phaser/src/core/Group.js

/**
* @author       Richard Davey <rich@photonstorm.com>
* @copyright    2013 Photon Storm Ltd.
* @license      {@link https://github.com/photonstorm/phaser/blob/master/license.txt|MIT License}
*/

/**
* Phaser Group constructor.
* @class Phaser.Group
* @classdesc A Group is a container for display objects that allows for fast pooling, recycling and collision checks.
* @constructor
* @param {Phaser.Game} game - A reference to the currently running game.
* @param {*} parent - The parent Group or DisplayObjectContainer that will hold this group, if any.
* @param {string} [name=group] - A name for this Group. Not used internally but useful for debugging.
* @param {boolean} [useStage=false] - Should the DisplayObjectContainer this Group creates be added to the World (default, false) or direct to the Stage (true).
*/
Phaser.Group = function (game, parent, name, useStage) {

    if (typeof parent === 'undefined' || typeof parent === null)
    {
        parent = game.world;
    }

    if (typeof useStage === 'undefined')
    {
        useStage = false;
    }

    /**
    * @property {Phaser.Game} game - A reference to the currently running Game.
    */
    this.game = game;
    
    /**
    * @property {string} name - A name for this Group. Not used internally but useful for debugging.
    */
    this.name = name || 'group';

    if (useStage)
    {
        this._container = this.game.stage._stage;
    }
    else
    {
        this._container = new PIXI.DisplayObjectContainer();
        this._container.name = this.name;

        if (parent)
        {
            if (parent instanceof Phaser.Group)
            {
                parent._container.addChild(this._container);
                parent._container.updateTransform();
            }
            else
            {
                parent.addChild(this._container);
                parent.updateTransform();
            }
        }
        else
        {
            this.game.stage._stage.addChild(this._container);
            this.game.stage._stage.updateTransform();
        }
    }

    /**
    * @property {number} type - Internal Phaser Type value.
    * @protected
    */
    this.type = Phaser.GROUP;

    /**
    * @property {boolean} exists - If exists is true the the Group is updated, otherwise it is skipped.
    * @default
    */
    this.exists = true;

    //  Replaces the PIXI.Point with a slightly more flexible one.
    this._container.scale = new Phaser.Point(1, 1);

    /**
    * @property {Phaser.Point} scale - The scane of the Group container.
    */
    this.scale = this._container.scale;

    /**
    * The cursor is a simple way to iterate through the objects in a Group using the Group.next and Group.previous functions.
    * The cursor is set to the first child added to the Group and doesn't change unless you call next, previous or set it directly with Group.cursor.
    * @property {any} cursor - The current display object that the Group cursor is pointing to.
    */
    this.cursor = null;

};

/**
* @constant
* @type {number}
*/
Phaser.Group.RETURN_NONE = 0;

/**
* @constant
* @type {number}
*/
Phaser.Group.RETURN_TOTAL = 1;

/**
* @constant
* @type {number}
*/
Phaser.Group.RETURN_CHILD = 2;

/**
* @constant
* @type {number}
*/
Phaser.Group.SORT_ASCENDING = -1;

/**
* @constant
* @type {number}
*/
Phaser.Group.SORT_DESCENDING = 1;

Phaser.Group.prototype = {

    /**
    * Adds an existing object to this Group. The object can be an instance of Phaser.Sprite, Phaser.Button or any other display object.
    * The child is automatically added to the top of the Group, so renders on-top of everything else within the Group. If you need to control
    * that then see the addAt method.
    *
    * @see Phaser.Group#create
    * @see Phaser.Group#addAt
    * @method Phaser.Group#add
    * @param {*} child - An instance of Phaser.Sprite, Phaser.Button or any other display object..
    * @return {*} The child that was added to the Group.
    */
    add: function (child) {

        if (child.group !== this)
        {
            child.group = this;

            if (child.events)
            {
                child.events.onAddedToGroup.dispatch(child, this);
            }

            this._container.addChild(child);

            child.updateTransform();

            if (this.cursor === null)
            {
                this.cursor = child;
            }
        }

        return child;

    },

    /**
    * Adds an existing object to this Group. The object can be an instance of Phaser.Sprite, Phaser.Button or any other display object.
    * The child is added to the Group at the location specified by the index value, this allows you to control child ordering.
    *
    * @method Phaser.Group#addAt
    * @param {*} child - An instance of Phaser.Sprite, Phaser.Button or any other display object..
    * @param {number} index - The index within the Group to insert the child to.
    * @return {*} The child that was added to the Group.
    */
    addAt: function (child, index) {

        if (child.group !== this)
        {
            child.group = this;

            if (child.events)
            {
                child.events.onAddedToGroup.dispatch(child, this);
            }

            this._container.addChildAt(child, index);

            child.updateTransform();

            if (this.cursor === null)
            {
                this.cursor = child;
            }
        }

        return child;

    },

    /**
    * Returns the child found at the given index within this Group.
    *
    * @method Phaser.Group#getAt
    * @param {number} index - The index to return the child from.
    * @return {*} The child that was found at the given index.
    */
    getAt: function (index) {

        return this._container.getChildAt(index);

