Implementation for ClosureMirror.findInContext.

runtime/lib/mirrors_impl.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.
 
 // VM-specific implementation of the dart:mirrors library.
 
 import "dart:collection";
 
 // These values are allowed to be passed directly over the wire.
 bool _isSimpleValue(var value) {
@@ skipping 385 matching lines @@
   }
 
   Future<InstanceMirror> applyAsync(List positionalArguments,
                                     [Map<Symbol, dynamic> namedArguments]) {
     return new Future(() {
       return this.apply(_unwrapAsyncPositionals(positionalArguments),
                         _unwrapAsyncNamed(namedArguments));
     });
   }
 
-  Future<InstanceMirror> findInContext(Symbol name) {
-    throw new UnimplementedError(
-        'ClosureMirror.findInContext() is not implemented');
+  InstanceMirror findInContext(Symbol name, {ifAbsent: null}) {
+    List<String> parts = _n(name).split(".").toList(growable: false);
+    if (parts.length > 3) {
+      throw new ArgumentError("Invalid symbol: ${name}");
+    }
+    List tuple = _computeFindInContext(_reflectee, parts);
+    if (tuple[0]) {
+      return reflect(tuple[1]);
+    }
+    return ifAbsent == null ? null : ifAbsent();
   }
 
   String toString() => "ClosureMirror on '${Error.safeToString(_reflectee)}'";
 
   static _apply(reflectee, arguments, argumentNames)
       native 'ClosureMirror_apply';
 
   static _computeFunction(reflectee)
       native 'ClosureMirror_function';
+
+  static _computeFindInContext(reflectee, name)
+      native 'ClosureMirror_find_in_context';
 }
 
 class _LocalClassMirrorImpl extends _LocalObjectMirrorImpl
     implements ClassMirror {
   _LocalClassMirrorImpl(reflectee,
                         this._reflectedType,
                         String simpleName,
                         this._isGeneric,
                         this._isMixinTypedef,
                         this._isGenericDeclaration)
@@ skipping 893 matching lines @@
     if (typeMirror == null) {
       typeMirror = makeLocalTypeMirror(key);
       _instanitationCache[key] = typeMirror;
       if (typeMirror is ClassMirror && !typeMirror._isGeneric) {
         _declarationCache[key] = typeMirror;
       }
     }
     return typeMirror;
   }
 }