gistfile1.txt

/// Core undo/redo code.
typedef std::function< void() > ActionCallback;

struct EditorAction
{
	BcU32 ID_ = 0;
	const char* Name_ = nullptr;
	ActionCallback Do_;
	ActionCallback Undo_;

	BcU32 CombinedID_ = 0;
};
EditorAction ActiveAction_;
std::deque< EditorAction > UndoStack_;
std::deque< EditorAction > RedoStack_;


void Action( BcU32 ID, const char* Name, ActionCallback Do, ActionCallback Undo, bool Commit )
{
	BcU32 CombinedID = 0;
	CombinedID = BcHash::GenerateCRC32( CombinedID, &ID, sizeof( ID ) );
	CombinedID = BcHash::GenerateCRC32( CombinedID, Name, BcStrLength( Name ) );

	if( CombinedID != ActiveAction_.CombinedID_ )
	{
		if( ActiveAction_.CombinedID_ != 0 )
		{
			CommitAction();
		}

		ActiveAction_.Undo_ = Undo;
	}

	ActiveAction_.Do_ = Do;
	ActiveAction_.ID_ = ID;
	ActiveAction_.Name_ = Name;
	ActiveAction_.CombinedID_ = CombinedID;

	Do();
	RedoStack_.clear();

	if( Commit )
	{
		CommitAction();
	}
}

void CancelAction()
{
	PSY_LOGSCOPEDCATEGORY( Editor );
	if( ActiveAction_ .CombinedID_ != 0 )
	{
		PSY_LOG( "CancelAction: %u, %s", ActiveAction_.ID_, ActiveAction_.Name_ );
	}

	if( ActiveAction_.Undo_ )
	{
		ActiveAction_.Undo_();
	}

	ActiveAction_ = EditorAction();
}

void CommitAction()
{
	PSY_LOGSCOPEDCATEGORY( Editor );
	if( ActiveAction_ .CombinedID_ != 0 )
	{
		PSY_LOG( "CommitAction: %u, %s", ActiveAction_.ID_, ActiveAction_.Name_ );
	}

	if( ActiveAction_.CombinedID_ != 0 )
	{
		UndoStack_.push_back( ActiveAction_ );
		ActiveAction_ = EditorAction();
	}
}

void UndoAction()
{
	PSY_LOG( "UndoAction: %u", UndoStack_.size() );
	CommitAction();
	if( UndoStack_.size() > 0 )
	{
		ActiveAction_ = UndoStack_.back();
		RedoStack_.push_back( ActiveAction_ );
		UndoStack_.pop_back();
		CancelAction();
	}
}

void RedoAction()
{
	PSY_LOG( "RedoAction: %u", RedoStack_.size() );
	CommitAction();
	if( RedoStack_.size() > 0 )
	{
		ActiveAction_ = RedoStack_.back();
		RedoStack_.pop_back();
		ActiveAction_.Do_();
		CommitAction();
	}
}



/// Example usage:
Editor::Action( Idx, "Track Add Node", 
	// Do
	[ this, Idx, Result ]()
	{
		GaTrackPoint NewTrack;
		NewTrack.Position_ = Result.WorldPosition_;
		Points_.insert( Points_.begin() + Idx + 1, NewTrack );
		rebuildTrackMesh();
	},

	// Undo
	[ this, Points = Points_ ]()
	{
		Points_ = Points;
		rebuildTrackMesh();
	} );