initial sabre upgrade (needs lots of work - to wit: authentication, redo the browser interface, and rework event export/import)

10 files changed, 1507 insertions, 0 deletions

diff --git a/vendor/sabre/event/lib/EventEmitter.php b/vendor/sabre/event/lib/EventEmitter.php
new file mode 100644
index 000000000..1bb1c3cf9
--- /dev/null
+++ b/vendor/sabre/event/lib/EventEmitter.php
@@ -0,0 +1,18 @@
+<?php
+
+namespace Sabre\Event;
+
+/**
+ * EventEmitter object.
+ *
+ * Instantiate this class, or subclass it for easily creating event emitters.
+ *
+ * @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 EventEmitter implements EventEmitterInterface {
+
+    use EventEmitterTrait;
+
+}
diff --git a/vendor/sabre/event/lib/EventEmitterInterface.php b/vendor/sabre/event/lib/EventEmitterInterface.php
new file mode 100644
index 000000000..0e2be2cef
--- /dev/null
+++ b/vendor/sabre/event/lib/EventEmitterInterface.php
@@ -0,0 +1,100 @@
+<?php
+
+namespace Sabre\Event;
+
+/**
+ * Event Emitter Interface
+ *
+ * Anything that accepts listeners and emits events should implement this
+ * interface.
+ *
+ * @copyright Copyright (C) 2013-2015 fruux GmbH (https://fruux.com/).
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+interface EventEmitterInterface {
+
+    /**
+     * Subscribe to an event.
+     *
+     * @param string $eventName
+     * @param callable $callBack
+     * @param int $priority
+     * @return void
+     */
+    function on($eventName, callable $callBack, $priority = 100);
+
+    /**
+     * Subscribe to an event exactly once.
+     *
+     * @param string $eventName
+     * @param callable $callBack
+     * @param int $priority
+     * @return void
+     */
+    function once($eventName, callable $callBack, $priority = 100);
+
+    /**
+     * Emits an event.
+     *
+     * This method will return true if 0 or more listeners were succesfully
+     * handled. false is returned if one of the events broke the event chain.
+     *
+     * If the continueCallBack is specified, this callback will be called every
+     * time before the next event handler is called.
+     *
+     * If the continueCallback returns false, event propagation stops. This
+     * allows you to use the eventEmitter as a means for listeners to implement
+     * functionality in your application, and break the event loop as soon as
+     * some condition is fulfilled.
+     *
+     * Note that returning false from an event subscriber breaks propagation
+     * and returns false, but if the continue-callback stops propagation, this
+     * is still considered a 'successful' operation and returns true.
+     *
+     * Lastly, if there are 5 event handlers for an event. The continueCallback
+     * will be called at most 4 times.
+     *
+     * @param string $eventName
+     * @param array $arguments
+     * @param callback $continueCallBack
+     * @return bool
+     */
+    function emit($eventName, array $arguments = [], callable $continueCallBack = null);
+
+    /**
+     * Returns the list of listeners for an event.
+     *
+     * The list is returned as an array, and the list of events are sorted by
+     * their priority.
+     *
+     * @param string $eventName
+     * @return callable[]
+     */
+    function listeners($eventName);
+
+    /**
+     * Removes a specific listener from an event.
+     *
+     * If the listener could not be found, this method will return false. If it
+     * was removed it will return true.
+     *
+     * @param string $eventName
+     * @param callable $listener
+     * @return bool
+     */
+    function removeListener($eventName, callable $listener);
+
+    /**
+     * Removes all listeners.
+     *
+     * If the eventName argument is specified, all listeners for that event are
+     * removed. If it is not specified, every listener for every event is
+     * removed.
+     *
+     * @param string $eventName
+     * @return void
+     */
+    function removeAllListeners($eventName = null);
+
+}
diff --git a/vendor/sabre/event/lib/EventEmitterTrait.php b/vendor/sabre/event/lib/EventEmitterTrait.php
new file mode 100644
index 000000000..257629fae
--- /dev/null
+++ b/vendor/sabre/event/lib/EventEmitterTrait.php
@@ -0,0 +1,211 @@
+<?php
+
+namespace Sabre\Event;
+
+/**
+ * Event Emitter Trait
+ *
+ * This trait contains all the basic functions to implement an
+ * EventEmitterInterface.
