NodeList-data.js

dojo.provide("dojo.NodeList-data");
(function(d){
	
/*=====
	dojo.NodeList.prototype.data = function(key, value){
		// summary: stash or get some arbitrary data on/from these nodes. 
		//
		// description:
		//		Stash or get some arbirtrary data on/from these nodes. This private _data function is
		//		exposed publicly on `dojo.NodeList`, eg: as the result of a `dojo.query` call.
		//		DIFFERS from jQuery.data in that when used as a getter, the entire list is ALWAYS
		//		returned. EVEN WHEN THE LIST IS length == 1.
		//
		//		A single-node version of this function is provided as `dojo._nodeData`, which follows
		//		the same signature, though expects a String ID or DomNode reference in the first 
		//		position, before key/value arguments.
		//
		// node: String|DomNode 
		//		The node to associate data with
		//
		// key: Object?|String?
		//		If an object, act as a setter and iterate over said object setting data items as defined.
		//		If a string, and `value` present, set the data for defined `key` to `value`
		//		If a string, and `value` absent, act as a getter, returning the data associated with said `key`
		//
		// value: Anything?
		//		The value to set for said `key`, provided `key` is a string (and not an object)
		//
		// example:
		//		Set a key `bar` to some data, then retrieve it.
		//	|	dojo.query(".foo").data("bar", "touched");
		//	|	var touched = dojo.query(".foo").data("bar");
		//	|	if(touched[0] == "touched"){ alert('win'); }
		//
		// example:
		//		Get all the data items for a given node. 
		//	|	var list = dojo.query(".foo").data();
		//	|	var first = list[0];
		//
		// example:
		//		Set the data to a complex hash. Overwrites existing keys with new value
		//	|	dojo.query(".foo").data({ bar:"baz", foo:"bar" });
		//		Then get some random key:
		//	|	dojo.query(".foo").data("foo"); // returns [`bar`]
		//
		//	returns: Object|Anything|Nothing
		//		When used as a setter via `dojo.NodeList`, a NodeList instance is returned 
		//		for further chaning. When used as a getter via `dojo.NodeList` an ARRAY
		//		of items is returned. The items in the array correspond to the elements
		//		in the original list. This is true even when the list length is 1, eg:
		//		when looking up a node by ID (#foo)
	};
	
	dojo.NodeList.prototype.removeData = function(key){
		// summary: Remove the data associated with these nodes.
		// key: String?
		//		If ommitted, clean all data for this node.
		//		If passed, remove the data item found at `key`
	};
	
	dojo._nodeDataCache = {
		// summary: An alias to the private dataCache for NodeList-data. NEVER USE THIS!
		//		This private is only exposed for the benefit of unit testing, and is 
		//		removed during the build process.
	};
	
=====*/

	var dataCache = {}, x = 0, dataattr = "data-dojo-dataid", nl = d.NodeList,
		dopid = function(node){
			// summary: Return a uniqueish ID for the passed node reference
			var pid = d.attr(node, dataattr);
			if(!pid){
				pid = "pid" + (x++);
				d.attr(node, dataattr, pid);
			}
			return pid;
		}
	;
	
	//>>excludeStart("debugging", true);
	// exposed for unit tests:
	d._nodeDataCache = dataCache;
	//>>excludeEnd("debugging");
	
	var dodata = d._nodeData = function(node, key, value){

		var pid = dopid(node), r;
		if(!dataCache[pid]){ dataCache[pid] = {}; }
		
		// API discrepency: calling with only a node returns the whole object. $.data throws
		if(arguments.length == 1){ r = dataCache[pid]; }
		if(typeof key == "string"){
			// either getter or setter, based on `value` presence
			if(arguments.length > 2){
				dataCache[pid][key] = value;
			}else{
				r = dataCache[pid][key];
			}
		}else{
			// must be a setter, mix `value` into data hash
			// API discrepency: using object as setter works here
			r = d._mixin(dataCache[pid], key); 
		}
		
		return r; // Object|Anything|Nothing
	};
	
	var removeData = d._removeNodeData = function(node, key){
		// summary: Remove some data from this node
		// node: String|DomNode
		//		The node reference to remove data from
		// key: String?
		//		If omitted, remove all data in this dataset.
		//		If passed, remove only the passed `key` in the associated dataset
		var pid = dopid(node);
		if(dataCache[pid]){
			if(key){ 
				delete dataCache[pid][key];
			}else{ 
				delete dataCache[pid];
			}
		}
	};
	
	d._gcNodeData = function(){
		// summary: super expensive: GC all data in the data for nodes that no longer exist in the dom. 
		// description:
		//		super expensive: GC all data in the data for nodes that no longer exist in the dom. 
		//		MUCH safer to do this yourself, manually, on a per-node basis (via `NodeList.removeData()`)
		//		provided as a stop-gap for exceptionally large/complex applications with constantly changing
		//		content regions (eg: a dijit.layout.ContentPane with replacing data)
		//		There is NO automatic GC going on. If you dojo.destroy() a node, you should _removeNodeData 
		//		prior to destruction.
		var livePids = dojo.query("[" + dataattr + "]").map(dopid);
		for(var i in dataCache){
			if(dojo.indexOf(livePids, i) < 0){ delete dataCache[i]; }
		}
	};

	// make nodeData and removeNodeData public on dojo.NodeList:
	d.extend(nl, {
		data: nl._adaptWithCondition(dodata, function(a){
			return a.length === 0 || a.length == 1 && (typeof a[0] == "string");
		}),
		removeData: nl._adaptAsForEach(removeData)
	});

// TODO: this is the basic implemetation of adaptWithCondtionAndWhenMappedConsiderLength, for lack of a better API name
// it conflicts with the the `dojo.NodeList` way: always always return an arrayLike thinger. Consider for 2.0:
//
//	nl.prototype.data = function(key, value){
//		var a = arguments, r;
//		if(a.length === 0 || a.length == 1 && (typeof a[0] == "string")){
//			r = this.map(function(node){
//				return d._data(node, key);
//			});
//			if(r.length == 1){ r = r[0]; } // the offending line, and the diff on adaptWithCondition
//		}else{
//			r = this.forEach(function(node){
//				d._data(node, key, value);
//			});
//		}
//		return r; // dojo.NodeList|Array|SingleItem
//	};
	
})(dojo);