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index.js
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/**
* CIRCULAR DOUBLY LIST Class
*
* @author Brice Chevalier
*
* @desc Doubly list data structure
*
* Method Time Complexity
* ___________________________________
*
* add O(1)
* remove O(n)
* removeByRef O(1)
* getFirst O(1)
* getLast O(1)
* getCount O(1)
* apply O(n)
* clear O(n)
*
* Memory Complexity in O(n)
*/
function Node(obj, previous, next) {
this.object = obj;
this.previous = previous;
this.next = next;
}
function CircularDoublyList() {
this.count = 0;
this.last = null;
this.first = null;
}
CircularDoublyList.prototype.add = function (obj) {
this.count += 1;
var newNode = new Node(obj, this.last, this.first);
if (this.first === null) {
this.first = newNode;
this.last = newNode;
newNode.previous = newNode;
newNode.next = newNode;
} else {
// insertion before the this.last one
this.last.next = newNode;
this.last = newNode;
this.first.previous = newNode;
}
return newNode;
};
CircularDoublyList.prototype.remove = function (obj) {
if (this.first === this.last) {
if (this.first.object === obj) {
this.first = null;
this.last = null;
this.count -= 1;
}
return;
}
var current = this.first;
while (current !== this.last) {
if (current.object === obj) {
// Removing any reference to the node
current.next.previous = current.previous;
if (current === this.first) {
this.first = current.next;
} else {
current.previous.next = current.next;
}
// Removing any reference from the node to any other element of the list
current.previous = null;
current.next = null;
this.count -= 1;
return;
}
current = current.next;
}
if (current.object === obj) {
// Removing any reference to the node
this.last = current.previous;
if (current === this.first) {
this.first = current.next;
} else {
current.previous.next = current.next;
}
// Removing any reference from the node to any other element of the list
current.previous = null;
current.next = null;
this.count -= 1;
return;
}
};
CircularDoublyList.prototype.removeByRef = function (node) {
// Removing any reference to the node
if (node.next === null) {
this.last = node.previous;
} else {
node.next.previous = node.previous;
}
if (node.previous === null) {
this.first = node.next;
} else {
node.previous.next = node.next;
}
// Removing any reference from the node to any other element of the list
node.previous = null;
node.next = null;
this.count -= 1;
};
CircularDoublyList.prototype.getFirst = function () {
return this.first;
};
CircularDoublyList.prototype.getLast = function () {
return this.last;
};
CircularDoublyList.prototype.clear = function () {
this.first = null;
this.last = null;
};
CircularDoublyList.prototype.getCount = function () {
return this.count;
};
CircularDoublyList.prototype.forEach = function (processingFunc, params) {
for (var current = this.first; current !== this.last; current = current.next) {
processingFunc(current.object, params);
}
if (current !== null) {
processingFunc(current.object, params);
}
};
CircularDoublyList.prototype.forEachReverse = function (processingFunc, params) {
for (var current = this.last; current !== this.first; current = current.next) {
processingFunc(current.object, params);
}
if (current !== null) {
processingFunc(current.object, params);
}
};
module.exports = CircularDoublyList;