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Normal data structures implemented in languages like javascript etc. plz note that object based data structure perform faster than the array based data structure.
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var queue = []; | |
queue.push(2); // [2] | |
queue.push(5); // [2, 5] | |
var i = queue.shift(); // [5] // i = 2 |
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function Queue() { | |
var first, last, item; | |
function Item(fn) { | |
this.fn = fn; | |
this.next = void 0; | |
} | |
return { | |
peek: function peek() { | |
return first.fn; | |
}, | |
enqueue: function enqueue(fn) { | |
item = new Item(fn); | |
if (last) { | |
last.next = item; | |
} else { | |
first = item; | |
} | |
last = item; | |
item = void 0; | |
}, | |
drain: function drain() { | |
var f = first; | |
first = last = cycle = null; | |
while (f) { | |
f.fn(); | |
f = f.next; | |
} | |
} | |
}; | |
} |
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/* | |
Queue.js | |
A function to represent a queue | |
Created by Stephen Morley - http://code.stephenmorley.org/ - and released under | |
the terms of the CC0 1.0 Universal legal code: | |
http://creativecommons.org/publicdomain/zero/1.0/legalcode | |
*/ | |
/* Creates a new queue. A queue is a first-in-first-out (FIFO) data structure - | |
* items are added to the end of the queue and removed from the front. | |
*/ | |
function Queue(){ | |
// initialise the queue and offset | |
var queue = []; | |
var offset = 0; | |
// Returns the length of the queue. | |
this.getLength = function(){ | |
return (queue.length - offset); | |
} | |
// Returns true if the queue is empty, and false otherwise. | |
this.isEmpty = function(){ | |
return (queue.length == 0); | |
} | |
/* Enqueues the specified item. The parameter is: | |
* | |
* item - the item to enqueue | |
*/ | |
this.enqueue = function(item){ | |
// queue.push(item); | |
queue[queue.length] = item; // alternative faster push | |
} | |
/* Dequeues an item and returns it. If the queue is empty, the value | |
* 'undefined' is returned. | |
*/ | |
this.dequeue = function(){ | |
// if the queue is empty, return immediately | |
if (queue.length == 0) return undefined; | |
// store the item at the front of the queue | |
var item = queue[offset]; | |
// increment the offset and remove the free space if necessary | |
if (++ offset * 2 >= queue.length){ | |
queue = queue.slice(offset); | |
offset = 0; | |
} | |
// return the dequeued item | |
return item; | |
} | |
/* Returns the item at the front of the queue (without dequeuing it). If the | |
* queue is empty then undefined is returned. | |
*/ | |
this.peek = function(){ | |
return (queue.length > 0 ? queue[offset] : undefined); | |
} | |
} |
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