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Diffstat (limited to 'vendor/sabre/event/lib/coroutine.php')
-rw-r--r-- | vendor/sabre/event/lib/coroutine.php | 120 |
1 files changed, 120 insertions, 0 deletions
diff --git a/vendor/sabre/event/lib/coroutine.php b/vendor/sabre/event/lib/coroutine.php new file mode 100644 index 000000000..19c0ba8a7 --- /dev/null +++ b/vendor/sabre/event/lib/coroutine.php @@ -0,0 +1,120 @@ +<?php + +namespace Sabre\Event; + +use Generator; +use Exception; + +/** + * Turn asynchronous promise-based code into something that looks synchronous + * again, through the use of generators. + * + * Example without coroutines: + * + * $promise = $httpClient->request('GET', '/foo'); + * $promise->then(function($value) { + * + * return $httpClient->request('DELETE','/foo'); + * + * })->then(function($value) { + * + * return $httpClient->request('PUT', '/foo'); + * + * })->error(function($reason) { + * + * echo "Failed because: $reason\n"; + * + * }); + * + * Example with coroutines: + * + * coroutine(function() { + * + * try { + * yield $httpClient->request('GET', '/foo'); + * yield $httpClient->request('DELETE', /foo'); + * yield $httpClient->request('PUT', '/foo'); + * } catch(\Exception $reason) { + * echo "Failed because: $reason\n"; + * } + * + * }); + * + * @copyright Copyright (C) 2013-2015 fruux GmbH. All rights reserved. + * @author Evert Pot (http://evertpot.com/) + * @license http://sabre.io/license/ Modified BSD License + */ +function coroutine(callable $gen) { + + $generator = $gen(); + if (!$generator instanceof Generator) { + throw new \InvalidArgumentException('You must pass a generator function'); + } + + // This is the value we're returning. + $promise = new Promise(); + + $lastYieldResult = null; + + /** + * So tempted to use the mythical y-combinator here, but it's not needed in + * PHP. + */ + $advanceGenerator = function() use (&$advanceGenerator, $generator, $promise, &$lastYieldResult) { + + while ($generator->valid()) { + + $yieldedValue = $generator->current(); + if ($yieldedValue instanceof Promise) { + $yieldedValue->then( + function($value) use ($generator, &$advanceGenerator, &$lastYieldResult) { + $lastYieldResult = $value; + $generator->send($value); + $advanceGenerator(); + }, + function($reason) use ($generator, $advanceGenerator) { + if ($reason instanceof Exception) { + $generator->throw($reason); + } elseif (is_scalar($reason)) { + $generator->throw(new Exception($reason)); + } else { + $type = is_object($reason) ? get_class($reason) : gettype($reason); + $generator->throw(new Exception('Promise was rejected with reason of type: ' . $type)); + } + $advanceGenerator(); + } + )->error(function($reason) use ($promise) { + // This error handler would be called, if something in the + // generator throws an exception, and it's not caught + // locally. + $promise->reject($reason); + }); + // We need to break out of the loop, because $advanceGenerator + // will be called asynchronously when the promise has a result. + break; + } else { + // If the value was not a promise, we'll just let it pass through. + $lastYieldResult = $yieldedValue; + $generator->send($yieldedValue); + } + + } + + // If the generator is at the end, and we didn't run into an exception, + // we can fullfill the promise with the last thing that was yielded to + // us. + if (!$generator->valid() && $promise->state === Promise::PENDING) { + $promise->fulfill($lastYieldResult); + } + + }; + + try { + $advanceGenerator(); + } catch (Exception $e) { + $promise->reject($e); + } + + return $promise; + +} |