
Data Structure

This illustrates a data structure, a means of storing data within a program.

You may see other such structures in the Data Structures category.
 Illustration of FIFO behavior
Task

Implement a FIFO queue.

Elements are added at one side and popped from the other in the order of insertion.



Operations:

   push   (aka enqueue)    - add element
   pop     (aka dequeue)    - pop first element
   empty                             - return truth value when empty


Errors:

   handle the error of trying to pop from an empty queue (behavior depends on the language and platform)


See

   Queue/Usage   for the built-in FIFO or queue of your language or standard library.


See also

 Array
 Associative array: Creation, Iteration
 Collections
 Compound data type
 Doubly-linked list: Definition, Element definition, Element insertion, List Traversal, Element Removal
 Linked list
 Queue: Definition, Usage
 Set
 Singly-linked list: Element definition, Element insertion, List Traversal, Element Removal
 Stack


define myqueue => type {
    data store = list
 
    public onCreate(...) => {
        if(void != #rest) => {
            with item in #rest do .`store`->insert(#item)
        }
    }
 
    public push(value) => .`store`->insertLast(#value)
 
    public pop => {
        handle => {
            .`store`->removefirst
        }
 
        return .`store`->first
    }
 
    public isEmpty => (.`store`->size == 0)
}