1 files changed, 59 insertions, 0 deletions
diff --git a/dom/bindings/UnionMember.h b/dom/bindings/UnionMember.h
new file mode 100644
index 000000000..3842c6eb0
--- /dev/null
+++ b/dom/bindings/UnionMember.h
@@ -0,0 +1,59 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* A class for holding the members of a union. */
+
+#ifndef mozilla_dom_UnionMember_h
+#define mozilla_dom_UnionMember_h
+
+#include "mozilla/Alignment.h"
+
+namespace mozilla {
+namespace dom {
+
+// The union type has an enum to keep track of which of its UnionMembers has
+// been constructed.
+template<class T>
+class UnionMember
+{
+  AlignedStorage2<T> mStorage;
+
+public:
+  T& SetValue()
+  {
+    new (mStorage.addr()) T();
+    return *mStorage.addr();
+  }
+  template <typename T1>
+  T& SetValue(const T1& aValue)
+  {
+    new (mStorage.addr()) T(aValue);
+    return *mStorage.addr();
+  }
+  template<typename T1, typename T2>
+  T& SetValue(const T1& aValue1, const T2& aValue2)
+  {
+    new (mStorage.addr()) T(aValue1, aValue2);
+    return *mStorage.addr();
+  }
+  T& Value()
+  {
+    return *mStorage.addr();
+  }
+  const T& Value() const
+  {
+    return *mStorage.addr();
+  }
+  void Destroy()
+  {
+    mStorage.addr()->~T();
+  }
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_UnionMember_h