/**
* @return boolean
*/
public function isBinary()
{
if ($this->_frames->isEmpty()) {
throw new \UnderflowException('Not enough data has been received to determine if message is binary');
}
return Frame::OP_BINARY === $this->_frames->bottom()->getOpcode();
}
/**
* Retrieve the maintenance task entry, from unique identfier
* @param $maintenanceTaskEntryIdentifier Identifier to locate entry
* @return mixed|null Returns the maintenance task entry or null on error
* @throws InvalidArgumentException if the provided argument is not set or of correct type
*/
public function retrieveMaintenanceTaskEntry($maintenanceTaskEntryIdentifier)
{
if (!isset($maintenanceTaskEntryIdentifier)) {
//argument check
throw new InvalidArgumentException("Missing Argument");
} else {
if (!is_numeric($maintenanceTaskEntryIdentifier)) {
//argument check
throw new InvalidArgumentException("maintenanceTaskEntryIdentifier is not a number");
}
}
if ($this->maintenanceTaskList->isEmpty()) {
//if list is empty, unable to return entry
return null;
} else {
$this->maintenanceTaskList->setIteratorMode(SplDoublyLinkedList::IT_MODE_FIFO);
//set iteration FIFO
for ($this->maintenanceTaskList->rewind(); $this->maintenanceTaskList->valid(); $this->maintenanceTaskList->next()) {
if ($this->maintenanceTaskList->current()->getTaskEntryIdentifier() == $maintenanceTaskEntryIdentifier) {
//if entry identifier matches supplied identifier
return $this->maintenanceTaskList->current();
}
//return the matching entry
}
}
return null;
//entry with given identifier not found
}
/**
* Perform a depth-first traversal on the provided graph.
*
* @param Digraph $graph
* The graph on which to perform the depth-first search.
* @param DepthFirstVisitorInterface $visitor
* The visitor object to use during the traversal.
* @param object|\SplDoublyLinkedList $start
* A vertex, or vertices, to use as start points for the traversal. There
* are a few sub-behaviors here:
* - If an SplDoublyLinkedList, SplQueue, or SplStack is provided, the
* traversal will deque and visit vertices contained therein.
* - If a single vertex object is provided, it will be the sole
* originating point for the traversal.
* - If no value is provided, DepthFirst::find_sources() is called to
* search the graph for source vertices. These are place into an
* SplQueue in the order in which they are discovered, and traversal
* is then run over that queue in the same manner as if calling code
* had provided a queue directly. This method *guarantees* that all
* vertices in the graph will be visited.
*
* @throws RuntimeException
* Thrown if an invalid $start parameter is provided.
*/
public static function traverse(Digraph $graph, DepthFirstVisitorInterface $visitor, $start = NULL)
{
if ($start === NULL) {
$queue = self::find_sources($graph, $visitor);
} else {
if ($start instanceof \SplDoublyLinkedList) {
$queue = $start;
} else {
if (is_object($start)) {
$queue = new \SplDoublyLinkedList();
$queue->push($start);
}
}
}
if ($queue->isEmpty()) {
throw new RuntimeException('No start vertex or vertices were provided, and no source vertices could be found in the provided graph.', E_WARNING);
}
$visiting = new \SplObjectStorage();
$visited = new \SplObjectStorage();
$visitor->beginTraversal();
$visit = function ($vertex) use($graph, $visitor, &$visit, $visiting, $visited) {
if ($visiting->contains($vertex)) {
$visitor->onBackEdge($vertex, $visit);
} else {
if (!$visited->contains($vertex)) {
$visiting->attach($vertex);
$visitor->onStartVertex($vertex, $visit);
foreach ($graph->successorsOf($vertex) as $head) {
$visitor->onExamineEdge($vertex, $head, $visit);
$visit($head);
}
$visitor->onFinishVertex($vertex, $visit);
$visiting->detach($vertex);
$visited->attach($vertex);
}
}
};
// TODO experiment with adding a generator-producing visitor method that yields the queue here
while (!$queue->isEmpty()) {
$vertex = $queue->shift();
$visit($vertex);
}
$visitor->endTraversal();
}
/**
* Perform a depth-first traversal on the provided graph.
*
* @param DirectedGraph $graph
* The graph on which to perform the depth-first search.
* @param DepthFirstVisitorInterface $visitor
* The visitor object to use during the traversal.
* @param object|\SplDoublyLinkedList $start
* A vertex, or vertices, to use as start points for the traversal. There
* are a few sub-behaviors here:
* - If an SplDoublyLinkedList, SplQueue, or SplStack is provided, the
* traversal will deque and visit vertices contained therein.
* - If a single vertex object is provided, it will be the sole
* originating point for the traversal.
* - If no value is provided, DepthFirst::find_sources() is called to
* search the graph for source vertices. These are place into an
* SplQueue in the order in which they are discovered, and traversal
* is then run over that queue in the same manner as if calling code
* had provided a queue directly. This method *guarantees* that all
* vertices in the graph will be visited.
