ceph/src/boost/libs/bimap/include/boost/bimap/relation/support/value_type_of.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 relation/support/value_type_of.hpp
  10 /// \brief value_type_of<tag,relation> metafunction
  11
  12 #ifndef BOOST_BIMAP_RELATION_SUPPORT_VALUE_TYPE_OF_HPP
  13 #define BOOST_BIMAP_RELATION_SUPPORT_VALUE_TYPE_OF_HPP
  14
  15 #if defined(_MSC_VER)
  16 #pragma once
  17 #endif
  18
  19 #include <boost/config.hpp>
  20
  21 #include <boost/bimap/relation/detail/metadata_access_builder.hpp>
  22
  23 /** \struct boost::bimaps::relation::support::value_type_of
  24
  25 \brief Metafunction to obtain the value type of one of the sides.
  26
  27 \code
  28
  29 template< class Tag, class Relation >
  30 struct value_type_of
  31 {
  32         typedef typename Relation::{side}_type type;
  33 };
  34
  35 \endcode
  36
  37 See also member_at, get().
  38 \ingroup relation_group
  39                                                                     **/
  40
  41 namespace boost {
  42 namespace bimaps {
  43 namespace relation {
  44 namespace support {
  45
  46 // Metafunction value_type_of
  47 /*
  48
  49     template< class Tag, class Relation >
  50     struct value_type_of
  51     {
  52         typedef -unspecified- type;
  53     };
  54
  55 */
  56
  57 BOOST_BIMAP_SYMMETRIC_METADATA_ACCESS_BUILDER
  58 (
  59     value_type_of,
  60     left_value_type,
  61     right_value_type
  62 )
  63
  64 // Add support for info tags to value_type_of
  65
  66 template< class Tag, class SymmetricType >
  67 struct value_type_of
  68 <
  69     Tag, SymmetricType,
  70     BOOST_DEDUCED_TYPENAME enable_if
  71     <
  72         ::boost::bimaps::relation::support::is_tag_of_member_at_info
  73         <
  74             Tag,
  75             SymmetricType
  76         >
  77
  78     >::type
  79 >
  80 {
  81     typedef BOOST_DEDUCED_TYPENAME SymmetricType::info_type type;
  82 };
  83
  84 } // namespace support
  85 } // namespace relation
  86 } // namespace bimaps
  87 } // namespace boost
  88
  89
  90 #endif // BOOST_BIMAP_RELATION_SUPPORT_VALUE_TYPE_OF_HPP
  91