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diff --git a/vendor/sabre/event/lib/Promise.php b/vendor/sabre/event/lib/Promise.php
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+<?php
+
+namespace Sabre\Event;
+
+use Exception;
+
+/**
+ * An implementation of the Promise pattern.
+ *
+ * A promise represents the result of an asynchronous operation.
+ * At any given point a promise can be in one of three states:
+ *
+ * 1. Pending (the promise does not have a result yet).
+ * 2. Fulfilled (the asynchronous operation has completed with a result).
+ * 3. Rejected (the asynchronous operation has completed with an error).
+ *
+ * To get a callback when the operation has finished, use the `then` method.
+ *
+ * @copyright Copyright (C) 2013-2015 fruux GmbH (https://fruux.com/).
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class Promise {
+
+    /**
+     * The asynchronous operation is pending.
+     */
+    const PENDING = 0;
+
+    /**
+     * The asynchronous operation has completed, and has a result.
+     */
+    const FULFILLED = 1;
+
+    /**
+     * The asynchronous operation has completed with an error.
+     */
+    const REJECTED = 2;
+
+    /**
+     * The current state of this promise.
+     *
+     * @var int
+     */
+    public $state = self::PENDING;
+
+    /**
+     * Creates the promise.
+     *
+     * The passed argument is the executor. The executor is automatically
+     * called with two arguments.
+     *
+     * Each are callbacks that map to $this->fulfill and $this->reject.
+     * Using the executor is optional.
+     *
+     * @param callable $executor
+     */
+    function __construct(callable $executor = null) {
+
+        if ($executor) {
+            $executor(
+                [$this, 'fulfill'],
+                [$this, 'reject']
+            );
+        }
+
+    }
+
+    /**
+     * This method allows you to specify the callback that will be called after
+     * the promise has been fulfilled or rejected.
+     *
+     * Both arguments are optional.
+     *
+     * This method returns a new promise, which can be used for chaining.
+     * If either the onFulfilled or onRejected callback is called, you may
+     * return a result from this callback.
+     *
+     * If the result of this callback is yet another promise, the result of
+     * _that_ promise will be used to set the result of the returned promise.
+     *
+     * If either of the callbacks return any other value, the returned promise
+     * is automatically fulfilled with that value.
+     *
+     * If either of the callbacks throw an exception, the returned promise will
+     * be rejected and the exception will be passed back.
+     *
+     * @param callable $onFulfilled
+     * @param callable $onRejected
+     * @return Promise
+     */
+    function then(callable $onFulfilled = null, callable $onRejected = null) {
+
+        // This new subPromise will be returned from this function, and will
+        // be fulfilled with the result of the onFulfilled or onRejected event
+        // handlers.
+        $subPromise = new self();
+
+        switch ($this->state) {
+            case self::PENDING :
+                // The operation is pending, so we keep a reference to the
+                // event handlers so we can call them later.
+                $this->subscribers[] = [$subPromise, $onFulfilled, $onRejected];
+                break;
+            case self::FULFILLED :
+                // The async operation is already fulfilled, so we trigger the
+                // onFulfilled callback asap.
+                $this->invokeCallback($subPromise, $onFulfilled);
+                break;
+            case self::REJECTED :
+                // The async operation failed, so we call teh onRejected
+                // callback asap.
+                $this->invokeCallback($subPromise, $onRejected);
+                break;
+        }
+        return $subPromise;
+
+    }
+
+    /**
+     * Add a callback for when this promise is rejected.
+     *
+     * Its usage is identical to then(). However, the otherwise() function is
+     * preferred.
+     *
+     * @param callable $onRejected
+     * @return Promise
+     */
+    function otherwise(callable $onRejected) {
+
+        return $this->then(null, $onRejected);
+
+    }
+
+    /**
+     * Marks this promise as fulfilled and sets its return value.
+     *
+     * @param mixed $value
+     * @return void
+     */
+    function fulfill($value = null) {
+        if ($this->state !== self::PENDING) {
+            throw new PromiseAlreadyResolvedException('This promise is already resolved, and you\'re not allowed to resolve a promise more than once');
+        }
+        $this->state = self::FULFILLED;
+        $this->value = $value;
+        foreach ($this->subscribers as $subscriber) {
+            $this->invokeCallback($subscriber[0], $subscriber[1]);
+        }
+    }
+
+    /**
+     * Marks this promise as rejected, and set it's rejection reason.
+     *
+     * While it's possible to use any PHP value as the reason, it's highly
+     * recommended to use an Exception for this.
