libt2n: (gerd) some progress with T2nWrapper (compiles but not complete yet)

[libt2n] / src / client_wrapper.hxx

/***************************************************************************
 *   Copyright (C) 2008 by Gerd v. Egidy and Reinhard Pfau                 *
 *   gve@intra2net.com                                                     *
 *                                                                         *
 *   This library is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU Lesser General Public License version   *
 *   2.1 as published by the Free Software Foundation.                     *
 *                                                                         *
 *   This library is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU Lesser General Public License for more details.                   *
 *                                                                         *
 *   You should have received a copy of the GNU Lesser General Public      *
 *   License along with this program; if not, write to the                 *
 *   Free Software Foundation, Inc.,                                       *
 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
 ***************************************************************************/
#ifndef __LIBT2N_CLIENT_WRAPPER
#define __LIBT2N_CLIENT_WRAPPER

#include <functional>

#include <boost/config.hpp>
#include <boost/any.hpp>
#include <boost/bind.hpp>
#include <boost/function.hpp>
#include <boost/preprocessor.hpp>

#include <client.hxx>
#include <command_client.hxx>

#ifndef T2NWRAPPER_MAX_ARGS
#define T2NWRAPPER_MAX_ARGS 9
#endif

namespace libt2n
{

class ConnectionInitData
{
    public:

        virtual std::auto_ptr<client_connection> createConnection()=0;

        virtual ~ConnectionInitData()
            { }
};

class TrivialHandler
{
    public:
        static void handle( boost::function< void() > f)
        {
            f();
        }
};

// contains the internal stuff needed for T2nWrapper
namespace detail
{

    template< typename T >
    struct TypeWrap
    {
        typedef T type;
    };

    template< >
    struct TypeWrap< void >
    {
        typedef int type;
    };

    template< typename R >
    struct Call
    {
        typedef boost::function< R() > FuncType;

        FuncType function;
        R& result;

        Call( FuncType f, R& res ) : function(f), result( res ) {}

        void operator()()
        {
            result= function();
        }
    };

    template< >
    struct Call<void>
    {
        typedef boost::function< void() > FuncType;
        typedef TypeWrap< void >::type ResultType;

        FuncType function;
        ResultType& result;

        Call( FuncType f, ResultType& res ) : function(f), result( res ) {}

        void operator()()
        {
            function();
            result= ResultType();
        }
    };
} // eo namespace detail

template<
    class Client,
    class Handler = TrivialHandler
>
class T2nWrapper
{
    private:

        std::auto_ptr<client_connection> conndConn;
        std::auto_ptr<Client> client;

        static std::auto_ptr<T2nWrapper> singletonObject;
        static std::auto_ptr<ConnectionInitData> initData;

        // create a prep-method for each possible number of parameters
#define _GEN_ARG(z,n,d) Arg ## n arg ##n
#define _GEN_PREP(z,n,d) \
        template< typename R  BOOST_PP_COMMA_IF(n) BOOST_PP_ENUM_PARAMS(n,typename Arg) > \
        static boost::function< R(Client*) > prep \
        ( \
            R(Client::*f)( BOOST_PP_ENUM_PARAMS(n,Arg) ) \
            BOOST_PP_COMMA_IF(n) \
            BOOST_PP_ENUM( n, _GEN_ARG, ~ ) \
        ) \
        { \
            return boost::bind< R > \
                ( \
                    f, _1  BOOST_PP_COMMA_IF(n) BOOST_PP_ENUM_PARAMS(n,arg) \
                ); \
        } // eo prep

        BOOST_PP_REPEAT( BOOST_PP_ADD(T2NWRAPPER_MAX_ARGS,1) , _GEN_PREP, ~ )

#undef _GEN_PREP
#undef _GEN_ARG

        static void ensureSingletonThere(void)
        {
            if (singletonObject.get() == NULL)
            {
                // we need to initialize

                if (initData.get() == NULL)
                    throw std::logic_error("T2nWrapper singleton used before setting initData");

                std::auto_ptr<client_connection> myConndConn=initData->createConnection();

            }
        }

        template< typename R >
        static
        typename detail::TypeWrap<R>::type real_exec( boost::function< R(Client*) > f)
        {
            ensureSingletonThere();

            typename detail::TypeWrap<R>::type result;
            detail::Call<R> call( boost::bind( f, &(*(singletonObject->client))), result );
            Handler::handle( call );
            return result;
        }

    public:

        static void setInitData(std::auto_ptr<ConnectionInitData> newInitData)
            { initData=newInitData; }
        static ConnectionInitData* getInitData(void)
            { return initData.get(); }

        T2nWrapper()
        {
            client=std::auto_ptr<Client>(new Client(*conndConn));
        }

        // create an exec-method for each possible number of parameters
#define _GEN_PLACEHOLDER(z,n,d) BOOST_PP_CAT(_,BOOST_PP_ADD(n,1))
#define _GEN_EXEC(z,n,d) \
        template< typename R  BOOST_PP_COMMA_IF(n) BOOST_PP_ENUM_PARAMS(n,typename Arg) > \
        static boost::function< R( BOOST_PP_ENUM_PARAMS(n,Arg) ) > exec \
        ( \
            R(Client::*f)( BOOST_PP_ENUM_PARAMS(n,Arg) ) \
        ) \
        { \
            boost::function<R(Client*)>(*p)(R(Client::*)( BOOST_PP_ENUM_PARAMS(n,Arg) ) \
                    BOOST_PP_COMMA_IF(n) BOOST_PP_ENUM_PARAMS(n,Arg)) \
                = &T2nWrapper::template prep<R BOOST_PP_COMMA_IF(n) BOOST_PP_ENUM_PARAMS(n,Arg) >; \
            return boost::bind \
            ( \
                T2nWrapper::template real_exec<R>, \
                boost::bind( p, f BOOST_PP_COMMA_IF(n) \
                BOOST_PP_ENUM(n, _GEN_PLACEHOLDER, ~ ) ) \
            ); \
        } // eo exec

        BOOST_PP_REPEAT( BOOST_PP_ADD(T2NWRAPPER_MAX_ARGS,1), _GEN_EXEC, ~ )

#undef _GEN_EXEC
#undef _GEN_PLACEHOLDER

};

}
#endif