+ *
+ * Using the trait + interface allows you to add EventEmitter capabilities
+ * without having to change your base-class.
+ *
+ * @copyright Copyright (C) 2013-2015 fruux GmbH (https://fruux.com/).
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+trait EventEmitterTrait {
+
+    /**
+     * The list of listeners
+     *
+     * @var array
+     */
+    protected $listeners = [];
+
+    /**
+     * Subscribe to an event.
+     *
+     * @param string $eventName
+     * @param callable $callBack
+     * @param int $priority
+     * @return void
+     */
+    function on($eventName, callable $callBack, $priority = 100) {
+
+        if (!isset($this->listeners[$eventName])) {
+            $this->listeners[$eventName] = [
+                true,  // If there's only one item, it's sorted
+                [$priority],
+                [$callBack]
+            ];
+        } else {
+            $this->listeners[$eventName][0] = false; // marked as unsorted
+            $this->listeners[$eventName][1][] = $priority;
+            $this->listeners[$eventName][2][] = $callBack;
+        }
+
+    }
+
+    /**
+     * Subscribe to an event exactly once.
+     *
+     * @param string $eventName
+     * @param callable $callBack
+     * @param int $priority
+     * @return void
+     */
+    function once($eventName, callable $callBack, $priority = 100) {
+
+        $wrapper = null;
+        $wrapper = function() use ($eventName, $callBack, &$wrapper) {
+
+            $this->removeListener($eventName, $wrapper);
+            return call_user_func_array($callBack, func_get_args());
+
+        };
+
+        $this->on($eventName, $wrapper, $priority);
+
+    }
+
+    /**
+     * Emits an event.
+     *
+     * This method will return true if 0 or more listeners were succesfully
+     * handled. false is returned if one of the events broke the event chain.
+     *
+     * If the continueCallBack is specified, this callback will be called every
+     * time before the next event handler is called.
+     *
+     * If the continueCallback returns false, event propagation stops. This
+     * allows you to use the eventEmitter as a means for listeners to implement
+     * functionality in your application, and break the event loop as soon as
+     * some condition is fulfilled.
+     *
+     * Note that returning false from an event subscriber breaks propagation
+     * and returns false, but if the continue-callback stops propagation, this
+     * is still considered a 'successful' operation and returns true.
+     *
+     * Lastly, if there are 5 event handlers for an event. The continueCallback
+     * will be called at most 4 times.
+     *
+     * @param string $eventName
+     * @param array $arguments
+     * @param callback $continueCallBack
+     * @return bool
+     */
+    function emit($eventName, array $arguments = [], callable $continueCallBack = null) {
+
+        if (is_null($continueCallBack)) {
+
+            foreach ($this->listeners($eventName) as $listener) {
+
+                $result = call_user_func_array($listener, $arguments);
+                if ($result === false) {
+                    return false;
+                }
+            }
+
+        } else {
+
+            $listeners = $this->listeners($eventName);
+            $counter = count($listeners);
+
+            foreach ($listeners as $listener) {
+
+                $counter--;
+                $result = call_user_func_array($listener, $arguments);
+                if ($result === false) {
+                    return false;
+                }
+
+                if ($counter > 0) {
+                    if (!$continueCallBack()) break;
+                }
+
+            }
+
+        }
+
+        return true;
+
+    }
+
+    /**
+     * Returns the list of listeners for an event.
+     *
+     * The list is returned as an array, and the list of events are sorted by
+     * their priority.
