| // Copyright David Abrahams 2006. Distributed under the Boost |
| // Software License, Version 1.0. (See accompanying |
| // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
| #ifndef BOOST_PARAMETER_AUX_PARENTHESIZED_TYPE_DWA2006414_HPP |
| # define BOOST_PARAMETER_AUX_PARENTHESIZED_TYPE_DWA2006414_HPP |
| |
| # include <boost/config.hpp> |
| # include <boost/detail/workaround.hpp> |
| |
| namespace boost { namespace parameter { namespace aux { |
| |
| // A macro that takes a parenthesized C++ type name (T) and transforms |
| // it into an un-parenthesized type expression equivalent to T. |
| # define BOOST_PARAMETER_PARENTHESIZED_TYPE(x) \ |
| boost::parameter::aux::unaryfunptr_arg_type< void(*)x >::type |
| |
| // A metafunction that transforms void(*)(T) -> T |
| template <class UnaryFunctionPointer> |
| struct unaryfunptr_arg_type; |
| |
| # if !BOOST_WORKAROUND(BOOST_MSVC, <= 1300) |
| |
| template <class Arg> |
| struct unaryfunptr_arg_type<void(*)(Arg)> |
| { |
| typedef Arg type; |
| }; |
| |
| # else |
| |
| // Use the "native typeof" bugfeatures of older versions of MSVC to |
| // accomplish what we'd normally do with partial specialization. This |
| // capability was discovered by Igor Chesnokov. |
| |
| # if BOOST_WORKAROUND(BOOST_MSVC, != 1300) |
| |
| // This version applies to VC6.5 and VC7.1 (except that we can just |
| // use partial specialization for the latter in this case). |
| |
| // This gets used as a base class. |
| template<typename Address> |
| struct msvc_type_memory |
| { |
| // A nullary metafunction that will yield the Value type "stored" |
| // at this Address. |
| struct storage; |
| }; |
| |
| template<typename Value, typename Address> |
| struct msvc_store_type : msvc_type_memory<Address> |
| { |
| // VC++ somehow lets us define the base's nested storage |
| // metafunction here, where we have the Value type we'd like to |
| // "store" in it. Later we can come back to the base class and |
| // extract the "stored type." |
| typedef msvc_type_memory<Address> location; |
| struct location::storage |
| { |
| typedef Value type; |
| }; |
| }; |
| |
| # else |
| |
| // This slightly more complicated version of the same thing is |
| // required for msvc-7.0 |
| template<typename Address> |
| struct msvc_type_memory |
| { |
| template<bool> |
| struct storage_impl; |
| |
| typedef storage_impl<true> storage; |
| }; |
| |
| template<typename Value, typename Address> |
| struct msvc_store_type : msvc_type_memory<Address> |
| { |
| // Rather than supplying a definition for the base class' nested |
| // class, we specialize the base class' nested template |
| template<> |
| struct storage_impl<true> |
| { |
| typedef Value type; |
| }; |
| }; |
| |
| # endif |
| |
| // Function template argument deduction does many of the same things |
| // as type matching during partial specialization, so we call a |
| // function template to "store" T into the type memory addressed by |
| // void(*)(T). |
| template <class T> |
| msvc_store_type<T,void(*)(T)> |
| msvc_store_argument_type(void(*)(T)); |
| |
| template <class FunctionPointer> |
| struct unaryfunptr_arg_type |
| { |
| // We don't want the function to be evaluated, just instantiated, |
| // so protect it inside of sizeof. |
| enum { dummy = sizeof(msvc_store_argument_type((FunctionPointer)0)) }; |
| |
| // Now pull the type out of the instantiated base class |
| typedef typename msvc_type_memory<FunctionPointer>::storage::type type; |
| }; |
| |
| # endif |
| |
| template <> |
| struct unaryfunptr_arg_type<void(*)(void)> |
| { |
| typedef void type; |
| }; |
| |
| }}} // namespace boost::parameter::aux |
| |
| #endif // BOOST_PARAMETER_AUX_PARENTHESIZED_TYPE_DWA2006414_HPP |