Added support for exports and re-exports.

lib/compiler/implementation/tree/nodes.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.
 
 abstract class Visitor<R> {
   R visitBlock(Block node);
   R visitBreakStatement(BreakStatement node);
   R visitCascade(Cascade node);
   R visitCascadeReceiver(CascadeReceiver node);
   R visitCaseMatch(CaseMatch node);
@@ skipping 1624 matching lines @@
 
   accept(Visitor visitor) => visitor.visitLibraryName(this);
 
   visitChildren(Visitor visitor) => name.accept(visitor);
 
   Token getBeginToken() => libraryKeyword;
 
   Token getEndToken() => name.getEndToken().next;
 }
 
-class Import extends LibraryTag {
+abstract class ImportExport extends LibraryTag {

[Lasse Reichstein Nielsen, 2012/09/28 07:45:36]

Call it LibraryDependency (or something better if you have it).
Add doc-comment: This tag describes a dependency between one library and the
exported identifiers of another library. The other library is specified by the
[uri]. Combinators filter away some identifiers from the other library.

[Johnni Winther, 2012/10/09 09:47:10]

Done.

   final LiteralString uri;
-  final Identifier prefix;
   final NodeList combinators;
 
+  ImportExport(this.uri, this.combinators);
+}
+
+class Import extends ImportExport {

[Lasse Reichstein Nielsen, 2012/09/28 07:45:36]

Comment to the effect that an Import is dependency on another library where the
exported identifiers are put into the import scope of the importing library. The
import scope is only visible inside the library.

[Johnni Winther, 2012/10/09 09:47:10]

Done.

+  final Identifier prefix;
   final Token importKeyword;
 
-  Import(this.importKeyword, this.uri, this.prefix, this.combinators);
+  Import(this.importKeyword, LiteralString uri,
+         this.prefix, NodeList combinators)
+      : super(uri, combinators);
 
   bool get isImport => true;
 
   Import asImport() => this;
 
   accept(Visitor visitor) => visitor.visitImport(this);
 
   visitChildren(Visitor visitor) {
     uri.accept(visitor);
     if (prefix !== null) prefix.accept(visitor);
     if (combinators !== null) combinators.accept(visitor);
   }
 
   Token getBeginToken() => importKeyword;
 
   Token getEndToken() {
     if (combinators !== null) return combinators.getEndToken().next;
     if (prefix !== null) return prefix.getEndToken().next;
     return uri.getEndToken().next;
   }
 }
 
-class Export extends LibraryTag {
-  final LiteralString uri;
-  final NodeList combinators;
-
+class Export extends ImportExport {

[Lasse Reichstein Nielsen, 2012/09/28 07:45:36]

And a comment too, describing what an export is relative to a LibraryDependency.

[Johnni Winther, 2012/10/09 09:47:10]

Done.

   final Token exportKeyword;
 
-  Export(this.exportKeyword, this.uri, this.combinators);
+  Export(this.exportKeyword, LiteralString uri, NodeList combinators)
+      : super(uri, combinators);
 
   bool get isExport => true;
 
   Export asExport() => this;
 
   accept(Visitor visitor) => visitor.visitExport(this);
 
   visitChildren(Visitor visitor) {
     uri.accept(visitor);
     if (combinators !== null) combinators.accept(visitor);
@@ skipping 201 matching lines @@
  * argument).
  *
  * TODO(ahe): This method is controversial, the team needs to discuss
  * if top-level methods are acceptable and what naming conventions to
  * use.
  */
 initializerDo(Node node, f(Node node)) {
   SendSet send = node.asSendSet();
   if (send !== null) return f(send.arguments.head);
 }