Subversion Repositories php-qbpwcf

<?php

namespace React\Promise;

class Promise implements ExtendedPromiseInterface, CancellablePromiseInterface

{

    private $canceller;

    private $result;

    private $handlers = [];

    private $progressHandlers = [];

    private $requiredCancelRequests = 0;

    private $cancelRequests = 0;

    public function __construct(callable $resolver, callable $canceller = null)

    {

        $this->canceller = $canceller;

        // Explicitly overwrite arguments with null values before invoking

        // resolver function. This ensure that these arguments do not show up

        // in the stack trace in PHP 7+ only.

        $cb = $resolver;

        $resolver = $canceller = null;

        $this->call($cb);

    }

    public function then(callable $onFulfilled = null, callable $onRejected = null, callable $onProgress = null)

    {

        if (null !== $this->result) {

            return $this->result->then($onFulfilled, $onRejected, $onProgress);

        }

        if (null === $this->canceller) {

            return new static($this->resolver($onFulfilled, $onRejected, $onProgress));

        }

        // This promise has a canceller, so we create a new child promise which

        // has a canceller that invokes the parent canceller if all other

        // followers are also cancelled. We keep a reference to this promise

        // instance for the static canceller function and clear this to avoid

        // keeping a cyclic reference between parent and follower.

        $parent = $this;

        ++$parent->requiredCancelRequests;

        return new static(

            $this->resolver($onFulfilled, $onRejected, $onProgress),

            static function () use (&$parent) {

                if (++$parent->cancelRequests >= $parent->requiredCancelRequests) {

                    $parent->cancel();

                }

                $parent = null;

            }

        );

    }

    public function done(callable $onFulfilled = null, callable $onRejected = null, callable $onProgress = null)

    {

        if (null !== $this->result) {

            return $this->result->done($onFulfilled, $onRejected, $onProgress);

        }

        $this->handlers[] = static function (ExtendedPromiseInterface $promise) use ($onFulfilled, $onRejected) {

            $promise

                ->done($onFulfilled, $onRejected);

        };

        if ($onProgress) {

            $this->progressHandlers[] = $onProgress;

        }

    }

    public function otherwise(callable $onRejected)

    {

        return $this->then(null, static function ($reason) use ($onRejected) {

            if (!_checkTypehint($onRejected, $reason)) {

                return new RejectedPromise($reason);

            }

            return $onRejected($reason);

        });

    }

    public function always(callable $onFulfilledOrRejected)

    {

        return $this->then(static function ($value) use ($onFulfilledOrRejected) {

            return resolve($onFulfilledOrRejected())->then(function () use ($value) {

                return $value;

            });

        }, static function ($reason) use ($onFulfilledOrRejected) {

            return resolve($onFulfilledOrRejected())->then(function () use ($reason) {

                return new RejectedPromise($reason);

            });

        });

    }

    public function progress(callable $onProgress)

    {

        return $this->then(null, null, $onProgress);

    }

    public function cancel()

    {

        if (null === $this->canceller || null !== $this->result) {

            return;

        }

        $canceller = $this->canceller;

        $this->canceller = null;

        $this->call($canceller);

    }

    private function resolver(callable $onFulfilled = null, callable $onRejected = null, callable $onProgress = null)

    {

        return function ($resolve, $reject, $notify) use ($onFulfilled, $onRejected, $onProgress) {

            if ($onProgress) {

                $progressHandler = static function ($update) use ($notify, $onProgress) {

                    try {

                        $notify($onProgress($update));

                    } catch (\Throwable $e) {

                        $notify($e);

                    } catch (\Exception $e) {

                        $notify($e);

                    }

                };

            } else {

                $progressHandler = $notify;

            }

            $this->handlers[] = static function (ExtendedPromiseInterface $promise) use ($onFulfilled, $onRejected, $resolve, $reject, $progressHandler) {

                $promise

                    ->then($onFulfilled, $onRejected)

                    ->done($resolve, $reject, $progressHandler);

            };

            $this->progressHandlers[] = $progressHandler;

        };

    }

    private function reject($reason = null)

    {

        if (null !== $this->result) {

            return;

        }

        $this->settle(reject($reason));

    }

    private function settle(ExtendedPromiseInterface $promise)

    {

        $promise = $this->unwrap($promise);

        if ($promise === $this) {

            $promise = new RejectedPromise(

                new \LogicException('Cannot resolve a promise with itself.')

            );

        }

        $handlers = $this->handlers;

        $this->progressHandlers = $this->handlers = [];

        $this->result = $promise;

        $this->canceller = null;

        foreach ($handlers as $handler) {

            $handler($promise);

        }

    }

    private function unwrap($promise)

    {

        $promise = $this->extract($promise);

        while ($promise instanceof self && null !== $promise->result) {

            $promise = $this->extract($promise->result);

        }

        return $promise;

    }

    private function extract($promise)

    {

        if ($promise instanceof LazyPromise) {

            $promise = $promise->promise();

        }

        return $promise;

    }

    private function call(callable $cb)

    {

        // Explicitly overwrite argument with null value. This ensure that this

        // argument does not show up in the stack trace in PHP 7+ only.

        $callback = $cb;

        $cb = null;

        // Use reflection to inspect number of arguments expected by this callback.

        // We did some careful benchmarking here: Using reflection to avoid unneeded

        // function arguments is actually faster than blindly passing them.

        // Also, this helps avoiding unnecessary function arguments in the call stack

        // if the callback creates an Exception (creating garbage cycles).

        if (\is_array($callback)) {

            $ref = new \ReflectionMethod($callback[0], $callback[1]);

        } elseif (\is_object($callback) && !$callback instanceof \Closure) {

            $ref = new \ReflectionMethod($callback, '__invoke');

        } else {

            $ref = new \ReflectionFunction($callback);

        }

        $args = $ref->getNumberOfParameters();

        try {

            if ($args === 0) {

                $callback();

            } else {

                // Keep references to this promise instance for the static resolve/reject functions.

                // By using static callbacks that are not bound to this instance

                // and passing the target promise instance by reference, we can

                // still execute its resolving logic and still clear this

                // reference when settling the promise. This helps avoiding

                // garbage cycles if any callback creates an Exception.

                // These assumptions are covered by the test suite, so if you ever feel like

                // refactoring this, go ahead, any alternative suggestions are welcome!

                $target =& $this;

                $progressHandlers =& $this->progressHandlers;

                $callback(

                    static function ($value = null) use (&$target) {

                        if ($target !== null) {

                            $target->settle(resolve($value));

                            $target = null;

                        }

                    },

                    static function ($reason = null) use (&$target) {

                        if ($target !== null) {

                            $target->reject($reason);

                            $target = null;

                        }

                    },

                    static function ($update = null) use (&$progressHandlers) {

                        foreach ($progressHandlers as $handler) {

                            $handler($update);

                        }

                    }

                );

            }

        } catch (\Throwable $e) {

            $target = null;

            $this->reject($e);

        } catch (\Exception $e) {

            $target = null;

            $this->reject($e);

        }

    }

}