ceph/src/boost/libs/bimap/include/boost/bimap/container_adaptor/detail/functor_bag.hpp

   1 // Boost.Bimap
   2 //
   3 // Copyright (c) 2006-2007 Matias Capeletto
   4 //
   5 // Distributed under the Boost Software License, Version 1.0.
   6 // (See accompanying file LICENSE_1_0.txt or copy at
   7 // http://www.boost.org/LICENSE_1_0.txt)
   8
   9 /// \file container_adaptor/detail/functor_bag.hpp
  10 /// \brief Defines a EBO optimizacion helper for functors.
  11
  12 #ifndef BOOST_BIMAP_CONTAINER_ADAPTOR_DETAIL_FUNCTOR_BAG_HPP
  13 #define BOOST_BIMAP_CONTAINER_ADAPTOR_DETAIL_FUNCTOR_BAG_HPP
  14
  15 #if defined(_MSC_VER)
  16 #pragma once
  17 #endif
  18
  19 #include <boost/config.hpp>
  20
  21 #if defined(BOOST_MSVC)
  22 // This bogus warning will appear when add_const is applied to a
  23 // const volatile reference because we can't detect const volatile
  24 // references with MSVC6.
  25 #   pragma warning(push)
  26 #   pragma warning(disable:4181)
  27 // warning C4181: qualifier applied to reference type ignored
  28 #endif
  29
  30 #include <boost/mpl/placeholders.hpp>
  31
  32 #include <boost/type_traits/add_reference.hpp>
  33 #include <boost/type_traits/is_base_of.hpp>
  34
  35 #include <boost/mpl/inherit_linearly.hpp>
  36 #include <boost/mpl/inherit.hpp>
  37
  38 namespace boost {
  39 namespace bimaps {
  40 namespace container_adaptor {
  41 namespace detail {
  42
  43 /// \brief EBO optimizacion helper for functors
  44 /**
  45
  46 This class is a generalization of a helper class explained in an article by
  47 Nathan C. Myers.\n
  48 See it at \link http://www.cantrip.org/emptyopt.html
  49                                                                                     **/
  50
  51 template < class Data, class FunctorList >
  52 struct data_with_functor_bag :
  53
  54     public mpl::inherit_linearly<
  55
  56         FunctorList,
  57         mpl::if_< is_base_of< mpl::_2, mpl::_1 >,
  58         //   {
  59                  mpl::_1,
  60         //   }
  61         //   else
  62         //   {
  63                  mpl::inherit< mpl::_1, mpl::_2 >
  64         //   }
  65         >
  66
  67     >::type
  68 {
  69     Data data;
  70
  71     data_with_functor_bag() {}
  72
  73     data_with_functor_bag(BOOST_DEDUCED_TYPENAME add_reference<Data>::type d)
  74         : data(d) {}
  75
  76     template< class Functor >
  77     Functor& functor()
  78     {
  79         return *(static_cast<Functor*>(this));
  80     }
  81
  82     template< class Functor >
  83     const Functor& functor() const
  84     {
  85         return *(static_cast<Functor const *>(this));
  86     }
  87 };
  88
  89 } // namespace detail
  90 } // namespace container_adaptor
  91 } // namespace bimaps
  92 } // namespace boost
  93
  94 #if defined(BOOST_MSVC)
  95 #   pragma warning(pop)
  96 #endif
  97
  98 #endif // BOOST_BIMAP_CONTAINER_ADAPTOR_DETAIL_FUNCTOR_BAG_HPP
  99
 100