fix(transformer): Add getters for events.

closes https://github.com/angular/angular/issues/2725

modules/angular2/src/transform/bind_generator/generator.dart

@@ -9,22 +9,32 @@ import 'package:barback/barback.dart';
 
 import 'visitor.dart';
 
-Future<String> createNgSetters(AssetReader reader, AssetId entryPoint) async {
+Future<String> createNgSettersAndGetters(
+    AssetReader reader, AssetId entryPoint) async {
   NgDeps ngDeps = await NgDeps.parse(reader, entryPoint);
 
   String code = ngDeps.code;
-  var setters = _generateSetters(_createBindMap(ngDeps));
+  var setters = _generateSetters(_createPropertiesMap(ngDeps));
+  var getters = _generateGetters(_createEventsMap(ngDeps));
 
-  if (setters.length == 0) return code;
+  if (setters.isEmpty && getters.isEmpty) return code;
+  var out = new StringBuffer();
   var codeInjectIdx = ngDeps.registeredTypes.last.registerMethod.end;
-  return '${code.substring(0, codeInjectIdx)}'
-      '..registerSetters({${setters.join(', ')}})'
-      '${code.substring(codeInjectIdx)}';
+  out.write(code.substring(0, codeInjectIdx));
+  if (setters.isNotEmpty) {
+    out.write('..registerSetters({${setters.join(', ')}})');
+  }
+  if (getters.isNotEmpty) {
+    out.write('..registerGetters({${getters.join(', ')}})');
+  }
+  out.write(code.substring(codeInjectIdx));
+  return '$out';
 }
 
 // TODO(kegluneq): De-dupe from template_compiler/generator.dart.
 
-/// Consumes the map generated by {@link _createBindMap} to codegen setters.
+/// Consumes the map generated by {@link _createPropertiesMap} to codegen
+/// setters.
 List<String> _generateSetters(Map<String, String> bindMap) {
   var setters = [];
   // TODO(kegluneq): Include types for receivers. See #886.
@@ -43,8 +53,8 @@ List<String> _generateSetters(Map<String, String> bindMap) {
 /// Collapses all `properties` in {@link ngDeps} into a map where the keys are
 /// the bind properties and the values are either the one and only type
 /// binding to that property or the empty string.
-Map<String, String> _createBindMap(NgDeps ngDeps) {
-  var visitor = new ExtractSettersVisitor();
+Map<String, String> _createPropertiesMap(NgDeps ngDeps) {
+  var visitor = new ExtractNamedExpressionVisitor('properties');
   var bindMap = {};
   ngDeps.registeredTypes.forEach((RegisteredType t) {
     visitor.bindConfig.clear();
@@ -68,3 +78,37 @@ Map<String, String> _createBindMap(NgDeps ngDeps) {
   });
   return bindMap;
 }
+
+/// Consumes the map generated by {@link _createEventsMap} to codegen getters.
+List<String> _generateGetters(Map<String, String> bindMap) {
+  var getters = [];
+  // TODO(kegluneq): Include types for receivers. See #886.
+  bindMap.forEach((getterName, eventName) {
+    if (!prop.isValid(eventName)) {
+      // TODO(kegluenq): Eagerly throw here once #1295 is addressed.
+      getters.add(prop.lazyInvalidGetter(eventName));
+    } else {
+      getters.add(''' '${prop.sanitize(eventName)}': (o) => o.$getterName''');
+    }
+  });
+  return getters;
+}
+
+/// Collapses all `events` in {@link ngDeps} into a map where the keys are
+/// the property names for the event emitters and the values are the event name.
+Map<String, String> _createEventsMap(NgDeps ngDeps) {
+  var visitor = new ExtractNamedExpressionVisitor('events');
+  var bindMap = {};
+  ngDeps.registeredTypes.forEach((RegisteredType t) {
+    visitor.bindConfig.clear();
+    t.annotations.accept(visitor);
+    visitor.bindConfig.forEach((String config) {
+      // See comments for `Directive` in annotations_impl/annotations.ts for
+      // details on how `events` is specified.
+      var parts = config.split(':').map((p) => p.trim()).toList();
+      bindMap[parts[0]] = parts.length > 1 ? parts[1] : parts[0];
+    });
+  });
+  return bindMap;
+}
+

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

@@ -31,11 +31,11 @@ class BindGenerator extends Transformer {
     try {
       var id = transform.primaryInput.id;
       var reader = new AssetReader.fromTransform(transform);
-      var transformedCode = await createNgSetters(reader, id);
+      var transformedCode = await createNgSettersAndGetters(reader, id);
       transform.addOutput(new Asset.fromString(
           id, formatter.format(transformedCode, uri: id.path)));
     } catch (ex, stackTrace) {
-      log.logger.error('Creating ng setters failed.\n'
+      log.logger.error('Creating ng setters/getters failed.\n'
           'Exception: $ex\n'
           'Stack Trace: $stackTrace');
     }

modules/angular2/src/transform/bind_generator/visitor.dart

@@ -6,18 +6,22 @@ import 'package:angular2/src/transform/common/logging.dart';
 /// Visitor responsible for crawling the "annotations" value in a
 /// `registerType` call and pulling out the properties of any "bind"
 /// values found.
-class ExtractSettersVisitor extends Object with RecursiveAstVisitor<Object> {
+class ExtractNamedExpressionVisitor extends Object with
+    RecursiveAstVisitor<Object> {
   final ConstantEvaluator _evaluator = new ConstantEvaluator();
   final List<String> bindConfig = [];
+  final String nameToExtract;
+
+  ExtractNamedExpressionVisitor(this.nameToExtract);
 
   @override
   Object visitNamedExpression(NamedExpression node) {
-    if ('${node.name.label}' == 'properties') {
+    if ('${node.name.label}' == nameToExtract) {
       var evaluated = node.expression.accept(_evaluator);
       if (evaluated is List) {
         bindConfig.addAll(evaluated);
       } else {
-        logger.error('`properties` currently only supports List values');
+        logger.error('`$nameToExtract` currently only supports List values');
       }
       return null;
     }