Generative constructors in the new dart backend.

pkg/compiler/lib/src/dart_backend/backend_ast_nodes.dart

 // Copyright (c) 2014, 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.
 
 library backend_ast_nodes;
 
 import '../constants/values.dart' as values;
 import '../dart_types.dart' as types;
 import '../elements/elements.dart' as elements;
 import '../tree/tree.dart' as tree;
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                      [ this.defaultValue ]) : type = returnType {
     assert(parameters != null);
   }
 
   /// True if this is a function parameter.
   bool get isFunction => parameters != null;
 }
 
 // EXPRESSIONS
 
+abstract class Initializer extends Expression {}
+
+class FieldInitializer extends Initializer {
+  final elements.FieldElement element;
+  final Expression body;
+
+  FieldInitializer(this.element, this.body);
+}
+
+class SuperInitializer extends Initializer {
+  final elements.ConstructorElement target;
+  final List<Argument> arguments;
+
+  SuperInitializer(this.target, this.arguments);
+}
+
 class FunctionExpression extends Expression implements ExecutableDefinition {
   final TypeAnnotation returnType;
   String name;
   final Parameters parameters;
   final Statement body;
   final bool isGetter;
   final bool isSetter;
 
   elements.FunctionElement element;
 
   FunctionExpression(this.parameters,
                      this.body,
                      { this.name,
                        this.returnType,
                        this.isGetter: false,
                        this.isSetter: false }) {
     // Function must have a name if it has a return type
     assert(returnType == null || name != null);
   }
 }
 
+class ConstructorDefinition extends FunctionExpression {
+  final List<Initializer> initializers;
+  final bool isConst;
+
+  ConstructorDefinition(Parameters parameters, Statement body,
+                        this.initializers, String name, this.isConst)
+      : super(parameters, body, name: name);
+}
+
 class Conditional extends Expression {
   final Expression condition;
   final Expression thenExpression;
   final Expression elseExpression;
 
   Conditional(this.condition, this.thenExpression, this.elseExpression);
 }
 
 /// An identifier expression.
 /// The unparser does not concern itself with scoping rules, and it is the
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   final StringChunk previous;
   final tree.StringQuoting quoting;
   num cost;
 
   OpenStringChunk(this.previous, this.quoting, this.cost);
 
   StringChunk end(int endIndex) {
     return new StringChunk(previous, quoting, endIndex);
   }
 }