boost/type_traits/decay.hpp

   1 //  (C) Copyright John Maddock & Thorsten Ottosen 2005.
   2 //  Use, modification and distribution are subject to the Boost Software License,
   3 //  Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   4 //  http://www.boost.org/LICENSE_1_0.txt).
   5 //
   6 //  See http://www.boost.org/libs/type_traits for most recent version including documentation.
   7
   8
   9 #ifndef BOOST_TT_DECAY_HPP_INCLUDED
  10 #define BOOST_TT_DECAY_HPP_INCLUDED
  11
  12 #include <boost/type_traits/config.hpp>
  13 #include <boost/type_traits/is_array.hpp>
  14 #include <boost/type_traits/is_function.hpp>
  15 #include <boost/type_traits/remove_bounds.hpp>
  16 #include <boost/type_traits/add_pointer.hpp>
  17 #include <boost/type_traits/remove_reference.hpp>
  18 #include <boost/mpl/eval_if.hpp>
  19 #include <boost/mpl/identity.hpp>
  20
  21 namespace boost
  22 {
  23
  24     template< class T >
  25     struct decay
  26     {
  27     private:
  28         typedef BOOST_DEDUCED_TYPENAME remove_reference<T>::type Ty;
  29     public:
  30         typedef BOOST_DEDUCED_TYPENAME mpl::eval_if<
  31             is_array<Ty>,
  32             mpl::identity<BOOST_DEDUCED_TYPENAME remove_bounds<Ty>::type*>,
  33             BOOST_DEDUCED_TYPENAME mpl::eval_if<
  34                 is_function<Ty>,
  35                 add_pointer<Ty>,
  36                 mpl::identity<Ty>
  37             >
  38         >::type type;
  39     };
  40
  41 } // namespace boost
  42
  43
  44 #endif // BOOST_TT_DECAY_HPP_INCLUDED