
// not advance the iterator after adding the first promise. This
// helps work around issues with generators that might not have the
// next value to yield until promise callbacks are called.
while (--$concurrency
&& $this->advanceIterator()
&& $this->addPending());
}
private function addPending()
{
if (!$this->iterable || !$this->iterable->valid()) {
return false;
}
$promise = promise_for($this->iterable->current());
$idx = $this->iterable->key();
$this->pending[$idx] = $promise->then(
function ($value) use ($idx) {
if ($this->onFulfilled) {
call_user_func(
$this->onFulfilled, $value, $idx, $this->aggregate
);
}
$this->step($idx);
},
function ($reason) use ($idx) {
if ($this->onRejected) {
call_user_func(
$this->onRejected, $reason, $idx, $this->aggregate
);
}
$this->step($idx);
}
);
return true;
}
private function advanceIterator()
{
// Place a lock on the iterator so that we ensure to not recurse,
// preventing fatal generator errors.
if ($this->mutex) {
return false;
}
$this->mutex = true;
try {
$this->iterable->next();
$this->mutex = false;
return true;
} catch (\Throwable $e) {
$this->aggregate->reject($e);
$this->mutex = false;
return false;
} catch (\Exception $e) {
$this->aggregate->reject($e);
$this->mutex = false;
return false;
}
}
private function step($idx)
{
// If the promise was already resolved, then ignore this step.
if ($this->aggregate->getState() !== PromiseInterface::PENDING) {
return;
}
unset($this->pending[$idx]);
// Only refill pending promises if we are not locked, preventing the
// EachPromise to recursively invoke the provided iterator, which
// cause a fatal error: "Cannot resume an already running generator"
if ($this->advanceIterator() && !$this->checkIfFinished()) {
// Add more pending promises if possible.
$this->refillPending();
}
}
private function checkIfFinished()
{
if (!$this->pending && !$this->iterable->valid()) {
// Resolve the promise if there's nothing left to do.
$this->aggregate->resolve(null);
return true;
}
return false;
}
}

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<?php
namespace GuzzleHttp\Promise;
/**
* A promise that has been fulfilled.
*
* Thenning off of this promise will invoke the onFulfilled callback
* immediately and ignore other callbacks.
*/
class FulfilledPromise implements PromiseInterface
{
private $value;
public function __construct($value)
{
if (method_exists($value, 'then')) {
throw new \InvalidArgumentException(
'You cannot create a FulfilledPromise with a promise.');
}
$this->value = $value;
}
public function then(
callable $onFulfilled = null,
callable $onRejected = null
) {
// Return itself if there is no onFulfilled function.
if (!$onFulfilled) {
return $this;
}
$queue = queue();
$p = new Promise([$queue, 'run']);
$value = $this->value;
$queue->add(static function () use ($p, $value, $onFulfilled) {
if ($p->getState() === self::PENDING) {
try {
$p->resolve($onFulfilled($value));
} catch (\Throwable $e) {
$p->reject($e);
} catch (\Exception $e) {
$p->reject($e);
}
}
});
return $p;
}
public function otherwise(callable $onRejected)
{
return $this->then(null, $onRejected);
}
public function wait($unwrap = true, $defaultDelivery = null)
{
return $unwrap ? $this->value : null;
}
public function getState()
{
return self::FULFILLED;
}
public function resolve($value)
{
if ($value !== $this->value) {
throw new \LogicException("Cannot resolve a fulfilled promise");
}
}
public function reject($reason)
{
throw new \LogicException("Cannot reject a fulfilled promise");
}
public function cancel()
{
// pass
}
}

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<?php
namespace GuzzleHttp\Promise;
/**
* Promises/A+ implementation that avoids recursion when possible.
*
* @link https://promisesaplus.com/
*/
class Promise implements PromiseInterface
{
private $state = self::PENDING;
private $result;
private $cancelFn;
private $waitFn;
private $waitList;
private $handlers = [];
/**
* @param callable $waitFn Fn that when invoked resolves the promise.
* @param callable $cancelFn Fn that when invoked cancels the promise.
