feat(dart/transform): Remove unnecessary .ng_deps.dart files

Removes `.ng_deps.dart` files which

1. Do not register any `@Injectable` classes
2. Do not call `initReflector` on any other `.ng_deps.dart` files.

Closes #1929

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

@@ -3,9 +3,13 @@ library angular2.transform.common.options;
 import 'annotation_matcher.dart';
 import 'mirror_mode.dart';
 
-const ENTRY_POINT_PARAM = 'entry_points';
-const REFLECTION_ENTRY_POINT_PARAM = 'reflection_entry_points';
+/// See `optimizationPhases` below for an explanation.
+const DEFAULT_OPTIMIZATION_PHASES = 5;
+
 const CUSTOM_ANNOTATIONS_PARAM = 'custom_annotations';
+const ENTRY_POINT_PARAM = 'entry_points';
+const OPTIMIZATION_PHASES_PARAM = 'optimization_phases';
+const REFLECTION_ENTRY_POINT_PARAM = 'reflection_entry_points';
 
 /// Provides information necessary to transform an Angular2 app.
 class TransformerOptions {
@@ -28,20 +32,32 @@ class TransformerOptions {
   /// The [AnnotationMatcher] which is used to identify angular annotations.
   final AnnotationMatcher annotationMatcher;
 
+  /// The number of phases to spend optimizing output size.
+  /// Each additional phase adds time to the transformation but may decrease
+  /// final output size. There is a limit beyond which this will no longer
+  /// decrease size, that is, setting this to 20 may not decrease size any
+  /// more than setting it to 10, but you will still pay an additional
+  /// penalty in transformation time.
+  /// The "correct" number of phases varies with the structure of the app.
+  final int optimizationPhases;
+
   TransformerOptions._internal(this.entryPoints, this.reflectionEntryPoints,
       this.modeName, this.mirrorMode, this.initReflector,
-      this.annotationMatcher);
+      this.annotationMatcher, this.optimizationPhases);
 
   factory TransformerOptions(List<String> entryPoints,
       {List<String> reflectionEntryPoints, String modeName: 'release',
       MirrorMode mirrorMode: MirrorMode.none, bool initReflector: true,
-      List<AnnotationDescriptor> customAnnotationDescriptors: const []}) {
+      List<AnnotationDescriptor> customAnnotationDescriptors: const [],
+      int optimizationPhases: DEFAULT_OPTIMIZATION_PHASES}) {
     if (reflectionEntryPoints == null || reflectionEntryPoints.isEmpty) {
       reflectionEntryPoints = entryPoints;
     }
     var annotationMatcher = new AnnotationMatcher()
       ..addAll(customAnnotationDescriptors);
+    optimizationPhases = optimizationPhases.isNegative ? 0 : optimizationPhases;
     return new TransformerOptions._internal(entryPoints, reflectionEntryPoints,
-        modeName, mirrorMode, initReflector, annotationMatcher);
+        modeName, mirrorMode, initReflector, annotationMatcher,
+        optimizationPhases);
   }
 }

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

@@ -26,12 +26,15 @@ TransformerOptions parseBarbackSettings(BarbackSettings settings) {
       mirrorMode = MirrorMode.none;
       break;
   }
+  var optimizationPhases = _readInt(config, OPTIMIZATION_PHASES_PARAM,
+      defaultValue: DEFAULT_OPTIMIZATION_PHASES);
   return new TransformerOptions(entryPoints,
       reflectionEntryPoints: reflectionEntryPoints,
       modeName: settings.mode.name,
       mirrorMode: mirrorMode,
       initReflector: initReflector,
-      customAnnotationDescriptors: _readCustomAnnotations(config));
+      customAnnotationDescriptors: _readCustomAnnotations(config),
+      optimizationPhases: optimizationPhases);
 }
 
 /// Cribbed from the polymer project.
@@ -56,6 +59,18 @@ List<String> _readFileList(Map config, String paramName) {
   return files;
 }
 