*
* @throws RuntimeException
* Thrown if an invalid $start parameter is provided.
*/
public static function traverse(DirectedGraph $graph, DepthFirstVisitorInterface $visitor, $start = NULL)
{
if ($start === NULL) {
$queue = self::find_sources($graph, $visitor);
} else {
if ($start instanceof \SplDoublyLinkedList) {
$queue = $start;
} else {
if (is_object($start)) {
$queue = new \SplDoublyLinkedList();
$queue->push($start);
}
}
}
if ($queue->isEmpty()) {
throw new RuntimeException('No start vertex or vertices were provided, and no source vertices could be found in the provided graph.', E_WARNING);
}
$visiting = new \SplObjectStorage();
$visited = new \SplObjectStorage();
$visitor->beginTraversal();
$visit = function ($vertex) use($graph, $visitor, &$visit, $visiting, $visited) {
if ($visiting->contains($vertex)) {
$visitor->onBackEdge($vertex, $visit);
} else {
if (!$visited->contains($vertex)) {
$visiting->attach($vertex);
$visitor->onStartVertex($vertex, $visit);
$graph->eachAdjacent($vertex, function ($to) use($vertex, &$visit, $visitor) {
$visitor->onExamineEdge($vertex, $to, $visit);
$visit($to);
});
$visitor->onFinishVertex($vertex, $visit);
$visiting->detach($vertex);
$visited->attach($vertex);
}
}
};
while (!$queue->isEmpty()) {
$vertex = $queue->shift();
$visit($vertex);
}
$visitor->endTraversal();
}
$list->top(); // bottom() // 返回第一个节点的值 $list->bottom(); // next() // 指针移到下一个节点 $list->next(); // prev() // 指针移到上一个节点, 如果原本指针在第一个，那么前一个节点为-1，并且将无法获得当前值 $list->prev(); // valid() // 判断该链表是否有更多的值，返回bool $list->valid(); // isEmpty() // 判断该链表是否为空链表，返回bool $list->isEmpty(); // offsetExists($index) // 判断参索引是否存在，返回bool $list->offsetExists(2); // offsetGet($index) // 返回参数索引的节点值 $list->offsetGet(2); // offsetSet($index, $newValue) // 设置参数索引的节点值, $index必须在链表的键范围中。 // 当一个节点用offsetUnset删掉时时，并不能用offsetSet重新给已删掉的节点设置值，只能对当前可见的节点的值进行修改 $list->offsetSet(3, 'value6'); // offsetUnset($index) // 删除参数索引的节点 $list->offsetUnset(3); // add($index, $value); // 对指定的索引新增一个新值。 当一个节点用offsetUnset时，并没有直接删除，该节点还仍然会保存在内存中。用add可以重新给该节点设置值
/**
* Make an iterable that will yield this iterable's values in reverse order. Keys in the
* original iterable will be preserved.
*
* This iterable will be consumed in its entirety when `reverse()` is called.
*
* Examples
*
* Crankshaft::Iter(['a', 'b', 'c', 'd', 'e'])->reverse()->to_array()
* // => [4 => 'e', 3 => 'd, 2 => 'c', 1 => 'b', 0 => 'a']
*
* Returns an Iterable.
*/
public function reverse()
{
$keys = new \SplDoublyLinkedList();
$values = new \SplDoublyLinkedList();
foreach ($this as $key => $value) {
$keys->push($key);
$values->push($value);
}
$reversed = [];
while (!$values->isEmpty()) {
$reversed[$keys->pop()] = $values->pop();
}
return Crankshaft::Iter($reversed);
}
<?php // Create a new Doubly Linked List $dll = new SplDoublyLinkedList(); var_dump($dll->isEmpty());
<?php
// Create a new Doubly Linked List
$dll = new SplDoublyLinkedList();
// Add some items to the list
$dll->push(1);
$dll->push(2);
$dll->push(3);
//var_dump($dll);
var_dump($dll->isEmpty("test"));
/**
* Notify observers, this method will store the return value from each
* observer in a SplDoublyLinkedList. If any one of the observers returns
* 'false', then the notification stops with the last value of the List
* being 'false'.
*
* @param string $event
* @param mixed $args
* @return SplDoublyLinkedList | return values from the observers
*/
public function notify($event, $args = null)
{
$args = $args instanceof \stdClass && $args->name === 'static' ? $args->args : array_slice(func_get_args(), 1);
$list = new SplDoublyLinkedList();
foreach ($this->getObservers($event) as $observer) {
$list->push($this->invoke($event, $observer, $args));
if (!$list->isEmpty() && $list->top() === false) {
break;
}
}
return $list;
}
/**
* Checks whether the list is empty or not.
*
* @return bool True if the list is empty, false otherwise.
* @link http://www.php.net/manual/en/spldoublylinkedlist.isempty.php
*/
public function isEmpty()
{
return $this->tokens->isEmpty();
}