*/
public function __construct(
callable $waitFn = null,
callable $cancelFn = null
) {
$this->waitFn = $waitFn;
$this->cancelFn = $cancelFn;
}
public function then(
callable $onFulfilled = null,
callable $onRejected = null
) {
if ($this->state === self::PENDING) {
$p = new Promise(null, [$this, 'cancel']);
$this->handlers[] = [$p, $onFulfilled, $onRejected];
$p->waitList = $this->waitList;
$p->waitList[] = $this;
return $p;
}
// Return a fulfilled promise and immediately invoke any callbacks.
if ($this->state === self::FULFILLED) {
return $onFulfilled
? promise_for($this->result)->then($onFulfilled)
: promise_for($this->result);
}
// It's either cancelled or rejected, so return a rejected promise
// and immediately invoke any callbacks.
$rejection = rejection_for($this->result);
return $onRejected ? $rejection->then(null, $onRejected) : $rejection;
}
public function otherwise(callable $onRejected)
{
return $this->then(null, $onRejected);
}
public function wait($unwrap = true)
{
$this->waitIfPending();
$inner = $this->result instanceof PromiseInterface
? $this->result->wait($unwrap)
: $this->result;
if ($unwrap) {
if ($this->result instanceof PromiseInterface
|| $this->state === self::FULFILLED
) {
return $inner;
} else {
// It's rejected so "unwrap" and throw an exception.
throw exception_for($inner);
}
}
}
public function getState()
{
return $this->state;
}
public function cancel()
{
if ($this->state !== self::PENDING) {
return;
}
$this->waitFn = $this->waitList = null;
if ($this->cancelFn) {
$fn = $this->cancelFn;
$this->cancelFn = null;
try {
$fn();
} catch (\Throwable $e) {
$this->reject($e);
} catch (\Exception $e) {
$this->reject($e);
}
}
// Reject the promise only if it wasn't rejected in a then callback.
if ($this->state === self::PENDING) {
$this->reject(new CancellationException('Promise has been cancelled'));
}
}
public function resolve($value)
{
$this->settle(self::FULFILLED, $value);
}
public function reject($reason)
{
$this->settle(self::REJECTED, $reason);
}
private function settle($state, $value)
{
if ($this->state !== self::PENDING) {
// Ignore calls with the same resolution.
if ($state === $this->state && $value === $this->result) {
return;
}
throw $this->state === $state
? new \LogicException("The promise is already {$state}.")
: new \LogicException("Cannot change a {$this->state} promise to {$state}");
}
if ($value === $this) {
throw new \LogicException('Cannot fulfill or reject a promise with itself');
}
// Clear out the state of the promise but stash the handlers.
$this->state = $state;
$this->result = $value;
$handlers = $this->handlers;
$this->handlers = null;
$this->waitList = $this->waitFn = null;
$this->cancelFn = null;
if (!$handlers) {
return;
}
// If the value was not a settled promise or a thenable, then resolve
// it in the task queue using the correct ID.
if (!method_exists($value, 'then')) {
$id = $state === self::FULFILLED ? 1 : 2;
// It's a success, so resolve the handlers in the queue.
queue()->add(static function () use ($id, $value, $handlers) {
foreach ($handlers as $handler) {
self::callHandler($id, $value, $handler);
}
});
} elseif ($value instanceof Promise
&& $value->getState() === self::PENDING
) {
// We can just merge our handlers onto the next promise.
$value->handlers = array_merge($value->handlers, $handlers);
} else {
// Resolve the handlers when the forwarded promise is resolved.
$value->then(
static function ($value) use ($handlers) {
foreach ($handlers as $handler) {
self::callHandler(1, $value, $handler);
}
},
static function ($reason) use ($handlers) {
foreach ($handlers as $handler) {
self::callHandler(2, $reason, $handler);
}
}
);
}
}
/**
* Call a stack of handlers using a specific callback index and value.
*
* @param int $index 1 (resolve) or 2 (reject).
* @param mixed $value Value to pass to the callback.
