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
82template <typename T, typename RecursiveVariant, typename NoWrapper>
83struct enable_recursive
84 : BOOST_VARIANT_AUX_ENABLE_RECURSIVE_IMPL(
85 T, RecursiveVariant, ::boost::recursive_variant_
86 )
87{
88};
89
90template <typename T, typename RecursiveVariant>
91struct enable_recursive< T,RecursiveVariant,mpl::false_ >
92{
93private: // helpers, for metafunction result (below)
94
95 typedef typename BOOST_VARIANT_AUX_ENABLE_RECURSIVE_IMPL(
96 T, RecursiveVariant, ::boost::recursive_variant_
97 )::type t_;
98
99public: // metafunction result
100
101 // [Wrap with recursive_wrapper only if rebind really changed something:]
102 typedef typename mpl::if_<
103 mpl::or_<
104 is_same< t_,T >
105 , is_reference<t_>
106 , is_pointer<t_>
107 >
108 , t_
109 , boost::recursive_wrapper<t_>
110 >::type type;
111
112};
113
114
115///////////////////////////////////////////////////////////////////////////////
116// (detail) metafunction class quoted_enable_recursive
117//
118// Same behavior as enable_recursive metafunction (see above).
119//
120template <typename RecursiveVariant, typename NoWrapper>
121struct quoted_enable_recursive
122{
123 template <typename T>
124 struct apply
125 : enable_recursive<T, RecursiveVariant, NoWrapper>
126 {
127 };
128};
129
130}} // namespace detail::variant
131} // namespace boost
132
133#endif // BOOST_VARIANT_DETAIL_ENABLE_RECURSIVE_HPP
134