Added support for exports and re-exports.

lib/compiler/implementation/elements/elements.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.
 
 #library('elements');
 
 #import('dart:uri');
 
 #import('../tree/tree.dart');
 #import('../scanner/scannerlib.dart');
@@ skipping 86 matching lines @@
   static const ElementKind TYPEDEF =
     const ElementKind('typedef', ElementCategory.ALIAS);
 
   static const ElementKind STATEMENT =
     const ElementKind('statement', ElementCategory.NONE);
   static const ElementKind LABEL =
     const ElementKind('label', ElementCategory.NONE);
   static const ElementKind VOID =
     const ElementKind('void', ElementCategory.NONE);
 
+  static const ElementKind ERRONEOUS =

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

It should be called ERROR - a noun - and not ERRONEOUS - an adjective.
It represents an error condition. It does so correctly, not erroneously.

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

Done.

+      const ElementKind('erroneous', ElementCategory.NONE);
+
   toString() => id;
 }
 
 class Element implements Hashable, Spannable {
   final SourceString name;
   final ElementKind kind;
   final Element enclosingElement;
   Link<MetadataAnnotation> metadata = const EmptyLink<MetadataAnnotation>();
 
   Element(this.name, this.kind, this.enclosingElement) {
@@ skipping 247 matching lines @@
  * to check for unresolvable elements instead of
  *   [: element == null :].
  */
 class ErroneousElement extends Element {
   final MessageKind messageKind;
   final List messageArguments;
   final SourceString targetName;
 
   ErroneousElement(this.messageKind, this.messageArguments,
                    this.targetName, Element enclosing)
-      : super(const SourceString('erroneous element'), null, enclosing);
+      : super(const SourceString('erroneous element'),
+              ElementKind.ERRONEOUS, enclosing);
 
   isErroneous() => true;
 
   unsupported() {
     throw 'unsupported operation on erroneous element';
   }
 
   SourceString get name => unsupported();
-  ElementKind get kind => unsupported();
   Link<MetadataAnnotation> get metadata => unsupported();
 
   getLibrary() => enclosingElement.getLibrary();
 }
 
 class ErroneousFunctionElement extends ErroneousElement
                                implements FunctionElement {
   ErroneousFunctionElement(MessageKind messageKind, List messageArguments,
                            SourceString targetName, Element enclosing)
       : super(messageKind, messageArguments, targetName, enclosing);
@@ skipping 149 matching lines @@
   LibraryElement patch = null;
 
   /**
    * Map for elements imported through import declarations.
    *
    * Addition to the map is performed by [addImport]. Lookup is done trough
    * [find].
    */
   final Map<SourceString, Element> importScope;
 
+  /**
+   * Map for elements exported either through export declarations or through
+   * declaration.
+   *
+   * [ImportExportHandler] sets this map when the library is loaded.
+   */
+  Map<SourceString, Element> _exportScope;
+
+  Map<SourceString, Element> get exportScope {

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

Please don't export the map. Someone will just do bad stuff to it. Can you wrap
it in something opaque that only exposes simple lookup and foreach operations?

[Bob Nystrom, 2012/09/28 16:41:27]

Drive-by comment: I see stuff like this frequently. It makes me wonder if we
should have better support for providing read-only access to collections.

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

Changed to used a linked list.

+    assert(invariant(this, _exportScope !== null));
+    return _exportScope;
+  }
+
+  void set exportScope(Map<SourceString, Element> map) {
+    assert(invariant(this, _exportScope === null));
+    assert(invariant(this, map !== null));
+    _exportScope = map;
+  }
+
   LibraryElement(Script script, [Uri uri])
     : this.uri = ((uri === null) ? script.uri : uri),
       importScope = new Map<SourceString, Element>(),
       super(new SourceString(script.name), ElementKind.LIBRARY, null) {
     entryCompilationUnit = new CompilationUnitElement(script, this);
   }
 
-
   bool get isPatched => patch !== null;
 
   void addCompilationUnit(CompilationUnitElement element) {
     compilationUnits = compilationUnits.prepend(element);
   }
 
   void addTag(LibraryTag tag, DiagnosticListener listener) {
     tags = tags.prepend(tag);
   }
 
   /**
    * Adds [element] to the import scope of this library.
    *
    * If an element by the same name is already in the imported scope, an
    * [ErroneousElement] will be put in the imported scope, allowing for the
    * detection of ambiguous uses of imported names.
    */
   void addImport(Element element, DiagnosticListener listener) {
-    Element existing = importScope.putIfAbsent(element.name, () => element);
+    SourceString name = element.name;
+    Element existing = importScope.putIfAbsent(name, () => element);
     if (existing !== element && existing !== null) {

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

Add a comment that you are not following the current spec here by testing for
(existing !== element). Importing the same element twice is specified as an
error.

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

Implementation changed to follow spec.

       if (!existing.isErroneous()) {
         // TODO(johnniwinther): Provide access to both the new and existing
         // elements.
-        importScope[element.name] = new ErroneousElement(
+        importScope[name] = new ErroneousElement(
             MessageKind.DUPLICATE_IMPORT,
-            [element.name], element.name, this);
+            [name], name, this);
       }
     }
   }
 
-
   /**
    * Look up a top-level element in this library. The element could
    * potentially have been imported from another library. Returns
    * null if no such element exist and an [ErroneousElement] if multiple
    * elements have been imported.
    */
   Element find(SourceString elementName) {
     Element result = localScope[elementName];
     if (result === null) {
       result = importScope[elementName];
@@ skipping 11 matching lines @@
 
   void forEachExport(f(Element element)) {
     localScope.forEach((_, Element e) {
       if (this === e.getLibrary()
           && e.kind !== ElementKind.PREFIX
           && e.kind !== ElementKind.FOREIGN
           && !e.name.isPrivate()) {
         f(e);
       }
     });
+    exportScope.forEach((_, Element e) => f(e));
   }
 
   bool hasLibraryName() => libraryTag !== null;
 
   /**
    * Returns the library name (as defined by the #library tag) or for script
    * (which have no #library tag) the script file name. The latter case is used
    * to private 'library name' for scripts to use for instance in dartdoc.
    */
   String getLibraryOrScriptName() {
@@ skipping 1198 matching lines @@
 
   MetadataAnnotation ensureResolved(Compiler compiler) {
     if (resolutionState == STATE_NOT_STARTED) {
       compiler.resolver.resolveMetadataAnnotation(this);
     }
     return this;
   }
 
   String toString() => 'MetadataAnnotation($value, $resolutionState)';
 }