WIP: fixes for expression caching

Author: IgorMinar

src/ng/parse.js

@@ -1052,8 +1052,7 @@ function $ParseProvider() {
               parsedExpression = wrapSharedExpression(parsedExpression);
               parsedExpression.$$watchDelegate = parsedExpression.literal ?
                 oneTimeLiteralWatchDelegate : oneTimeWatchDelegate;
-            }
-            else if (parsedExpression.inputs) {
+            } else if (parsedExpression.inputs) {
               parsedExpression.$$watchDelegate = inputsWatchDelegate;
             }
 
@@ -1075,8 +1074,7 @@ function $ParseProvider() {
         if (!input.constant) {
           if (input.inputs) {
             collectExpressionInputs(input.inputs, list);
-          }
-          else if (-1 === list.indexOf(input)) {
+          } else if (list.indexOf(input) === -1) { // TODO(perf) can we do better?
             list.push(input);
           }
         }
@@ -1089,21 +1087,18 @@ function $ParseProvider() {
       if (o1 == null || o2 == null) return o1 === o2; // null/undefined
 
       if (typeof o1 === "object") {
-        //The same object is not supported because it may have been mutated
+        // The same object is not supported because it may have been mutated
         if (o1 === o2) return false;
 
         if (typeof o2 !== "object") return false;
 
-        //Dates
-        if (isDate(o1) && isDate(o2)) {
+        // Dates
+        if (isDate(o1) && isDate(o2)) { // TODO(perf): make this more generic via valueOf
           o1 = o1.getTime();
           o2 = o2.getTime();
-
-          //Fallthru to the primitive equality check
-        }
-
-        //Otherwise objects are not supported - recursing over arrays/object would be too expensive
-        else {
+          // Fallthru to the primitive equality check
+        } else {
+          // objects/arrays are not supported - deep-watching them would be too expensive
           return false;
         }
       }
@@ -1116,29 +1111,33 @@ function $ParseProvider() {
       var inputExpressions = parsedExpression.$$inputs ||
                     (parsedExpression.$$inputs = collectExpressionInputs(parsedExpression.inputs, []));
 
-      var inputs = [simpleEquals/*=something that will never equal an evaluated input*/];
       var lastResult;
 
-      if (1 === inputExpressions.length) {
-        inputs = inputs[0];
+      if (inputExpressions.length === 1) {
+        var oldInputValue = simpleEquals; // init to something unique so that equals check fails
         inputExpressions = inputExpressions[0];
         return scope.$watch(function expressionInputWatch(scope) {
-          var newVal = inputExpressions(scope);
-          if (!simpleEquals(newVal, inputs)) {
+          var newInputValue = inputExpressions(scope);
+          if (!simpleEquals(newInputValue, oldInputValue)) {
             lastResult = parsedExpression(scope);
-            inputs = newVal;
+            oldInputValue = newInputValue;
           }
           return lastResult;
         }, listener, objectEquality);
       }
 
+      var oldInputValues = [];
+      for (var i = 0, ii = inputExpressions.length; i < ii; i++) {
+        oldInputValues[i] = simpleEquals; // init to something unique so that equals check fails
+      }
+
       return scope.$watch(function expressionInputsWatch(scope) {
         var changed = false;
 
-        for (var i=0, ii=inputExpressions.length; i<ii; i++) {
-          var valI = inputExpressions[i](scope);
-          if (changed || (changed = !simpleEquals(valI, inputs[i]))) {
-            inputs[i] = valI;
+        for (var i = 0, ii = inputExpressions.length; i < ii; i++) {
+          var newInputValue = inputExpressions[i](scope);
+          if (changed || (changed = !simpleEquals(newInputValue, oldInputValues[i]))) {
+            oldInputValues[i] = newInputValue;
           }
         }