Calendar options binding/triggering system

lumbar.json

@@ -38,6 +38,7 @@
         "src/common/View.js",
         "src/common/Scroller.js",
         "src/Calendar.js",
+        "src/Calendar.options.js",
         "src/defaults.js",
         "src/lang.js",
         "src/Header.js",

src/Calendar.options.js

@@ -0,0 +1,62 @@
+/*
+Options binding/triggering system.
+*/
+Calendar.mixin({
+
+	// A map of option names to arrays of handler objects. Initialized to {} in Calendar.
+	// Format for a handler object:
+	// {
+	//   func // callback function to be called upon change
+	//   names // option names whose values should be given to func
+	// }
+	optionHandlers: null, 
+
+	// Calls handlerFunc immediately, and when the given option has changed.
+	// handlerFunc will be given the option value.
+	bindOption: function(optionName, handlerFunc) {
+		this.bindOptions([ optionName ], handlerFunc);
+	},
+
+	// Calls handlerFunc immediately, and when any of the given options change.
+	// handlerFunc will be given each option value as ordered function arguments.
+	bindOptions: function(optionNames, handlerFunc) {
+		var handlerObj = { func: handlerFunc, names: optionNames };
+		var i;
+
+		for (i = 0; i < optionNames.length; i++) {
+			this.registerOptionHandlerObj(optionNames[i], handlerObj);
+		}
+
+		this.triggerOptionHandlerObj(handlerObj);
+	},
+
+	// Puts the given handler object into the internal hash
+	registerOptionHandlerObj: function(optionName, handlerObj) {
+		(this.optionHandlers[optionName] || (this.optionHandlers[optionName] = []))
+			.push(handlerObj);
+	},
+
+	// Reports that the given option has changed, and calls all appropriate handlers.
+	triggerOptionHandlers: function(optionName) {
+		var handlerObjs = this.optionHandlers[optionName] || [];
+		var i;
+
+		for (i = 0; i < handlerObjs.length; i++) {
+			this.triggerOptionHandlerObj(handlerObjs[i]);
+		}
+	},
+
+	// Calls the callback for a specific handler object, passing in the appropriate arguments.
+	triggerOptionHandlerObj: function(handlerObj) {
+		var optionNames = handlerObj.names;
+		var optionValues = [];
+		var i;
+
+		for (i = 0; i < optionNames.length; i++) {
+			optionValues.push(this.options[optionNames[i]]);
+		}
+
+		handlerObj.func.apply(this, optionValues); // maintain the Calendar's `this` context
+	}
+
+});