+     *
+     * @param string $eventName
+     * @return callable[]
+     */
+    function listeners($eventName) {
+
+        if (!isset($this->listeners[$eventName])) {
+            return [];
+        }
+
+        // The list is not sorted
+        if (!$this->listeners[$eventName][0]) {
+
+            // Sorting
+            array_multisort($this->listeners[$eventName][1], SORT_NUMERIC, $this->listeners[$eventName][2]);
+
+            // Marking the listeners as sorted
+            $this->listeners[$eventName][0] = true;
+        }
+
+        return $this->listeners[$eventName][2];
+
+    }
+
+    /**
+     * Removes a specific listener from an event.
+     *
+     * If the listener could not be found, this method will return false. If it
+     * was removed it will return true.
+     *
+     * @param string $eventName
+     * @param callable $listener
+     * @return bool
+     */
+    function removeListener($eventName, callable $listener) {
+
+        if (!isset($this->listeners[$eventName])) {
+            return false;
+        }
+        foreach ($this->listeners[$eventName][2] as $index => $check) {
+            if ($check === $listener) {
+                unset($this->listeners[$eventName][1][$index]);
+                unset($this->listeners[$eventName][2][$index]);
+                return true;
+            }
+        }
+        return false;
+
+    }
+
+    /**
+     * Removes all listeners.
+     *
+     * If the eventName argument is specified, all listeners for that event are
+     * removed. If it is not specified, every listener for every event is
+     * removed.
+     *
+     * @param string $eventName
+     * @return void
+     */
+    function removeAllListeners($eventName = null) {
+
+        if (!is_null($eventName)) {
+            unset($this->listeners[$eventName]);
+        } else {
+            $this->listeners = [];
+        }
+
+    }
+
+}
diff --git a/vendor/sabre/event/lib/Loop/Loop.php b/vendor/sabre/event/lib/Loop/Loop.php
new file mode 100644
index 000000000..86ee7c8b0
--- /dev/null
+++ b/vendor/sabre/event/lib/Loop/Loop.php
@@ -0,0 +1,386 @@
+<?php
+
+namespace Sabre\Event\Loop;
+
+/**
+ * A simple eventloop implementation.
+ *
+ * This eventloop supports:
+ *   * nextTick
+ *   * setTimeout for delayed functions
+ *   * setInterval for repeating functions
+ *   * stream events using stream_select
+ *
+ * @copyright Copyright (C) 2007-2015 fruux GmbH. (https://fruux.com/)
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+class Loop {
+
+    /**
+     * Executes a function after x seconds.
+     *
+     * @param callable $cb
+     * @param float $timeout timeout in seconds
+     * @return void
+     */
+    function setTimeout(callable $cb, $timeout) {
+
+        $triggerTime = microtime(true) + ($timeout);
+
+        if (!$this->timers) {
+            // Special case when the timers array was empty.
+            $this->timers[] = [$triggerTime, $cb];
+            return;
+        }
+
+        // We need to insert these values in the timers array, but the timers
+        // array must be in reverse-order of trigger times.
+        //
+        // So here we search the array for the insertion point.
+        $index = count($this->timers) - 1;
+        while (true) {
+            if ($triggerTime < $this->timers[$index][0]) {
+                array_splice(
+                    $this->timers,
+                    $index + 1,
+                    0,
+                    [[$triggerTime, $cb]]
+                );
+                break;
+            } elseif ($index === 0) {
+                array_unshift($this->timers, [$triggerTime, $cb]);
+                break;
+            }
+            $index--;
+
+        }
+
+    }
+
+    /**
+     * Executes a function every x seconds.
+     *
+     * The value this function returns can be used to stop the interval with
+     * clearInterval.
+     *
+     * @param callable $cb
+     * @param float $timeout
+     * @return array
+     */
+    function setInterval(callable $cb, $timeout) {
+
+        $keepGoing = true;
+        $f = null;
+
+        $f = function() use ($cb, &$f, $timeout, &$keepGoing) {
+            if ($keepGoing) {
+                $cb();
+                $this->setTimeout($f, $timeout);
+            }
+        };
+        $this->setTimeout($f, $timeout);
+
+        // Really the only thing that matters is returning the $keepGoing
+        // boolean value.
+        //
+        // We need to pack it in an array to allow returning by reference.
