/Src/Dependencies/Boost/boost/variant/detail/enable_recursive.hpp

  1//-----------------------------------------------------------------------------
  2// boost variant/detail/enable_recursive.hpp header file
  3// See http://www.boost.org for updates, documentation, and revision history.
  4//-----------------------------------------------------------------------------
  5//
  6// Copyright (c) 2003
  7// Eric Friedman
  8//
  9// Distributed under the Boost Software License, Version 1.0. (See
 10// accompanying file LICENSE_1_0.txt or copy at
 11// http://www.boost.org/LICENSE_1_0.txt)
 12
 13#ifndef BOOST_VARIANT_DETAIL_ENABLE_RECURSIVE_HPP
 14#define BOOST_VARIANT_DETAIL_ENABLE_RECURSIVE_HPP
 15
 16#include "boost/variant/detail/enable_recursive_fwd.hpp"
 17#include "boost/variant/variant_fwd.hpp"
 18
 19#if !defined(BOOST_VARIANT_NO_FULL_RECURSIVE_VARIANT_SUPPORT)
 20#   include "boost/mpl/apply.hpp"
 21#   include "boost/mpl/eval_if.hpp"
 22#   include "boost/mpl/lambda.hpp"
 23#endif
 24
 25#include "boost/variant/detail/substitute.hpp"
 26#include "boost/mpl/aux_/config/ctps.hpp"
 27#include "boost/mpl/bool_fwd.hpp"
 28#include "boost/mpl/if.hpp"
 29#include "boost/mpl/or.hpp"
 30#include "boost/type_traits/is_pointer.hpp"
 31#include "boost/type_traits/is_reference.hpp"
 32#include "boost/type_traits/is_same.hpp"
 33
 34#include "boost/variant/recursive_wrapper.hpp"
 35
 36namespace boost {
 37namespace detail { namespace variant {
 38
 39#if !defined(BOOST_VARIANT_DETAIL_NO_SUBSTITUTE)
 40
 41#   define BOOST_VARIANT_AUX_ENABLE_RECURSIVE_IMPL(T,Dest,Source) \
 42    substitute< T , Dest , Source > \
 43    /**/
 44
 45#else // defined(BOOST_VARIANT_DETAIL_NO_SUBSTITUTE)
 46
 47///////////////////////////////////////////////////////////////////////////////
 48// (detail) class template rebind1
 49//
 50// Limited workaround in case 'substitute' metafunction unavailable.
 51//
 52
 53template <typename T, typename U1>
 54struct rebind1
 55{
 56private:
 57    typedef typename mpl::lambda<
 58          mpl::identity<T>
 59        >::type le_;
 60
 61public:
 62    typedef typename mpl::eval_if<
 63          is_same< le_, mpl::identity<T> >
 64        , le_ // identity<T>
 65        , mpl::apply1<le_, U1>
 66        >::type type;
 67};
 68
 69#   define BOOST_VARIANT_AUX_ENABLE_RECURSIVE_IMPL(T,Dest,Source) \
 70    rebind1< T , Dest > \
 71    /**/
 72
 73#endif // !defined(BOOST_VARIANT_DETAIL_NO_SUBSTITUTE)
 74
 75///////////////////////////////////////////////////////////////////////////////
 76// (detail) metafunction enable_recursive
 77//
 78// See boost/variant/detail/enable_recursive_fwd.hpp for more information.
 79//
 80
 81#if !defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
 82
 83template <typename T, typename RecursiveVariant, typename NoWrapper>
 84struct enable_recursive
 85    : BOOST_VARIANT_AUX_ENABLE_RECURSIVE_IMPL(
 86          T, RecursiveVariant, ::boost::recursive_variant_
 87        )
 88{
 89};
 90
 91template <typename T, typename RecursiveVariant>
 92struct enable_recursive< T,RecursiveVariant,mpl::false_ >
 93{
 94private: // helpers, for metafunction result (below)
 95
 96    typedef typename BOOST_VARIANT_AUX_ENABLE_RECURSIVE_IMPL(
 97          T, RecursiveVariant, ::boost::recursive_variant_
 98        )::type t_;
 99
100public: // metafunction result
101
102    // [Wrap with recursive_wrapper only if rebind really changed something:]
103    typedef typename mpl::if_<
104          mpl::or_<
105              is_same< t_,T >
106            , is_reference<t_>
107            , is_pointer<t_>
108            >
109        , t_
110        , boost::recursive_wrapper<t_>
111        >::type type;
112
113};
114
115#else // defined(BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION)
116
117template <typename T, typename RecursiveVariant, typename NoWrapper>
118struct enable_recursive
119{
120private: // helpers, for metafunction result (below)
121
122    typedef typename BOOST_VARIANT_AUX_ENABLE_RECURSIVE_IMPL(
123          T, RecursiveVariant, ::boost::recursive_variant_
124        )::type t_;
125
126public: // metafunction result
127
128    // [Wrap with recursive_wrapper only if rebind really changed something:]
129    typedef typename mpl::if_<
130          mpl::or_<
131              NoWrapper
132            , is_same< t_,T >
133            , is_reference<t_>
134            , is_pointer<t_>
135            >
136        , t_
137        , boost::recursive_wrapper<t_>
138        >::type type;
139
140};
141
142#endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION workaround
143
144///////////////////////////////////////////////////////////////////////////////
145// (detail) metafunction class quoted_enable_recursive
146//
147// Same behavior as enable_recursive metafunction (see above).
148//
149template <typename RecursiveVariant, typename NoWrapper>
150struct quoted_enable_recursive
151{
152    template <typename T>
153    struct apply
154        : enable_recursive<T, RecursiveVariant, NoWrapper>
155    {
156    };
157};
158
159}} // namespace detail::variant
160} // namespace boost
161
162#endif // BOOST_VARIANT_DETAIL_ENABLE_RECURSIVE_HPP