refactor(change_detection): introduce enum ChangeDetectionStrategy

BREAKING CHANGE

Closes #2497

- change detection strategy type changes from string to ChangeDetectionStrategy
- CHECK_ONCE => ChangeDetectionStrategy.CheckOnce
- CHECKED => ChangeDetectionStrategy.Checked
- CHECK_ALWAYS => ChangeDetectionStrategy.CheckAlways
- DETACHED => ChangeDetectionStrategy.Detached
- ON_PUSH => ChangeDetectionStrategy.OnPush
- DEFAULT => ChangeDetectionStrategy.Default
- ON_PUSH_OBSERVE => ChangeDetectionStrategy.OnPushObserve

modules_dart/transform/lib/src/transform/common/convert.dart

@@ -0,0 +1,71 @@
+library angular2.transform.common.convert;
+
+import "package:angular2/src/core/facade/collection.dart"
+    show ListWrapper, MapWrapper;
+import "package:angular2/src/core/facade/lang.dart" show isPresent, isArray;
+import "package:angular2/src/core/render/api.dart" show RenderDirectiveMetadata;
+import "package:angular2/src/core/change_detection/change_detection.dart"
+    show ChangeDetectionStrategy;
+
+/**
+ * Converts a [DirectiveMetadata] to a map representation. This creates a copy,
+ * that is, subsequent changes to `meta` will not be mirrored in the map.
+ */
+Map<String, dynamic> directiveMetadataToMap(RenderDirectiveMetadata meta) {
+  return MapWrapper.createFromPairs([
+    ["id", meta.id],
+    ["selector", meta.selector],
+    ["compileChildren", meta.compileChildren],
+    ["hostProperties", _cloneIfPresent(meta.hostProperties)],
+    ["hostListeners", _cloneIfPresent(meta.hostListeners)],
+    ["hostAttributes", _cloneIfPresent(meta.hostAttributes)],
+    ["properties", _cloneIfPresent(meta.properties)],
+    ["readAttributes", _cloneIfPresent(meta.readAttributes)],
+    ["type", meta.type],
+    ["exportAs", meta.exportAs],
+    ["callOnDestroy", meta.callOnDestroy],
+    ["callOnCheck", meta.callOnCheck],
+    ["callOnInit", meta.callOnInit],
+    ["callOnChange", meta.callOnChange],
+    ["callOnAllChangesDone", meta.callOnAllChangesDone],
+    ["events", meta.events],
+    ["changeDetection", meta.changeDetection == null ? null : meta.changeDetection.index],
+    ["version", 1]
+  ]);
+}
+/**
+ * Converts a map representation of [DirectiveMetadata] into a
+ * [DirectiveMetadata] object. This creates a copy, that is, subsequent changes
+ * to `map` will not be mirrored in the [DirectiveMetadata] object.
+ */
+RenderDirectiveMetadata directiveMetadataFromMap(Map<String, dynamic> map) {
+  return new RenderDirectiveMetadata(
+      id: (map["id"] as String),
+      selector: (map["selector"] as String),
+      compileChildren: (map["compileChildren"] as bool),
+      hostProperties: (_cloneIfPresent(
+          map["hostProperties"]) as Map<String, String>),
+      hostListeners: (_cloneIfPresent(
+          map["hostListeners"]) as Map<String, String>),
+      hostAttributes: (_cloneIfPresent(
+          map["hostAttributes"]) as Map<String, String>),
+      properties: (_cloneIfPresent(map["properties"]) as List<String>),
+      readAttributes: (_cloneIfPresent(map["readAttributes"]) as List<String>),
+      type: (map["type"] as num),
+      exportAs: (map["exportAs"] as String),
+      callOnDestroy: (map["callOnDestroy"] as bool),
+      callOnCheck: (map["callOnCheck"] as bool),
+      callOnChange: (map["callOnChange"] as bool),
+      callOnInit: (map["callOnInit"] as bool),
+      callOnAllChangesDone: (map["callOnAllChangesDone"] as bool),
+      events: (_cloneIfPresent(map["events"]) as List<String>),
+      changeDetection: map["changeDetection"] == null ? null
+          : ChangeDetectionStrategy.values[map["changeDetection"] as int]);
+}
+/**
+ * Clones the [List] or [Map] `o` if it is present.
+ */
+dynamic _cloneIfPresent(o) {
+  if (!isPresent(o)) return null;
+  return isArray(o) ? ListWrapper.clone(o) : MapWrapper.clone(o);
+}

