ceph/src/boost/libs/multi_index/include/boost/multi_index/detail/cons_stdtuple.hpp

   1 /* Copyright 2003-2014 Joaquin M Lopez Munoz.
   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  * See http://www.boost.org/libs/multi_index for library home page.
   7  */
   8
   9 #ifndef BOOST_MULTI_INDEX_DETAIL_CONS_STDTUPLE_HPP
  10 #define BOOST_MULTI_INDEX_DETAIL_CONS_STDTUPLE_HPP
  11
  12 #if defined(_MSC_VER)
  13 #pragma once
  14 #endif
  15
  16 #include <boost/config.hpp> /* keep it first to prevent nasty warns in MSVC */
  17 #include <boost/mpl/if.hpp>
  18 #include <boost/tuple/tuple.hpp>
  19 #include <tuple>
  20
  21 namespace boost{
  22
  23 namespace multi_index{
  24
  25 namespace detail{
  26
  27 /* std::tuple wrapper providing the cons-based interface of boost::tuple for
  28  * composite_key interoperability.
  29  */
  30
  31 template<typename StdTuple,std::size_t N>
  32 struct cons_stdtuple;
  33
  34 struct cons_stdtuple_ctor_terminal
  35 {
  36   typedef boost::tuples::null_type result_type;
  37
  38   template<typename StdTuple>
  39   static result_type create(const StdTuple&)
  40   {
  41     return boost::tuples::null_type();
  42   }
  43 };
  44
  45 template<typename StdTuple,std::size_t N>
  46 struct cons_stdtuple_ctor_normal
  47 {
  48   typedef cons_stdtuple<StdTuple,N> result_type;
  49
  50   static result_type create(const StdTuple& t)
  51   {
  52     return result_type(t);
  53   }
  54 };
  55
  56 template<typename StdTuple,std::size_t N=0>
  57 struct cons_stdtuple_ctor:
  58   boost::mpl::if_c<
  59     N<std::tuple_size<StdTuple>::value,
  60     cons_stdtuple_ctor_normal<StdTuple,N>,
  61     cons_stdtuple_ctor_terminal
  62   >::type
  63 {};
  64
  65 template<typename StdTuple,std::size_t N>
  66 struct cons_stdtuple
  67 {
  68   typedef typename std::tuple_element<N,StdTuple>::type head_type;
  69   typedef cons_stdtuple_ctor<StdTuple,N+1>              tail_ctor;
  70   typedef typename tail_ctor::result_type               tail_type;
  71
  72   cons_stdtuple(const StdTuple& t_):t(t_){}
  73
  74   const head_type& get_head()const{return std::get<N>(t);}
  75   tail_type get_tail()const{return tail_ctor::create(t);}
  76
  77   const StdTuple& t;
  78 };
  79
  80 template<typename StdTuple>
  81 typename cons_stdtuple_ctor<StdTuple>::result_type
  82 make_cons_stdtuple(const StdTuple& t)
  83 {
  84   return cons_stdtuple_ctor<StdTuple>::create(t);
  85 }
  86
  87 } /* namespace multi_index::detail */
  88
  89 } /* namespace multi_index */
  90
  91 } /* namespace boost */
  92
  93 #endif