SplQueue::dequeue

(PHP 5 >= 5.3.0, PHP 7, PHP 8)

SplQueue::dequeue — Dequeues a node from the queue

说明

public SplQueue::dequeue ( ) : mixed

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 03:31


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 03:30


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 11:10


<?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 20-Jan-2010 08:57


If the queue is empty, dequeue() will raise an 'RuntimeException' with message 'Can't shift from an empty datastructure'.