Add TypeMirror.isSubtypeOf, TypeMirror.isAssignableTo, ClassMirror.isSubclassOf

runtime/lib/mirrors_impl.dart

Index: runtime/lib/mirrors_impl.dart
diff --git a/runtime/lib/mirrors_impl.dart b/runtime/lib/mirrors_impl.dart
index 7a337304068e4ec82e16bfa2bbc5b2286a68145b..c30ffffd3172ac31bd2fe19cbf3953bcaed6cbfd 100644
--- a/runtime/lib/mirrors_impl.dart
+++ b/runtime/lib/mirrors_impl.dart
@@ -108,6 +108,12 @@ String _makeSignatureString(TypeMirror returnType,
 List _metadata(reflectee)
     native 'DeclarationMirror_metadata';
 
+bool _subtypeTest(Type a, Type b)
+    native 'TypeMirror_subtypeTest';
+
+bool _moreSpecificTest(Type a, Type b)
+    native 'TypeMirror_moreSpecificTest';
+
 class _LocalMirrorSystem extends MirrorSystem {
   final Map<Uri, LibraryMirror> libraries;
   final IsolateMirror isolate;
@@ -760,6 +766,31 @@ class _LocalClassMirror extends _LocalObjectMirror
 
   int get hashCode => simpleName.hashCode;
 
+  bool isSubtypeOf(TypeMirror other) {
+    if (other == currentMirrorSystem().dynamicType) return true;
+    if (other == currentMirrorSystem().voidType) return false;
+    return _subtypeTest(_reflectedType, other._reflectedType);
+  }
+
+  bool isAssignableTo(TypeMirror other) {
+    if (other == currentMirrorSystem().dynamicType) return true;
+    if (other == currentMirrorSystem().voidType) return false;
+    return _moreSpecificTest(_reflectedType, other._reflectedType)
+        || _moreSpecificTest(other._reflectedType, _reflectedType);
+  }
+
+  bool isSubclassOf(ClassMirror other) {
+    if (other is! ClassMirror) throw new ArgumentError(other);
+    ClassMirror otherDeclaration = other.originalDeclaration;
+    ClassMirror c = this;
+    while (c != null) {
+      c = c.originalDeclaration;
+      if (c == otherDeclaration) return true;
+      c = c.superclass;
+    }
+    return false;
+  }
+
   static _library(reflectee)
       native "ClassMirror_library";
 
@@ -932,7 +963,8 @@ class _LocalTypeVariableMirror extends _LocalDeclarationMirror
   }
 
   bool get hasReflectedType => false;
-  Type get reflectedType => throw new UnsupportedError() ;
+  Type get reflectedType => throw new UnsupportedError();
+  Type get _reflectedType => _reflectee;
 
   List<TypeVariableMirror> get typeVariables => emptyList;
   List<TypeMirror> get typeArguments => emptyList;
@@ -949,6 +981,19 @@ class _LocalTypeVariableMirror extends _LocalDeclarationMirror
   }
   int get hashCode => simpleName.hashCode;
 
+  bool isSubtypeOf(TypeMirror other) {
+    if (other == currentMirrorSystem().dynamicType) return true;
+    if (other == currentMirrorSystem().voidType) return false;
+    return _subtypeTest(_reflectedType, other._reflectedType);
+  }
+
+  bool isAssignableTo(TypeMirror other) {
+    if (other == currentMirrorSystem().dynamicType) return true;
+    if (other == currentMirrorSystem().voidType) return false;
+    return _moreSpecificTest(_reflectedType, other._reflectedType)
+        || _moreSpecificTest(other._reflectedType, _reflectedType);
+  }
+
   static DeclarationMirror _TypeVariableMirror_owner(reflectee)
       native "TypeVariableMirror_owner";
 
@@ -1036,6 +1081,19 @@ class _LocalTypedefMirror extends _LocalDeclarationMirror
 
   String toString() => "TypedefMirror on '${_n(simpleName)}'";
 
+  bool isSubtypeOf(TypeMirror other) {
+    if (other == currentMirrorSystem().dynamicType) return true;
+    if (other == currentMirrorSystem().voidType) return false;
+    return _subtypeTest(_reflectedType, other._reflectedType);
+  }
+
+  bool isAssignableTo(TypeMirror other) {
+    if (other == currentMirrorSystem().dynamicType) return true;
+    if (other == currentMirrorSystem().voidType) return false;
+    return _moreSpecificTest(_reflectedType, other._reflectedType)
+        || _moreSpecificTest(other._reflectedType, _reflectedType);
+  }
+
   static _nativeReferent(reflectedType)
       native "TypedefMirror_referent";
 
@@ -1441,6 +1499,15 @@ class _SpecialTypeMirror extends _LocalMirror
   int get hashCode => simpleName.hashCode;
 
   String toString() => "TypeMirror on '${_n(simpleName)}'";
+
+  bool isSubtypeOf(TypeMirror other) {
+    return this == other ||
+           (other is _SpecialTypeMirror && other.simpleName == #dynamic);
+  }
+
+  bool isAssignableTo(TypeMirror other) {
+    return simpleName == #dynamic || other is _SpecialTypeMirror;
+  }
 }
 
 class _Mirrors {