+int _readInt(Map config, String paramName, {int defaultValue: null}) {
+  if (!config.containsKey(paramName)) return defaultValue;
+  var value = config[paramName];
+  if (value is String) {
+    value = int.parse(value);
+  }
+  if (value is! int) {
+    throw new ArgumentError.value(value, paramName, 'Expected an integer');
+  }
+  return value;
+}
+
 /// Parse the [CUSTOM_ANNOTATIONS_PARAM] options out of the transformer into
 /// [AnnotationDescriptor]s.
 List<AnnotationDescriptor> _readCustomAnnotations(Map config) {

modules/angular2/src/transform/di_transformer.dart

@@ -22,9 +22,11 @@ class DiTransformerGroup extends TransformerGroup {
   factory DiTransformerGroup(TransformerOptions options) {
     var phases = [
       [new ReflectionRemover(options)],
-      [new DirectiveProcessor(null)],
-      [new DirectiveLinker()]
+      [new DirectiveProcessor(null)]
     ];
+    phases.addAll(new List.generate(
+        options.optimizationPhases, (_) => [new EmptyNgDepsRemover()]));
+    phases.add([new DirectiveLinker()]);
     return new DiTransformerGroup._(phases);
   }
 

modules/angular2/src/transform/directive_linker/linker.dart

@@ -11,18 +11,56 @@ import 'package:barback/barback.dart';
 import 'package:code_transformers/assets.dart';
 import 'package:path/path.dart' as path;
 
+/// Checks the `.ng_deps.dart` file represented by `entryPoint` and
+/// determines whether it is necessary to the functioning of the Angular 2
+/// Dart app.
+///
+/// An `.ng_deps.dart` file is not necessary if:
+/// 1. It does not register any `@Injectable` types with the system.
+/// 2. It does not import any libraries whose `.ng_deps.dart` files register
+///    any `@Injectable` types with the system.
+///
+/// Since `@Directive` and `@Component` inherit from `@Injectable`, we know
+/// we will not miss processing any classes annotated with those tags.
+Future<bool> isNecessary(AssetReader reader, AssetId entryPoint) async {
+  var parser = new Parser(reader);
+  NgDeps ngDeps = await parser.parse(entryPoint);
+
+  if (ngDeps.registeredTypes.isNotEmpty) return true;
+
+  // We do not register any @Injectables, do we call any dependencies?
+  var linkedDepsMap =
+      await _processNgImports(reader, entryPoint, _getSortedDeps(ngDeps));
+  return linkedDepsMap.isNotEmpty;
+}
+
+/// Modifies the `.ng_deps.dart` file represented by `entryPoint` to call its
+/// dependencies associated `initReflector` methods.
+///
+/// For example, if entry_point.ng_deps.dart imports dependency.dart, this
+/// will check if dependency.ng_deps.dart exists. If it does, we add:
+///
+/// ```
+/// import 'dependency.ng_deps.dart' as i0;
+/// ...
+/// void setupReflection(reflector) {
+///   ...
+///   i0.initReflector(reflector);
+/// }
+/// ```
 Future<String> linkNgDeps(AssetReader reader, AssetId entryPoint) async {
   var parser = new Parser(reader);
   NgDeps ngDeps = await parser.parse(entryPoint);
+
   if (ngDeps == null) return null;
 
-  var allDeps = <UriBasedDirective>[]
-    ..addAll(ngDeps.imports)
-    ..addAll(ngDeps.exports)
-    ..sort((a, b) => a.end.compareTo(b.end));
+  var allDeps = _getSortedDeps(ngDeps);
   var linkedDepsMap = await _processNgImports(reader, entryPoint, allDeps);
 
-  if (linkedDepsMap.isEmpty) return ngDeps.code;
+  if (linkedDepsMap.isEmpty) {
+    // We are not calling `initReflector` on any other libraries.
+    return ngDeps.code;
+  }
 
   var importBuf = new StringBuffer();
   var declarationBuf = new StringBuffer();
@@ -49,6 +87,15 @@ Future<String> linkNgDeps(AssetReader reader, AssetId entryPoint) async {
       '${code.substring(declarationSeamIdx)}';
 }
 
+/// All `import`s and `export`s in `ngDeps` sorted by order of appearance in
+/// the file.
+List<UriBasedDirective> _getSortedDeps(NgDeps ngDeps) {
+  return <UriBasedDirective>[]
+    ..addAll(ngDeps.imports)
+    ..addAll(ngDeps.exports)
+    ..sort((a, b) => a.end.compareTo(b.end));
+}
+
 String _toDepsUri(String importUri) =>
     '${path.withoutExtension(importUri)}${DEPS_EXTENSION}';
 
