collection.js

/*global a2d */
/**
 * @class 
 * Implements an array-like collection
 */
a2d.Collection = function() {
    /**
     * length of the collection
     */
	this.length = 0;

    /**
     * Add an item to the end of the collection
     * @param {any} item item to be added
     */
	this.push = function(item) {
        if(typeof(item) === "object") {
            item.parent = this;
        }
		this[this.length] = item;        
		this.length += 1;
	};
    
	/**
     * Remove item from the end of the collection
     * and return it.
     * @returns {any} the removed item     
     */
	this.pop = function() {
		this.length -= 1;
		return this[this.length];
	};
    
	/**
     * Remove item at given index
     * @param {number} idx Index of the item to be removed
     * @returns {any} the removed item     
     */
	this.remove = function(idx) {
		var item = this[idx],
			i;
        delete this[idx];
		for(i = idx + 1; i < this.length; i++) {
			this[i - 1] = this[i];
		}
		this.length -= 1;
		return item;
	};
	
    /**
     * Remove the first item from the collection and return it.
     * @returns {any} the removed item
     */
	this.shift = function() {
		return this.remove(0);
	};

    /**
     * Add an item to the beginning of this collection
     * @param {any} item The item to be added;
     * @returns the new length of the collection
     */
	this.unshift = function(item) {
		var i;
		for(i = 0; i < this.length; i++) {
			this[i + 1] = this[i];
		}
		this[0] = item;
		this.length += 1;
		return this.length;
	};
	/**
     * Get the index of the given item in the collection
     * @param {any} item The item to look up
     * @returns {number} the index
     */
	this.indexOf = function(item) {
		var i;
		for(i = 0; i < this.length; i++){
			if(this[i] == item) {
				return i;
			}
		}
		return -1;
	};
	/**
     * Append the contents of another collection to this one.
     * @param {a2d.Collection} other Other collection
     */
	this.append = function(other) {
		var i;
		for(i = 0; i < other.length; i++) {
			this.push(other[i]);
		}	
	};

	/**
	 * Sort contents of this collection. There is no default sorting method,
	 * it must be supplied.
	 * @param {Function} sort function. Takes two arguments(a, b), returns a negative value if b > a, positive if a > b, 0 if they are equal.
	 */
	this.sort = function(sort) {
		for(var i = 1; i < this.length; i++) {
			if(sort(this[i], this[i - 1]) < 0) {
				var t = this[i];
				this[i] = this[i - 1];
				this[i - 1] = t;
			}
		}
	};

	/**
	 * foreach
	 * @param {Function} callback to call for each item in this collection.
	 */
	this.foreach = function(eachfunc) {
		for(var i = 0; i < this.length; i++) {
			eachfunc(this[i]);
		}
	};
};