+     *
+     * @param mixed $reason
+     * @return void
+     */
+    function reject($reason = null) {
+        if ($this->state !== self::PENDING) {
+            throw new PromiseAlreadyResolvedException('This promise is already resolved, and you\'re not allowed to resolve a promise more than once');
+        }
+        $this->state = self::REJECTED;
+        $this->value = $reason;
+        foreach ($this->subscribers as $subscriber) {
+            $this->invokeCallback($subscriber[0], $subscriber[2]);
+        }
+
+    }
+
+    /**
+     * Stops execution until this promise is resolved.
+     *
+     * This method stops exection completely. If the promise is successful with
+     * a value, this method will return this value. If the promise was
+     * rejected, this method will throw an exception.
+     *
+     * This effectively turns the asynchronous operation into a synchronous
+     * one. In PHP it might be useful to call this on the last promise in a
+     * chain.
+     *
+     * @throws Exception
+     * @return mixed
+     */
+    function wait() {
+
+        $hasEvents = true;
+        while ($this->state === self::PENDING) {
+
+            if (!$hasEvents) {
+                throw new \LogicException('There were no more events in the loop. This promise will never be fulfilled.');
+            }
+
+            // As long as the promise is not fulfilled, we tell the event loop
+            // to handle events, and to block.
+            $hasEvents = Loop\tick(true);
+
+        }
+
+        if ($this->state === self::FULFILLED) {
+            // If the state of this promise is fulfilled, we can return the value.
+            return $this->value;
+        } else {
+            // If we got here, it means that the asynchronous operation
+            // errored. Therefore we need to throw an exception.
+            $reason = $this->value;
+            if ($reason instanceof Exception) {
+                throw $reason;
+            } elseif (is_scalar($reason)) {
+                throw new Exception($reason);
+            } else {
+                $type = is_object($reason) ? get_class($reason) : gettype($reason);
+                throw new Exception('Promise was rejected with reason of type: ' . $type);
+            }
+        }
+
+
+    }
+
+
+    /**
+     * A list of subscribers. Subscribers are the callbacks that want us to let
+     * them know if the callback was fulfilled or rejected.
+     *
+     * @var array
+     */
+    protected $subscribers = [];
+
+    /**
+     * The result of the promise.
+     *
+     * If the promise was fulfilled, this will be the result value. If the
+     * promise was rejected, this property hold the rejection reason.
+     *
+     * @var mixed
+     */
+    protected $value = null;
+
+    /**
+     * This method is used to call either an onFulfilled or onRejected callback.
+     *
+     * This method makes sure that the result of these callbacks are handled
+     * correctly, and any chained promises are also correctly fulfilled or
+     * rejected.
+     *
+     * @param Promise $subPromise
+     * @param callable $callBack
+     * @return void
+     */
+    private function invokeCallback(Promise $subPromise, callable $callBack = null) {
+
+        // We use 'nextTick' to ensure that the event handlers are always
+        // triggered outside of the calling stack in which they were originally
+        // passed to 'then'.
+        //
+        // This makes the order of execution more predictable.
+        Loop\nextTick(function() use ($callBack, $subPromise) {
+            if (is_callable($callBack)) {
+                try {
+
+                    $result = $callBack($this->value);
+                    if ($result instanceof self) {
+                        // If the callback (onRejected or onFulfilled)
+                        // returned a promise, we only fulfill or reject the
+                        // chained promise once that promise has also been
+                        // resolved.
+                        $result->then([$subPromise, 'fulfill'], [$subPromise, 'reject']);
+                    } else {
+                        // If the callback returned any other value, we
+                        // immediately fulfill the chained promise.
+                        $subPromise->fulfill($result);
+                    }
+                } catch (Exception $e) {
+                    // If the event handler threw an exception, we need to make sure that
+                    // the chained promise is rejected as well.
+                    $subPromise->reject($e);
+                }
+            } else {
+                if ($this->state === self::FULFILLED) {
+                    $subPromise->fulfill($this->value);
+                } else {
+                    $subPromise->reject($this->value);
+                }
+            }
+        });
+    }
+
+    /**
+     * Alias for 'otherwise'.
+     *
+     * This function is now deprecated and will be removed in a future version.
+     *
+     * @param callable $onRejected
+     * @deprecated
+     * @return Promise
+     */
+    function error(callable $onRejected) {
+
+        return $this->otherwise($onRejected);
+
+    }
+
+    /**
+     * Deprecated.
+     *
+     * Please use Sabre\Event\Promise::all
+     *
+     * @param Promise[] $promises
+     * @deprecated
+     * @return Promise
+     */
+    static function all(array $promises) {
+
+        return Promise\all($promises);
+
+    }
+
+}