Generative constructor factories for native objects

sdk/lib/_internal/compiler/implementation/js_emitter/code_emitter_task.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart2js.js_emitter;
 
 /**
  * Generates the code for all used classes in the program. Static fields (even
  * in classes) are ignored, since they can be treated as non-class elements.
  *
@@ skipping 1475 matching lines @@
   }
 
   /**
    * Emit initializer for [mapTypeToInterceptor] data structure used by
    * [findInterceptorForType].  See declaration of [mapTypeToInterceptor] in
    * `interceptors.dart`.
    */
   void emitMapTypeToInterceptor(CodeBuffer buffer) {
     // TODO(sra): Perhaps inject a constant instead?
     // TODO(sra): Filter by subclasses of native types.
+    // TODO(13835): Don't generate this unless we generated the functions that
+    // use the data structure.
     List<jsAst.Expression> elements = <jsAst.Expression>[];
     ConstantHandler handler = compiler.constantHandler;
     List<Constant> constants = handler.getConstantsForEmission();
     for (Constant constant in constants) {
       if (constant is TypeConstant) {
         TypeConstant typeConstant = constant;
         Element element = typeConstant.representedType.element;
         if (element is ClassElement) {
           ClassElement classElement = element;
           elements.add(backend.emitter.constantReference(constant));
           elements.add(js(namer.isolateAccess(classElement)));
+
+          // Create JavaScript Object map for by-name lookup of generative
+          // constructors.  For example, the class A has three generative
+          // constructors
+          //
+          //     class A {
+          //       A() {}
+          //       A.foo() {}
+          //       A.bar() {}
+          //     }
+          //
+          // Which are described by the map
+          //
+          //     {"": A.A$, "foo": A.A$foo, "bar": A.A$bar}
+          //
+          // We expect most of the time the map will be a singleton.
+          var properties = [];
+          classElement.forEachMember(
+              (ClassElement enclosingClass, Element member) {
+                if (member.isGenerativeConstructor()) {
+                  properties.add(
+                      new jsAst.Property(
+                          js.string(member.name.slowToString()),
+                          new jsAst.VariableUse(
+                              backend.namer.isolateAccess(member))));
+                }
+              },
+              includeBackendMembers: false,
+              includeSuperAndInjectedMembers: false);
+
+          var map = new jsAst.ObjectInitializer(properties);
+          elements.add(map);
         }
       }
     }
 
     jsAst.ArrayInitializer array = new jsAst.ArrayInitializer.from(elements);
     String name =
         backend.namer.getNameOfGlobalField(backend.mapTypeToInterceptor);
     jsAst.Expression assignment = js('$isolateProperties.$name = #', array);
 
     buffer.write(jsAst.prettyPrint(assignment, compiler));
@@ skipping 595 matching lines @@
     return compiler.deferredLoadTask.isDeferred(element);
   }
 
   bool get areAnyElementsDeferred {
     return compiler.deferredLoadTask.areAnyElementsDeferred;
   }
 }
 
 // TODO(ahe): Move code for interceptors to own file.
 // TODO(ahe): Move code for reifying metadata/types to own file.