    },

    /**
    * Automatically creates a new Phaser.Sprite object and adds it to the top of this Group.
    * Useful if you don't need to create the Sprite instances before-hand.
    *
    * @method Phaser.Group#create
    * @param {number} x - The x coordinate to display the newly created Sprite at. The value is in relation to the Group.x point.
    * @param {number} y - The y coordinate to display the newly created Sprite at. The value is in relation to the Group.y point.
    * @param {string} key - The Game.cache key of the image that this Sprite will use.
    * @param {number|string} [frame] - If the Sprite image contains multiple frames you can specify which one to use here.
    * @param {boolean} [exists=true] - The default exists state of the Sprite.
    * @return {Phaser.Sprite} The child that was created.
    */
    create: function (x, y, key, frame, exists) {

        if (typeof exists == 'undefined') { exists = true; }

        var child = new Phaser.Sprite(this.game, x, y, key, frame);

        child.group = this;
        child.exists = exists;
        child.visible = exists;
        child.alive = exists;

        if (child.events)
        {
            child.events.onAddedToGroup.dispatch(child, this);
        }

        this._container.addChild(child);
            
        child.updateTransform();

        if (this.cursor === null)
        {
            this.cursor = child;
        }

        return child;

    },

    /**
    * Automatically creates multiple Phaser.Sprite objects and adds them to the top of this Group.
    * Useful if you need to quickly generate a pool of identical sprites, such as bullets. By default the sprites will be set to not exist
    * and will be positioned at 0, 0 (relative to the Group.x/y)
    *
    * @method Phaser.Group#createMultiple
    * @param {number} quantity - The number of Sprites to create.
    * @param {string} key - The Game.cache key of the image that this Sprite will use.
    * @param {number|string} [frame] - If the Sprite image contains multiple frames you can specify which one to use here.
    * @param {boolean} [exists=false] - The default exists state of the Sprite.
    */
    createMultiple: function (quantity, key, frame, exists) {

        if (typeof exists == 'undefined') { exists = false; }

        for (var i = 0; i < quantity; i++)
        {
            var child = new Phaser.Sprite(this.game, 0, 0, key, frame);

            child.group = this;
            child.exists = exists;
            child.visible = exists;
            child.alive = exists;

            if (child.events)
            {
                child.events.onAddedToGroup.dispatch(child, this);
            }

            this._container.addChild(child);
            child.updateTransform();

            if (this.cursor === null)
            {
                this.cursor = child;
            }

        }

    },

    /**
    * Advances the Group cursor to the next object in the Group. If it's at the end of the Group it wraps around to the first object.
    *
    * @method Phaser.Group#next
    */
    next: function () {

        if (this.cursor)
        {
            //  Wrap the cursor?
            if (this.cursor == this._container.last)
            {
                this.cursor = this._container._iNext;
            }
            else
            {
                this.cursor = this.cursor._iNext;
            }
        }

    },

    /**
    * Moves the Group cursor to the previous object in the Group. If it's at the start of the Group it wraps around to the last object.
    *
    * @method Phaser.Group#previous
    */
    previous: function () {

        if (this.cursor)
        {
            //  Wrap the cursor?
            if (this.cursor == this._container._iNext)
            {
                this.cursor = this._container.last;
            }
            else
            {
                this.cursor = this.cursor._iPrev;
            }
        }

    },

    childTest: function (prefix, child) {

        var s = prefix + ' next: ';

        if (child._iNext)
        {
            s = s + child._iNext.name;
        }
        else
        {
            s = s + '-null-';
        }

        s = s + ' ' + prefix + ' prev: ';

        if (child._iPrev)
        {
            s = s + child._iPrev.name;
        }
        else
        {
            s = s + '-null-';
        }

        console.log(s);

    },

    swapIndex: function (index1, index2) {

        var child1 = this.getAt(index1);
        var child2 = this.getAt(index2);

        console.log('swapIndex ', index1, ' with ', index2);

        this.swap(child1, child2);

    },

    /**
    * Swaps the position of two children in this Group. Both children must be in this Group.
    * You cannot swap a child with itself, or swap un-parented children, doing so will return false.
    *
    * @method Phaser.Group#swap
    * @param {*} child1 - The first child to swap.
    * @param {*} child2 - The second child to swap.
    * @return {boolean} True if the swap was successful, otherwise false.
    */
    swap: function (child1, child2) {

        if (child1 === child2 || !child1.parent || !child2.parent || child1.group !== this || child2.group !== this)
        {
            return false;
        }

        //  Cache the values
        var child1Prev = child1._iPrev;
        var child1Next = child1._iNext;
        var child2Prev = child2._iPrev;
        var child2Next = child2._iNext;

        var endNode = this._container.last._iNext;
        var currentNode = this.game.stage._stage;
            
        do
        {
            if (currentNode !== child1 && currentNode !== child2)
            {
                if (currentNode.first === child1)
                {
                    currentNode.first = child2;
                }
                else if (currentNode.first === child2)
                {
                    currentNode.first = child1;
                }

                if (currentNode.last === child1)
                {
                    currentNode.last = child2;
                }
                else if (currentNode.last === child2)
                {
                    currentNode.last = child1;
                }
            }

            currentNode = currentNode._iNext;
        }
        while (currentNode != endNode)

        if (child1._iNext == child2)
        {
            //  This is a downward (A to B) neighbour swap
            child1._iNext = child2Next;
            child1._iPrev = child2;
            child2._iNext = child1;
            child2._iPrev = child1Prev;

            if (child1Prev) { child1Prev._iNext = child2; }
            if (child2Next) { child2Next._iPrev = child1; }

