Implement LibraryMirror.metadata.

dart/sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart

Index: dart/sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart
diff --git a/dart/sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart b/dart/sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart
index 6ecbfd5099e1e4ab723fd545a494966e5544cb0b..d29e89a9d59d23b382d3a7c82a015a01abcc7dc7 100644
--- a/dart/sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart
+++ b/dart/sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart
@@ -2940,6 +2940,24 @@ if (typeof document !== "undefined" && document.readyState !== "complete") {
     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
@@ -3045,6 +3063,9 @@ if (typeof document !== "undefined" && document.readyState !== "complete") {
             mainBuffer
                 ..write('["${library.getLibraryOrScriptName()}",$_')
                 ..write('"${uri}",$_')
+                ..write(
+                    jsAst.prettyPrint(buildMetadataFunction(library), compiler))
+                ..write(',$_')
                 ..write('{$n')
                 ..addBuffer(buffer)
                 ..write('}],$n');
@@ -3054,6 +3075,7 @@ if (typeof document !== "undefined" && document.readyState !== "complete") {
             deferredBuffer
                 ..write('["${library.getLibraryOrScriptName()}",$_')
                 ..write('"${uri}",$_')
+                ..write('[],$_')
                 ..write('{$n')
                 ..addBuffer(buffer)
                 ..write('}],$n');
@@ -3240,7 +3262,8 @@ const String REFLECTION_DATA_PARSER = r'''
     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) {
@@ -3255,6 +3278,6 @@ const String REFLECTION_DATA_PARSER = r'''
         classes.push(element[""]);
       }
     }
-    libraries.push([name, uri, classes, functions]);
+    libraries.push([name, uri, classes, functions, metadata]);
   }
 })''';