ceph/src/boost/boost/multi_index/detail/hash_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_HASH_INDEX_ARGS_HPP
  10 #define BOOST_MULTI_INDEX_DETAIL_HASH_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/functional/hash.hpp>
  18 #include <boost/mpl/aux_/na.hpp>
  19 #include <boost/mpl/eval_if.hpp>
  20 #include <boost/mpl/identity.hpp>
  21 #include <boost/mpl/if.hpp>
  22 #include <boost/multi_index/tag.hpp>
  23 #include <boost/static_assert.hpp>
  24 #include <boost/type_traits/is_same.hpp>
  25 #include <functional>
  26
  27 namespace boost{
  28
  29 namespace multi_index{
  30
  31 namespace detail{
  32
  33 /* Hashed index specifiers can be instantiated in two forms:
  34  *
  35  *   (hashed_unique|hashed_non_unique)<
  36  *     KeyFromValue,
  37  *     Hash=boost::hash<KeyFromValue::result_type>,
  38  *     Pred=std::equal_to<KeyFromValue::result_type> >
  39  *   (hashed_unique|hashed_non_unique)<
  40  *     TagList,
  41  *     KeyFromValue,
  42  *     Hash=boost::hash<KeyFromValue::result_type>,
  43  *     Pred=std::equal_to<KeyFromValue::result_type> >
  44  *
  45  * hashed_index_args implements the machinery to accept this
  46  * argument-dependent polymorphism.
  47  */
  48
  49 template<typename KeyFromValue>
  50 struct index_args_default_hash
  51 {
  52   typedef ::boost::hash<typename KeyFromValue::result_type> type;
  53 };
  54
  55 template<typename KeyFromValue>
  56 struct index_args_default_pred
  57 {
  58   typedef std::equal_to<typename KeyFromValue::result_type> type;
  59 };
  60
  61 template<typename Arg1,typename Arg2,typename Arg3,typename Arg4>
  62 struct hashed_index_args
  63 {
  64   typedef is_tag<Arg1> full_form;
  65
  66   typedef typename mpl::if_<
  67     full_form,
  68     Arg1,
  69     tag< > >::type                                   tag_list_type;
  70   typedef typename mpl::if_<
  71     full_form,
  72     Arg2,
  73     Arg1>::type                                      key_from_value_type;
  74   typedef typename mpl::if_<
  75     full_form,
  76     Arg3,
  77     Arg2>::type                                      supplied_hash_type;
  78   typedef typename mpl::eval_if<
  79     mpl::is_na<supplied_hash_type>,
  80     index_args_default_hash<key_from_value_type>,
  81     mpl::identity<supplied_hash_type>
  82   >::type                                            hash_type;
  83   typedef typename mpl::if_<
  84     full_form,
  85     Arg4,
  86     Arg3>::type                                      supplied_pred_type;
  87   typedef typename mpl::eval_if<
  88     mpl::is_na<supplied_pred_type>,
  89     index_args_default_pred<key_from_value_type>,
  90     mpl::identity<supplied_pred_type>
  91   >::type                                            pred_type;
  92
  93   BOOST_STATIC_ASSERT(is_tag<tag_list_type>::value);
  94   BOOST_STATIC_ASSERT(!mpl::is_na<key_from_value_type>::value);
  95   BOOST_STATIC_ASSERT(!mpl::is_na<hash_type>::value);
  96   BOOST_STATIC_ASSERT(!mpl::is_na<pred_type>::value);
  97 };
  98
  99 } /* namespace multi_index::detail */
 100
 101 } /* namespace multi_index */
 102
 103 } /* namespace boost */
 104
 105 #endif