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author | Anton Luka Šijanec <anton@sijanec.eu> | 2022-01-11 12:35:47 +0100 |
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committer | Anton Luka Šijanec <anton@sijanec.eu> | 2022-01-11 12:35:47 +0100 |
commit | 19985dbb8c0aa66dc4bf7905abc1148de909097d (patch) | |
tree | 2cd5a5d20d7e80fc2a51adf60d838d8a2c40999e /vendor/guzzlehttp/promises/src/Promise.php | |
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Diffstat (limited to 'vendor/guzzlehttp/promises/src/Promise.php')
-rw-r--r-- | vendor/guzzlehttp/promises/src/Promise.php | 278 |
1 files changed, 278 insertions, 0 deletions
diff --git a/vendor/guzzlehttp/promises/src/Promise.php b/vendor/guzzlehttp/promises/src/Promise.php new file mode 100644 index 0000000..7593905 --- /dev/null +++ b/vendor/guzzlehttp/promises/src/Promise.php @@ -0,0 +1,278 @@ +<?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) { + $promise = Create::promiseFor($this->result); + return $onFulfilled ? $promise->then($onFulfilled) : $promise; + } + + // It's either cancelled or rejected, so return a rejected promise + // and immediately invoke any callbacks. + $rejection = Create::rejectionFor($this->result); + return $onRejected ? $rejection->then(null, $onRejected) : $rejection; + } + + public function otherwise(callable $onRejected) + { + return $this->then(null, $onRejected); + } + + public function wait($unwrap = true) + { + $this->waitIfPending(); + + if ($this->result instanceof PromiseInterface) { + return $this->result->wait($unwrap); + } + if ($unwrap) { + if ($this->state === self::FULFILLED) { + return $this->result; + } + // It's rejected so "unwrap" and throw an exception. + throw Create::exceptionFor($this->result); + } + } + + 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. + /** @psalm-suppress RedundantCondition */ + 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 (!is_object($value) || !method_exists($value, 'then')) { + $id = $state === self::FULFILLED ? 1 : 2; + // It's a success, so resolve the handlers in the queue. + Utils::queue()->add(static function () use ($id, $value, $handlers) { + foreach ($handlers as $handler) { + self::callHandler($id, $value, $handler); + } + }); + } elseif ($value instanceof Promise && Is::pending($value)) { + // 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 $handler Array of handler data (promise and callbacks). + */ + private static function callHandler($index, $value, array $handler) + { + /** @var PromiseInterface $promise */ + $promise = $handler[0]; + + // The promise may have been cancelled or resolved before placing + // this thunk in the queue. + if (Is::settled($promise)) { + return; + } + + try { + if (isset($handler[$index])) { + /* + * If $f throws an exception, then $handler will be in the exception + * stack trace. Since $handler contains a reference to the callable + * itself we get a circular reference. We clear the $handler + * here to avoid that memory leak. + */ + $f = $handler[$index]; + unset($handler); + $promise->resolve($f($value)); + } elseif ($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 no wait function, then reject the promise. + $this->reject('Cannot wait on a promise that has ' + . 'no internal wait function. You must provide a wait ' + . 'function when constructing the promise to be able to ' + . 'wait on a promise.'); + } + + Utils::queue()->run(); + + /** @psalm-suppress RedundantCondition */ + if ($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) { + do { + $result->waitIfPending(); + $result = $result->result; + } while ($result instanceof Promise); + + if ($result instanceof PromiseInterface) { + $result->wait(false); + } + } + } +} |