1//-----------------------------------------------------------------------------
2// boost variant/detail/enable_recursive_fwd.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_FWD_HPP
14#define BOOST_VARIANT_DETAIL_ENABLE_RECURSIVE_FWD_HPP
15
16#include <boost/mpl/aux_/config/ctps.hpp>
17
18#include <boost/mpl/bool_fwd.hpp>
19
20# include <boost/mpl/bool.hpp>
21
22namespace boost {
23namespace detail { namespace variant {
24
25///////////////////////////////////////////////////////////////////////////////
26// (detail) tag recursive_flag
27//
28// Signifies that the variant should perform recursive substituion.
29//
30
31
32template <typename T>
33struct recursive_flag
34{
35 typedef T type;
36};
37
38
39///////////////////////////////////////////////////////////////////////////////
40// (detail) metafunction is_recursive_flag
41//
42// Signifies that the variant should perform recursive substituion.
43//
44
45
46template <typename T>
47struct is_recursive_flag
48 : mpl::false_
49{
50};
51
52template <typename T>
53struct is_recursive_flag< recursive_flag<T> >
54 : mpl::true_
55{
56};
57
58
59///////////////////////////////////////////////////////////////////////////////
60// (detail) metafunction enable_recursive
61//
62// Attempts recursive_variant_ tag substitution, wrapping with
63// boost::recursive_wrapper if substituion occurs w/ non-indirect result
64// (i.e., not a reference or pointer) *and* NoWrapper is false_.
65//
66template <
67 typename T
68 , typename RecursiveVariant
69 , typename NoWrapper = mpl::false_
70 >
71struct enable_recursive;
72
73///////////////////////////////////////////////////////////////////////////////
74// (detail) metafunction class quoted_enable_recursive
75//
76// Same behavior as enable_recursive metafunction (see above).
77//
78template <
79 typename RecursiveVariant
80 , typename NoWrapper = mpl::false_
81 >
82struct quoted_enable_recursive;
83
84}} // namespace detail::variant
85} // namespace boost
86
87#endif // BOOST_VARIANT_DETAIL_ENABLE_RECURSIVE_FWD_HPP
88