* @param array $handler Array of handler data (promise and callbacks).
*
* @return array Returns the next group to resolve.
*/
private static function callHandler($index, $value, array $handler)
{
/** @var PromiseInterface $promise */
$promise = $handler[0];
// The promise may have been cancelled or resolved before placing
// this thunk in the queue.
if ($promise->getState() !== self::PENDING) {
return;
}
try {
if (isset($handler[$index])) {
$promise->resolve($handler[$index]($value));
} elseif ($index === 1) {
// Forward resolution values as-is.
$promise->resolve($value);
} else {
// Forward rejections down the chain.
$promise->reject($value);
}
} catch (\Throwable $reason) {
$promise->reject($reason);
} catch (\Exception $reason) {
$promise->reject($reason);
}
}
private function waitIfPending()
{
if ($this->state !== self::PENDING) {
return;
} elseif ($this->waitFn) {
$this->invokeWaitFn();
} elseif ($this->waitList) {
$this->invokeWaitList();
} else {
// If there's not wait function, then reject the promise.
$this->reject('Cannot wait on a promise that has '
. 'no internal wait function. You must provide a wait '
. 'function when constructing the promise to be able to '
. 'wait on a promise.');
}
queue()->run();
if ($this->state === self::PENDING) {
$this->reject('Invoking the wait callback did not resolve the promise');
}
}
private function invokeWaitFn()
{
try {
$wfn = $this->waitFn;
$this->waitFn = null;
$wfn(true);
} catch (\Exception $reason) {
if ($this->state === self::PENDING) {
// The promise has not been resolved yet, so reject the promise
// with the exception.
$this->reject($reason);
} else {
// The promise was already resolved, so there's a problem in
// the application.
throw $reason;
}
}
}
private function invokeWaitList()
{
$waitList = $this->waitList;
$this->waitList = null;
foreach ($waitList as $result) {
while (true) {
$result->waitIfPending();
if ($result->result instanceof Promise) {
$result = $result->result;
} else {
if ($result->result instanceof PromiseInterface) {
$result->result->wait(false);
}
break;
}
}
}
}
}

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<?php
namespace GuzzleHttp\Promise;
/**
* A promise represents the eventual result of an asynchronous operation.
*
* The primary way of interacting with a promise is through its then method,
* which registers callbacks to receive either a promises eventual value or
* the reason why the promise cannot be fulfilled.
*
* @link https://promisesaplus.com/
*/
interface PromiseInterface
{
const PENDING = 'pending';
const FULFILLED = 'fulfilled';
const REJECTED = 'rejected';
/**
* Appends fulfillment and rejection handlers to the promise, and returns
* a new promise resolving to the return value of the called handler.
*
* @param callable $onFulfilled Invoked when the promise fulfills.
* @param callable $onRejected Invoked when the promise is rejected.
*
* @return PromiseInterface
*/
public function then(
callable $onFulfilled = null,
callable $onRejected = null
);
/**
* Appends a rejection handler callback to the promise, and returns a new
* promise resolving to the return value of the callback if it is called,
* or to its original fulfillment value if the promise is instead
* fulfilled.
*
* @param callable $onRejected Invoked when the promise is rejected.
*
* @return PromiseInterface
*/
public function otherwise(callable $onRejected);
/**
* Get the state of the promise ("pending", "rejected", or "fulfilled").
*
* The three states can be checked against the constants defined on
* PromiseInterface: PENDING, FULFILLED, and REJECTED.
*
* @return string
*/
public function getState();
/**
* Resolve the promise with the given value.
*
* @param mixed $value
* @throws \RuntimeException if the promise is already resolved.
*/
public function resolve($value);
/**
* Reject the promise with the given reason.
*
* @param mixed $reason
* @throws \RuntimeException if the promise is already resolved.
*/
public function reject($reason);
/**
* Cancels the promise if possible.
*
* @link https://github.com/promises-aplus/cancellation-spec/issues/7
*/
public function cancel();
/**
* Waits until the promise completes if possible.
*
* Pass $unwrap as true to unwrap the result of the promise, either
* returning the resolved value or throwing the rejected exception.
