queue.js

Queue

Queue is a data structure which implements an array friendly interface

Class Methods

push(data)
pop()
unshift(data)
shift()
forEach(func, condition)
concat()

Getters

head    // points to head node. head.data points to queue data at head
tail    // same as above for tail
length  // number of items in queue

Example

 
var Queue = require('queue.js')
 

Create empty queue

 
var q = new Queue();
 
console.log('q.head:', q.head); // should be "undefined"
console.log('q.tail:', q.tail); // should be "undefined"
 

Instantiation

 
var q1 = new Queue().push(1).push(2).push(3);
 
var q2 = new Queue();
 
[1,2,3].forEach(function(a) { q2.push(a) });
 
var q3 = new Queue();
 
[4,5,6].forEach(function(a) { q3.unshift(a) } );
 

concatenate multiple queues

var allq = new Queue().concat(q1).concat(q2).concat(q3);

peek

 
console.log('allq.head',      allq.head.data);      // 1
console.log('allq.head.next', allq.head.next.data); // 2
console.log('allq.tail.prev', allq.tail.prev.data); // 5
console.log('allq.tail',      allq.tail.data);      // 4
 

remove from queue

 
// pop removes from end of queue, shift from start
console.log('tail and head', allq.pop(), allq.shift()); // 4, 1
 

remove an arbitrary node

 
var q4 = new Queue().push(1).push(2).push(3);
q4.remove(q4.head.next);
 

forEach: General purpose iterator

 
var i = 0;
allq.forEach(function(a) {
    console.log('Item at', i++, 'is', a);
})
 

map using forEach. Use similarly for filter, fold, etc.

 
var qmap = [];
 
allq.forEach(function(a) {
  qmap.push(a*a);
})
 
console.log('Squares', qmap);
 

iterate until condition met

var condition = function(a) { return a < 4; }
 
allq.forEach(function(a) {
  console.log('Must be < 4:', a);
}, condition);
 

Look at the test suite for more example

How to contribute

This repository follows (more or less) the Felix's Node.js Style Guide, your contribution must be consistent with this style.

The test suite is written on top of visionmedia/mocha and it took hours of hard work. Please use the tests to check if your contribution is breaking some part of the library and add new tests for each new feature.

⚡ npm test

License

This software is released under the MIT license cited below.

Copyright (c) 2015 Bharath Rao. All Rights Reserved.

Permission is hereby granted, free of charge, to any person
obtaining a copy of this software and associated documentation
files (the 'Software'), to deal in the Software without
restriction, including without limitation the rights to use,
copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following
conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.