The SplQueue class

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

Introduction

The SplQueue class provides the main functionalities of a queue implemented using a doubly linked list by setting the iterator mode to SplDoublyLinkedList::IT_MODE_FIFO.

Class synopsis

class SplQueue extends SplDoublyLinkedList {
/* Inherited constants */
public const int SplDoublyLinkedList::IT_MODE_LIFO;
public const int SplDoublyLinkedList::IT_MODE_FIFO;
public const int SplDoublyLinkedList::IT_MODE_DELETE;
public const int SplDoublyLinkedList::IT_MODE_KEEP;
/* Methods */
public dequeue(): mixed
public enqueue(mixed $value): void
/* Inherited methods */
public SplDoublyLinkedList::add(int $index, mixed $value): void
public SplDoublyLinkedList::bottom(): mixed
public SplDoublyLinkedList::count(): int
public SplDoublyLinkedList::current(): mixed
public SplDoublyLinkedList::getIteratorMode(): int
public SplDoublyLinkedList::isEmpty(): bool
public SplDoublyLinkedList::key(): int
public SplDoublyLinkedList::next(): void
public SplDoublyLinkedList::offsetExists(int $index): bool
public SplDoublyLinkedList::offsetGet(int $index): mixed
public SplDoublyLinkedList::offsetSet(?int $index, mixed $value): void
public SplDoublyLinkedList::offsetUnset(int $index): void
public SplDoublyLinkedList::pop(): mixed
public SplDoublyLinkedList::prev(): void
public SplDoublyLinkedList::push(mixed $value): void
public SplDoublyLinkedList::rewind(): void
public SplDoublyLinkedList::serialize(): string
public SplDoublyLinkedList::setIteratorMode(int $mode): int
public SplDoublyLinkedList::shift(): mixed
public SplDoublyLinkedList::top(): mixed
public SplDoublyLinkedList::unserialize(string $data): void
public SplDoublyLinkedList::unshift(mixed $value): void
public SplDoublyLinkedList::valid(): bool
}

Examples

Example #1 SplQueue example

<?php
$q = new SplQueue();
$q[] = 1;
$q[] = 2;
$q[] = 3;
foreach ($q as $elem) {
echo $elem."\n";
}
?>

The above example will output:

1
2
3

Example #2 Efficiently handling tasks with SplQueue

<?php
$q = new SplQueue();
$q->setIteratorMode(SplQueue::IT_MODE_DELETE);
// ... enqueue some tasks on the queue ...
// process them
foreach ($q as $task) {
// ... process $task ...
// add new tasks on the queue
$q[] = $newTask;
// ...
}
?>

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