1 files changed, 39 insertions, 0 deletions
diff --git a/editor/txmgr/nsTransactionStack.h b/editor/txmgr/nsTransactionStack.h
new file mode 100644
index 0000000000..f6f6c3a2ef
--- /dev/null
+++ b/editor/txmgr/nsTransactionStack.h
@@ -0,0 +1,39 @@
+/* -*- 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 nsTransactionStack_h__
+#define nsTransactionStack_h__
+
+#include "nsDeque.h"
+
+class nsCycleCollectionTraversalCallback;
+class nsTransactionItem;
+
+class nsTransactionStack : private nsDeque
+{
+public:
+  enum Type { FOR_UNDO, FOR_REDO };
+
+  explicit nsTransactionStack(Type aType);
+  ~nsTransactionStack();
+
+  void Push(nsTransactionItem *aTransactionItem);
+  void Push(already_AddRefed<nsTransactionItem> aTransactionItem);
+  already_AddRefed<nsTransactionItem> Pop();
+  already_AddRefed<nsTransactionItem> PopBottom();
+  already_AddRefed<nsTransactionItem> Peek();
+  already_AddRefed<nsTransactionItem> 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;
+};
+
+#endif // nsTransactionStack_h__