avoid calling a specific decorator's update() if it doesn't need to b…

…e updated.

not really for performance improvements, as the objects comparaison it not that cheap, but more like correctness.

multi-decorator.js

@@ -7,34 +7,70 @@
 
     'use strict';
 
-    function multi(node, args) {
+    var multi = function(node, args) {
         var decorators = {};
 
-        var self = this;
-
         Object.keys(args).forEach(function(name) {
-            if(typeof self.decorators[name] === 'function') {
-                decorators[name] = self.decorators[name].apply(self, [node].concat(args[name]));
+            if (typeof this.decorators[name] === 'function') {
+                decorators[name] = {decorator: this.decorators[name].apply(this, [node].concat(args[name])), args: args[name]};
             }
-        }.bind(self));
+        }.bind(this));
 
         return {
             update: function(args) {
                 Object.keys(args).forEach(function(name) {
-                    if(decorators[name]) {
-                        decorators[name].update.apply(self, [].concat(args[name]));
+                    if (decorators[name] && decorators[name].decorator && decorators[name].decorator.update && !equalObjects(args[name], decorators[name].args)) {
+                        decorators[name].args = args[name];
+                        decorators[name].decorator.update.apply(this, [].concat(args[name]));
                     }
-                }.bind(self));
+                }.bind(this));
             },
             teardown: function() {
                 Object.keys(args).forEach(function(name) {
-                    if(decorators[name]) {
-                        decorators[name].teardown.apply(self);
+                    if (decorators[name] && decorators[name].decorator) {
+                        decorators[name].teardown.apply(this);
                     }
-                }.bind(self));
+                }.bind(this));
             }
-        };
-    }
+        }
+    };
+
+    // since ractive will call the multi.update for any update on any of the decorator's arguments,
+    // we want to avoid calling update on the decorators that don't need to be updated,
+    // so we compare their last arguments with the new ones, so if they weren't updated, the decorator.update() won't be called
+    var equalObjects = function () {
+        var args = Array.prototype.slice.call(arguments, 0);
+        var result;
+
+        // 1 or 0 arguments, then i don't know, it's not equal to nothing i guess
+        if (args.length < 2) {
+            return false;
+        }
+
+        var argI, argJ, caught;
+
+        for (var i = 0; i < args.length - 1; i++) {
+            caught = false;
+            try {
+                argI = JSON.stringify(args[i]);
+                argJ = JSON.stringify(args[i + 1]);
+            } catch (e) {
+                // if any of the arguments could not be stringified
+                // it's probably a circular object, so we check for reference equality
+                // if they don't point to the same thing, we assume they are NOT equal,
+                caught = true;
+                result = args[i] == args[i + 1];
+            }
+            if (!caught) {
+                result = argI == argJ;
+            }
+            if (!result) {
+                return result;
+            }
+        }
+        return result;
+    };
+
 
     // Common JS (i.e. browserify) environment
     if(typeof module !== 'undefined' && module.exports && typeof require === 'function') {