feat(dart/transform): Add DirectiveMetadataExtractor transform step

Add a step that reads `DirectiveMetadata` object off annotated classes
into `.ng_meta.dart` files. These will be used by the `TemplateCompiler`
step as inputs to the Angular 2 render compiler.

Update one test to avoid unsupported functionality, format others.

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

@@ -1,9 +1,9 @@
-library angular2.transform.template_compiler.directive_metadata_reader;
+library angular2.transform.common.directive_metadata_reader;
 
 import 'package:analyzer/analyzer.dart';
 import 'package:angular2/src/render/api.dart';
-import 'package:angular2/src/transform/common/logging.dart';
-import 'package:angular2/src/transform/common/parser.dart';
+import 'logging.dart';
+import 'parser.dart';
 
 /// Reads [DirectiveMetadata] from the `attributes` of `t`.
 DirectiveMetadata readDirectiveMetadata(RegisteredType t) {

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

@@ -4,6 +4,7 @@ const SETUP_METHOD_NAME = 'initReflector';
 const REFLECTOR_VAR_NAME = 'reflector';
 const TRANSFORM_DYNAMIC_MODE = 'transform_dynamic';
 const DEPS_EXTENSION = '.ng_deps.dart';
+const META_EXTENSION = '.ng_meta.dart';
 const REFLECTION_CAPABILITIES_NAME = 'ReflectionCapabilities';
 const REGISTER_TYPE_METHOD_NAME = 'registerType';
 const REGISTER_GETTERS_METHOD_NAME = 'registerGetters';

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

@@ -0,0 +1,28 @@
+library angular2.transform.directive_metadata_extractor.extractor;
+
+import 'dart:async';
+
+import 'package:angular2/src/render/api.dart';
+import 'package:angular2/src/transform/common/asset_reader.dart';
+import 'package:angular2/src/transform/common/directive_metadata_reader.dart';
+import 'package:angular2/src/transform/common/parser.dart';
+import 'package:barback/barback.dart';
+
+/// Returns a map from a class name (that is, its `Identifier` stringified)
+/// to its [DirectiveMetadata].
+/// Will return `null` if there are no `Directive`-annotated classes in
+/// `entryPoint`.
+Future<Map<String, DirectiveMetadata>> extractDirectiveMetadata(
+    AssetReader reader, AssetId entryPoint) async {
+  var parser = new Parser(reader);
+  NgDeps ngDeps = await parser.parse(entryPoint);
+  if (ngDeps == null || ngDeps.registeredTypes.isEmpty) return null;
+  var retVal = <String, DirectiveMetadata>{};
+  ngDeps.registeredTypes.forEach((rType) {
+    var meta = readDirectiveMetadata(rType);
+    if (meta != null) {
+      retVal['${rType.typeName}'] = meta;
+    }
+  });
+  return retVal;
+}

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

@@ -0,0 +1,56 @@
+library angular2.transform.directive_metadata_extractor.transformer;
+
+import 'dart:async';
+import 'dart:convert';
+
+import 'package:angular2/src/render/dom/convert.dart';
+import 'package:angular2/src/transform/common/asset_reader.dart';
+import 'package:angular2/src/transform/common/logging.dart' as log;
+import 'package:angular2/src/transform/common/names.dart';
+import 'package:barback/barback.dart';
+
+import 'extractor.dart';
+
+/// Transformer responsible for processing .ng_deps.dart files created by
+/// {@link DirectiveProcessor} and creating associated `.ng_meta.dart` files.
+/// These files contain commented Json-formatted representations of all
+/// `Directive`s in the associated file.
+class DirectiveMetadataExtractor extends Transformer {
+  DirectiveMetadataExtractor();
+
+  @override
+  bool isPrimary(AssetId id) => id.path.endsWith(DEPS_EXTENSION);
+
+  @override
+  Future apply(Transform transform) async {
+    log.init(transform);
+
+    try {
+      var reader = new AssetReader.fromTransform(transform);
+      var fromAssetId = transform.primaryInput.id;
+
+      var metadataMap = await extractDirectiveMetadata(reader, fromAssetId);
+      if (metadataMap != null) {
+        var jsonMap = <String, Map>{};
+        metadataMap.forEach((k, v) {
+          jsonMap[k] = directiveMetadataToMap(v);
+        });
+        transform.addOutput(new Asset.fromString(
+            _outputAssetId(fromAssetId), '// ${JSON.encode(jsonMap)}'));
+      }
+    } catch (ex, stackTrace) {
+      log.logger.error('Extracting ng metadata failed.\n'
+          'Exception: $ex\n'
+          'Stack Trace: $stackTrace');
+    }
+    return null;
+  }
+}
+
+AssetId _outputAssetId(AssetId inputAssetId) {
+  assert(inputAssetId.path.endsWith(DEPS_EXTENSION));
+  var pathIn = inputAssetId.path;
+  return new AssetId(inputAssetId.package,
+      '${pathIn.substring(0, pathIn.length - DEPS_EXTENSION.length)}'
+      '${META_EXTENSION}');
+}

modules/angular2/src/transform/transformer.dart

@@ -4,6 +4,7 @@ import 'package:barback/barback.dart';
 import 'package:dart_style/dart_style.dart';
 
 import 'directive_linker/transformer.dart';
+import 'directive_metadata_extractor/transformer.dart';
 import 'directive_processor/transformer.dart';
 import 'bind_generator/transformer.dart';
 import 'reflection_remover/transformer.dart';
@@ -24,7 +25,7 @@ class AngularTransformerGroup extends TransformerGroup {
     var phases = [
       [new ReflectionRemover(options)],
       [new DirectiveProcessor(options)],
-      [new DirectiveLinker()],
+      [new DirectiveLinker(), new DirectiveMetadataExtractor()],
       [new BindGenerator(options)],
       [new TemplateCompiler(options)]
     ];