+        // Because I'm worried people will be confused by using a boolean as a
+        // sort of identifier, I added an extra string.
+        return ['I\'m an implementation detail', &$keepGoing];
+
+    }
+
+    /**
+     * Stops a running internval.
+     *
+     * @param array $intervalId
+     * @return void
+     */
+    function clearInterval($intervalId) {
+
+        $intervalId[1] = false;
+
+    }
+
+    /**
+     * Runs a function immediately at the next iteration of the loop.
+     *
+     * @param callable $cb
+     * @return void
+     */
+    function nextTick(callable $cb) {
+
+        $this->nextTick[] = $cb;
+
+    }
+
+
+    /**
+     * Adds a read stream.
+     *
+     * The callback will be called as soon as there is something to read from
+     * the stream.
+     *
+     * You MUST call removeReadStream after you are done with the stream, to
+     * prevent the eventloop from never stopping.
+     *
+     * @param resource $stream
+     * @param callable $cb
+     * @return void
+     */
+    function addReadStream($stream, callable $cb) {
+
+        $this->readStreams[(int)$stream] = $stream;
+        $this->readCallbacks[(int)$stream] = $cb;
+
+    }
+
+    /**
+     * Adds a write stream.
+     *
+     * The callback will be called as soon as the system reports it's ready to
+     * receive writes on the stream.
+     *
+     * You MUST call removeWriteStream after you are done with the stream, to
+     * prevent the eventloop from never stopping.
+     *
+     * @param resource $stream
+     * @param callable $cb
+     * @return void
+     */
+    function addWriteStream($stream, callable $cb) {
+
+        $this->writeStreams[(int)$stream] = $stream;
+        $this->writeCallbacks[(int)$stream] = $cb;
+
+    }
+
+    /**
+     * Stop watching a stream for reads.
+     *
+     * @param resource $stream
+     * @return void
+     */
+    function removeReadStream($stream) {
+
+        unset(
+            $this->readStreams[(int)$stream],
+            $this->readCallbacks[(int)$stream]
+        );
+
+    }
+
+    /**
+     * Stop watching a stream for writes.
+     *
+     * @param resource $stream
+     * @return void
+     */
+    function removeWriteStream($stream) {
+
+        unset(
+            $this->writeStreams[(int)$stream],
+            $this->writeCallbacks[(int)$stream]
+        );
+
+    }
+
+
+    /**
+     * Runs the loop.
+     *
+     * This function will run continiously, until there's no more events to
+     * handle.
+     *
+     * @return void
+     */
+    function run() {
+
+        $this->running = true;
+
+        do {
+
+            $hasEvents = $this->tick(true);
+
+        } while ($this->running && $hasEvents);
+        $this->running = false;
+
+    }
+
+    /**
+     * Executes all pending events.
+     *
+     * If $block is turned true, this function will block until any event is
+     * triggered.
+     *
+     * If there are now timeouts, nextTick callbacks or events in the loop at
+     * all, this function will exit immediately.
+     *
+     * This function will return true if there are _any_ events left in the
+     * loop after the tick.
+     *
+     * @param bool $block
+     * @return bool
+     */
+    function tick($block = false) {
+
+        $this->runNextTicks();
+        $nextTimeout = $this->runTimers();
+
+        // Calculating how long runStreams should at most wait.
+        if (!$block) {
+            // Don't wait
+            $streamWait = 0;
+        } elseif ($this->nextTick) {
+            // There's a pending 'nextTick'. Don't wait.
+            $streamWait = 0;
+        } elseif (is_numeric($nextTimeout)) {
+            // Wait until the next Timeout should trigger.
+            $streamWait = $nextTimeout;
+        } else {
+            // Wait indefinitely
+            $streamWait = null;
+        }
+
+        $this->runStreams($streamWait);
+
+        return ($this->readStreams || $this->writeStreams || $this->nextTick || $this->timers);
+
+    }
+
+    /**
+     * Stops a running eventloop
+     *
+     * @return void
+     */
+    function stop() {
+
+        $this->running = false;
+
+    }
+
+    /**
+     * Executes all 'nextTick' callbacks.