            if (child1.__renderGroup)
            {
                child1.__renderGroup.updateTexture(child1);
            }

            if (child2.__renderGroup)
            {
                child2.__renderGroup.updateTexture(child2);
            }

            return true;
        }
        else if (child2._iNext == child1)
        {
            //  This is an upward (B to A) neighbour swap
            child1._iNext = child2;
            child1._iPrev = child2Prev;
            child2._iNext = child1Next;
            child2._iPrev = child1;

            if (child2Prev) { child2Prev._iNext = child1; }
            if (child1Next) { child1Next._iPrev = child2; }

            if (child1.__renderGroup)
            {
                child1.__renderGroup.updateTexture(child1);
            }

            if (child2.__renderGroup)
            {
                child2.__renderGroup.updateTexture(child2);
            }

            return true;
        }
        else
        {
            //  Children are far apart
            child1._iNext = child2Next;
            child1._iPrev = child2Prev;
            child2._iNext = child1Next;
            child2._iPrev = child1Prev;

            if (child1Prev) { child1Prev._iNext = child2; }
            if (child1Next) { child1Next._iPrev = child2; }
            if (child2Prev) { child2Prev._iNext = child1; }
            if (child2Next) { child2Next._iPrev = child1; }

            if (child1.__renderGroup)
            {
                child1.__renderGroup.updateTexture(child1);
            }

            if (child2.__renderGroup)
            {
                child2.__renderGroup.updateTexture(child2);
            }

            return true;
        }

        return false;
        
    },

    /**
    * Brings the given child to the top of this Group so it renders above all other children.
    *
    * @method Phaser.Group#bringToTop
    * @param {*} child - The child to bring to the top of this Group.
    * @return {*} The child that was moved.
    */
    bringToTop: function (child) {

        if (child.group === this)
        {
            this.remove(child);
            this.add(child);
        }

        return child;

    },

    /**
    * Get the index position of the given child in this Group.
    *
    * @method Phaser.Group#getIndex
    * @param {*} child - The child to get the index for.
    * @return {number} The index of the child or -1 if it's not a member of this Group.
    */
    getIndex: function (child) {

        return this._container.children.indexOf(child);

    },

    /**
    * Replaces a child of this Group with the given newChild. The newChild cannot be a member of this Group.
    *
    * @method Phaser.Group#replace
    * @param {*} oldChild - The child in this Group that will be replaced.
    * @param {*} newChild - The child to be inserted into this group.
    */
    replace: function (oldChild, newChild) {

        if (!this._container.first._iNext)
        {
            return;
        }

        var index = this.getIndex(oldChild);
        
        if (index != -1)
        {
            if (newChild.parent !== undefined)
            {
                newChild.events.onRemovedFromGroup.dispatch(newChild, this);
                newChild.parent.removeChild(newChild);
            }

            this._container.removeChild(oldChild);
            this._container.addChildAt(newChild, index);

            newChild.events.onAddedToGroup.dispatch(newChild, this);
            newChild.updateTransform();

            if (this.cursor == oldChild)
            {
                this.cursor = this._container._iNext;
            }
        }

    },

    /**
    * Sets the given property to the given value on the child. The operation controls the assignment of the value.
    *
    * @method Phaser.Group#setProperty
    * @param {*} child - The child to set the property value on.
    * @param {array} key - An array of strings that make up the property that will be set.
    * @param {*} value - The value that will be set.
    * @param {number} [operation=0] - Controls how the value is assigned. A value of 0 replaces the value with the new one. A value of 1 adds it, 2 subtracts it, 3 multiplies it and 4 divides it.
    */
    setProperty: function (child, key, value, operation) {

        operation = operation || 0;

        //  As ugly as this approach looks, and although it's limited to a depth of only 4, it's extremely fast.
        //  Much faster than a for loop or object iteration. There are no checks, so if the key isn't valid then it'll fail
        //  but as you are likely to call this from inner loops that have to perform well, I'll take that trade off.

        //  0 = Equals
        //  1 = Add
        //  2 = Subtract
        //  3 = Multiply
        //  4 = Divide

        var len = key.length;

        if (len == 1)
        {
            if (operation === 0) { child[key[0]] = value; }
            else if (operation == 1) { child[key[0]] += value; }
            else if (operation == 2) { child[key[0]] -= value; }
            else if (operation == 3) { child[key[0]] *= value; }
            else if (operation == 4) { child[key[0]] /= value; }
        }
        else if (len == 2)
        {
            if (operation === 0) { child[key[0]][key[1]] = value; }
            else if (operation == 1) { child[key[0]][key[1]] += value; }
            else if (operation == 2) { child[key[0]][key[1]] -= value; }
            else if (operation == 3) { child[key[0]][key[1]] *= value; }
            else if (operation == 4) { child[key[0]][key[1]] /= value; }
        }
        else if (len == 3)
        {
            if (operation === 0) { child[key[0]][key[1]][key[2]] = value; }
            else if (operation == 1) { child[key[0]][key[1]][key[2]] += value; }
            else if (operation == 2) { child[key[0]][key[1]][key[2]] -= value; }
            else if (operation == 3) { child[key[0]][key[1]][key[2]] *= value; }
            else if (operation == 4) { child[key[0]][key[1]][key[2]] /= value; }
        }
        else if (len == 4)
        {
            if (operation === 0) { child[key[0]][key[1]][key[2]][key[3]] = value; }
            else if (operation == 1) { child[key[0]][key[1]][key[2]][key[3]] += value; }
            else if (operation == 2) { child[key[0]][key[1]][key[2]][key[3]] -= value; }
            else if (operation == 3) { child[key[0]][key[1]][key[2]][key[3]] *= value; }
            else if (operation == 4) { child[key[0]][key[1]][key[2]][key[3]] /= value; }
        }
        
