sylvester-es6/src/CircularLinkedList.js

Fork of the famous Sylvester vector, matrix and geometry library. Rewritten in ES6 and including the glUtils.js add-ons.

"use strict";

import { LinkedList } from "./LinkedList";

export class CircularLinkedList extends LinkedList
{
    append (node)
    {
        if (this.first === null)
        {
            node.prev = node;
            node.next = node;
            this.first = node;
            this.last = node;
        }
        else
        {
            node.prev = this.last;
            node.next = this.first;
            this.first.prev = node;
            this.last.next = node;
            this.last = node;
        }
        this.length++;
    }

    prepend (node)
    {
        if (this.first === null)
        {
            this.append(node);
            return;
        }
        else
        {
            node.prev = this.last;
            node.next = this.first;
            this.first.prev = node;
            this.last.next = node;
            this.first = node;
        }
        this.length++;
    }

    insertAfter (node, newNode)
    {
        newNode.prev = node;
        newNode.next = node.next;
        node.next.prev = newNode;
        node.next = newNode;
        if (newNode.prev === this.last)
        {
            this.last = newNode;
        }
        this.length++;
    }

    insertBefore (node, newNode)
    {
        newNode.prev = node.prev;
        newNode.next = node;
        node.prev.next = newNode;
        node.prev = newNode;
        if (newNode.next === this.first)
        {
            this.first = newNode;
        }
        this.length++;
    }

    remove (node)
    {
        if (this.length > 1)
        {
            node.prev.next = node.next;
            node.next.prev = node.prev;
            if (node === this.first)
            {
                this.first = node.next;
            }
            if (node === this.last)
            {
                this.last = node.prev;
            }
        }
        else
        {
            this.first = null;
            this.last = null;
        }
        node.prev = null;
        node.next = null;
        this.length--;
    }

    withData (data)
    {
        var nodeFromStart = this.first, nodeFromEnd = this.last, n = Math.ceil(this.length / 2);
        while (n--)
        {
            if (nodeFromStart.data === data)
            {
                return nodeFromStart;
            }
            if (nodeFromEnd.data === data)
            {
                return nodeFromEnd;
            }
            nodeFromStart = nodeFromStart.next;
            nodeFromEnd = nodeFromEnd.prev;
        }
        return null;
    }
};

CircularLinkedList.fromArray = function(list, useNodes) {
    var linked = new CircularLinkedList();
    var n = list.length;
    while (n--)
    {
        linked.prepend(useNodes ? new LinkedList.Node(list[n]) : list[n]);
    }
    return linked;
};