@@ -67,10 +114,8 @@ Future<Map<UriBasedDirective, String>> _processNgImports(AssetReader reader,
           .where(_isNotDartDirective)
           .map((UriBasedDirective directive) {
     var ngDepsUri = _toDepsUri(stringLiteralToString(directive.uri));
-    var ngDepsAsset = uriToAssetId(entryPoint, ngDepsUri, logger,
-        null /*
-    span */
-        );
+    var spanArg = null;
+    var ngDepsAsset = uriToAssetId(entryPoint, ngDepsUri, logger, spanArg);
     if (ngDepsAsset == entryPoint) return nullFuture;
     return reader.hasInput(ngDepsAsset).then((hasInput) {
       if (hasInput) {

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

@@ -29,8 +29,10 @@ class DirectiveLinker extends Transformer {
       var assetId = transform.primaryInput.id;
       var assetPath = assetId.path;
       var transformedCode = await linkNgDeps(reader, assetId);
-      var formattedCode = formatter.format(transformedCode, uri: assetPath);
-      transform.addOutput(new Asset.fromString(assetId, formattedCode));
+      if (transformedCode != null) {
+        var formattedCode = formatter.format(transformedCode, uri: assetPath);
+        transform.addOutput(new Asset.fromString(assetId, formattedCode));
+      }
     } catch (ex, stackTrace) {
       log.logger.error('Linking ng directives failed.\n'
           'Exception: $ex\n'
@@ -39,3 +41,29 @@ class DirectiveLinker extends Transformer {
     return null;
   }
 }
+
+/// Transformer responsible for removing unnecessary `.ng_deps.dart` files
+/// created by {@link DirectiveProcessor}.
+class EmptyNgDepsRemover extends Transformer {
+  EmptyNgDepsRemover();
+
+  @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);
+      if (!(await isNecessary(reader, transform.primaryInput.id))) {
+        transform.consumePrimary();
+      }
+    } catch (ex, stackTrace) {
+      log.logger.error('Removing unnecessary ng deps failed.\n'
+          'Exception: $ex\n'
+          'Stack Trace: $stackTrace');
+    }
+    return null;
+  }
+}

modules/angular2/src/transform/directive_processor/rewriter.dart

@@ -31,6 +31,12 @@ Future<String> createNgDeps(AssetReader reader, AssetId assetId,
       writer, assetId, new XhrImpl(reader, assetId), annotationMatcher);
   var code = await reader.readAsString(assetId);
   parseCompilationUnit(code, name: assetId.path).accept(visitor);
+
+  // If this library does not define an `@Injectable` and it does not import
+  // any libaries that could, then we do not need to generate a `.ng_deps
+  // .dart` file for it.
+  if (!visitor._foundNgInjectable && !visitor._usesNonLangLibs) return null;
+
   return await writer.asyncToString();
 }
 
@@ -38,8 +44,13 @@ Future<String> createNgDeps(AssetReader reader, AssetId assetId,
 /// associated .ng_deps.dart file.
 class CreateNgDepsVisitor extends Object with SimpleAstVisitor<Object> {
   final AsyncStringWriter writer;
-  bool _foundNgDirectives = false;
-  bool _wroteImport = false;
+  /// Whether an Angular 2 `Injectable` has been found.
+  bool _foundNgInjectable = false;
+  /// Whether this library `imports` or `exports` any non-'dart:' libraries.
+  bool _usesNonLangLibs = false;
+  /// Whether we have written an import of base file
+  /// (the file we are processing).
+  bool _wroteBaseLibImport = false;
   final ToSourceVisitor _copyVisitor;
   final FactoryTransformVisitor _factoryVisitor;
   final ParameterTransformVisitor _paramsVisitor;
@@ -79,20 +90,27 @@ class CreateNgDepsVisitor extends Object with SimpleAstVisitor<Object> {
   /// Write the import to the file the .ng_deps.dart file is based on if it
   /// has not yet been written.
   void _maybeWriteImport() {
-    if (_wroteImport) return;
-    _wroteImport = true;
+    if (_wroteBaseLibImport) return;
+    _wroteBaseLibImport = true;
     writer.print('''import '${path.basename(assetId.path)}';''');
   }
 
