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    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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