ceph/src/boost/boost/multi_index/detail/no_duplicate_tags.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_NO_DUPLICATE_TAGS_HPP
  10 #define BOOST_MULTI_INDEX_DETAIL_NO_DUPLICATE_TAGS_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/fold.hpp>
  18 #include <boost/mpl/set/set0.hpp>
  19
  20 namespace boost{
  21
  22 namespace multi_index{
  23
  24 namespace detail{
  25
  26 /* no_duplicate_tags check at compile-time that a tag list
  27  * has no duplicate tags.
  28  * The algorithm deserves some explanation: tags
  29  * are sequentially inserted into a mpl::set if they were
  30  * not already present. Due to the magic of mpl::set
  31  * (mpl::has_key is contant time), this operation takes linear
  32  * time, and even MSVC++ 6.5 handles it gracefully (other obvious
  33  * solutions are quadratic.)
  34  */
  35
  36 struct duplicate_tag_mark{};
  37
  38 struct duplicate_tag_marker
  39 {
  40   template <typename MplSet,typename Tag>
  41   struct apply
  42   {
  43     typedef mpl::s_item<
  44       typename mpl::if_<mpl::has_key<MplSet,Tag>,duplicate_tag_mark,Tag>::type,
  45       MplSet
  46     > type;
  47   };
  48 };
  49
  50 template<typename TagList>
  51 struct no_duplicate_tags
  52 {
  53   typedef typename mpl::fold<
  54     TagList,
  55     mpl::set0<>,
  56     duplicate_tag_marker
  57   >::type aux;
  58
  59   BOOST_STATIC_CONSTANT(
  60     bool,value=!(mpl::has_key<aux,duplicate_tag_mark>::value));
  61 };
  62
  63 /* Variant for an index list: duplication is checked
  64  * across all the indices.
  65  */
  66
  67 struct duplicate_tag_list_marker
  68 {
  69   template <typename MplSet,typename Index>
  70   struct apply:mpl::fold<
  71     BOOST_DEDUCED_TYPENAME Index::tag_list,
  72     MplSet,
  73     duplicate_tag_marker>
  74   {
  75   };
  76 };
  77
  78 template<typename IndexList>
  79 struct no_duplicate_tags_in_index_list
  80 {
  81   typedef typename mpl::fold<
  82     IndexList,
  83     mpl::set0<>,
  84     duplicate_tag_list_marker
  85   >::type aux;
  86
  87   BOOST_STATIC_CONSTANT(
  88     bool,value=!(mpl::has_key<aux,duplicate_tag_mark>::value));
  89 };
  90
  91 } /* namespace multi_index::detail */
  92
  93 } /* namespace multi_index */
  94
  95 } /* namespace boost */
  96
  97 #endif