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

@@ -0,0 +1,155 @@
+library angular2.transform.common.directive_metadata_reader;
+
+import 'package:analyzer/analyzer.dart';
+import 'package:angular2/src/render/api.dart';
+import 'logging.dart';
+import 'parser.dart';
+
+/// Reads [DirectiveMetadata] from the `attributes` of `t`.
+DirectiveMetadata readDirectiveMetadata(RegisteredType t) {
+  var visitor = new _DirectiveMetadataVisitor();
+  t.annotations.accept(visitor);
+  return visitor.meta;
+}
+
+num _getDirectiveType(String annotationName) {
+  // TODO(kegluneq): Detect subtypes & implementations of `Directive`s.
+  switch (annotationName) {
+    case 'Directive':
+      return DirectiveMetadata.DIRECTIVE_TYPE;
+    case 'Component':
+      return DirectiveMetadata.COMPONENT_TYPE;
+    default:
+      return -1;
+  }
+}
+
+/// Visitor responsible for processing the `annotations` property of a
+/// [RegisterType] object and pulling out [DirectiveMetadata].
+class _DirectiveMetadataVisitor extends Object
+    with RecursiveAstVisitor<Object> {
+  DirectiveMetadata meta;
+
+  @override
+  Object visitInstanceCreationExpression(InstanceCreationExpression node) {
+    var directiveType = _getDirectiveType('${node.constructorName.type.name}');
+    if (directiveType >= 0) {
+      if (meta != null) {
+        logger.error('Only one Directive is allowed per class. '
+            'Found "$node" but already processed "$meta".');
+      }
+      meta = new DirectiveMetadata(
+          type: directiveType,
+          compileChildren: false,
+          properties: {},
+          hostListeners: {},
+          hostProperties: {},
+          readAttributes: []);
+      super.visitInstanceCreationExpression(node);
+    }
+    // Annotation we do not recognize - no need to visit.
+    return null;
+  }
+
+  @override
+  Object visitNamedExpression(NamedExpression node) {
+    // TODO(kegluneq): Remove this limitation.
+    if (node.name is! Label || node.name.label is! SimpleIdentifier) {
+      logger.error(
+          'Angular 2 currently only supports simple identifiers in directives.'
+          ' Source: ${node}');
+      return null;
+    }
+    var keyString = '${node.name.label}';
+    // TODO(kegluneq): Populate the other values in [DirectiveMetadata] once
+    // they are specified as `hostAttributes` and `hostSetters`.
+    // See [https://github.com/angular/angular/issues/1244]
+    switch (keyString) {
+      case 'selector':
+        _populateSelector(node.expression);
+        break;
+      case 'compileChildren':
+        _populateCompileChildren(node.expression);
+        break;
+      case 'properties':
+        _populateProperties(node.expression);
+        break;
+      case 'hostProperties':
+        _populateHostProperties(node.expression);
+        break;
+      case 'hostListeners':
+        _populateHostListeners(node.expression);
+    }
+    return null;
+  }
+
+  String _expressionToString(Expression node, String nodeDescription) {
+    // TODO(kegluneq): Accept more options.
+    if (node is! SimpleStringLiteral) {
+      logger.error('Angular 2 currently only supports string literals '
+          'in $nodeDescription. Source: ${node}');
+      return null;
+    }
+    return stringLiteralToString(node);
+  }
+
+  void _populateSelector(Expression selectorValue) {
+    meta.selector = _expressionToString(selectorValue, 'Directive#selector');
+  }
+
+  void _populateCompileChildren(Expression compileChildrenValue) {
+    if (compileChildrenValue is! BooleanLiteral) {
+      logger.error(
+          'Angular 2 currently only supports boolean literal values for '
+          'Directive#compileChildren.'
+          ' Source: ${compileChildrenValue}');
+      return;
+    }
+    meta.compileChildren = (compileChildrenValue as BooleanLiteral).value;
+  }
+
+  void _populateProperties(Expression propertiesValue) {
+    if (propertiesValue is! MapLiteral) {
+      logger.error('Angular 2 currently only supports map literal values for '
+          'Directive#properties.'
+          ' Source: ${propertiesValue}');
+      return;
+    }
+    for (MapLiteralEntry entry in (propertiesValue as MapLiteral).entries) {
+      var sKey = _expressionToString(entry.key, 'Directive#properties keys');
+      var sVal = _expressionToString(entry.value, 'Direcive#properties values');
+      meta.properties[sKey] = sVal;
+    }
+  }
+
+  void _populateHostListeners(Expression hostListenersValue) {
+    if (hostListenersValue is! MapLiteral) {
+      logger.error('Angular 2 currently only supports map literal values for '
+          'Directive#hostListeners.'
+          ' Source: ${hostListenersValue}');
+      return;
+    }
+    for (MapLiteralEntry entry in (hostListenersValue as MapLiteral).entries) {
+      var sKey = _expressionToString(entry.key, 'Directive#hostListeners keys');
+      var sVal =
+          _expressionToString(entry.value, 'Directive#hostListeners values');
+      meta.hostListeners[sKey] = sVal;
+    }
+  }
+
+  void _populateHostProperties(Expression hostPropertyValue) {
+    if (hostPropertyValue is! MapLiteral) {
+      logger.error('Angular 2 currently only supports map literal values for '
+          'Directive#hostProperties.'
+          ' Source: ${hostPropertyValue}');
+      return;
+    }
+    for (MapLiteralEntry entry in (hostPropertyValue as MapLiteral).entries) {
+      var sKey =
+          _expressionToString(entry.key, 'Directive#hostProperties keys');
+      var sVal =
+          _expressionToString(entry.value, 'Directive#hostProperties values');
+      meta.hostProperties[sKey] = sVal;
+    }
+  }
+}

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';