Start resolving classes and default constructors.

frog/leg/tree/nodes.dart

 // Copyright (c) 2011, 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.
 
 interface Visitor<R> {
   R visitBlock(Block node);
   R visitClassNode(ClassNode node);
   R visitDoWhile(DoWhile node);
   R visitExpressionStatement(ExpressionStatement node);
   R visitFor(For node);
@@ skipping 213 matching lines @@
 
 class NodeList extends Node {
   // TODO(floitsch): don't make nodes private. This is needed, because we
   // work around a bug in Frog that doesn't allow to initialize the field
   // with a const object.
   final Link<Node> _nodes;
   Link<Node> get nodes() => _nodes !== null ? _nodes : const EmptyLink<Node>();
   final Token beginToken;
   final Token endToken;
   final SourceString delimiter;
+  bool isEmpty() => nodes.isEmpty();
 
   // TODO(floitsch): second argument should be this.nodes.
   NodeList([this.beginToken, nodes, this.endToken, this.delimiter])
       : _nodes = nodes;
 
   NodeList.singleton(Node node) : this(null, new Link<Node>(node));
+  NodeList.empty() : this(null, const EmptyLink<Node>());
 
   NodeList asNodeList() => this;
 
   accept(Visitor visitor) => visitor.visitNodeList(this);
 
   Token getBeginToken() {
     if (beginToken !== null) return beginToken;
      if (nodes !== null) {
        for (Link<Node> link = nodes; !link.isEmpty(); link = link.tail) {
          if (link.head.getBeginToken() !== null) {
@@ skipping 64 matching lines @@
 }
 
 class For extends Loop {
   /** Either a variable declaration or an ExpressionStatement. */
   final Statement initializer;
   final ExpressionStatement conditionStatement;
   final Node update; // TODO(ahe): Should be an expression list.
 
   final Token forToken;
 
-  For(this.initializer, this.conditionStatement, this.update, body, 
+  For(this.initializer, this.conditionStatement, this.update, body,
       this.forToken) : super(body);
 
   For asFor() => this;
 
   Expression get condition() {
     return conditionStatement.expression;
   }
 
   accept(Visitor visitor) => visitor.visitFor(this);
 
@@ skipping 274 matching lines @@
 }
 
 /** Representation of modifiers such as static, abstract, final, etc. */
 class Modifiers {
   final Link<Token> modifiers;
   /** Bit pattern to easy check what modifiers are present. */
   final int flags;
 
   const Modifiers([this.modifiers, this.flags = 0]);
 }