        //  TODO - Deep property scane

    },

    /**
    * This function allows you to quickly set the same property across all children of this Group to a new value.
    * The operation parameter controls how the new value is assigned to the property, from simple replacement to addition and multiplication.
    *
    * @method Phaser.Group#setAll
    * @param {string} key - The property, as a string, to be set. For example: 'body.velocity.x'
    * @param {*} value - The value that will be set.
    * @param {boolean} [checkAlive=false] - If set then only children with alive=true will be updated.
    * @param {boolean} [checkVisible=false] - If set then only children with visible=true will be updated.
    * @param {number} [operation=0] - Controls how the value is assigned. A value of 0 replaces the value with the new one. A value of 1 adds it, 2 subtracts it, 3 multiplies it and 4 divides it.
    */
    setAll: function (key, value, checkAlive, checkVisible, operation) {

        key = key.split('.');

        if (typeof checkAlive === 'undefined') { checkAlive = false; }
        if (typeof checkVisible === 'undefined') { checkVisible = false; }

        operation = operation || 0;

        if (this._container.children.length > 0 && this._container.first._iNext)
        {
            var currentNode = this._container.first._iNext;
                
            do
            {
                if ((checkAlive === false || (checkAlive && currentNode.alive)) && (checkVisible === false || (checkVisible && currentNode.visible)))
                {
                    this.setProperty(currentNode, key, value, operation);
                }

                currentNode = currentNode._iNext;
            }
            while (currentNode != this._container.last._iNext)
        }

    },

    /**
    * Adds the amount to the given property on all children in this Group.
    * Group.addAll('x', 10) will add 10 to the child.x value.
    *
    * @method Phaser.Group#addAll
    * @param {string} property - The property to increment, for example 'body.velocity.x' or 'angle'.
    * @param {number} amount - The amount to increment the property by. If child.x = 10 then addAll('x', 40) would make child.x = 50.
    * @param {boolean} checkAlive - If true the property will only be changed if the child is alive.
    * @param {boolean} checkVisible - If true the property will only be changed if the child is visible.
    */
    addAll: function (property, amount, checkAlive, checkVisible) {

        this.setAll(property, amount, checkAlive, checkVisible, 1);

    },

    /**
    * Subtracts the amount from the given property on all children in this Group.
    * Group.subAll('x', 10) will minus 10 from the child.x value.
    *
    * @method Phaser.Group#subAll
    * @param {string} property - The property to decrement, for example 'body.velocity.x' or 'angle'.
    * @param {number} amount - The amount to subtract from the property. If child.x = 50 then subAll('x', 40) would make child.x = 10.
    * @param {boolean} checkAlive - If true the property will only be changed if the child is alive.
    * @param {boolean} checkVisible - If true the property will only be changed if the child is visible.
    */
    subAll: function (property, amount, checkAlive, checkVisible) {

        this.setAll(property, amount, checkAlive, checkVisible, 2);

    },

    /**
    * Multiplies the given property by the amount on all children in this Group.
    * Group.multiplyAll('x', 2) will x2 the child.x value.
    *
    * @method Phaser.Group#multiplyAll
    * @param {string} property - The property to multiply, for example 'body.velocity.x' or 'angle'.
    * @param {number} amount - The amount to multiply the property by. If child.x = 10 then multiplyAll('x', 2) would make child.x = 20.
    * @param {boolean} checkAlive - If true the property will only be changed if the child is alive.
    * @param {boolean} checkVisible - If true the property will only be changed if the child is visible.
    */
    multiplyAll: function (property, amount, checkAlive, checkVisible) {

        this.setAll(property, amount, checkAlive, checkVisible, 3);

    },

    /**
    * Divides the given property by the amount on all children in this Group.
    * Group.divideAll('x', 2) will half the child.x value.
    *
    * @method Phaser.Group#divideAll
    * @param {string} property - The property to divide, for example 'body.velocity.x' or 'angle'.
    * @param {number} amount - The amount to divide the property by. If child.x = 100 then divideAll('x', 2) would make child.x = 50.
    * @param {boolean} checkAlive - If true the property will only be changed if the child is alive.
    * @param {boolean} checkVisible - If true the property will only be changed if the child is visible.
    */
    divideAll: function (property, amount, checkAlive, checkVisible) {

        this.setAll(property, amount, checkAlive, checkVisible, 4);

    },

    /**
    * Calls a function on all of the children that have exists=true in this Group.
    * After the existsValue parameter you can add as many parameters as you like, which will all be passed to the child callback.
    * 
    * @method Phaser.Group#callAllExists
    * @param {function} callback - The function that exists on the children that will be called.
    * @param {boolean} existsValue - Only children with exists=existsValue will be called.
    * @param {...*} parameter - Additional parameters that will be passed to the callback.
    */
    callAllExists: function (callback, existsValue) {

        var args = Array.prototype.splice.call(arguments, 2);

        if (this._container.children.length > 0 && this._container.first._iNext)
        {
            var currentNode = this._container.first._iNext;
                
            do
            {
                if (currentNode.exists == existsValue && currentNode[callback])
                {
                    currentNode[callback].apply(currentNode, args);
                }

                currentNode = currentNode._iNext;
            }
            while (currentNode != this._container.last._iNext)

