/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* 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/. */

#ifndef mozilla_TransactionStack_h

#define mozilla_TransactionStack_h

#include "nsDeque.h"

class nsCycleCollectionTraversalCallback;

namespace mozilla {

class TransactionItem;

class TransactionStack : private nsDeque

{

public:

  enum Type { FOR_UNDO, FOR_REDO };

  explicit TransactionStack(Type aType);

  ~TransactionStack();

  void Push(TransactionItem* aTransactionItem);

  void Push(already_AddRefed<TransactionItem> aTransactionItem);

  already_AddRefed<TransactionItem> Pop();

  already_AddRefed<TransactionItem> PopBottom();

  already_AddRefed<TransactionItem> Peek();

  already_AddRefed<TransactionItem> GetItem(int32_t aIndex);

  void Clear();

  int32_t GetSize() const { return static_cast<int32_t>(nsDeque::GetSize()); }

  bool IsEmpty() const { return GetSize() == 0; }

  void DoUnlink() { Clear(); }

  void DoTraverse(nsCycleCollectionTraversalCallback &cb);

private:

  const Type mType;

};

} // namespace mozilla

#endif // mozilla_TransactionStack_h