SplQueue::dequeue

(PHP 5 >= 5.3.0, PHP 7)

SplQueue::dequeue — Dequeues a node from the queue

说明

mixed SplQueue::dequeue ( void )

Dequeues value from the top of the queue.

Note:

SplQueue::dequeue() is an alias of SplDoublyLinkedList::shift().

参数

此函数没有参数。

返回值

The value of the dequeued node.

User Contributed Notes

mark at bull-roarer dot com 06-Jul-2013 12:31
I just thought this was a fun and interesting way for lining up method calls and then calling them back-to-back. Might be useful as a basis for a transactional execution class or something.

<?php
$q = new SplQueue();
$q->setIteratorMode(SplQueue::IT_MODE_DELETE);

$q->enqueue(array("FooBar", "foo"));
$q->enqueue(array("FooBar", "bar"));
$q->enqueue(array("FooBar", "msg", "Hi there!"));

foreach ($q as $task) {
  if (count($task) > 2) {
    list($class, $method, $args) = $task;
    $class::$method($args);
  } else {
    list($class, $method) = $task;
    $class::$method();
  }
}

class FooBar {
  public static function foo() {
    echo "FooBar::foo() called.\n";
  }
  public static function bar() {
    echo "FooBar::bar() called.\n";
  }
  public static function msg($msg) {
    echo "$msg\n";
  }
}
?>

Results:
FooBar::foo() called.
FooBar::bar() called.
Hi there!
mark at bull-roarer dot com 06-Jul-2013 12:30
I just thought this was a fun and interesting way for lining up method calls and then calling them back-to-back. Might be useful as a basis for a transactional execution class or something.

<?php
$q = new SplQueue();
$q->setIteratorMode(SplQueue::IT_MODE_DELETE);

$q->enqueue(array("FooBar", "foo"));
$q->enqueue(array("FooBar", "bar"));
$q->enqueue(array("FooBar", "msg", "Hi there!"));

foreach ($q as $task) {
  if (count($task) > 2) {
    list($class, $method, $args) = $task;
    $class::$method($args);
  } else {
    list($class, $method) = $task;
    $class::$method();
  }
}

class FooBar {
  public static function foo() {
    echo "FooBar::foo() called.\n";
  }
  public static function bar() {
    echo "FooBar::bar() called.\n";
  }
  public static function msg($msg) {
    echo "$msg\n";
  }
}
?>

Results:
FooBar::foo() called.
FooBar::bar() called.
Hi there!
andresdzphp at php dot net 30-Sep-2011 08:10
<?php
$q = new SplQueue();
$q->setIteratorMode(SplQueue::IT_MODE_DELETE);
$q->enqueue('item 1');
$q->enqueue('item 2');
$q->enqueue('item 3');

$q->dequeue();
$q->dequeue();

foreach ($q as $item) {
    echo $item;
}

//Result: item 3

$q->dequeue(); //Fatal error: Uncaught exception 'RuntimeException'
              //with message 'Can't shift from an empty datastructure'
?>
xuecan at gmail dot com 21-Jan-2010 05:57
If the queue is empty, dequeue() will raise an 'RuntimeException' with message 'Can't shift from an empty datastructure'.