Implement LibraryMirror.metadata.

dart/sdk/lib/_internal/compiler/implementation/js_backend/emitter.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.
 
 part of js_backend;
 
 /**
  * A function element that represents a closure call. The signature is copied
  * from the given element.
  */
@@ skipping 2922 matching lines @@
     ..addAll(buildDefineClassAndFinishClassFunctionsIfNecessary())
     ..addAll(buildLazyInitializerFunctionIfNecessary())
     ..addAll(buildFinishIsolateConstructor())
     );
     jsAst.FunctionDeclaration decl = new jsAst.FunctionDeclaration(
         new jsAst.VariableDeclaration('init'), fun);
     buffer.write(jsAst.prettyPrint(decl, compiler).getText());
     if (compiler.enableMinification) buffer.write('\n');
   }
 
+  /// The metadata function returns the metadata associated with
+  /// [element] in generated code.  The metadata needs to be wrapped
+  /// in a function as it refers to constants that may not have been
+  /// constructed yet.  For example, a class is allowed to be
+  /// annotated with itself.  The metadata function is used by
+  /// mirrors_patch to implement DeclarationMirror.metadata.
+  jsAst.Expression buildMetadataFunction(Element element) {
+    if (compiler.mirrorSystemClass == null) return new jsAst.LiteralString('');

[kasperl, 2013/05/30 13:16:39]

Add comment.

[ahe, 2013/05/30 13:28:45]

Done.

+    var metadata = [];
+    for (Link link = element.metadata;
+         // TODO(ahe): Why is metadata sometimes null?

[kasperl, 2013/05/30 13:16:39]

Maybe move this check out of the loop so it sticks out?

[ahe, 2013/05/30 13:28:45]

Done.

+         link != null && !link.isEmpty;
+         link = link.tail) {
+      metadata.add(constantReference(link.head.value));
+    }
+    return js.fun([], [js.return_(new jsAst.ArrayInitializer.from(metadata))]);
+  }
+
   String assembleProgram() {
     measure(() {
       // Compute the required type checks to know which classes need a
       // 'is$' method.
       computeRequiredTypeChecks();
 
       computeNeededClasses();
 
       mainBuffer.add(GENERATED_BY);
       addComment(HOOKS_API_USAGE, mainBuffer);
@@ skipping 85 matching lines @@
             // TODO(ahe): It is a hack to use compiler.sourceMapUri
             // here.  It should be relative to the main JavaScript
             // output file.
             uri = relativize(
                 compiler.sourceMapUri, library.canonicalUri, false);
           }
           if (buffer != null) {
             mainBuffer
                 ..write('["${library.getLibraryOrScriptName()}",$_')
                 ..write('"${uri}",$_')
+                ..write(
+                    jsAst.prettyPrint(buildMetadataFunction(library), compiler))
+                ..write(',$_')
                 ..write('{$n')
                 ..addBuffer(buffer)
                 ..write('}],$n');
           }
           buffer = buffers[1];
           if (buffer != null) {
             deferredBuffer
                 ..write('["${library.getLibraryOrScriptName()}",$_')
                 ..write('"${uri}",$_')
+                ..write('[],$_')
                 ..write('{$n')
                 ..addBuffer(buffer)
                 ..write('}],$n');
           }
           libraryBuffers[library] = const [];
         }
         mainBuffer.write('])$N');
 
         deferredBuffer.write('])$N');
         if (!deferredClasses.isEmpty) {
@@ skipping 166 matching lines @@
 const String REFLECTION_DATA_PARSER = r'''
 (function (reflectionData) {
   if (!init.libraries) init.libraries = [];
   var libraries = init.libraries;
   var hasOwnProperty = Object.prototype.hasOwnProperty;
   var length = reflectionData.length;
   for (var i = 0; i < length; i++) {
     var data = reflectionData[i];
     var name = data[0];
     var uri = data[1];
-    var descriptor = data[2];
+    var metadata = data[2];
+    var descriptor = data[3];
     var classes = [];
     var functions = [];
     for (var property in descriptor) {
       if (!hasOwnProperty.call(descriptor, property)) continue;
       var element = descriptor[property];
       if (typeof element === "function") {
         $[property] = element;
         functions.push(property);
       } else {
         $$[property] = element;
         classes.push(property);
         classes.push(element[""]);
       }
     }
-    libraries.push([name, uri, classes, functions]);
+    libraries.push([name, uri, classes, functions, metadata]);
   }
 })''';