fix(dart/transform): Handle `hostAttributes` in DirectiveMetadata

Handle `hostAttributes` in the transformer.
`hostAttributes` was introduced in 51839ca677

Closes #1742

modules/angular2/src/transform/common/directive_metadata_reader.dart

@@ -47,6 +47,7 @@ class _DirectiveMetadataVisitor extends Object
           properties: {},
           hostListeners: {},
           hostProperties: {},
+          hostAttributes: {},
           readAttributes: []);
       super.visitInstanceCreationExpression(node);
     }
@@ -80,6 +81,9 @@ class _DirectiveMetadataVisitor extends Object
       case 'hostProperties':
         _populateHostProperties(node.expression);
         break;
+      case 'hostAttributes':
+        _populateHostAttributes(node.expression);
+        break;
       case 'hostListeners':
         _populateHostListeners(node.expression);
     }
@@ -155,4 +159,20 @@ class _DirectiveMetadataVisitor extends Object
       meta.hostProperties[sKey] = sVal;
     }
   }
+
+  void _populateHostAttributes(Expression hostAttributeValue) {
+    if (hostAttributeValue is! MapLiteral) {
+      logger.error('Angular 2 currently only supports map literal values for '
+          'Directive#hostAttributes.'
+          ' Source: ${hostAttributeValue}');
+      return;
+    }
+    for (MapLiteralEntry entry in (hostAttributeValue as MapLiteral).entries) {
+      var sKey =
+          _expressionToString(entry.key, 'Directive#hostAttributes keys');
+      var sVal =
+          _expressionToString(entry.value, 'Directive#hostAttributes values');
+      meta.hostAttributes[sKey] = sVal;
+    }
+  }
 }

modules/angular2/src/transform/directive_metadata_extractor/transformer.dart

@@ -16,6 +16,8 @@ import 'extractor.dart';
 /// These files contain commented Json-formatted representations of all
 /// `Directive`s in the associated file.
 class DirectiveMetadataExtractor extends Transformer {
+  final _encoder = const JsonEncoder.withIndent('  ');
+
   DirectiveMetadataExtractor();
 
   @override
@@ -36,7 +38,7 @@ class DirectiveMetadataExtractor extends Transformer {
           jsonMap[k] = directiveMetadataToMap(v);
         });
         transform.addOutput(new Asset.fromString(
-            _outputAssetId(fromAssetId), JSON.encode(jsonMap)));
+            _outputAssetId(fromAssetId), _encoder.convert(jsonMap)));
       }
     } catch (ex, stackTrace) {
       log.logger.error('Extracting ng metadata failed.\n'

modules/angular2/src/transform/template_compiler/view_definition_creator.dart

@@ -29,6 +29,10 @@ class ViewDefinitionResults {
 String _getComponentId(AssetId assetId, String className) =>
     '$assetId:$className';
 
+// TODO(kegluenq): Improve this test.
+bool _isViewAnnotation(InstanceCreationExpression node) =>
+    '${node.constructorName.type}' == 'View';
+
 /// Creates [ViewDefinition] objects for all `View` `Directive`s defined in
 /// `entryPoint`.
 class _ViewDefinitionCreator {
@@ -108,8 +112,9 @@ class _ViewDefinitionCreator {
   /// ```
   ///
   /// This method will look for `component.ng_meta.json`to contain the
-  /// serialized [DirectiveMetadata] `MyComponent` and any other `Directive`s
-  /// declared in `component.dart`. We use this information to build a map:
+  /// serialized [DirectiveMetadata] for `MyComponent` and any other
+  /// `Directive`s declared in `component.dart`. We use this information to
+  /// build a map:
   ///
   /// ```
   /// {
@@ -146,7 +151,7 @@ class _ViewDefinitionCreator {
 }
 
 /// Visitor responsible for processing the `annotations` property of a
-/// {@link RegisterType} object and pulling out [ViewDefinition] information.
+/// [RegisterType] object and pulling out [ViewDefinition] information.
 class _TemplateExtractVisitor extends Object with RecursiveAstVisitor<Object> {
   ViewDefinition viewDef = null;
   final Map<String, DirectiveMetadata> _metadataMap;
@@ -160,7 +165,7 @@ class _TemplateExtractVisitor extends Object with RecursiveAstVisitor<Object> {
   /// These correspond to the annotations themselves.
   @override
   Object visitInstanceCreationExpression(InstanceCreationExpression node) {
-    if ('${node.constructorName.type}' == 'View') {
+    if (_isViewAnnotation(node)) {
       viewDef = new ViewDefinition(directives: <DirectiveMetadata>[]);
       node.visitChildren(this);
     }
@@ -182,6 +187,10 @@ class _TemplateExtractVisitor extends Object with RecursiveAstVisitor<Object> {
       _readDirectives(node.expression);
     }
     if (keyString == 'template' || keyString == 'templateUrl') {
+      // This could happen in a non-View annotation with a `template` or
+      // `templateUrl` property.
+      if (viewDef == null) return null;
+
       if (node.expression is! SimpleStringLiteral) {
         logger.error(
             'Angular 2 currently only supports string literals in directives.'
@@ -207,6 +216,10 @@ class _TemplateExtractVisitor extends Object with RecursiveAstVisitor<Object> {
   }
 
   void _readDirectives(Expression node) {
+    // This could happen in a non-View annotation with a `directives`
+    // parameter.
+    if (viewDef == null) return;
+
     if (node is! ListLiteral) {
       logger.error(
           'Angular 2 currently only supports list literals as values for'

modules/angular2/test/transform/integration/simple_annotation_files/expected/bar.ng_meta.json

@@ -1 +1,14 @@
-{"MyComponent":{"id":"MyComponent","selector":"[soup]","compileChildren":true,"hostListeners":{},"hostProperties":{},"properties":{},"readAttributes":[],"type":1,"version":1}}
+{
+  "MyComponent": {
+    "id": "MyComponent",
+    "selector": "[soup]",
+    "compileChildren": true,
+    "hostListeners": {},
+    "hostProperties": {},
+    "hostAttributes": {},
+    "properties": {},
+    "readAttributes": [],
+    "type": 1,
+    "version": 1
+  }
+}