ceph/src/boost/libs/function_types/include/boost/function_types/detail/class_transform.hpp

   1
   2 // (C) Copyright Tobias Schwinger
   3 //
   4 // Use modification and distribution are subject to the boost Software License,
   5 // Version 1.0. (See http://www.boost.org/LICENSE_1_0.txt).
   6
   7 //------------------------------------------------------------------------------
   8
   9 #ifndef BOOST_FT_DETAIL_CLASS_TRANSFORM_HPP_INCLUDED
  10 #define BOOST_FT_DETAIL_CLASS_TRANSFORM_HPP_INCLUDED
  11
  12 #include <boost/mpl/apply.hpp>
  13 #include <boost/mpl/always.hpp>
  14 #include <boost/mpl/identity.hpp>
  15 #include <boost/mpl/placeholders.hpp>
  16
  17 #include <boost/type_traits/remove_cv.hpp>
  18 #include <boost/type_traits/add_pointer.hpp>
  19 #include <boost/type_traits/add_reference.hpp>
  20
  21 namespace boost { namespace function_types { namespace detail {
  22
  23 using mpl::placeholders::_;
  24
  25 // Transformation metafunction for the class type of member function pointers.
  26 template<typename T, typename L>
  27 struct class_transform
  28 { typedef typename mpl::apply1<L,T>::type type; };
  29
  30
  31 // We can short-circuit the mechanism implemented in the primary template for
  32 // the most common lambda expression and save both the "un-lambdaing" and the
  33 // type traits invocation (we know that T can only be a class type).
  34
  35 template<typename T> struct class_transform< T, mpl::identity<_> >
  36 { typedef T type; };
  37
  38 template<typename T> struct class_transform< T, add_reference<_> >
  39 { typedef T & type; };
  40
  41 template<typename T> struct class_transform< T, add_pointer<_> >
  42 { typedef T * type; };
  43
  44 template<typename T> struct class_transform< T, remove_cv<_> >
  45 { typedef typename boost::remove_cv<T>::type type; };
  46
  47 template<typename T> struct class_transform< T, add_reference< remove_cv<_> > >
  48 { typedef typename boost::remove_cv<T>::type & type; };
  49
  50 template<typename T> struct class_transform< T, add_pointer< remove_cv<_> > >
  51 { typedef typename boost::remove_cv<T>::type * type; };
  52
  53 template<typename T, typename U> struct class_transform< T, mpl::always<U> >
  54 { typedef U type; };
  55
  56
  57 } } } // namespace ::boost::function_types::detail
  58
  59 #endif
  60