        }

    },

    /**
    * Calls a function on all of the children that have exists=true in this Group.
    * 
    * @method Phaser.Group#callbackFromArray
    * @param {object} child - The object to inspect.
    * @param {array} callback - The array of function names.
    * @param {number} length - The size of the array (pre-calculated in callAll).
    * @protected
    */
    callbackFromArray: function (child, callback, length) {

        //  Kinda looks like a Christmas tree

        if (length == 1)
        {
            if (child[callback[0]])
            {
                return child[callback[0]];
            }
        }
        else if (length == 2)
        {
            if (child[callback[0]][callback[1]])
            {
                return child[callback[0]][callback[1]];
            }
        }
        else if (length == 3)
        {
            if (child[callback[0]][callback[1]][callback[2]])
            {
                return child[callback[0]][callback[1]][callback[2]];
            }
        }
        else if (length == 4)
        {
            if (child[callback[0]][callback[1]][callback[2]][callback[3]])
            {
                return child[callback[0]][callback[1]][callback[2]][callback[3]];
            }
        }
        else
        {
            if (child[callback])
            {
                return child[callback];
            }
        }

        return false;

    },

    /**
    * Calls a function on all of the children regardless if they are dead or alive (see callAllExists if you need control over that)
    * After the method parameter and context you can add as many extra parameters as you like, which will all be passed to the child.
    * 
    * @method Phaser.Group#callAll
    * @param {string} method - A string containing the name of the function that will be called. The function must exist on the child.
    * @param {string} [context=''] - A string containing the context under which the method will be executed. Leave to '' to default to the child.
    * @param {...*} parameter - Additional parameters that will be passed to the method.
    */
    callAll: function (method, context) {

        if (typeof method === 'undefined')
        {
            return;
        }

        //  Extract the method into an array
        method = method.split('.');

        var methodLength = method.length;

        if (typeof context === 'undefined')
        {
            context = null;
        }
        else
        {
            //  Extract the context into an array
            if (typeof context === 'string')
            {
                context = context.split('.');
                var contextLength = context.length;
            }
        }

        var args = Array.prototype.splice.call(arguments, 2);
        var callback = null;
        var callbackContext = null;

        if (this._container.children.length > 0 && this._container.first._iNext)
        {
            var child = this._container.first._iNext;
                
            do
            {
                callback = this.callbackFromArray(child, method, methodLength);

                if (context && callback)
                {
                    callbackContext = this.callbackFromArray(child, context, contextLength);
    
                    if (callback)
                    {
                        callback.apply(callbackContext, args);
                    }
                }
                else if (callback)
                {
                    callback.apply(child, args);
                }

                child = child._iNext;
            }
            while (child != this._container.last._iNext)

        }

    },

    /**
    * Allows you to call your own function on each member of this Group. You must pass the callback and context in which it will run.
    * After the checkExists parameter you can add as many parameters as you like, which will all be passed to the callback along with the child.
    * For example: Group.forEach(awardBonusGold, this, true, 100, 500)
    * 
    * @method Phaser.Group#forEach
    * @param {function} callback - The function that will be called. Each child of the Group will be passed to it as its first parameter.
    * @param {Object} callbackContext - The context in which the function should be called (usually 'this').
    * @param {boolean} checkExists - If set only children with exists=true will be passed to the callback, otherwise all children will be passed.
    */
    forEach: function (callback, callbackContext, checkExists) {

        if (typeof checkExists === 'undefined')
        {
            checkExists = false;
        }

        var args = Array.prototype.splice.call(arguments, 3);
        args.unshift(null);

        if (this._container.children.length > 0 && this._container.first._iNext)
        {
            var currentNode = this._container.first._iNext;
                
            do
            {
                if (checkExists === false || (checkExists && currentNode.exists))
                {
                    args[0] = currentNode;
                    callback.apply(callbackContext, args);
                }

                currentNode = currentNode._iNext;
            }
            while (currentNode != this._container.last._iNext);

        }

    },

    /**
    * Allows you to call your own function on each alive member of this Group (where child.alive=true). You must pass the callback and context in which it will run.
    * You can add as many parameters as you like, which will all be passed to the callback along with the child.
    * For example: Group.forEachAlive(causeDamage, this, 500)
    * 
    * @method Phaser.Group#forEachAlive
    * @param {function} callback - The function that will be called. Each child of the Group will be passed to it as its first parameter.
    * @param {Object} callbackContext - The context in which the function should be called (usually 'this').
    */
    forEachExists: function (callback, callbackContext) {

        var args = Array.prototype.splice.call(arguments, 2);
        args.unshift(null);

        this.iterate('exists', true, Phaser.Group.RETURN_TOTAL, callback, callbackContext, args);

    },

    /**
    * Allows you to call your own function on each alive member of this Group (where child.alive=true). You must pass the callback and context in which it will run.
    * You can add as many parameters as you like, which will all be passed to the callback along with the child.
    * For example: Group.forEachAlive(causeDamage, this, 500)
    * 
    * @method Phaser.Group#forEachAlive
    * @param {function} callback - The function that will be called. Each child of the Group will be passed to it as its first parameter.
    * @param {Object} callbackContext - The context in which the function should be called (usually 'this').
    */
    forEachAlive: function (callback, callbackContext) {

        var args = Array.prototype.splice.call(arguments, 2);
        args.unshift(null);

        this.iterate('alive', true, Phaser.Group.RETURN_TOTAL, callback, callbackContext, args);