modules_dart/transform/lib/src/transform/common/directive_metadata_reader.dart

@@ -3,6 +3,7 @@ library angular2.transform.common.directive_metadata_reader;
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/src/generated/element.dart';
 import 'package:angular2/src/core/render/api.dart';
+import 'package:angular2/src/core/change_detection/change_detection.dart';
 
 /// Reads [RenderDirectiveMetadata] from the `node`. `node` is expected to be an
 /// instance of [Annotation], [NodeList<Annotation>], ListLiteral, or
@@ -63,7 +64,7 @@ class _DirectiveMetadataVisitor extends Object
   bool _callOnCheck;
   bool _callOnInit;
   bool _callOnAllChangesDone;
-  String _changeDetection;
+  ChangeDetectionStrategy _changeDetection;
   List<String> _events;
 
   final ConstantEvaluator _evaluator = new ConstantEvaluator();
@@ -283,6 +284,9 @@ class _DirectiveMetadataVisitor extends Object
 
   void _populateChangeDetection(Expression value) {
     _checkMeta();
-    _changeDetection = _expressionToString(value, 'Directive#changeDetection');
+    _changeDetection = changeDetectionStrategies[value.toSource()];
   }
 }
+
+final Map<String, ChangeDetectionStrategy> changeDetectionStrategies
+  = new Map.fromIterable(ChangeDetectionStrategy.values, key: (v) => v.toString());

modules_dart/transform/lib/src/transform/common/ng_meta.dart

@@ -1,7 +1,7 @@
 library angular2.transform.common.ng_meta;
 
 import 'package:angular2/src/core/render/api.dart';
-import 'package:angular2/src/core/render/dom/convert.dart';
+import 'convert.dart';
 import 'logging.dart';
 
 /// Metadata about directives and directive aliases.

modules_dart/transform/lib/src/transform/template_compiler/change_detector_codegen.dart

@@ -1,5 +1,6 @@
 library angular2.transform.template_compiler.change_detector_codegen;
 
+import 'package:angular2/src/core/change_detection/change_detection.dart';
 import 'package:angular2/src/core/change_detection/change_detection_util.dart';
 import 'package:angular2/src/core/change_detection/codegen_facade.dart';
 import 'package:angular2/src/core/change_detection/codegen_logic_util.dart';
@@ -75,7 +76,7 @@ class _CodegenState {
   /// The name of the generated change detector class. This is an implementation
   /// detail and should not be visible to users.
   final String _changeDetectorTypeName;
-  final String _changeDetectionStrategy;
+  final ChangeDetectionStrategy _changeDetectionStrategy;
   final List<DirectiveRecord> _directiveRecords;
   final List<ProtoRecord> _records;
   final List<EventBinding> _eventBindings;
@@ -84,6 +85,9 @@ class _CodegenState {
   final ChangeDetectorGenConfig _genConfig;
   final List<BindingTarget> _propertyBindingTargets;
 
+  String get _changeDetectionStrategyAsCode =>
+    _changeDetectionStrategy == null ? 'null' : '${_GEN_PREFIX}.${_changeDetectionStrategy}';
+
   _CodegenState._(
       this._changeDetectorDefId,
       this._contextTypeName,
@@ -129,7 +133,7 @@ class _CodegenState {
               dispatcher, ${_records.length},
               ${_changeDetectorTypeName}.gen_propertyBindingTargets,
               ${_changeDetectorTypeName}.gen_directiveIndices,
-              ${codify(_changeDetectionStrategy)}) {
+              ${_changeDetectionStrategyAsCode}) {
           dehydrateDirectives(false);
         }