*
* If the promise cannot be waited on, then the promise will be rejected.
*
* @param bool $unwrap
*
* @return mixed
* @throws \LogicException if the promise has no wait function or if the
* promise does not settle after waiting.
*/
public function wait($unwrap = true);
}

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<?php
namespace GuzzleHttp\Promise;
/**
* Interface used with classes that return a promise.
*/
interface PromisorInterface
{
/**
* Returns a promise.
*
* @return PromiseInterface
*/
public function promise();
}

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<?php
namespace GuzzleHttp\Promise;
/**
* A promise that has been rejected.
*
* Thenning off of this promise will invoke the onRejected callback
* immediately and ignore other callbacks.
*/
class RejectedPromise implements PromiseInterface
{
private $reason;
public function __construct($reason)
{
if (method_exists($reason, 'then')) {
throw new \InvalidArgumentException(
'You cannot create a RejectedPromise with a promise.');
}
$this->reason = $reason;
}
public function then(
callable $onFulfilled = null,
callable $onRejected = null
) {
// If there's no onRejected callback then just return self.
if (!$onRejected) {
return $this;
}
$queue = queue();
$reason = $this->reason;
$p = new Promise([$queue, 'run']);
$queue->add(static function () use ($p, $reason, $onRejected) {
if ($p->getState() === self::PENDING) {
try {
// Return a resolved promise if onRejected does not throw.
$p->resolve($onRejected($reason));
} catch (\Throwable $e) {
// onRejected threw, so return a rejected promise.
$p->reject($e);
} catch (\Exception $e) {
// onRejected threw, so return a rejected promise.
$p->reject($e);
}
}
});
return $p;
}
public function otherwise(callable $onRejected)
{
return $this->then(null, $onRejected);
}
public function wait($unwrap = true, $defaultDelivery = null)
{
if ($unwrap) {
throw exception_for($this->reason);
}
}
public function getState()
{
return self::REJECTED;
}
public function resolve($value)
{
throw new \LogicException("Cannot resolve a rejected promise");
}
public function reject($reason)
{
if ($reason !== $this->reason) {
throw new \LogicException("Cannot reject a rejected promise");
}
}
public function cancel()
{
// pass
}
}

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<?php
namespace GuzzleHttp\Promise;
/**
* A special exception that is thrown when waiting on a rejected promise.
*
* The reason value is available via the getReason() method.
*/
class RejectionException extends \RuntimeException
{
/** @var mixed Rejection reason. */
private $reason;
/**
* @param mixed $reason Rejection reason.
* @param string $description Optional description
*/
public function __construct($reason, $description = null)
{
$this->reason = $reason;
$message = 'The promise was rejected';
if ($description) {
$message .= ' with reason: ' . $description;
} elseif (is_string($reason)
|| (is_object($reason) && method_exists($reason, '__toString'))
) {
$message .= ' with reason: ' . $this->reason;
} elseif ($reason instanceof \JsonSerializable) {
$message .= ' with reason: '
. json_encode($this->reason, JSON_PRETTY_PRINT);
}
parent::__construct($message);
}
/**
* Returns the rejection reason.
*
* @return mixed
*/
public function getReason()
{
return $this->reason;
}
}

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<?php
namespace GuzzleHttp\Promise;
/**
* A task queue that executes tasks in a FIFO order.
*
* This task queue class is used to settle promises asynchronously and
* maintains a constant stack size. You can use the task queue asynchronously
* by calling the `run()` function of the global task queue in an event loop.
*
* GuzzleHttp\Promise\queue()->run();
*/
class TaskQueue implements TaskQueueInterface
{
private $enableShutdown = true;
private $queue = [];
public function __construct($withShutdown = true)
{
if ($withShutdown) {
register_shutdown_function(function () {
if ($this->enableShutdown) {
// Only run the tasks if an E_ERROR didn't occur.
