Merge the work on Generic Types Reification from 'dart-lang/reify' repo

pkg/kernel/runtime/reify/interceptors.dart

+// Copyright (c) 2016, 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.
+
+library kernel.transformations.reify.runtime.interceptors;
+
+import 'types.dart' show ReifiedType;
+
+/// Helper method that generates a [ReifiedType] corresponding to the literal
+/// type [type].
+///
+/// Calls to this method are recognized in the transformation and replaced by
+/// code that constructs the correct type.
+ReifiedType reify(Type type) {
+  throw "This method should never be called in translated code";
+}
+
+/// Marker interface to indicate that we can extract the runtime type using
+/// a property getter.
+abstract class HasRuntimeTypeGetter {
+  ReifiedType get $type;
+}
+
+/// Interceptor to safely access the type of an object.
+///
+/// For native objects that do not have the `$type` field on them, the
+/// interceptor directly returns the type, otherwise the value of the field is
+/// returned.
+ReifiedType type(dynamic o) {
+  if (o == null) {
+    return reify(Null);
+  } else if (o is HasRuntimeTypeGetter) {
+    return o.$type;
+  } else if (o is bool) {
+    return reify(bool);
+  } else if (o is String) {
+    return reify(String);
+  } else if (o is int) {
+    return reify(int);
+  } else if (o is double) {
+    return reify(double);
+  } else if (o is Type) {
+    return reify(Type);
+  } else if (o is AbstractClassInstantiationError) {
+    return reify(AbstractClassInstantiationError);
+  } else if (o is NoSuchMethodError) {
+    return reify(NoSuchMethodError);
+  } else if (o is CyclicInitializationError) {
+    return reify(CyclicInitializationError);
+  } else if (o is UnsupportedError) {
+    return reify(UnsupportedError);
+  } else if (o is IntegerDivisionByZeroException) {
+    return reify(IntegerDivisionByZeroException);
+  } else if (o is RangeError) {
+    return reify(RangeError);
+  } else if (o is ArgumentError) {
+    return reify(ArgumentError);
+  }
+  ReifiedType type = _type[o];
+  if (type != null) {
+    return type;
+  }
+  throw 'Unable to get runtime type of ${o.runtimeType}';
+}
+
+// This constructor call is not intercepted with [attachType] since the runtime
+// library is currently never transformed.
+final Expando _type = new Expando();
+
+dynamic attachType(Object o, ReifiedType t) {
+  _type[o] = t;
+  return o;
+}