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

   1 /* Copyright 2003-2013 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_ORD_INDEX_ARGS_HPP
  10 #define BOOST_MULTI_INDEX_DETAIL_ORD_INDEX_ARGS_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/aux_/na.hpp>
  18 #include <boost/mpl/eval_if.hpp>
  19 #include <boost/mpl/identity.hpp>
  20 #include <boost/mpl/if.hpp>
  21 #include <boost/multi_index/tag.hpp>
  22 #include <boost/static_assert.hpp>
  23 #include <boost/type_traits/is_same.hpp>
  24 #include <functional>
  25
  26 namespace boost{
  27
  28 namespace multi_index{
  29
  30 namespace detail{
  31
  32 /* Oredered index specifiers can be instantiated in two forms:
  33  *
  34  *   (ordered_unique|ordered_non_unique)<
  35  *     KeyFromValue,Compare=std::less<KeyFromValue::result_type> >
  36  *   (ordered_unique|ordered_non_unique)<
  37  *     TagList,KeyFromValue,Compare=std::less<KeyFromValue::result_type> >
  38  *
  39  * index_args implements the machinery to accept this argument-dependent
  40  * polymorphism.
  41  */
  42
  43 template<typename KeyFromValue>
  44 struct index_args_default_compare
  45 {
  46   typedef std::less<typename KeyFromValue::result_type> type;
  47 };
  48
  49 template<typename Arg1,typename Arg2,typename Arg3>
  50 struct ordered_index_args
  51 {
  52   typedef is_tag<Arg1> full_form;
  53
  54   typedef typename mpl::if_<
  55     full_form,
  56     Arg1,
  57     tag< > >::type                                   tag_list_type;
  58   typedef typename mpl::if_<
  59     full_form,
  60     Arg2,
  61     Arg1>::type                                      key_from_value_type;
  62   typedef typename mpl::if_<
  63     full_form,
  64     Arg3,
  65     Arg2>::type                                      supplied_compare_type;
  66   typedef typename mpl::eval_if<
  67     mpl::is_na<supplied_compare_type>,
  68     index_args_default_compare<key_from_value_type>,
  69     mpl::identity<supplied_compare_type>
  70   >::type                                            compare_type;
  71
  72   BOOST_STATIC_ASSERT(is_tag<tag_list_type>::value);
  73   BOOST_STATIC_ASSERT(!mpl::is_na<key_from_value_type>::value);
  74   BOOST_STATIC_ASSERT(!mpl::is_na<compare_type>::value);
  75 };
  76
  77 } /* namespace multi_index::detail */
  78
  79 } /* namespace multi_index */
  80
  81 } /* namespace boost */
  82
  83 #endif