$err = error_get_last();
if (!$err || ($err['type'] ^ E_ERROR)) {
$this->run();
}
}
});
}
}
public function isEmpty()
{
return !$this->queue;
}
public function add(callable $task)
{
$this->queue[] = $task;
}
public function run()
{
/** @var callable $task */
while ($task = array_shift($this->queue)) {
$task();
}
}
/**
* The task queue will be run and exhausted by default when the process
* exits IFF the exit is not the result of a PHP E_ERROR error.
*
* You can disable running the automatic shutdown of the queue by calling
* this function. If you disable the task queue shutdown process, then you
* MUST either run the task queue (as a result of running your event loop
* or manually using the run() method) or wait on each outstanding promise.
*
* Note: This shutdown will occur before any destructors are triggered.
*/
public function disableShutdown()
{
$this->enableShutdown = false;
}
}

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<?php
namespace GuzzleHttp\Promise;
interface TaskQueueInterface
{
/**
* Returns true if the queue is empty.
*
* @return bool
*/
public function isEmpty();
/**
* Adds a task to the queue that will be executed the next time run is
* called.
*
* @param callable $task
*/
public function add(callable $task);
/**
* Execute all of the pending task in the queue.
*/
public function run();
}

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<?php
namespace GuzzleHttp\Promise;
/**
* Get the global task queue used for promise resolution.
*
* This task queue MUST be run in an event loop in order for promises to be
* settled asynchronously. It will be automatically run when synchronously
* waiting on a promise.
*
* <code>
* while ($eventLoop->isRunning()) {
* GuzzleHttp\Promise\queue()->run();
* }
* </code>
*
* @param TaskQueueInterface $assign Optionally specify a new queue instance.
*
* @return TaskQueueInterface
*/
function queue(TaskQueueInterface $assign = null)
{
static $queue;
if ($assign) {
$queue = $assign;
} elseif (!$queue) {
$queue = new TaskQueue();
}
return $queue;
}
/**
* Adds a function to run in the task queue when it is next `run()` and returns
* a promise that is fulfilled or rejected with the result.
*
* @param callable $task Task function to run.
*
* @return PromiseInterface
*/
function task(callable $task)
{
$queue = queue();
$promise = new Promise([$queue, 'run']);
$queue->add(function () use ($task, $promise) {
try {
$promise->resolve($task());
} catch (\Throwable $e) {
$promise->reject($e);
} catch (\Exception $e) {
$promise->reject($e);
}
});
return $promise;
}
/**
* Creates a promise for a value if the value is not a promise.
*
* @param mixed $value Promise or value.
*
* @return PromiseInterface
*/
function promise_for($value)
{
if ($value instanceof PromiseInterface) {
return $value;
}
// Return a Guzzle promise that shadows the given promise.
if (method_exists($value, 'then')) {
$wfn = method_exists($value, 'wait') ? [$value, 'wait'] : null;
$cfn = method_exists($value, 'cancel') ? [$value, 'cancel'] : null;
$promise = new Promise($wfn, $cfn);
$value->then([$promise, 'resolve'], [$promise, 'reject']);
return $promise;
}
return new FulfilledPromise($value);
}
/**
* Creates a rejected promise for a reason if the reason is not a promise. If
* the provided reason is a promise, then it is returned as-is.
*
* @param mixed $reason Promise or reason.
*
* @return PromiseInterface
*/
function rejection_for($reason)
{
if ($reason instanceof PromiseInterface) {
return $reason;
}
return new RejectedPromise($reason);
}
/**
* Create an exception for a rejected promise value.
*
* @param mixed $reason
*
* @return \Exception|\Throwable
*/
function exception_for($reason)
{
return $reason instanceof \Exception || $reason instanceof \Throwable
? $reason
: new RejectionException($reason);
}
/**
* Returns an iterator for the given value.
*
* @param mixed $value
*
* @return \Iterator
*/
function iter_for($value)
{
if ($value instanceof \Iterator) {
return $value;
} elseif (is_array($value)) {
return new \ArrayIterator($value);
} else {
return new \ArrayIterator([$value]);
}
}
/**
* Synchronously waits on a promise to resolve and returns an inspection state
* array.
