| 1 | |
|---|---|
| 2 | #ifndef BOOST_MPL_VOID_HPP_INCLUDED |
| 3 | #define BOOST_MPL_VOID_HPP_INCLUDED |
| 4 | |
| 5 | // Copyright Aleksey Gurtovoy 2001-2004 |
| 6 | // |
| 7 | // Distributed under the Boost Software License, Version 1.0. |
| 8 | // (See accompanying file LICENSE_1_0.txt or copy at |
| 9 | // http://www.boost.org/LICENSE_1_0.txt) |
| 10 | // |
| 11 | // See http://www.boost.org/libs/mpl for documentation. |
| 12 | |
| 13 | // $Id$ |
| 14 | // $Date$ |
| 15 | // $Revision$ |
| 16 | |
| 17 | #include <boost/mpl/void_fwd.hpp> |
| 18 | #include <boost/mpl/bool.hpp> |
| 19 | #include <boost/mpl/aux_/na_spec.hpp> |
| 20 | #include <boost/mpl/aux_/config/msvc.hpp> |
| 21 | #include <boost/mpl/aux_/config/workaround.hpp> |
| 22 | |
| 23 | BOOST_MPL_AUX_ADL_BARRIER_NAMESPACE_OPEN |
| 24 | |
| 25 | // [JDG Feb-4-2003] made void_ a complete type to allow it to be |
| 26 | // instantiated so that it can be passed in as an object that can be |
| 27 | // used to select an overloaded function. Possible use includes signaling |
| 28 | // a zero arity functor evaluation call. |
| 29 | struct void_ { typedef void_ type; }; |
| 30 | |
| 31 | BOOST_MPL_AUX_ADL_BARRIER_NAMESPACE_CLOSE |
| 32 | |
| 33 | namespace boost { namespace mpl { |
| 34 | |
| 35 | template< typename T > |
| 36 | struct is_void_ |
| 37 | : false_ |
| 38 | { |
| 39 | #if BOOST_WORKAROUND(BOOST_MSVC, < 1300) |
| 40 | using false_::value; |
| 41 | #endif |
| 42 | }; |
| 43 | |
| 44 | template<> |
| 45 | struct is_void_<void_> |
| 46 | : true_ |
| 47 | { |
| 48 | #if BOOST_WORKAROUND(BOOST_MSVC, < 1300) |
| 49 | using true_::value; |
| 50 | #endif |
| 51 | }; |
| 52 | |
| 53 | template< typename T > |
| 54 | struct is_not_void_ |
| 55 | : true_ |
| 56 | { |
| 57 | #if BOOST_WORKAROUND(BOOST_MSVC, < 1300) |
| 58 | using true_::value; |
| 59 | #endif |
| 60 | }; |
| 61 | |
| 62 | template<> |
| 63 | struct is_not_void_<void_> |
| 64 | : false_ |
| 65 | { |
| 66 | #if BOOST_WORKAROUND(BOOST_MSVC, < 1300) |
| 67 | using false_::value; |
| 68 | #endif |
| 69 | }; |
| 70 | |
| 71 | BOOST_MPL_AUX_NA_SPEC(1, is_void_) |
| 72 | BOOST_MPL_AUX_NA_SPEC(1, is_not_void_) |
| 73 | |
| 74 | }} |
| 75 | |
| 76 | #endif // BOOST_MPL_VOID_HPP_INCLUDED |
| 77 |