ceph/src/boost/boost/parameter/required.hpp

   1 // Copyright David Abrahams, Daniel Wallin 2003.
   2 // Distributed under the Boost Software License, Version 1.0.
   3 // (See accompanying file LICENSE_1_0.txt or copy at
   4 // http://www.boost.org/LICENSE_1_0.txt)
   5
   6 #ifndef BOOST_PARAMETER_REQUIRED_HPP
   7 #define BOOST_PARAMETER_REQUIRED_HPP
   8
   9 #include <boost/parameter/aux_/use_default.hpp>
  10
  11 namespace boost { namespace parameter {
  12
  13     // This metafunction can be used to describe the treatment of particular
  14     // named parameters for the purposes of overload elimination with SFINAE,
  15     // by placing specializations in the parameters<...> list.  In order for
  16     // a treated function to participate in overload resolution:
  17     //
  18     //   - all keyword tags wrapped in required<...> must have a matching
  19     //     actual argument
  20     //
  21     //   - The actual argument type matched by every keyword tag
  22     //     associated with a predicate must satisfy that predicate
  23     template <
  24         typename Tag
  25       , typename Predicate = ::boost::parameter::aux::use_default
  26     >
  27     struct required
  28     {
  29         typedef Tag key_type;
  30         typedef Predicate predicate;
  31     };
  32 }}
  33
  34 #include <boost/parameter/config.hpp>
  35
  36 #if defined(BOOST_PARAMETER_CAN_USE_MP11)
  37 #include <boost/mp11/integral.hpp>
  38 #else
  39 #include <boost/mpl/bool.hpp>
  40 #endif
  41
  42 namespace boost { namespace parameter { namespace aux {
  43
  44     template <typename T>
  45     struct is_required
  46 #if defined(BOOST_PARAMETER_CAN_USE_MP11)
  47       : ::boost::mp11::mp_false
  48 #else
  49       : ::boost::mpl::false_
  50 #endif
  51     {
  52     };
  53
  54     template <typename Tag, typename Predicate>
  55     struct is_required< ::boost::parameter::required<Tag,Predicate> >
  56 #if defined(BOOST_PARAMETER_CAN_USE_MP11)
  57       : ::boost::mp11::mp_true
  58 #else
  59       : ::boost::mpl::true_
  60 #endif
  61     {
  62     };
  63 }}} // namespace boost::parameter::aux
  64
  65 #endif  // include guard
  66