///////////////////////////////////////////////////////////////
//
// DynaLinkResolver.h: interface for the CDynaLinkResolver class.
//
// 2002 (c) Igor Vartanov
//
// Version 1.1
//
// Last update: Jul 19 2002
//
// mailto:ivartanov@rsdn.ru
// FIDOnet 2:5025/16.26 AKA /38.70
//
///////////////////////////////////////////////////////////////

#if !defined(AFX_DYNALINKRESOLVER_H__A0D0B3AB_097C_11D6_9C72_000476186749__INCLUDED_)
#define AFX_DYNALINKRESOLVER_H__A0D0B3AB_097C_11D6_9C72_000476186749__INCLUDED_

#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000

#include <crtdbg.h>

template <class T>
class CDynaLinkResolver  
{
protected:
    T         m_pRef;
    HINSTANCE m_hLib;

public:

    CDynaLinkResolver() : m_pRef( NULL ), m_hLib( NULL )
    {
    }
    
    CDynaLinkResolver( LPCTSTR pszLib, LPCSTR pszName ) : m_pRef( NULL ), m_hLib( NULL )
    {
        Link( pszLib, pszName );
    }
    
    virtual ~CDynaLinkResolver()
    {
        Unlink();
    }
    
    BOOL IsValid()
    { 
        return BOOL( m_pRef ); 
    }

    BOOL Link( LPCTSTR pszLib, LPCSTR pszName )
    {
        _ASSERTE( !m_hLib );
        m_hLib = ::LoadLibrary( pszLib );
        if( m_hLib )
        {
            if( !( m_pRef = (T) ::GetProcAddress( m_hLib, pszName ) ) )
                Unlink();
        }
        _ASSERTE( m_pRef ); // func isn't resolved OK
        return BOOL( m_pRef );
    }

    BOOL Unlink()
    {
        _ASSERTE( m_hLib );
        if( m_hLib )
        {
            BOOL res = ::FreeLibrary( m_hLib );
            _ASSERTE( res );
            m_pRef = NULL;
            m_hLib = NULL;
            return res;
        }
        return FALSE;
    }

    HINSTANCE GetInstance()
    {
        return m_hLib;
    }

    T Refer()
    {
        _ASSERTE(m_pRef);
        return m_pRef;
    }

    T operator()()
    {
        _ASSERTE(m_pRef);
        return m_pRef; 
    }
};

#ifndef stringer
#define stringer( x ) ( #x )
#endif

#define DYNA_LINK_NAME( funcname, libname, type ) \
    CDynaLinkResolver< type > funcname ( _T( #libname ), stringer( funcname ) );

#define DYNA_LINK_NAME_( objname, funcname, libname, type ) \
    CDynaLinkResolver< type > objname ( _T( #libname ), stringer( funcname ) );

#define DYNA_LINK_PTR( ptrname, type ) \
    CDynaLinkResolver< type > * ptrname = new CDynaLinkResolver< type >;

#define DYNA_LINK_PTR_( ptrname, funcname, libname, type ) \
    CDynaLinkResolver< type > * ptrname =                  \
        new CDynaLinkResolver< type > ( _T( #libname ), stringer( funcname ) );

#endif // !defined(AFX_DYNALINKRESOLVER_H__A0D0B3AB_097C_11D6_9C72_000476186749__INCLUDED_)