AdapterRegistry.js

define(["./_base/kernel", "./_base/lang"], function(dojo, lang){
// module:
//		dojo/AdapterRegistry

var AdapterRegistry = dojo.AdapterRegistry = function(/*Boolean?*/ returnWrappers){
	// summary:
	//		A registry to make contextual calling/searching easier.
	// description:
	//		Objects of this class keep list of arrays in the form [name, check,
	//		wrap, directReturn] that are used to determine what the contextual
	//		result of a set of checked arguments is. All check/wrap functions
	//		in this registry should be of the same arity.
	// example:
	//	|	// create a new registry
	//	|	require(["dojo/AdapterRegistry"],
	//	|	function(AdapterRegistry){
	//	|		var reg = new AdapterRegistry();
	//	|		reg.register("handleString",
	//	|			function(str){
	//	|				return typeof val == "string"
	//	|			},
	//	|			function(str){
	//	|				// do something with the string here
	//	|			}
	//	|		);
	//	|		reg.register("handleArr",
	//	|			dojo.isArray,
	//	|			function(arr){
	//	|				// do something with the array here
	//	|			}
	//	|		);
	//	|
	//	|		// now we can pass reg.match() *either* an array or a string and
	//	|		// the value we pass will get handled by the right function
	//	|		reg.match("someValue"); // will call the first function
	//	|		reg.match(["someValue"]); // will call the second
	//	|	});

	this.pairs = [];
	this.returnWrappers = returnWrappers || false; // Boolean
};

lang.extend(AdapterRegistry, {
	register: function(/*String*/ name, /*Function*/ check, /*Function*/ wrap, /*Boolean?*/ directReturn, /*Boolean?*/ override){
		// summary:
		//		register a check function to determine if the wrap function or
		//		object gets selected
		// name:
		//		a way to identify this matcher.
		// check:
		//		a function that arguments are passed to from the adapter's
		//		match() function.  The check function should return true if the
		//		given arguments are appropriate for the wrap function.
		// directReturn:
		//		If directReturn is true, the value passed in for wrap will be
		//		returned instead of being called. Alternately, the
		//		AdapterRegistry can be set globally to "return not call" using
		//		the returnWrappers property. Either way, this behavior allows
		//		the registry to act as a "search" function instead of a
		//		function interception library.
		// override:
		//		If override is given and true, the check function will be given
		//		highest priority. Otherwise, it will be the lowest priority
		//		adapter.
		this.pairs[((override) ? "unshift" : "push")]([name, check, wrap, directReturn]);
	},

	match: function(/* ... */){
		// summary:
		//		Find an adapter for the given arguments. If no suitable adapter
		//		is found, throws an exception. match() accepts any number of
		//		arguments, all of which are passed to all matching functions
		//		from the registered pairs.
		for(var i = 0; i < this.pairs.length; i++){
			var pair = this.pairs[i];
			if(pair[1].apply(this, arguments)){
				if((pair[3])||(this.returnWrappers)){
					return pair[2];
				}else{
					return pair[2].apply(this, arguments);
				}
			}
		}
		throw new Error("No match found");
	},

	unregister: function(name){
		// summary:
		//		Remove a named adapter from the registry
		// name: String
		//		The name of the adapter.
		// returns: Boolean
		//		Returns true if operation is successful.
		//		Returns false if operation fails.
	
		// FIXME: this is kind of a dumb way to handle this. On a large
		// registry this will be slow-ish and we can use the name as a lookup
		// should we choose to trade memory for speed.
		for(var i = 0; i < this.pairs.length; i++){
			var pair = this.pairs[i];
			if(pair[0] == name){
				this.pairs.splice(i, 1);
				return true;
			}
		}
		return false;
	}
});

return AdapterRegistry;
});