*
* Returns a state associative array containing a "state" key mapping to a
* valid promise state. If the state of the promise is "fulfilled", the array
* will contain a "value" key mapping to the fulfilled value of the promise. If
* the promise is rejected, the array will contain a "reason" key mapping to
* the rejection reason of the promise.
*
* @param PromiseInterface $promise Promise or value.
*
* @return array
*/
function inspect(PromiseInterface $promise)
{
try {
return [
'state' => PromiseInterface::FULFILLED,
'value' => $promise->wait()
];
} catch (RejectionException $e) {
return ['state' => PromiseInterface::REJECTED, 'reason' => $e->getReason()];
} catch (\Throwable $e) {
return ['state' => PromiseInterface::REJECTED, 'reason' => $e];
} catch (\Exception $e) {
return ['state' => PromiseInterface::REJECTED, 'reason' => $e];
}
}
/**
* Waits on all of the provided promises, but does not unwrap rejected promises
* as thrown exception.
*
* Returns an array of inspection state arrays.
*
* @param PromiseInterface[] $promises Traversable of promises to wait upon.
*
* @return array
* @see GuzzleHttp\Promise\inspect for the inspection state array format.
*/
function inspect_all($promises)
{
$results = [];
foreach ($promises as $key => $promise) {
$results[$key] = inspect($promise);
}
return $results;
}
/**
* Waits on all of the provided promises and returns the fulfilled values.
*
* Returns an array that contains the value of each promise (in the same order
* the promises were provided). An exception is thrown if any of the promises
* are rejected.
*
* @param mixed $promises Iterable of PromiseInterface objects to wait on.
*
* @return array
* @throws \Exception on error
* @throws \Throwable on error in PHP >=7
*/
function unwrap($promises)
{
$results = [];
foreach ($promises as $key => $promise) {
$results[$key] = $promise->wait();
}
return $results;
}
/**
* Given an array of promises, return a promise that is fulfilled when all the
* items in the array are fulfilled.
*
* The promise's fulfillment value is an array with fulfillment values at
* respective positions to the original array. If any promise in the array
* rejects, the returned promise is rejected with the rejection reason.
*
* @param mixed $promises Promises or values.
*
* @return PromiseInterface
*/
function all($promises)
{
$results = [];
return each(
$promises,
function ($value, $idx) use (&$results) {
$results[$idx] = $value;
},
function ($reason, $idx, Promise $aggregate) {
$aggregate->reject($reason);
}
)->then(function () use (&$results) {
ksort($results);
return $results;
});
}
/**
* Initiate a competitive race between multiple promises or values (values will
* become immediately fulfilled promises).
*
* When count amount of promises have been fulfilled, the returned promise is
* fulfilled with an array that contains the fulfillment values of the winners
* in order of resolution.
*
* This prommise is rejected with a {@see GuzzleHttp\Promise\AggregateException}
* if the number of fulfilled promises is less than the desired $count.
*
* @param int $count Total number of promises.
* @param mixed $promises Promises or values.
*
* @return PromiseInterface
*/
function some($count, $promises)
{
$results = [];
$rejections = [];
return each(
$promises,
function ($value, $idx, PromiseInterface $p) use (&$results, $count) {
if ($p->getState() !== PromiseInterface::PENDING) {
return;
}
$results[$idx] = $value;
if (count($results) >= $count) {
$p->resolve(null);
}
},
function ($reason) use (&$rejections) {
$rejections[] = $reason;
}
)->then(
function () use (&$results, &$rejections, $count) {
if (count($results) !== $count) {
throw new AggregateException(
'Not enough promises to fulfill count',
$rejections
);
}
ksort($results);
return array_values($results);
}
);
}
/**
* Like some(), with 1 as count. However, if the promise fulfills, the
* fulfillment value is not an array of 1 but the value directly.
*
* @param mixed $promises Promises or values.
*
* @return PromiseInterface
*/
function any($promises)
{
return some(1, $promises)->then(function ($values) { return $values[0]; });
}
/**
* Returns a promise that is fulfilled when all of the provided promises have
* been fulfilled or rejected.
