demotool/c-undo.hh

#pragma once
#ifndef REAL_BUILD
# include "externals.hh"
#endif


// Interface for undo actions
class A_UndoAction
{
    public:
	virtual ~A_UndoAction( ) = 0;
	virtual void undo( ) const noexcept = 0;
	virtual void redo( ) const noexcept = 0;
};
using P_UndoAction = T_OwnPtr< A_UndoAction >;


// Undo manager
class T_UndoManager
{
    private:
	static constexpr uint32_t MaxUndo = 1024;
	
	ebcl::T_StaticArray< P_UndoAction , MaxUndo > actions_;
	uint32_t start_{ 0 };
	uint32_t count_{ 0 };
	uint32_t pos_{ 0 };

    public:
	T_UndoManager( ) noexcept;
	DEF_MOVE( T_UndoManager );
	NO_COPY( T_UndoManager );

	// Undo last action
	void undo( ) noexcept;
	// Redo last undone action
	void redo( ) noexcept;

	// Check if it is possible to undo or redo
	bool canUndo( ) const noexcept
		{ return pos_ > 0; }
	bool canRedo( ) const noexcept
		{ return pos_ < count_; }

	// Add an action using a pointer
	A_UndoAction& addAction( P_UndoAction action ) noexcept;

	// Construct and add an action
	template<
		typename T ,
		typename... Args
	> T& add( Args&&... args ) noexcept;
};


template<
	typename T ,
	typename... Args
> inline T& T_UndoManager::add(
		Args&&... args ) noexcept
{
	return reinterpret_cast< T& >( addAction(
		NewOwned< T >( std::forward< Args >( args ) ... ) ) );
}