[WIP] fix(parser): Allow access to Map properties in expressions

- E.g. `map.keys`, `map.length`, etc. This is a proposed solution to
dart-archive#394.
- Add support for the watching of map properties whose types are
primitive (not collections). Work still needs to be done for map.keys
and map.values.

Author: chalin

bin/parser_generator_for_spec.dart

@@ -101,6 +101,11 @@ main(arguments) {
       'items[1].name',
       'list[3] = 2',
       'map["square"] = 6',
+      'map.isEmpty',
+      'map.isNotEmpty',
+      'map.keys',
+      'map.length',
+      'map.values',
       'method',
       'method()',
       'notAFn()',

lib/change_detection/dirty_checking_change_detector.dart

@@ -3,6 +3,7 @@ library dirty_checking_change_detector;
 import 'dart:mirrors';
 import 'dart:collection';
 import 'package:angular/change_detection/change_detection.dart';
+import 'package:angular/core/parser/utils.dart' show isMapProperty;
 
 typedef FieldGetter(object);
 
@@ -424,7 +425,9 @@ class DirtyCheckingRecord<H> implements Record<H>, WatchRecord<H> {
       return;
     }
 
-    if (obj is Map) {
+    if (obj is Map && (!isMapProperty(field)
+        || field == "values") // TODO: seems to be treated specially re. NgForm
+        ) {
       _mode =  _MODE_MAP_FIELD_;
       _instanceMirror = null;
     } else if (_getter != null) {

lib/core/parser/eval_access.dart

@@ -80,7 +80,7 @@ abstract class AccessReflective {
     if (holder == null) {
       _cachedKind = CACHED_VALUE;
       return _cachedValue = null;
-    } else if (holder is Map) {
+    } else if (holder is Map && !isMapProperty(name)) {
       _cachedKind = CACHED_MAP;
       _cachedValue = null;
       return holder[name];
@@ -164,7 +164,7 @@ abstract class AccessFast {
 
   _eval(holder) {
     if (holder == null) return null;
-    return (holder is Map) ? holder[name] : getter(holder);
+    return (holder is Map && !isMapProperty(name)) ? holder[name] : getter(holder);
   }
 
   _assign(scope, holder, value) {

lib/core/parser/utils.dart

@@ -103,3 +103,13 @@ setKeyed(object, key, value) {
 Symbol newSymbol(String name) {
   return isReservedWord(name) ? null : new Symbol(name);
 }
+
+final Set<String> _MAP_PROPERTIES = new Set<String>.from([
+  "hashCode", // any reason to exclude this?
+  "isEmpty",
+  "isNotEmpty",
+  "keys",
+  "length",
+  "runtimeType", // any reason to exclude this?
+  "values"]);
+bool isMapProperty(String key) => _MAP_PROPERTIES.contains(key);

lib/tools/parser_generator/dart_code_gen.dart

@@ -2,6 +2,7 @@ library dart_code_gen;
 
 import 'package:angular/utils.dart' show isReservedWord;
 import 'package:angular/core/parser/syntax.dart';
+import 'package:angular/core/parser/utils.dart';
 
 escape(String s) => s.replaceAllMapped(new RegExp(r'(\"|\$|\n)'), (m) {
   var char = m[1];
@@ -11,7 +12,7 @@ escape(String s) => s.replaceAllMapped(new RegExp(r'(\"|\$|\n)'), (m) {
 
 class DartCodeGen {
   final HelperMap getters = new HelperMap('_',
-      getterTemplate, getterTemplateForReserved);
+      getterTemplate, getterTemplateForReserved, getterTemplateWithoutMapTest);
   final HelperMap holders = new HelperMap('_ensure\$',
       holderTemplate, holderTemplateForReserved);
   final HelperMap setters = new HelperMap('_set\$',
@@ -226,14 +227,17 @@ class HelperMap {
   final String prefix;
   final Function template;
   final Function templateForReserved;
+  final Function templateWithoutMapTest;
 
-  HelperMap(this.prefix, this.template, this.templateForReserved);
+  HelperMap(this.prefix, this.template, this.templateForReserved, [this.templateWithoutMapTest]);
 
   String lookup(String key) {
     String name = _computeName(key);
     if (helpers.containsKey(key)) return name;
     helpers[key] = isReservedWord(key)
         ? templateForReserved(name, key)
+        : isMapProperty(key) && templateWithoutMapTest != null
+          ? templateWithoutMapTest(name, key)
         : template(name, key);
     return name;
   }
@@ -264,6 +268,9 @@ $name(o) {
 }
 """;
 
+String getterTemplateWithoutMapTest(String name, String key) => """
+$name(o) => o == null ? null : o.$key;
+""";
 
 // ------------------------------------------------------------------
 // Templates for generated holders (getters for assignment).

test/core/parser/parser_spec.dart

@@ -743,6 +743,16 @@ main() {
       });
 
 
+      it('should evaluate map item and field access', () {
+        context['map'] = { 'a': 1.1, 'b': 'B' };
+        expect(eval("map.isEmpty")).toEqual(false);
+        expect(eval("map.isNotEmpty")).toEqual(true);
+        expect(eval("map.keys")).toEqual(['a', 'b']);
+        expect(eval("map.length")).toEqual(2);
+        expect(eval("map.values")).toEqual([1.1, 'B']);
+      });
+
+
       it('should evaluate JSON', () {
         expect(eval("[{}]")).toEqual([{}]);
         expect(eval("[{a:[]}, {b:1}]")).toEqual([{"a":[]},{"b":1}]);

test/core/scope_spec.dart

@@ -48,6 +48,23 @@ void main() {
         expect(logger).toEqual(['AB', '123', 'XYZ']);
       }));
 
+      it('should watch map property of a primitive type', inject((Logger logger, Map context, RootScope rootScope) {
+        context['a'] =  {'b': 'AB', 'lengthx' : 2};
+        rootScope.watch('a.length', (value, previous) => logger(value));
+        rootScope.watch('a.isEmpty', (value, previous) => logger(value));
+        rootScope.watch('a.isNotEmpty', (value, previous) => logger(value));
+        rootScope.digest();
+        expect(logger).toEqual([2, false, true]);
+        context['a']['c'] = '123';
+        logger.clear();
+        rootScope.digest();
+        expect(logger).toEqual([3]);
+        context['a'] = {};
+        logger.clear();
+        rootScope.digest();
+        expect(logger).toEqual([0, true, false]);
+      }));
+
       it('should watch math operations', inject((Logger logger, Map context, RootScope rootScope) {
         context['a'] = 1;
         context['b'] = 2;