    },

    /**
    * Allows you to call your own function on each dead member of this Group (where alive=false). You must pass the callback and context in which it will run.
    * You can add as many parameters as you like, which will all be passed to the callback along with the child.
    * For example: Group.forEachDead(bringToLife, this)
    * 
    * @method Phaser.Group#forEachDead
    * @param {function} callback - The function that will be called. Each child of the Group will be passed to it as its first parameter.
    * @param {Object} callbackContext - The context in which the function should be called (usually 'this').
    */
    forEachDead: function (callback, callbackContext) {

        var args = Array.prototype.splice.call(arguments, 2);
        args.unshift(null);

        this.iterate('alive', false, Phaser.Group.RETURN_TOTAL, callback, callbackContext, args);

    },

    /**
    * Call this function to sort the group according to a particular value and order.
    * For example to depth sort Sprites for Zelda-style game you might call `group.sort('y', Phaser.Group.SORT_ASCENDING)` at the bottom of your `State.update()`.
    *
    * @method Phaser.Group#sort
    * @param {string} [index='y'] - The `string` name of the property you want to sort on.
    * @param {number} [order=Phaser.Group.SORT_ASCENDING] - The `Group` constant that defines the sort order. Possible values are Phaser.Group.SORT_ASCENDING and Phaser.Group.SORT_DESCENDING.
    */
    sort: function (index, order) {

        if (typeof index === 'undefined') { index = 'y'; }
        if (typeof order === 'undefined') { order = Phaser.Group.SORT_ASCENDING; }

        var swapped;
        var temp;

        do {

            swapped = false;

            for (var i = 0, len = this._container.children.length - 1; i < len; i++)
            {
                if (order == Phaser.Group.SORT_ASCENDING)
                {
                    if (this._container.children[i][index] > this._container.children[i + 1][index])
                    {
                        this.swap(this.getAt(i), this.getAt(i + 1));
                        temp = this._container.children[i];
                        this._container.children[i] = this._container.children[i + 1];
                        this._container.children[i + 1] = temp;
                        swapped = true;
                    }
                }
                else
                {
                    if (this._container.children[i][index] < this._container.children[i + 1][index])
                    {
                        this.swap(this.getAt(i), this.getAt(i + 1));
                        temp = this._container.children[i];
                        this._container.children[i] = this._container.children[i + 1];
                        this._container.children[i + 1] = temp;
                        swapped = true;
                    }
                }
            }
        } while (swapped);

    },

    /**
    * Iterates over the children of the Group. When a child has a property matching key that equals the given value, it is considered as a match.
    * Matched children can be sent to the optional callback, or simply returned or counted.
    * You can add as many callback parameters as you like, which will all be passed to the callback along with the child, after the callbackContext parameter.
    * 
    * @method Phaser.Group#iterate
    * @param {string} key - The child property to check, i.e. 'exists', 'alive', 'health'
    * @param {any} value - If child.key === this value it will be considered a match. Note that a strict comparison is used.
    * @param {number} returnType - How to return the data from this method. Either Phaser.Group.RETURN_NONE, Phaser.Group.RETURN_TOTAL or Phaser.Group.RETURN_CHILD.
    * @param {function} [callback=null] - Optional function that will be called on each matching child. Each child of the Group will be passed to it as its first parameter.
    * @param {Object} [callbackContext] - The context in which the function should be called (usually 'this').
    */
    iterate: function (key, value, returnType, callback, callbackContext, args) {

        if (returnType === Phaser.Group.RETURN_TOTAL && this._container.children.length === 0)
        {
            return -1;
        }

        if (typeof callback === 'undefined')
        {
            callback = false;
        }

        var total = 0;

        if (this._container.children.length > 0 && this._container.first._iNext)
        {
            var currentNode = this._container.first._iNext;
                
            do
            {
                if (currentNode[key] === value)
                {
                    total++;

                    if (callback)
                    {
                        args[0] = currentNode;
                        callback.apply(callbackContext, args);
                    }

                    if (returnType === Phaser.Group.RETURN_CHILD)
                    {
                        return currentNode;
                    }
                }

                currentNode = currentNode._iNext;
            }
            while (currentNode != this._container.last._iNext);
        }

        if (returnType === Phaser.Group.RETURN_TOTAL)
        {
            return total;
        }
        else if (returnType === Phaser.Group.RETURN_CHILD)
        {
            return null;
        }

    },

    /**
    * Call this function to retrieve the first object with exists == (the given state) in the Group.
    *
    * @method Phaser.Group#getFirstExists
    * @param {boolean} state - True or false.
    * @return {Any} The first child, or null if none found.
    */
    getFirstExists: function (state) {

        if (typeof state !== 'boolean')
        {
            state = true;
        }

        return this.iterate('exists', state, Phaser.Group.RETURN_CHILD);

    },

    /**
    * Call this function to retrieve the first object with alive === true in the group.
    * This is handy for checking if everything has been wiped out, or choosing a squad leader, etc.
    *
    * @method Phaser.Group#getFirstAlive
    * @return {Any} The first alive child, or null if none found.
    */
    getFirstAlive: function () {

        return this.iterate('alive', true, Phaser.Group.RETURN_CHILD);

