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amp/lib/Future.php
2014-10-20 12:08:09 -04:00

178 lines
4.4 KiB
PHP

<?php
namespace Amp;
class Future implements Promisor, Promise {
private $reactor;
private $isWaiting = false;
private $isResolved = false;
private $watchers = [];
private $whens = [];
private $error;
private $result;
/**
* @param \Amp\Reactor $reactor
*/
public function __construct(Reactor $reactor = null) {
$this->reactor = $reactor ?: reactor();
}
/**
* Retrieve the Promise placeholder for this deferred value
*
* This implementation acts as both Promisor and Promise so we simply return the
* current instance. If users require a Promisor that can only be resolved by code
* holding a reference to the Promisor they may instead use Amp\PrivateFuture.
*
* @return \Amp\Promise
*/
public function promise() {
return $this;
}
/**
* Notify the $func callback when the promise resolves (whether successful or not)
*
* $func callbacks are invoked with parameters in error-first style.
*
* @param callable $func
* @return self
*/
public function when(callable $func) {
if ($this->isResolved) {
$func($this->error, $this->result);
} else {
$this->whens[] = $func;
}
return $this;
}
/**
* Notify the $func callback when resolution progress events are emitted
*
* @param callable $func
* @return self
*/
public function watch(callable $func) {
if (!$this->isResolved) {
$this->watchers[] = $func;
}
return $this;
}
/**
* Block script execution indefinitely until the promise resolves
*
* @throws \Exception
* @return mixed
*/
public function wait() {
if ($this->error) {
throw $this->error;
} elseif ($this->isResolved) {
return $this->result;
}
$resolvedError;
$resolvedResult;
$this->whens[] = function($error, $result) use (&$resolvedError, &$resolvedResult) {
$resolvedError = $error;
$resolvedResult = $result;
$this->isWaiting = false;
};
$this->isWaiting = true;
while ($this->isWaiting) {
$this->reactor->tick();
}
if ($resolvedError) {
throw $resolvedError;
}
return $resolvedResult;
}
/**
* Update watchers of resolution progress events
*
* @param mixed $progress
* @throws \LogicException
* @return void
*/
public function update($progress) {
if ($this->isResolved) {
throw new \LogicException(
'Cannot update resolved promise'
);
}
foreach ($this->watchers as $watcher) {
$watcher($progress);
}
}
/**
* Resolve the promised value as a success
*
* @param mixed $result
* @throws \LogicException
* @return void
*/
public function succeed($result = null) {
if ($this->isResolved) {
throw new \LogicException(
'Promise already resolved'
);
} elseif ($result === $this) {
throw new \LogicException(
'A Promise cannot act as its own resolution result'
);
} elseif ($result instanceof Promise) {
$result->when(function(\Exception $error = null, $result = null) {
if ($error) {
$this->fail($error);
} else {
$this->succeed($result);
}
});
} else {
$this->isResolved = true;
$this->result = $result;
$error = null;
foreach ($this->whens as $when) {
$when($error, $result);
}
$this->whens = $this->watchers = [];
}
}
/**
* Resolve the promised value as a failure
*
* @param \Exception $error
* @throws \LogicException If the Promise has already resolved
* @return void
*/
public function fail(\Exception $error) {
if ($this->isResolved) {
throw new \LogicException(
'Promise already resolved'
);
}
$this->isResolved = true;
$this->error = $error;
$result = null;
foreach ($this->whens as $when) {
$when($error, $result);
}
$this->whens = $this->watchers = [];
}
}