1 files changed, 46 insertions, 16 deletions

diff --git a/src/Scope.js b/src/Scope.js
index daf4b36c..d22604fd 100644
--- a/src/Scope.js
+++ b/src/Scope.js
@@ -1,14 +1,22 @@
 function Scope(initialState, name) {
-  this.widgets = [];
-  this.watchListeners = {};
-  this.name = name;
+  var self = this;
+  self.widgets = [];
+  self.evals = [];
+  self.watchListeners = {};
+  self.name = name;
   initialState = initialState || {};
   var State = function(){};
   State.prototype = initialState;
-  this.state = new State();
-  this.state['$parent'] = initialState;
+  self.state = new State();
+  extend(self.state, {
+    '$parent': initialState,
+    '$watch': bind(self, self.addWatchListener),
+    '$eval': bind(self, self.eval),
+    // change name to onEval?
+    '$addEval': bind(self, self.addEval)
+  });
   if (name == "ROOT") {
-    this.state['$root'] = this.state;
+    self.state['$root'] = self.state;
   }
 };
 
@@ -44,20 +52,33 @@ Scope.getter = function(instance, path) {
 };
 
 Scope.prototype = {
+  // TODO: rename to update? or eval?
   updateView: function() {
     var self = this;
     this.fireWatchers();
-    _.each(this.widgets, function(widget){
+    foreach(this.widgets, function(widget){
       self.evalWidget(widget, "", {}, function(){
         this.updateView(self);
       });
     });
+    foreach(this.evals, bind(this, this.apply));
   },
 
   addWidget: function(controller) {
     if (controller) this.widgets.push(controller);
   },
 
+  addEval: function(fn, listener) {
+    // todo: this should take a function/string and a listener
+    // todo: this is a hack, which will need to be cleaned up.
+    var self = this,
+        listenFn = listener || noop,
+        expr = bind(self, self.compile(fn), {scope: self, self: self.state});
+    this.evals.push(function(){
+      self.apply(listenFn, expr());
+    });
+  },
+
   isProperty: function(exp) {
     for ( var i = 0; i < exp.length; i++) {
       var ch = exp.charAt(i);
@@ -94,15 +115,21 @@ Scope.prototype = {
     this.eval(expressionText + "=" + toJson(value));
   },
 
-  eval: function(expressionText, context) {
-//    log('Scope.eval', expressionText);
-    var expression = Scope.expressionCache[expressionText];
-    if (!expression) {
-      var parser = new Parser(expressionText);
-      expression = parser.statements();
+  compile: function(exp) {
+    if (isFunction(exp)) return exp;
+    var expFn = Scope.expressionCache[exp];
+    if (!expFn) {
+      var parser = new Parser(exp);
+      expFn = parser.statements();
       parser.assertAllConsumed();
-      Scope.expressionCache[expressionText] = expression;
+      Scope.expressionCache[exp] = expFn;
     }
+    return expFn;
+  },
+
+  eval: function(expressionText, context) {
+//    log('Scope.eval', expressionText);
+    var expression = this.compile(expressionText);
     context = context || {};
     context.scope = this;
     context.self = this.state;
@@ -189,8 +216,7 @@ Scope.prototype = {
   },
 
   fireWatchers: function() {
-    var self = this;
-    var fired = false;
+    var self = this, fired = false;
     foreach(this.watchListeners, function(watcher) {
       var value = self.eval(watcher.expression);
       if (value !== watcher.lastValue) {
@@ -202,5 +228,9 @@ Scope.prototype = {
       }
     });
     return fired;
+  },
+
+  apply: function(fn) {
+    fn.apply(this.state, slice.call(arguments, 1, arguments.length));
   }
 };