    },

    /**
    * Call this function to retrieve the first object with alive === false in the group.
    * This is handy for checking if everything has been wiped out, or choosing a squad leader, etc.
    *
    * @method Phaser.Group#getFirstDead
    * @return {Any} The first dead child, or null if none found.
    */
    getFirstDead: function () {

        return this.iterate('alive', false, Phaser.Group.RETURN_CHILD);

    },

    /**
    * Call this function to find out how many members of the group are alive.
    *
    * @method Phaser.Group#countLiving
    * @return {number} The number of children flagged as alive. Returns -1 if Group is empty.
    */
    countLiving: function () {

        return this.iterate('alive', true, Phaser.Group.RETURN_TOTAL);

    },

    /**
    * Call this function to find out how many members of the group are dead.
    *
    * @method Phaser.Group#countDead
    * @return {number} The number of children flagged as dead. Returns -1 if Group is empty.
    */
    countDead: function () {

        return this.iterate('alive', false, Phaser.Group.RETURN_TOTAL);

    },

    /**
    * Returns a member at random from the group.
    *
    * @method Phaser.Group#getRandom
    * @param {number} startIndex - Optional offset off the front of the array. Default value is 0, or the beginning of the array.
    * @param {number} length - Optional restriction on the number of values you want to randomly select from.
    * @return {Any} A random child of this Group.
    */
    getRandom: function (startIndex, length) {

        if (this._container.children.length === 0)
        {
            return null;
        }

        startIndex = startIndex || 0;
        length = length || this._container.children.length;

        return this.game.math.getRandom(this._container.children, startIndex, length);

    },

    /**
    * Removes the given child from this Group and sets its group property to null.
    *
    * @method Phaser.Group#remove
    * @param {Any} child - The child to remove.
    * @return {boolean} true if the child was removed from this Group, otherwise false.
    */
    remove: function (child) {

        if (child.group !== this)
        {
            return false;
        }

        if (child.events)
        {
            child.events.onRemovedFromGroup.dispatch(child, this);
        }

        //  Check it's actually in the container
        if (child.parent === this._container)
        {
            this._container.removeChild(child);
        }

        if (this.cursor == child)
        {
            if (this._container._iNext)
            {
                this.cursor = this._container._iNext;
            }
            else
            {
                this.cursor = null;
            }
        }

        child.group = null;

        return true;

    },

    /**
    * Removes all children from this Group, setting all group properties to null.
    * The Group container remains on the display list.
    *
    * @method Phaser.Group#removeAll
    */
    removeAll: function () {

        if (this._container.children.length === 0)
        {
            return;
        }

        do
        {
            if (this._container.children[0].events)
            {
                this._container.children[0].events.onRemovedFromGroup.dispatch(this._container.children[0], this);
            }
            this._container.removeChild(this._container.children[0]);
        }
        while (this._container.children.length > 0);

        this.cursor = null;

    },

    /**
    * Removes all children from this Group whos index falls beteen the given startIndex and endIndex values.
    *
    * @method Phaser.Group#removeBetween
    * @param {number} startIndex - The index to start removing children from.
    * @param {number} endIndex - The index to stop removing children from. Must be higher than startIndex and less than the length of the Group.
    */
    removeBetween: function (startIndex, endIndex) {

        if (this._container.children.length === 0)
        {
            return;
        }

        if (startIndex > endIndex || startIndex < 0 || endIndex > this._container.children.length)
        {
            return false;
        }

        for (var i = startIndex; i < endIndex; i++)
        {
            var child = this._container.children[i];
            child.events.onRemovedFromGroup.dispatch(child, this);
            this._container.removeChild(child);
    
            if (this.cursor == child)
            {
                if (this._container._iNext)
                {
                    this.cursor = this._container._iNext;
                }
                else
                {
                    this.cursor = null;
                }
            }
        }

    },

    /**
    * Destroys this Group. Removes all children, then removes the container from the display list and nulls references.
    *
    * @method Phaser.Group#destroy
    */
    destroy: function () {

        this.removeAll();

        this._container.parent.removeChild(this._container);

        this._container = null;

        this.game = null;

        this.exists = false;

        this.cursor = null;

    },

    validate: function () {

        var testObject = this.game.stage._stage.last._iNext;
        var displayObject = this.game.stage._stage;
        var nextObject = null;
        var prevObject = null;
        var count = 0;

        do
        {
            if (count > 0)
            {
                //  check next
                if (displayObject !== nextObject)
                {
                    console.log('check next fail');
                    return false;
                }

                //  check previous
                if (displayObject._iPrev !== prevObject)
                {
                    console.log('check previous fail');
                    return false;
                }
            }

            //  Set the next object
            nextObject = displayObject._iNext;
            prevObject = displayObject;

            displayObject = displayObject._iNext;

            count++;

        }
        while(displayObject != testObject)

        return true;