*
* The returned promise is fulfilled with an array of inspection state arrays.
*
* @param mixed $promises Promises or values.
*
* @return PromiseInterface
* @see GuzzleHttp\Promise\inspect for the inspection state array format.
*/
function settle($promises)
{
$results = [];
return each(
$promises,
function ($value, $idx) use (&$results) {
$results[$idx] = ['state' => PromiseInterface::FULFILLED, 'value' => $value];
},
function ($reason, $idx) use (&$results) {
$results[$idx] = ['state' => PromiseInterface::REJECTED, 'reason' => $reason];
}
)->then(function () use (&$results) {
ksort($results);
return $results;
});
}
/**
* Given an iterator that yields promises or values, returns a promise that is
* fulfilled with a null value when the iterator has been consumed or the
* aggregate promise has been fulfilled or rejected.
*
* $onFulfilled is a function that accepts the fulfilled value, iterator
* index, and the aggregate promise. The callback can invoke any necessary side
* effects and choose to resolve or reject the aggregate promise if needed.
*
* $onRejected is a function that accepts the rejection reason, iterator
* index, and the aggregate promise. The callback can invoke any necessary side
* effects and choose to resolve or reject the aggregate promise if needed.
*
* @param mixed $iterable Iterator or array to iterate over.
* @param callable $onFulfilled
* @param callable $onRejected
*
* @return PromiseInterface
*/
function each(
$iterable,
callable $onFulfilled = null,
callable $onRejected = null
) {
return (new EachPromise($iterable, [
'fulfilled' => $onFulfilled,
'rejected' => $onRejected
]))->promise();
}
/**
* Like each, but only allows a certain number of outstanding promises at any
* given time.
*
* $concurrency may be an integer or a function that accepts the number of
* pending promises and returns a numeric concurrency limit value to allow for
* dynamic a concurrency size.
*
* @param mixed $iterable
* @param int|callable $concurrency
* @param callable $onFulfilled
* @param callable $onRejected
*
* @return PromiseInterface
*/
function each_limit(
$iterable,
$concurrency,
callable $onFulfilled = null,
callable $onRejected = null
) {
return (new EachPromise($iterable, [
'fulfilled' => $onFulfilled,
'rejected' => $onRejected,
'concurrency' => $concurrency
]))->promise();
}
/**
* Like each_limit, but ensures that no promise in the given $iterable argument
* is rejected. If any promise is rejected, then the aggregate promise is
* rejected with the encountered rejection.
*
* @param mixed $iterable
* @param int|callable $concurrency
* @param callable $onFulfilled
*
* @return PromiseInterface
*/
function each_limit_all(
$iterable,
$concurrency,
callable $onFulfilled = null
) {
return each_limit(
$iterable,
$concurrency,
$onFulfilled,
function ($reason, $idx, PromiseInterface $aggregate) {
$aggregate->reject($reason);
}
);
}
/**
* Returns true if a promise is fulfilled.
*
* @param PromiseInterface $promise
*
* @return bool
*/
function is_fulfilled(PromiseInterface $promise)
{
return $promise->getState() === PromiseInterface::FULFILLED;
}
/**
* Returns true if a promise is rejected.
*
* @param PromiseInterface $promise
*
* @return bool
*/
function is_rejected(PromiseInterface $promise)
{
return $promise->getState() === PromiseInterface::REJECTED;
}
/**
* Returns true if a promise is fulfilled or rejected.
*
* @param PromiseInterface $promise
*
* @return bool
*/
function is_settled(PromiseInterface $promise)
{
return $promise->getState() !== PromiseInterface::PENDING;
}
/**
* @see Coroutine
*
* @param callable $generatorFn
*
* @return PromiseInterface
*/
function coroutine(callable $generatorFn)
{
return new Coroutine($generatorFn);
}

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@ -0,0 +1,6 @@
<?php
// Don't redefine the functions if included multiple times.
if (!function_exists('GuzzleHttp\Promise\promise_for')) {
require __DIR__ . '/functions.php';
}