#ifndef TPERSIST_INCLUDED
#define TPERSIST_INCLUDED
 
//#include "tsmartpointer.h"
//#include "tpixel.h"
 
#include "tcommon.h"
 
#undef DVAPI
#undef DVVAR
#ifdef TSTREAM_EXPORTS
#define DVAPI DV_EXPORT_API
#define DVVAR DV_EXPORT_VAR
#else
#define DVAPI DV_IMPORT_API
#define DVVAR DV_IMPORT_VAR
#endif
 
//===================================================================
 
class TPersistDeclaration;
class TIStream;
class TOStream;
 
//===================================================================
//! This is an abstract class for load and save data from and to the file system (i.e files on the disk)
class DVAPI TPersist
{
public:
	virtual ~TPersist(){};
	/*!
		This is a pure virtual function and must be overridden with a method that implements 
		the object loading from a stream (i.e take the object's features from a formatted data stream). 
		For example the TStageObject class use his implementation to take the values of the parameters 
		that characterizes a stage object as name, coordinates, etc... from a file.
		\a is is an input file stream
	*/
	virtual void loadData(TIStream &is) = 0;
	/*!
		This is a pure virtual function and must be overridden with a method that implements 
		the object saving to a data stream (i.e put the object's features on a formatted data stream). 
		For example the TStageObject class use his implementation to save the values of the parameters 
		that characterizes a stage object as name, coordinates, etc... on a file
		\a os is an output file stream.
	*/
	virtual void saveData(TOStream &os) = 0;
	/*!
		Returns the string identifier of the object. For example a TXsheet object is identified by "xsheet", 
		a TStageObjectTree is identified by PegbarTree.
	*/
	inline string getStreamTag() const;
 
	/*!
		This pure virtual method is used to define a global pointer to the object.
		This method is overridden with the macro PERSIST_DECLARATION(T).
	\n	For example:
		\code
class DVAPI TStageObjectTree : public TPersist {
PERSIST_DECLARATION(TStageObjectTree)
public:
 
...
		
		\endcode 
	*/
	virtual const TPersistDeclaration *getDeclaration() const = 0;
 
	typedef TPersist *CreateProc();
	static void declare(CreateProc *);
	/*!
		If the object identified by \a name doesn't exist,
		this method creates it through TPersistDeclarationT class template.
		\sa getDeclaration()
	*/
	static TPersist *create(const string &name);
};
 
//===================================================================
/*!
		This class is used to store and retrieve the id associated to an object.
		\sa TPersist::getStreamTag().
		The class is istantiated by the macro  PERSIST_DECLARATION(T).
	*/
class DVAPI TPersistDeclaration
{
	string m_id;
 
public:
	TPersistDeclaration(const string &id);
	virtual ~TPersistDeclaration() {}
	string getId() const { return m_id; };
	virtual TPersist *create() const = 0;
};
 
//-------------------------------------------------------------------
 
inline string TPersist::getStreamTag() const { return getDeclaration()->getId(); }
 
//-------------------------------------------------------------------
/*!
		This template class is used to create an istance of the class \a T.
	*/
template <class T>
class TPersistDeclarationT : public TPersistDeclaration
{
public:
	/*!
		This is the constructor. Its argument is the id of the object.
		\sa TPersist::getStreamTag()
	*/
	TPersistDeclarationT(const string &id) : TPersistDeclaration(id) {}
	/*!
		Returns a pointer to a newly created object of type TPersist.
		This template class is called by the macro PERSIST_DECLARATION(T).
		A class that calls PERSIST_DECLARATION(T) must inherits TPersist.
	*/
	TPersist *create() const { return new T; };
};
 
//-------------------------------------------------------------------
/*!	\file tpersist.h  
	*/
/*!
		This macro must be included at the beginning of a class declaration,
		and permits to create a new object of type T with the use of template 
		class TPersistDeclarationT
	*/
#define PERSIST_DECLARATION(T)                        \
private:                                              \
	static TPersistDeclarationT<T> m_declaration;     \
                                                      \
public:                                               \
	const TPersistDeclaration *getDeclaration() const \
	{                                                 \
		return &m_declaration;                        \
	}
 
#define PERSIST_IDENTIFIER(T, I) \
	TPersistDeclarationT<T> T::m_declaration(I);
 
//===================================================================
 
#endif