define("dijit/_Contained", [
	"dojo/_base/declare", // declare
	"./registry"	// registry.getEnclosingWidget(), registry.byNode()
], function(declare, registry){

	// module:
	//		dijit/_Contained
	// summary:
	//		Mixin for widgets that are children of a container widget

	return declare("dijit._Contained", null, {
		// summary:
		//		Mixin for widgets that are children of a container widget
		//
		// example:
		// | 	// make a basic custom widget that knows about it's parents
		// |	declare("my.customClass",[dijit._Widget,dijit._Contained],{});

		_getSibling: function(/*String*/ which){
			// summary:
			//      Returns next or previous sibling
			// which:
			//      Either "next" or "previous"
			// tags:
			//      private
			var node = this.domNode;
			do{
				node = node[which+"Sibling"];
			}while(node && node.nodeType != 1);
			return node && registry.byNode(node);	// dijit._Widget
		},

		getPreviousSibling: function(){
			// summary:
			//		Returns null if this is the first child of the parent,
			//		otherwise returns the next element sibling to the "left".

			return this._getSibling("previous"); // dijit._Widget
		},

		getNextSibling: function(){
			// summary:
			//		Returns null if this is the last child of the parent,
			//		otherwise returns the next element sibling to the "right".

			return this._getSibling("next"); // dijit._Widget
		},

		getIndexInParent: function(){
			// summary:
			//		Returns the index of this widget within its container parent.
			//		It returns -1 if the parent does not exist, or if the parent
			//		is not a dijit._Container

			var p = this.getParent();
			if(!p || !p.getIndexOfChild){
				return -1; // int
			}
			return p.getIndexOfChild(this); // int
		}
	});
});