+     *
+     * return void
+     */
+    protected function runNextTicks() {
+
+        $nextTick = $this->nextTick;
+        $this->nextTick = [];
+
+        foreach ($nextTick as $cb) {
+            $cb();
+        }
+
+    }
+
+    /**
+     * Runs all pending timers.
+     *
+     * After running the timer callbacks, this function returns the number of
+     * seconds until the next timer should be executed.
+     *
+     * If there's no more pending timers, this function returns null.
+     *
+     * @return float
+     */
+    protected function runTimers() {
+
+        $now = microtime(true);
+        while (($timer = array_pop($this->timers)) && $timer[0] < $now) {
+            $timer[1]();
+        }
+        // Add the last timer back to the array.
+        if ($timer) {
+            $this->timers[] = $timer;
+            return $timer[0] - microtime(true);
+        }
+
+    }
+
+    /**
+     * Runs all pending stream events.
+     *
+     * @param float $timeout
+     */
+    protected function runStreams($timeout) {
+
+        if ($this->readStreams || $this->writeStreams) {
+
+            $read = $this->readStreams;
+            $write = $this->writeStreams;
+            $except = null;
+            if (stream_select($read, $write, $except, null, $timeout)) {
+
+                // See PHP Bug https://bugs.php.net/bug.php?id=62452
+                // Fixed in PHP7
+                foreach ($read as $readStream) {
+                    $readCb = $this->readCallbacks[(int)$readStream];
+                    $readCb();
+                }
+                foreach ($write as $writeStream) {
+                    $writeCb = $this->writeCallbacks[(int)$writeStream];
+                    $writeCb();
+                }
+
+            }
+
+        } elseif ($this->running && ($this->nextTick || $this->timers)) {
+            usleep($timeout !== null ? $timeout * 1000000 : 200000);
+        }
+
+    }
+
+    /**
+     * Is the main loop active
+     *
+     * @var bool
+     */
+    protected $running = false;
+
+    /**
+     * A list of timers, added by setTimeout.
+     *
+     * @var array
+     */
+    protected $timers = [];
+
+    /**
+     * A list of 'nextTick' callbacks.
+     *
+     * @var callable[]
+     */
+    protected $nextTick = [];
+
+    /**
+     * List of readable streams for stream_select, indexed by stream id.
+     *
+     * @var resource[]
+     */
+    protected $readStreams = [];
+
+    /**
+     * List of writable streams for stream_select, indexed by stream id.
+     *
+     * @var resource[]
+     */
+    protected $writeStreams = [];
+
+    /**
+     * List of read callbacks, indexed by stream id.
+     *
+     * @var callback[]
+     */
+    protected $readCallbacks = [];
+
+    /**
+     * List of write callbacks, indexed by stream id.
+     *
+     * @var callback[]
+     */
+    protected $writeCallbacks = [];
+
+
+}
diff --git a/vendor/sabre/event/lib/Loop/functions.php b/vendor/sabre/event/lib/Loop/functions.php
new file mode 100644
index 000000000..56c5bc8c7
--- /dev/null
+++ b/vendor/sabre/event/lib/Loop/functions.php
@@ -0,0 +1,183 @@
+<?php
+
+namespace Sabre\Event\Loop;
+
+/**
+ * Executes a function after x seconds.
+ *
+ * @param callable $cb
+ * @param float $timeout timeout in seconds
+ * @return void
+ */
+function setTimeout(callable $cb, $timeout) {
+
+    instance()->setTimeout($cb, $timeout);
+
+}
+
+/**
+ * Executes a function every x seconds.
+ *
+ * The value this function returns can be used to stop the interval with
+ * clearInterval.
+ *
+ * @param callable $cb
+ * @param float $timeout
+ * @return array
+ */
+function setInterval(callable $cb, $timeout) {
+
+    return instance()->setInterval($cb, $timeout);
+
+}
+
+/**
+ * Stops a running internval.