    },

    /**
    * Dumps out a list of Group children and their index positions to the browser console. Useful for group debugging.
    *
    * @method Phaser.Group#dump
    * @param {boolean} [full=false] - If full the dump will include the entire display list, start from the Stage. Otherwise it will only include this container.
    */
    dump: function (full) {

        if (typeof full == 'undefined')
        {
            full = false;
        }

        var spacing = 20;
        var output = "\n" + Phaser.Utils.pad('Node', spacing) + "|" + Phaser.Utils.pad('Next', spacing) + "|" + Phaser.Utils.pad('Previous', spacing) + "|" + Phaser.Utils.pad('First', spacing) + "|" + Phaser.Utils.pad('Last', spacing);

        console.log(output);

        var output = Phaser.Utils.pad('----------', spacing) + "|" + Phaser.Utils.pad('----------', spacing) + "|" + Phaser.Utils.pad('----------', spacing) + "|" + Phaser.Utils.pad('----------', spacing) + "|" + Phaser.Utils.pad('----------', spacing);
        console.log(output);

        if (full)
        {
            var testObject = this.game.stage._stage.last._iNext;
            var displayObject = this.game.stage._stage;
        }
        else
        {
            var testObject = this._container.last._iNext;
            var displayObject = this._container;
        }
        
        do
        {
            var name = displayObject.name || '*';

            if (this.cursor == displayObject)
            {
                var name = '> ' + name;
            }

            var nameNext = '-';
            var namePrev = '-';
            var nameFirst = '-';
            var nameLast = '-';

            if (displayObject._iNext)
            {
                nameNext = displayObject._iNext.name;
            }

            if (displayObject._iPrev)
            {
                namePrev = displayObject._iPrev.name;
            }

            if (displayObject.first)
            {
                nameFirst = displayObject.first.name;
            }

            if (displayObject.last)
            {
                nameLast = displayObject.last.name;
            }

            if (typeof nameNext === 'undefined')
            {
                nameNext = '-';
            }

            if (typeof namePrev === 'undefined')
            {
                namePrev = '-';
            }

            if (typeof nameFirst === 'undefined')
            {
                nameFirst = '-';
            }

            if (typeof nameLast === 'undefined')
            {
                nameLast = '-';
            }

            var output = Phaser.Utils.pad(name, spacing) + "|" + Phaser.Utils.pad(nameNext, spacing) + "|" + Phaser.Utils.pad(namePrev, spacing) + "|" + Phaser.Utils.pad(nameFirst, spacing) + "|" + Phaser.Utils.pad(nameLast, spacing);
            console.log(output);

            displayObject = displayObject._iNext;

        }
        while(displayObject != testObject)

    }

};

/**
* @name Phaser.Group#total
* @property {number} total - The total number of children in this Group who have a state of exists = true.
* @readonly
*/
Object.defineProperty(Phaser.Group.prototype, "total", {

    get: function () {
        return this.iterate('exists', true, Phaser.Group.RETURN_TOTAL);
    }

});

/**
* @name Phaser.Group#length
* @property {number} length - The total number of children in this Group, regardless of their exists/alive status.
* @readonly
*/
Object.defineProperty(Phaser.Group.prototype, "length", {

    get: function () {
        return this._container.children.length;
    }

});

/**
* The x coordinate of the Group container. You can adjust the Group container itself by modifying its coordinates.
* This will have no impact on the x/y coordinates of its children, but it will update their worldTransform and on-screen position.
* @name Phaser.Group#x
* @property {number} x - The x coordinate of the Group container.
*/
Object.defineProperty(Phaser.Group.prototype, "x", {

    get: function () {
        return this._container.position.x;
    },

    set: function (value) {
        this._container.position.x = value;
    }

});

/**
* The y coordinate of the Group container. You can adjust the Group container itself by modifying its coordinates.
* This will have no impact on the x/y coordinates of its children, but it will update their worldTransform and on-screen position.
* @name Phaser.Group#y
* @property {number} y - The y coordinate of the Group container.
*/
Object.defineProperty(Phaser.Group.prototype, "y", {

    get: function () {
        return this._container.position.y;
    },

    set: function (value) {
        this._container.position.y = value;
    }

});

/**
* The angle of rotation of the Group container. This will adjust the Group container itself by modifying its rotation.
* This will have no impact on the rotation value of its children, but it will update their worldTransform and on-screen position.
* @name Phaser.Group#angle
* @property {number} angle - The angle of rotation given in degrees, where 0 degrees = to the right.
*/
Object.defineProperty(Phaser.Group.prototype, "angle", {

    get: function() {
        return Phaser.Math.radToDeg(this._container.rotation);
    },

    set: function(value) {
        this._container.rotation = Phaser.Math.degToRad(value);
    }

});

/**
* The angle of rotation of the Group container. This will adjust the Group container itself by modifying its rotation.
* This will have no impact on the rotation value of its children, but it will update their worldTransform and on-screen position.
* @name Phaser.Group#rotation
* @property {number} rotation - The angle of rotation given in radians.
*/
Object.defineProperty(Phaser.Group.prototype, "rotation", {

    get: function () {
        return this._container.rotation;
    },

    set: function (value) {
        this._container.rotation = value;
    }

});

/**
* @name Phaser.Group#visible
* @property {boolean} visible - The visible state of the Group. Non-visible Groups and all of their children are not rendered.
*/
Object.defineProperty(Phaser.Group.prototype, "visible", {

    get: function () {
        return this._container.visible;
    },

    set: function (value) {
        this._container.visible = value;
    }

});

/**
* @name Phaser.Group#alpha
* @property {number} alpha - The alpha value of the Group container.
*/
Object.defineProperty(Phaser.Group.prototype, "alpha", {

    get: function () {
        return this._container.alpha;
    },

    set: function (value) {
        this._container.alpha = value;
    }

});