fix($parse): do not shallow-watch inputs when wrapped in an interceptor fn

Fixes angular#15905

Author: jbedard

src/ng/parse.js

@@ -622,6 +622,9 @@ function isStateless($filter, filterName) {
   return !fn.$stateful;
 }
 
+var PURITY_ABSOLUTE = 1;
+var PURITY_RELATIVE = 2;
+
 // Detect nodes which could depend on non-shallow state of objects
 function isPure(node, parentIsPure) {
   switch (node.type) {
@@ -634,18 +637,18 @@ function isPure(node, parentIsPure) {
 
     // Unary always convert to primative
     case AST.UnaryExpression:
-      return true;
+      return PURITY_ABSOLUTE;
 
     // The binary + operator can invoke a stateful toString().
     case AST.BinaryExpression:
-      return node.operator !== '+';
+      return node.operator !== '+' ? PURITY_ABSOLUTE : false;
 
     // Functions / filters probably read state from within objects
     case AST.CallExpression:
       return false;
   }
 
-  return (undefined === parentIsPure) || parentIsPure;
+  return (undefined === parentIsPure) ? PURITY_RELATIVE : parentIsPure;
 }
 
 function findConstantAndWatchExpressions(ast, $filter, parentIsPure) {
@@ -873,7 +876,7 @@ ASTCompiler.prototype = {
     forEach(inputs, function(input) {
       result.push('var ' + input.name + '=' + self.generateFunction(input.name, 's'));
       if (input.isPure) {
-        result.push(input.name, '.isPure=true;');
+        result.push(input.name, '.isPure=' + JSON.stringify(input.isPure) + ';');
       }
     });
     if (inputs.length) {
@@ -1963,7 +1966,14 @@ function $ParseProvider() {
         // If there is an interceptor, but no watchDelegate then treat the interceptor like
         // we treat filters - it is assumed to be a pure function unless flagged with $stateful
         fn.$$watchDelegate = inputsWatchDelegate;
-        fn.inputs = parsedExpression.inputs ? parsedExpression.inputs : [parsedExpression];
+        fn.inputs = (parsedExpression.inputs ? parsedExpression.inputs : [parsedExpression]).map(function(e) {
+              // Remove the isPure flag of inputs when it is not absolute because they are now wrapped in a
+              // potentially non-pure interceptor function.
+              if (e.isPure === PURITY_RELATIVE) {
+                return function depurifier(s) { return e(s); };
+              }
+              return e;
+            });
       }
 
       return fn;

test/ng/directive/ngClassSpec.js

@@ -517,6 +517,22 @@ describe('ngClass', function() {
     })
   );
 
+  // https://github.com/angular/angular.js/issues/15905
+  it('should support a mixed literal-array/object variable', inject(function($rootScope, $compile) {
+      element = $compile('<div ng-class="[classVar]"></div>')($rootScope);
+
+      $rootScope.classVar = {orange: true};
+      $rootScope.$digest();
+      expect(element).toHaveClass('orange');
+
+      $rootScope.classVar.orange = false;
+      $rootScope.$digest();
+
+      expect(element).not.toHaveClass('orange');
+    })
+  );
+
+
   it('should do value stabilization as expected when one-time binding',
     inject(function($rootScope, $compile) {
       element = $compile('<div ng-class="::className"></div>')($rootScope);
@@ -629,7 +645,7 @@ describe('ngClass', function() {
     }));
 
     it('should not be copied when using one-time binding', inject(function($compile, $rootScope) {
-      element = $compile('<div ng-class="::{foo: veryLargeObj, bar: bar}"></div>')($rootScope);
+      element = $compile('<div ng-class="::{foo: !!veryLargeObj, bar: bar}"></div>')($rootScope);
       $rootScope.veryLargeObj = veryLargeObj;
       $rootScope.$digest();
 

test/ng/parseSpec.js

@@ -3277,6 +3277,25 @@ describe('parser', function() {
             expect(called).toBe(true);
           }));
 
+          it('should always be invoked if inputs are non-primitive', inject(function($parse) {
+            var called = false;
+            function interceptor(v) {
+              called = true;
+              return v.sub;
+            }
+
+            scope.$watch($parse("[o]", interceptor));
+            scope.o = {sub: 1};
+
+            called = false;
+            scope.$digest();
+            expect(called).toBe(true);
+
+            called = false;
+            scope.$digest();
+            expect(called).toBe(true);
+          }));
+
           it('should not be invoked unless the input.valueOf() changes even if the instance changes', inject(function($parse) {
             var called = false;
             function interceptor(v) {