+ *
+ * @param array $intervalId
+ * @return void
+ */
+function clearInterval($intervalId) {
+
+    instance()->clearInterval($intervalId);
+
+}
+
+/**
+ * Runs a function immediately at the next iteration of the loop.
+ *
+ * @param callable $cb
+ * @return void
+ */
+function nextTick(callable $cb) {
+
+    instance()->nextTick($cb);
+
+}
+
+
+/**
+ * Adds a read stream.
+ *
+ * The callback will be called as soon as there is something to read from
+ * the stream.
+ *
+ * You MUST call removeReadStream after you are done with the stream, to
+ * prevent the eventloop from never stopping.
+ *
+ * @param resource $stream
+ * @param callable $cb
+ * @return void
+ */
+function addReadStream($stream, callable $cb) {
+
+    instance()->addReadStream($stream, $cb);
+
+}
+
+/**
+ * Adds a write stream.
+ *
+ * The callback will be called as soon as the system reports it's ready to
+ * receive writes on the stream.
+ *
+ * You MUST call removeWriteStream after you are done with the stream, to
+ * prevent the eventloop from never stopping.
+ *
+ * @param resource $stream
+ * @param callable $cb
+ * @return void
+ */
+function addWriteStream($stream, callable $cb) {
+
+    instance()->addWriteStream($stream, $cb);
+
+}
+
+/**
+ * Stop watching a stream for reads.
+ *
+ * @param resource $stream
+ * @return void
+ */
+function removeReadStream($stream) {
+
+    instance()->removeReadStream($stream);
+
+}
+
+/**
+ * Stop watching a stream for writes.
+ *
+ * @param resource $stream
+ * @return void
+ */
+function removeWriteStream($stream) {
+
+    instance()->removeWriteStream($stream);
+
+}
+
+
+/**
+ * Runs the loop.
+ *
+ * This function will run continiously, until there's no more events to
+ * handle.
+ *
+ * @return void
+ */
+function run() {
+
+    instance()->run();
+
+}
+
+/**
+ * Executes all pending events.
+ *
+ * If $block is turned true, this function will block until any event is
+ * triggered.
+ *
+ * If there are now timeouts, nextTick callbacks or events in the loop at
+ * all, this function will exit immediately.
+ *
+ * This function will return true if there are _any_ events left in the
+ * loop after the tick.
+ *
+ * @param bool $block
+ * @return bool
+ */
+function tick($block = false) {
+
+    return instance()->tick($block);
+
+}
+
+/**
+ * Stops a running eventloop
+ *
+ * @return void
+ */
+function stop() {
+
+    instance()->stop();
+
+}
+
+/**
+ * Retrieves or sets the global Loop object.
+ *
+ * @param Loop $newLoop
+ */
+function instance(Loop $newLoop = null) {
+
+    static $loop;
+    if ($newLoop) {
+        $loop = $newLoop;
+    } elseif (!$loop) {
+        $loop = new Loop();
+    }
+    return $loop;
+
+}
diff --git a/vendor/sabre/event/lib/Promise.php b/vendor/sabre/event/lib/Promise.php
new file mode 100644
index 000000000..1c874c1bd
--- /dev/null
+++ b/vendor/sabre/event/lib/Promise.php
@@ -0,0 +1,320 @@
+<?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);
+
+    }
+
+}
diff --git a/vendor/sabre/event/lib/Promise/functions.php b/vendor/sabre/event/lib/Promise/functions.php
new file mode 100644
index 000000000..3604b8aaa
--- /dev/null
+++ b/vendor/sabre/event/lib/Promise/functions.php
@@ -0,0 +1,135 @@
+<?php
+
+namespace Sabre\Event\Promise;
+
+use Sabre\Event\Promise;
+
+/**
+ * This file contains a set of functions that are useful for dealing with the
+ * Promise object.
+ *
+ * @copyright Copyright (C) 2013-2015 fruux GmbH (https://fruux.com/).
+ * @author Evert Pot (http://evertpot.com/)
+ * @license http://sabre.io/license/ Modified BSD License
+ */
+
+
+/**
+ * This function takes an array of Promises, and returns a Promise that
+ * resolves when all of the given arguments have resolved.
