Queue/Usage: Difference between revisions

Line 746:

E also has queues in the standard library such as <code><import:org.erights.e.examples.concurrency.makeQueue></code>, but they are designed for concurrency purposes and do not report emptiness but rather return a promise for the next element.

=={{header|Elena}}==

ELENA 3.4 :

ELENA 4.x :

<lang elena>import system'collections.

<lang elena>import system'collections;

import extensions.

import extensions;

public program

public program()

{

[

console.

// Create a queue and "push" items into it

var queue := ~~Queue~~ new.

var queue := new Queue();

queue push:1.

queue.push:1;

queue push:3.

queue.push:3;

queue push:5.

queue.push:5;

// "Pop" items from the queue in FIFO order

console printLine(queue pop). // 1

console.printLine(queue.pop()); // 1

console printLine(queue pop). // 3

console.printLine(queue.pop()); // 3

console printLine(queue pop). // 5

console.printLine(queue.pop()); // 5

// To tell if the queue is empty, we check the count

console printLine("queue is ",(queue ~~length~~ == 0) iif("empty","nonempty")).

console.printLine("queue is ",(queue.Length == 0).iif("empty","nonempty"));

// If we try to pop from an empty queue, an exception

// is thrown.

queue pop | ~~if(~~:e)[ console writeLine:"Queue empty.". ].

queue.pop() | on:(e){ console.writeLine:"Queue empty." }

]</lang>

}</lang>

=={{header|Elisa}}==