feat(components): change shadow boundary to ignore duplicate styles

Closes #1423

Author: vsavkin

lib/core_dom/directive_injector.dart

@@ -169,18 +169,11 @@ class DirectiveInjector implements DirectiveBinder {
   static Binding _tempBinding = new Binding();
 
   DirectiveInjector(DirectiveInjector parent, appInjector, this._node, this._nodeAttrs,
-      this._eventHandler, this.scope, this._animate, [View view, ShadowBoundary boundary])
+      this._eventHandler, this.scope, this._animate, [View view, this._shadowBoundary])
       : _parent = parent,
       _appInjector = appInjector,
       _view = view == null && parent != null ? parent._view : view,
-      _constructionDepth = _NO_CONSTRUCTION,
-      _shadowBoundary = _getShadowBoundary(boundary, parent);
-
-  static _getShadowBoundary(ShadowBoundary boundary, DirectiveInjector parent) {
-    if (boundary != null) return boundary;
-    if (parent != null) return parent._shadowBoundary;
-    return new DefaultShadowBoundary();
-  }
+      _constructionDepth = _NO_CONSTRUCTION;
 
   void bind(key, {dynamic toValue: DEFAULT_VALUE,
             Function toFactory: DEFAULT_VALUE,
@@ -317,7 +310,7 @@ class DirectiveInjector implements DirectiveBinder {
       case ELEMENT_PROBE_KEY_ID:          return elementProbe;
       case NG_ELEMENT_KEY_ID:             return ngElement;
       case EVENT_HANDLER_KEY_ID:          return _eventHandler;
-      case SHADOW_BOUNDARY_KEY_ID:        return _shadowBoundary;
+      case SHADOW_BOUNDARY_KEY_ID:        return _findShadowBoundary();
       case DESTINATION_LIGHT_DOM_KEY_ID:  return _destLightDom;
       case SOURCE_LIGHT_DOM_KEY_ID:       return _sourceLightDom;
       case VIEW_KEY_ID:                   return _view;
@@ -408,6 +401,9 @@ class DirectiveInjector implements DirectiveBinder {
   }
 
   DestinationLightDom get _destLightDom => _parent == null ? null : _parent.lightDom;
+
+  ShadowBoundary _findShadowBoundary() =>
+      _shadowBoundary != null ? _shadowBoundary : getFromParentByKey(SHADOW_BOUNDARY_KEY);
 }
 
 class TemplateDirectiveInjector extends DirectiveInjector {

lib/core_dom/module_internal.dart

@@ -111,6 +111,7 @@ class CoreDomModule extends Module {
     bind(ElementBinderFactory);
     bind(NgElement);
     bind(EventHandler);
+    bind(ShadowBoundary, toImplementation: DefaultShadowBoundary);
     // TODO(rkirov): remove this once clients have stopped relying on it.
     bind(DirectiveInjector, toValue: null);
   }

lib/core_dom/shadow_boundary.dart

@@ -6,27 +6,43 @@ part of angular.core.dom_internal;
 * [ShadowBoundary] is responsible for inserting style elements.
 */
 abstract class ShadowBoundary {
+  Set<dom.StyleElement> _insertedStyles;
+
   void insertStyleElements(List<dom.StyleElement> elements);
+
+  Iterable<dom.StyleElement> _newStyles(Iterable<dom.StyleElement> elements) {
+    if (_insertedStyles == null) return elements;
+    return elements.where((el) => !_insertedStyles.contains(el));
+  }
+
+  void _addInsertedStyles(Iterable<dom.StyleElement> elements) {
+    if (_insertedStyles == null) _insertedStyles = new Set();
+    _insertedStyles.addAll(elements);
+  }
 }
 
 @Injectable()
-class DefaultShadowBoundary implements ShadowBoundary {
+class DefaultShadowBoundary extends ShadowBoundary {
   void insertStyleElements(List<dom.StyleElement> elements) {
-    final cloned = elements.map((el) => el.clone(true));
+    final newStyles = _newStyles(elements);
+    final cloned = newStyles.map((el) => el.clone(true));
     dom.document.head.nodes.addAll(cloned);
+    _addInsertedStyles(newStyles);
   }
 }
 
 @Injectable()
-class ShadowRootBoundary implements ShadowBoundary {
+class ShadowRootBoundary extends ShadowBoundary {
   final dom.ShadowRoot shadowRoot;
   dom.StyleElement _lastStyleElement;
 
   ShadowRootBoundary(this.shadowRoot);
 
   void insertStyleElements(List<dom.StyleElement> elements) {
     if (elements.isEmpty) return;
-    final cloned = elements.map((el) => el.clone(true));
+
+    final newStyles = _newStyles(elements);
+    final cloned = newStyles.map((el) => el.clone(true));
 
     cloned.forEach((style) {
       if (_lastStyleElement != null) {
@@ -37,5 +53,7 @@ class ShadowRootBoundary implements ShadowBoundary {
         _lastStyleElement = shadowRoot.append(style);
       }
     });
+
+    _addInsertedStyles(newStyles);
   }
 }

test/core_dom/directive_injector_spec.dart

@@ -3,6 +3,7 @@ library directive_injector_spec;
 import '../_specs.dart';
 import 'package:angular/core_dom/directive_injector.dart';
 import 'package:angular/core_dom/static_keys.dart';
+import 'dart:html' as dom;
 
 void main() {
   describe('DirectiveInjector', () {
@@ -108,6 +109,35 @@ void main() {
         });
       });
 
+      describe("returning ShadowBoundary", () {
+        it('should return the shadow bounary of the injector', () {
+          final root = new dom.DivElement().createShadowRoot();
+          final boundary = new ShadowRootBoundary(root);
+          final childInjector = new DirectiveInjector(injector, null, null, null, null, null,
+              null, null, boundary);
+
+          expect(childInjector.getByKey(SHADOW_BOUNDARY_KEY)).toBe(boundary);
+        });
+
+        it('should return the shadow bounary of the parent injector', () {
+          final root = new dom.DivElement().createShadowRoot();
+          final boundary = new ShadowRootBoundary(root);
+          final parentInjector = new DirectiveInjector(injector, null, null, null, null, null,
+              null, null, boundary);
+          final childInjector = new DirectiveInjector(parentInjector, null, null, null, null, null,
+              null, null, null);
+
+          expect(childInjector.getByKey(SHADOW_BOUNDARY_KEY)).toBe(boundary);
+        });
+
+        it('should throw we cannot find a shadow boundary', () {
+          final childInjector = new DirectiveInjector(injector, null, null, null, null, null,
+              null, null, null);
+
+          expect(() => childInjector.getByKey(SHADOW_BOUNDARY_KEY)).toThrow("No provider found");
+        });
+      });
+
       describe('error handling', () {
         it('should throw circular dependency error', () {
           addDirective(_TypeC0);

test/core_dom/shadow_boundary_spec.dart

@@ -31,6 +31,18 @@ main() {
 
         expect(root).toHaveText(".style1{}adiv");
       });
+
+      it("should not insert the same style element twice", () {
+        final root = new dom.DivElement().createShadowRoot();
+        final boundary = new ShadowRootBoundary(root);
+
+        final s = new dom.StyleElement()..text = ".style1{}";
+
+        boundary.insertStyleElements([s]);
+        boundary.insertStyleElements([s]);
+
+        expect(root).toHaveText(".style1{}");
+      });
     });
   });
 }