Creates `reflectors`, as a meta-meta feature that enables dynamic selection of a "mirror system".

reflectable/lib/reflectable.dart

 // Copyright (c) 2015, the Dart Team. All rights reserved. Use of this
 // source code is governed by a BSD-style license that can be found in
 // the LICENSE file.
 
 // This is the main library in package reflectable.
 
 // TODO(eernst) doc: Write "library dartdoc" for this library.
 
 library reflectable.reflectable;
 
@@ skipping 72 matching lines @@
 /// -----
 /// **Footnotes:**
 /// 1. Currently, the only setup which is supported is when
 /// the metadata object is an instance of a direct subclass of the
 /// class [Reflectable], say `MyReflectable`, and that subclass defines
 /// a `const` constructor taking zero arguments.  This ensures that
 /// every subclass of Reflectable used as metadata is a singleton class,
 /// which means that the behavior of the instance can be expressed by
 /// generating code in the class.  Generalizations of this setup may
 /// be supported in the future if compelling use cases come up.
-class Reflectable extends implementation.ReflectableImpl
+abstract class Reflectable extends implementation.ReflectableImpl
     implements ReflectableInterface {
   // Intended to near-uniquely identify this class in target programs.
   static const thisClassName = reflectable_class_constants.name;
   static const thisClassId = reflectable_class_constants.id;
 
   /// Const constructor, to enable usage as metadata, allowing for varargs
   /// style invocation with up to ten arguments.
   const Reflectable([ReflectCapability cap0 = null,
       ReflectCapability cap1 = null, ReflectCapability cap2 = null,
       ReflectCapability cap3 = null, ReflectCapability cap4 = null,
       ReflectCapability cap5 = null, ReflectCapability cap6 = null,
       ReflectCapability cap7 = null, ReflectCapability cap8 = null,
       ReflectCapability cap9 = null])
       : super(cap0, cap1, cap2, cap3, cap4, cap5, cap6, cap7, cap8, cap9);
 
   const Reflectable.fromList(List<ReflectCapability> capabilities)
       : super.fromList(capabilities);
+
+
+  /// Returns the canonicalized instance of the given reflector [type].
+  ///
+  /// If [type] is not a subclass of [Reflectable], or if it is such a class
+  /// but no entities are covered (that is, it is unused, so we don't have
+  /// any reflection data for it) then [null] is returned.
+  static Reflectable getInstance(Type type) {
+    for (Reflectable reflector in implementation.reflectors) {
+      if (reflector.runtimeType == type) return reflector;
+    }
+    return null;
+  }
 }
 
 /// Returns true if the transformed version is running, false otherwise.
 bool get isTransformed => implementation.isTransformed;