--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/org.chromium.sdk/src/org/chromium/sdk/internal/protocolparser/dynamicimpl/SubtypeCaster.java	Wed Dec 23 17:13:18 2009 -0800
@@ -0,0 +1,37 @@
+// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.sdk.internal.protocolparser.dynamicimpl;
+
+import org.chromium.sdk.internal.protocolparser.JsonProtocolParseException;
+
+/**
+ * An internal facility for navigating from object of base type to object of subtype. Used only
+ * when user wants to parse JSON object as subtype.
+ * It works in terms of {@link ObjectData}.
+ */
+abstract class SubtypeCaster {
+  private final Class<?> baseType;
+  private final RefToType<?> subtypeRef;
+
+  SubtypeCaster(Class<?> baseType, RefToType<?> subtypeRef) {
+    this.baseType = baseType;
+    this.subtypeRef = subtypeRef;
+  }
+
+  abstract ObjectData getSubtypeObjectData(ObjectData baseObjectData)
+      throws JsonProtocolParseException;
+
+  Class<?> getSubtype() {
+    return subtypeRef.getTypeClass();
+  }
+
+  TypeHandler<?> getSubtypeHandler() {
+    return subtypeRef.get();
+  }
+
+  Class<?> getBaseType() {
+    return baseType;
+  }
+}