+  void _updateUsesNonLangLibs(UriBasedDirective directive) {
+    _usesNonLangLibs = _usesNonLangLibs ||
+        !stringLiteralToString(directive.uri).startsWith('dart:');
+  }
+
   @override
   Object visitImportDirective(ImportDirective node) {
     _maybeWriteImport();
+    _updateUsesNonLangLibs(node);
     return node.accept(_copyVisitor);
   }
 
   @override
   Object visitExportDirective(ExportDirective node) {
     _maybeWriteImport();
+    _updateUsesNonLangLibs(node);
     return node.accept(_copyVisitor);
   }
 
@@ -104,7 +122,7 @@ class CreateNgDepsVisitor extends Object with SimpleAstVisitor<Object> {
   }
 
   void _closeFunctionWrapper() {
-    if (_foundNgDirectives) {
+    if (_foundNgInjectable) {
       writer.print(';');
     }
     writer.print('}');
@@ -153,10 +171,10 @@ class CreateNgDepsVisitor extends Object with SimpleAstVisitor<Object> {
 
     var ctor = _getCtor(node);
 
-    if (!_foundNgDirectives) {
+    if (!_foundNgInjectable) {
       // The receiver for cascaded calls.
       writer.print(REFLECTOR_VAR_NAME);
-      _foundNgDirectives = true;
+      _foundNgInjectable = true;
     }
     writer.print('..registerType(');
     node.name.accept(this);

modules/angular2/src/transform/transformer.dart

@@ -24,11 +24,15 @@ class AngularTransformerGroup extends TransformerGroup {
   factory AngularTransformerGroup(TransformerOptions options) {
     var phases = [
       [new ReflectionRemover(options)],
-      [new DirectiveProcessor(options)],
+      [new DirectiveProcessor(options)]
+    ];
+    phases.addAll(new List.generate(
+        options.optimizationPhases, (_) => [new EmptyNgDepsRemover()]));
+    phases.addAll([
       [new DirectiveLinker(), new DirectiveMetadataExtractor()],
       [new BindGenerator(options)],
       [new TemplateCompiler(options)]
-    ];
+    ]);
     return new AngularTransformerGroup._(phases);
   }
 

modules/angular2/test/transform/directive_processor/all_tests.dart

@@ -50,13 +50,18 @@ void _testNgDeps(String name, String inputPath,
       reader.addAsset(assetId, await reader.readAsString(inputId));
       inputId = assetId;
     }
-    var annotationMatcher = new AnnotationMatcher()..addAll(customDescriptors);
-    var output = formatter
-        .format(await createNgDeps(reader, inputId, annotationMatcher));
     var expectedPath = path.join(path.dirname(inputPath), 'expected',
         path.basename(inputPath).replaceFirst('.dart', '.ng_deps.dart'));
     var expectedId = _assetIdForPath(expectedPath);
-    expect(output).toEqual(await reader.readAsString(expectedId));
+
+    var annotationMatcher = new AnnotationMatcher()..addAll(customDescriptors);
+    var output = await createNgDeps(reader, inputId, annotationMatcher);
+    if (output == null) {
+      expect(await reader.hasInput(expectedId)).toBeFalse();
+    } else {
+      expect(formatter.format(output))
+          .toEqual(await reader.readAsString(expectedId));
+    }
   });
 }
 

modules/angular2/test/transform/directive_processor/custom_metadata/expected/bad_soup.ng_deps.dart

@@ -1,9 +0,0 @@
-library dinner.bad_soup.ng_deps.dart;
-
-import 'bad_soup.dart';
-
-var _visited = false;
-void initReflector(reflector) {
-  if (_visited) return;
-  _visited = true;
-}

modules/angular2/test/transform/integration/list_of_types_files/expected/bar.ng_deps.dart

