/* -*- 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;

  // Copy construction can't be supported because C++ requires that any enclosed

  // T be initialized in a way C++ knows about -- that is, by |new| or similar.

  UnionMember(const UnionMember&) = delete;

 public:

  UnionMember() = default;

  ~UnionMember() = default;

  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