Towards compiling Hello World!

pkg/compiler/lib/src/universe/codegen_world_builder.dart

 // Copyright (c) 2017, 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 world_builder;
 
 /// World builder specific to codegen.
 ///
 /// This adds additional access to liveness of selectors and elements.
 abstract class CodegenWorldBuilder implements WorldBuilder {
   /// Calls [f] with every instance field, together with its declarer, in an
   /// instance of [cls].
   void forEachInstanceField(
       ClassEntity cls, void f(ClassEntity declarer, FieldEntity field));
 
   /// Calls [f] for each parameter of [function] providing the type and name of
-  /// the parameter.
-  void forEachParameter(
-      FunctionEntity function, void f(DartType type, String name));
+  /// the parameter and the [defaultValue] if the parameter is optional.
+  void forEachParameter(FunctionEntity function,
+      void f(DartType type, String name, ConstantValue defaultValue));
 
   void forEachInvokedName(
       f(String name, Map<Selector, SelectorConstraints> selectors));
 
   void forEachInvokedGetter(
       f(String name, Map<Selector, SelectorConstraints> selectors));
 
   void forEachInvokedSetter(
       f(String name, Map<Selector, SelectorConstraints> selectors));
 
+  /// Returns `true` if [field] constant or final with a constant initializer.
+  bool hasConstantFieldInitializer(FieldEntity field);
+
   /// Returns `true` if [member] is invoked as a setter.
   bool hasInvokedSetter(MemberEntity member, ClosedWorld world);
 
   bool hasInvokedGetter(MemberEntity member, ClosedWorld world);
 
   Map<Selector, SelectorConstraints> invocationsByName(String name);
 
   Map<Selector, SelectorConstraints> getterInvocationsByName(String name);
 
   Map<Selector, SelectorConstraints> setterInvocationsByName(String name);
@@ skipping 495 matching lines @@
   /// the constant use was new to the world.
   bool registerConstantUse(ConstantUse use) {
     if (use.kind == ConstantUseKind.DIRECT) {
       addCompileTimeConstantForEmission(use.value);
     }
     return _constantValues.add(use.value);
   }
 }
 
 class ElementCodegenWorldBuilderImpl extends CodegenWorldBuilderImpl {
+  final JavaScriptConstantCompiler _constants;
+
   ElementCodegenWorldBuilderImpl(
+      this._constants,
       ElementEnvironment elementEnvironment,
       NativeBasicData nativeBasicData,
       ClosedWorld world,
       SelectorConstraintsStrategy selectorConstraintsStrategy)
       : super(elementEnvironment, nativeBasicData, world,
             selectorConstraintsStrategy);
 
+  @override
+  bool hasConstantFieldInitializer(FieldElement field) {
+    return field.constant != null;
+  }
+
   /// Calls [f] with every instance field, together with its declarer, in an
   /// instance of [cls].
   void forEachInstanceField(
       ClassElement cls, void f(ClassEntity declarer, FieldEntity field)) {
     cls.implementation
         .forEachInstanceField(f, includeSuperAndInjectedMembers: true);
   }
 
   @override
-  void forEachParameter(
-      MethodElement function, void f(DartType type, String name)) {
+  void forEachParameter(MethodElement function,
+      void f(DartType type, String name, ConstantValue defaultValue)) {
     FunctionSignature parameters = function.functionSignature;
     parameters.forEachParameter((ParameterElement parameter) {
-      f(parameter.type, parameter.name);
+      ConstantValue value;
+      if (parameter.constant != null) {
+        value = _constants.getConstantValue(parameter.constant);
+      } else {
+        value = new NullConstantValue();
+      }
+      f(parameter.type, parameter.name, value);
     });
   }
 
   @override
   void _processInstantiatedClassMember(
       ClassEntity cls, MemberElement member, MemberUsedCallback memberUsed) {
     assert(member.isDeclaration, failedAt(member));
     if (member.isMalformed) return;
     super._processInstantiatedClassMember(cls, member, memberUsed);
   }
@@ skipping 15 matching lines @@
   void registerIsCheck(ResolutionDartType type) {
     // Even in checked mode, type annotations for return type and argument
     // types do not imply type checks, so there should never be a check
     // against the type variable of a typedef.
     assert(!type.isTypeVariable || !type.element.enclosingElement.isTypedef);
     super.registerIsCheck(type);
   }
 }
 
 class KernelCodegenWorldBuilder extends CodegenWorldBuilderImpl {
+  KernelToElementMapImpl _elementMap;
+
   KernelCodegenWorldBuilder(
+      this._elementMap,
       ElementEnvironment elementEnvironment,
       NativeBasicData nativeBasicData,
       ClosedWorld world,
       SelectorConstraintsStrategy selectorConstraintsStrategy)
       : super(elementEnvironment, nativeBasicData, world,
             selectorConstraintsStrategy);
 
   @override
-  void forEachParameter(
-      FunctionEntity function, void f(DartType type, String name)) {
-    throw new UnimplementedError('KernelCodegenWorldBuilder.forEachParameter');
+  bool hasConstantFieldInitializer(FieldEntity field) {
+    return _elementMap.hasConstantFieldInitializer(field);
   }
 
   @override
+  void forEachParameter(FunctionEntity function,
+      void f(DartType type, String name, ConstantValue defaultValue)) {
+    _elementMap.forEachParameter(function, f);
+  }
+
+  @override
   void forEachInstanceField(
       ClassEntity cls, void f(ClassEntity declarer, FieldEntity field)) {
     _elementEnvironment.forEachClassMember(cls,
         (ClassEntity declarer, MemberEntity member) {
       if (member.isField && member.isInstanceMember) f(declarer, member);
     });
   }
 }