Implement subtype checks on type arguments.

sdk/lib/_internal/compiler/implementation/js_backend/emitter.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 js_backend;
 
 /**
  * A function element that represents a closure call. The signature is copied
  * from the given element.
  */
@@ skipping 45 matching lines @@
    * A cache of closures that are used to closurize instance methods
    * of interceptors. These closures are dynamically bound to the
    * interceptor instance, and the actual receiver of the method.
    */
   final Map<int, String> interceptorClosureCache;
   Set<ClassElement> checkedClasses;
   Set<TypedefElement> checkedTypedefs;
 
   final bool generateSourceMap;
 
+  RuntimeTypeInformation get rti {

[ngeoffray, 2012/12/12 12:09:11]

I'd rather not have this getter.

[karlklose, 2012/12/12 14:50:47]

Done.

+    JavaScriptBackend backend = compiler.backend;
+    return backend.rti;
+  }
+
   CodeEmitterTask(Compiler compiler, Namer namer, this.generateSourceMap)
       : boundClosureBuffer = new CodeBuffer(),
         mainBuffer = new CodeBuffer(),
         this.namer = namer,
         boundClosureCache = new Map<int, String>(),
         interceptorClosureCache = new Map<int, String>(),
         constantEmitter = new ConstantEmitter(compiler, namer),
         super(compiler) {
     nativeEmitter = new NativeEmitter(this);
   }
@@ skipping 670 matching lines @@
       // Emit the noSuchMethod handlers on the Object prototype now,
       // so that the code in the dynamicFunction helper can find
       // them. Note that this helper is invoked before analyzing the
       // full JS script.
       if (!nativeEmitter.handleNoSuchMethod) {
         emitNoSuchMethodHandlers(defineInstanceMember);
       }
     }
   }
 
+  void emitRuntimeClassesAndTests(CodeBuffer buffer) {
+    TypeChecks typeChecks = rti.computeRequiredChecks();
+    // Create an object that holds the class name and the checks for all classes
+    // that are needed but do  not have a JS constructor.

[ngeoffray, 2012/12/12 12:09:11]

do  not -> do not

[ngeoffray, 2012/12/12 12:09:11]

What are those? Please add a comment.

[karlklose, 2012/12/12 14:50:47]

Done.

[karlklose, 2012/12/12 14:50:47]

Done.

+    for (ClassElement requiredClass in rti.requiredClasses) {
+      String holder = namer.isolateAccess(requiredClass);
+      String name = namer.getName(requiredClass);
+      buffer.add("$holder = {builtin\$cls: '$name'");
+      typeChecks[requiredClass].forEach((check) {
+        buffer.add(', is\$${namer.getName(check)}: true');
+      });
+      buffer.add('};\n');
+    }
+    // Add checks to the constructors of instantiated classes.
+    for (ClassElement cls in typeChecks) {
+      if (rti.requiredClasses.contains(cls)) {
+        // We already emitted the is-checks in the object definition for this
+        // class.
+        continue;
+      }
+      String holder = namer.isolateAccess(cls);
+      typeChecks[cls].forEach((check) {
+        buffer.add('$holder.is\$${namer.getName(check)} = true;\n');
+      });
+    }
+  }
+
   /**
    * Documentation wanted -- johnniwinther
    *
    * Invariant: [classElement] must be a declaration element.
    */
   void visitClassFields(ClassElement classElement,
                         void addField(Element member,
                                       String name,
                                       String accessorName,
                                       bool needsGetter,
@@ skipping 1145 matching lines @@
       mainBuffer.add('var $isolateProperties = $isolatePropertiesName;\n');
       emitClasses(mainBuffer);
       mainBuffer.add(boundClosureBuffer);
       // Clear the buffer, so that we can reuse it for the native classes.
       boundClosureBuffer.clear();
       emitStaticFunctions(mainBuffer);
       emitStaticFunctionGetters(mainBuffer);
       // We need to finish the classes before we construct compile time
       // constants.
       emitFinishClassesInvocationIfNecessary(mainBuffer);
+      emitRuntimeClassesAndTests(mainBuffer);
       emitCompileTimeConstants(mainBuffer);
       // Static field initializations require the classes and compile-time
       // constants to be set up.
       emitStaticNonFinalFieldInitializations(mainBuffer);
       emitGetInterceptorMethods(mainBuffer);
       emitLazilyInitializedStaticFields(mainBuffer);
 
       isolateProperties = isolatePropertiesName;
       // The following code should not use the short-hand for the
       // initialStatics.
@@ skipping 43 matching lines @@
 const String HOOKS_API_USAGE = """
 // Generated by dart2js, the Dart to JavaScript compiler.
 // The code supports the following hooks:
 // dartPrint(message)   - if this function is defined it is called
 //                        instead of the Dart [print] method.
 // dartMainRunner(main) - if this function is defined, the Dart [main]
 //                        method will not be invoked directly.
 //                        Instead, a closure that will invoke [main] is
 //                        passed to [dartMainRunner].
 """;