@@ -2,10 +2,7 @@ library bar.ng_deps.dart;
 
 import 'bar.dart';
 import 'package:angular2/src/core/annotations_impl/annotations.dart';
-import 'package:angular2/src/core/annotations_impl/annotations.ng_deps.dart'
-    as i0;
 import 'foo.dart';
-import 'foo.ng_deps.dart' as i1;
 
 var _visited = false;
 void initReflector(reflector) {
@@ -18,6 +15,4 @@ void initReflector(reflector) {
       'annotations':
           const [const Component(componentServices: const [MyContext])]
     });
-  i0.initReflector(reflector);
-  i1.initReflector(reflector);
 }

modules/angular2/test/transform/integration/simple_annotation_files/expected/bar.ng_deps.dart

@@ -2,8 +2,6 @@ library bar.ng_deps.dart;
 
 import 'bar.dart';
 import 'package:angular2/src/core/annotations_impl/annotations.dart';
-import 'package:angular2/src/core/annotations_impl/annotations.ng_deps.dart'
-    as i0;
 
 var _visited = false;
 void initReflector(reflector) {
@@ -15,5 +13,4 @@ void initReflector(reflector) {
       'parameters': const [],
       'annotations': const [const Component(selector: '[soup]')]
     });
-  i0.initReflector(reflector);
 }

modules/angular2/test/transform/integration/simple_annotation_files/expected/index.ng_deps.dart

@@ -2,16 +2,14 @@ library web_foo.ng_deps.dart;
 
 import 'index.dart';
 import 'package:angular2/src/core/application.dart';
-import 'package:angular2/src/core/application.ng_deps.dart' as i0;
 import 'package:angular2/src/reflection/reflection.dart';
 import 'index.ng_deps.dart' as ngStaticInit0;
 import 'bar.dart';
-import 'bar.ng_deps.dart' as i1;
+import 'bar.ng_deps.dart' as i0;
 
 var _visited = false;
 void initReflector(reflector) {
   if (_visited) return;
   _visited = true;
   i0.initReflector(reflector);
-  i1.initReflector(reflector);
 }

modules/angular2/test/transform/integration/synthetic_ctor_files/expected/bar.ng_deps.dart

@@ -2,8 +2,6 @@ library bar.ng_deps.dart;
 
 import 'bar.dart';
 import 'package:angular2/src/core/annotations_impl/annotations.dart';
-import 'package:angular2/src/core/annotations_impl/annotations.ng_deps.dart'
-    as i0;
 
 var _visited = false;
 void initReflector(reflector) {
@@ -15,5 +13,4 @@ void initReflector(reflector) {
       'parameters': const [],
       'annotations': const [const Component(selector: '[soup]')]
     });
-  i0.initReflector(reflector);
 }

modules/angular2/test/transform/integration/two_annotations_files/expected/bar.ng_deps.dart

@@ -2,10 +2,7 @@ library bar.ng_deps.dart;
 
 import 'bar.dart';
 import 'package:angular2/src/core/annotations_impl/annotations.dart';
-import 'package:angular2/src/core/annotations_impl/annotations.ng_deps.dart'
-    as i0;
 import 'package:angular2/src/core/annotations_impl/view.dart';
-import 'package:angular2/src/core/annotations_impl/view.ng_deps.dart' as i1;
 
 var _visited = false;
 void initReflector(reflector) {
@@ -20,6 +17,4 @@ void initReflector(reflector) {
         const View(template: 'Salad')
       ]
     });
-  i0.initReflector(reflector);
-  i1.initReflector(reflector);
 }

modules/angular2/test/transform/integration/two_deps_files/expected/bar.ng_deps.dart

@@ -2,10 +2,7 @@ library bar.ng_deps.dart;
 
 import 'bar.dart';
 import 'package:angular2/src/core/annotations_impl/annotations.dart';
-import 'package:angular2/src/core/annotations_impl/annotations.ng_deps.dart'
-    as i0;
 import 'foo.dart' as prefix;
-import 'foo.ng_deps.dart' as i1;
 
 var _visited = false;
 void initReflector(reflector) {
@@ -18,6 +15,4 @@ void initReflector(reflector) {
       'parameters': const [const [prefix.MyContext], const [String]],
       'annotations': const [const Component(selector: 'soup')]
     });
-  i0.initReflector(reflector);
-  i1.initReflector(reflector);
 }