boost/typeof/msvc/typeof_impl.hpp
// Copyright (C) 2005 Igor Chesnokov, mailto:ichesnokov@gmail.com
// Copyright (C) 2005 Peder Holt
// Use, modification and distribution is subject to the Boost Software
// License, Version 1.0. (http://www.boost.org/LICENSE_1_0.txt)
#ifndef BOOST_TYPEOF_MSVC_TYPEOF_IMPL_HPP_INCLUDED
# define BOOST_TYPEOF_MSVC_TYPEOF_IMPL_HPP_INCLUDED
# include <boost/config.hpp>
# include <boost/detail/workaround.hpp>
# include <boost/mpl/int.hpp>
# include <boost/type_traits/is_function.hpp>
# include <boost/utility/enable_if.hpp>
namespace boost
{
namespace type_of
{
//Compile time constant code
# if BOOST_WORKAROUND(BOOST_MSVC,>=1300) && defined(_MSC_EXTENSIONS)
template<int N> struct the_counter;
template<typename T,int N = 5/*for similarity*/>
struct encode_counter
{
__if_exists(the_counter<N + 256>)
{
BOOST_STATIC_CONSTANT(unsigned,count=(encode_counter<T,N + 257>::count));
}
__if_not_exists(the_counter<N + 256>)
{
__if_exists(the_counter<N + 64>)
{
BOOST_STATIC_CONSTANT(unsigned,count=(encode_counter<T,N + 65>::count));
}
__if_not_exists(the_counter<N + 64>)
{
__if_exists(the_counter<N + 16>)
{
BOOST_STATIC_CONSTANT(unsigned,count=(encode_counter<T,N + 17>::count));
}
__if_not_exists(the_counter<N + 16>)
{
__if_exists(the_counter<N + 4>)
{
BOOST_STATIC_CONSTANT(unsigned,count=(encode_counter<T,N + 5>::count));
}
__if_not_exists(the_counter<N + 4>)
{
__if_exists(the_counter<N>)
{
BOOST_STATIC_CONSTANT(unsigned,count=(encode_counter<T,N + 1>::count));
}
__if_not_exists(the_counter<N>)
{
BOOST_STATIC_CONSTANT(unsigned,count=N);
typedef the_counter<N> type;
}
}
}
}
}
};
# define BOOST_TYPEOF_INDEX(T) (encode_counter<T>::count)
# define BOOST_TYPEOF_NEXT_INDEX(next)
# else
template<int N> struct encode_counter : encode_counter<N - 1> {};
template<> struct encode_counter<0> {};
//Need to default to a larger value than 4, as due to MSVC's ETI errors. (sizeof(int)==4)
char (*encode_index(...))[5];
# define BOOST_TYPEOF_INDEX(T) (sizeof(*boost::type_of::encode_index((boost::type_of::encode_counter<1005>*)0)))
# define BOOST_TYPEOF_NEXT_INDEX(next) friend char (*encode_index(encode_counter<next>*))[next];
# endif
//Typeof code
# if BOOST_WORKAROUND(BOOST_MSVC,==1300)
template<typename ID>
struct msvc_extract_type
{
template<bool>
struct id2type_impl;
typedef id2type_impl<true> id2type;
};
template<typename T, typename ID>
struct msvc_register_type : msvc_extract_type<ID>
{
template<>
struct id2type_impl<true> //VC7.0 specific bugfeature
{
typedef T type;
};
};
# else
template<typename ID>
struct msvc_extract_type
{
struct id2type;
};
template<typename T, typename ID>
struct msvc_register_type : msvc_extract_type<ID>
{
typedef msvc_extract_type<ID> base_type;
struct base_type::id2type // This uses nice VC6.5 and VC7.1 bugfeature
{
typedef T type;
};
};
# endif
template<int ID>
struct msvc_typeid_wrapper {
typedef typename msvc_extract_type<mpl::int_<ID> >::id2type id2type;
typedef typename id2type::type type;
};
//Workaround for ETI-bug for VC6 and VC7
template<>
struct msvc_typeid_wrapper<1> {
typedef msvc_typeid_wrapper<1> type;
};
//Workaround for ETI-bug for VC7.1
template<>
struct msvc_typeid_wrapper<4> {
typedef msvc_typeid_wrapper<4> type;
};
//Tie it all together
template<typename T>
struct encode_type
{
//Get the next available compile time constants index
BOOST_STATIC_CONSTANT(unsigned,value=BOOST_TYPEOF_INDEX(T));
//Instantiate the template
typedef typename msvc_register_type<T,mpl::int_<value> >::id2type type;
//Set the next compile time constants index
BOOST_STATIC_CONSTANT(unsigned,next=value+1);
//Increment the compile time constant (only needed when extensions are not active
BOOST_TYPEOF_NEXT_INDEX(next);
};
template<class T>
struct sizer
{
typedef char(*type)[encode_type<T>::value];
};
# ifdef BOOST_NO_SFINAE
template<typename T>
typename sizer<T>::type encode_start(T const&);
# else
template<typename T> typename disable_if<
typename is_function<T>::type,
typename sizer<T>::type>::type encode_start(T const&);
template<typename T> typename enable_if<
typename is_function<T>::type,
typename sizer<T>::type>::type encode_start(T&);
# endif
}
}
# define BOOST_TYPEOF(expr) \
boost::type_of::msvc_typeid_wrapper<sizeof(*boost::type_of::encode_start(expr))>::type
# define BOOST_TYPEOF_TPL(expr) typename BOOST_TYPEOF(expr)
# define BOOST_TYPEOF_NESTED_TYPEDEF_TPL(name,expr) \
struct name {\
template<typename T>\
static boost::type_of::msvc_register_type<T,name> _typeof_register_function(const T&);\
BOOST_STATIC_CONSTANT(int,_typeof_register_value=sizeof(_typeof_register_function(expr)));\
typedef typename boost::type_of::msvc_extract_type<name>::id2type id2type;\
typedef typename id2type::type type;\
};
# define BOOST_TYPEOF_NESTED_TYPEDEF(name,expr) \
struct name {\
template<typename T>\
static boost::type_of::msvc_register_type<T,name> _typeof_register_function(const T&);\
BOOST_STATIC_CONSTANT(int,_typeof_register_value=sizeof(_typeof_register_function(expr)));\
typedef boost::type_of::msvc_extract_type<name>::id2type id2type;\
typedef id2type::type type;\
};
#endif//BOOST_TYPEOF_MSVC_TYPEOF_IMPL_HPP_INCLUDED
