/**
* Places the provided SnapShot on top
* of the stack.
*
* parameter snapShot: The one to put on top of the stack
*/
public static void PushToStack(SnapShot snapShot)
{
if (snapShot != null)
{
redoStack.Push(snapShot);
}
}
/**
* A newer TextStorage is loaded using a memento object.
*/
public void Redo()
{
SnapShot backup = RedoStack.PopFromStack();
if (backup != null)
{
textStorage.RestoreStorage(backup.text);
}
}
/**
* An older TextStorage is loaded using a memento object.
* Allows Redo functionality by saving this SnapShot
* to another stack.
* Makes sure that text is empty if a backup doesn't exist.
*/
public void Undo()
{
if (UndoStack.PeekAtStack() != null)
{
RedoStack.PushToStack(UndoStack.PeekAtStack());
}
SnapShot backup = UndoStack.PopFromStack();
if (backup == null)
{
textStorage.RestoreStorage("");
}
else
{
textStorage.RestoreStorage(backup.text);
}
}
/**
* Places the provided SnapShot on top
* of the stack.
*
* parameter snapShot: The one to put on top of the stack
*/
public static void PushToStack(SnapShot snapShot)
{
undoStack.Push(snapShot);
}
/**
* Makes a backup by creating a snapshot
* of the provided TextStorage.
*
* parameter storage: The TextStorage object to create a backup of
*/
public void MakeBackup(TextStorage storage)
{
backup = storage.CreateSnapshot();
UndoStack.PushToStack(backup);
}