CoolVLViewer/indra/llui/llundo.h

/**
 * @file llundo.h
 * @brief Generic interface for undo/redo circular buffer.
 *
 * $LicenseInfo:firstyear=2000&license=viewergpl$
 *
 * Copyright (c) 2000-2009, Linden Research, Inc.
 *
 * Second Life Viewer Source Code
 * The source code in this file ("Source Code") is provided by Linden Lab
 * to you under the terms of the GNU General Public License, version 2.0
 * ("GPL"), unless you have obtained a separate licensing agreement
 * ("Other License"), formally executed by you and Linden Lab.  Terms of
 * the GPL can be found in doc/GPL-license.txt in this distribution, or
 * online at http://secondlifegrid.net/programs/open_source/licensing/gplv2
 *
 * There are special exceptions to the terms and conditions of the GPL as
 * it is applied to this Source Code. View the full text of the exception
 * in the file doc/FLOSS-exception.txt in this software distribution, or
 * online at
 * http://secondlifegrid.net/programs/open_source/licensing/flossexception
 *
 * By copying, modifying or distributing this software, you acknowledge
 * that you have read and understood your obligations described above,
 * and agree to abide by those obligations.
 *
 * ALL LINDEN LAB SOURCE CODE IS PROVIDED "AS IS." LINDEN LAB MAKES NO
 * WARRANTIES, EXPRESS, IMPLIED OR OTHERWISE, REGARDING ITS ACCURACY,
 * COMPLETENESS OR PERFORMANCE.
 * $/LicenseInfo$
 */

#ifndef LL_LLUNDO_H
#define LL_LLUNDO_H


class LLUndoBuffer
{
public:
	class LLUndoAction
	{
		friend class LLUndoBuffer;

	public:
		virtual void undo() = 0;
		virtual void redo() = 0;
		virtual void cleanup()			{}

	protected:
		LL_INLINE LLUndoAction()
		:	mClusterID(0)
		{
		}

		virtual ~LLUndoAction() = default;

	private:
		S32		mClusterID;
	};

	LLUndoBuffer(LLUndoAction(*create_func()), S32 initial_count);
	virtual ~LLUndoBuffer();

	LLUndoAction* getNextAction(bool setClusterBegin = true);
	bool undoAction();
	bool redoAction();
	bool canUndo()						{ return mNextAction != mFirstAction; }
	bool canRedo()						{ return mNextAction != mLastAction; }

	void flushActions();

private:
	LLUndoAction**	mActions;		// Array of pointers to undoactions
	S32				mNumActions;	// Total number of actions in ring buffer
	S32				mNextAction;	// Next action to perform undo/redo on
	// Last action actually added to undo buffer
	S32				mLastAction;
	// Beginning of ring buffer (do not undo any further)
	S32				mFirstAction;
	// Current operation id, for undoing and redoing in clusters
	S32				mOperationID;
};

#endif //LL_LLUNDO_H