+ *
+ * The returned Promise will resolve with a value that's an array of all the
+ * values the given promises have been resolved with.
+ *
+ * This array will be in the exact same order as the array of input promises.
+ *
+ * If any of the given Promises fails, the returned promise will immidiately
+ * fail with the first Promise that fails, and its reason.
+ *
+ * @param Promise[] $promises
+ * @return Promise
+ */
+function all(array $promises) {
+
+    return new Promise(function($success, $fail) use ($promises) {
+
+        $successCount = 0;
+        $completeResult = [];
+
+        foreach ($promises as $promiseIndex => $subPromise) {
+
+            $subPromise->then(
+                function($result) use ($promiseIndex, &$completeResult, &$successCount, $success, $promises) {
+                    $completeResult[$promiseIndex] = $result;
+                    $successCount++;
+                    if ($successCount === count($promises)) {
+                        $success($completeResult);
+                    }
+                    return $result;
+                }
+            )->error(
+                function($reason) use ($fail) {
+                    $fail($reason);
+                }
+            );
+
+        }
+    });
+
+}
+
+/**
+ * The race function returns a promise that resolves or rejects as soon as
+ * one of the promises in the argument resolves or rejects.
+ *
+ * The returned promise will resolve or reject with the value or reason of
+ * that first promise.
+ *
+ * @param Promise[] $promises
+ * @return Promise
+ */
+function race(array $promises) {
+
+    return new Promise(function($success, $fail) use ($promises) {
+
+        $alreadyDone = false;
+        foreach ($promises as $promise) {
+
+            $promise->then(
+                function($result) use ($success, &$alreadyDone) {
+                    if ($alreadyDone) {
+                        return;
+                    }
+                    $alreadyDone = true;
+                    $success($result);
+                },
+                function($reason) use ($fail, &$alreadyDone) {
+                    if ($alreadyDone) {
+                        return;
+                    }
+                    $alreadyDone = true;
+                    $fail($reason);
+                }
+            );
+
+        }
+
+    });
+
+}
+
+
+/**
+ * Returns a Promise that resolves with the given value.
+ *
+ * If the value is a promise, the returned promise will attach itself to that
+ * promise and eventually get the same state as the followed promise.
+ *
+ * @param mixed $value
+ * @return Promise
+ */
+function resolve($value) {
+
+    if ($value instanceof Promise) {
+        return $value->then();
+    } else {
+        $promise = new Promise();
+        $promise->fulfill($value);
+        return $promise;
+    }
+
+}
+
+/**
+ * Returns a Promise that will reject with the given reason.
+ *
+ * @param mixed $reason
+ * @return Promise
+ */
+function reject($reason) {
+
+    $promise = new Promise();
+    $promise->reject($reason);
+    return $promise;
+
+}
diff --git a/vendor/sabre/event/lib/PromiseAlreadyResolvedException.php b/vendor/sabre/event/lib/PromiseAlreadyResolvedException.php
new file mode 100644
index 000000000..86a6c5b3f
--- /dev/null
+++ b/vendor/sabre/event/lib/PromiseAlreadyResolvedException.php
@@ -0,0 +1,15 @@
+<?php
+
+namespace Sabre\Event;
+
+/**
+ * This exception is thrown when the user tried to reject or fulfill a promise,
+ * after either of these actions were already performed.
+ *
+ * @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 PromiseAlreadyResolvedException extends \LogicException {
+
+}
diff --git a/vendor/sabre/event/lib/Version.php b/vendor/sabre/event/lib/Version.php
new file mode 100644
index 000000000..5de22193f
--- /dev/null
+++ b/vendor/sabre/event/lib/Version.php
@@ -0,0 +1,19 @@
+<?php
+
+namespace Sabre\Event;
+
+/**
+ * This class contains the version number for this package.
+ *
+ * @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 Version {
+
+    /**
+     * Full version number
+     */
+    const VERSION = '3.0.0';
+
+}
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;
+
+}