1 // (C) Copyright 2008 CodeRage, LLC (turkanis at coderage dot com)
2 // (C) Copyright 2003-2007 Jonathan Turkanis
3 // Distributed under the Boost Software License, Version 1.0. (See accompanying
4 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.)
5
6 // See http://www.boost.org/libs/iostreams for documentation.
7
8 #ifndef BOOST_IOSTREAMS_DETAIL_WRAP_UNWRAP_HPP_INCLUDED
9 #define BOOST_IOSTREAMS_DETAIL_WRAP_UNWRAP_HPP_INCLUDED
10
11 #if defined(_MSC_VER)
12 # pragma once
13 #endif
14
15 #include <boost/config.hpp> // SFINAE, MSVC.
16 #include <boost/detail/workaround.hpp>
17 #include <boost/iostreams/detail/enable_if_stream.hpp>
18 #include <boost/iostreams/traits_fwd.hpp> // is_std_io.
19 #include <boost/mpl/bool.hpp>
20 #include <boost/mpl/identity.hpp>
21 #include <boost/mpl/eval_if.hpp>
22 #include <boost/mpl/if.hpp>
23 #include <boost/ref.hpp>
24
25 namespace boost { namespace iostreams { namespace detail {
26
27 //------------------Definition of wrap/unwrap traits--------------------------//
28
29 template<typename T>
30 struct wrapped_type
31 : mpl::if_<is_std_io<T>, reference_wrapper<T>, T>
32 { };
33
34 template<typename T>
35 struct unwrapped_type
36 : unwrap_reference<T>
37 { };
38
39 template<typename T>
40 struct unwrap_ios
41 : mpl::eval_if<
42 is_std_io<T>,
43 unwrap_reference<T>,
44 mpl::identity<T>
45 >
46 { };
47
48 //------------------Definition of wrap----------------------------------------//
49
50 #ifndef BOOST_NO_SFINAE //----------------------------------------------------//
51 template<typename T>
wrap(const T & t BOOST_IOSTREAMS_DISABLE_IF_STREAM (T))52 inline T wrap(const T& t BOOST_IOSTREAMS_DISABLE_IF_STREAM(T))
53 { return t; }
54
55 template<typename T>
56 inline typename wrapped_type<T>::type
wrap(T & t BOOST_IOSTREAMS_ENABLE_IF_STREAM (T))57 wrap(T& t BOOST_IOSTREAMS_ENABLE_IF_STREAM(T)) { return boost::ref(t); }
58 #else // #ifndef BOOST_NO_SFINAE //-------------------------------------------//
59 template<typename T>
60 inline typename wrapped_type<T>::type // BCC 5.x needs namespace qualification.
wrap_impl(const T & t,mpl::true_)61 wrap_impl(const T& t, mpl::true_) { return boost::ref(const_cast<T&>(t)); }
62
63 template<typename T>
64 inline typename wrapped_type<T>::type // BCC 5.x needs namespace qualification.
wrap_impl(T & t,mpl::true_)65 wrap_impl(T& t, mpl::true_) { return boost::ref(t); }
66
67 template<typename T>
68 inline typename wrapped_type<T>::type
wrap_impl(const T & t,mpl::false_)69 wrap_impl(const T& t, mpl::false_) { return t; }
70
71 template<typename T>
72 inline typename wrapped_type<T>::type
wrap_impl(T & t,mpl::false_)73 wrap_impl(T& t, mpl::false_) { return t; }
74
75 template<typename T>
76 inline typename wrapped_type<T>::type
wrap(const T & t)77 wrap(const T& t) { return wrap_impl(t, is_std_io<T>()); }
78
79 template<typename T>
80 inline typename wrapped_type<T>::type
wrap(T & t)81 wrap(T& t) { return wrap_impl(t, is_std_io<T>()); }
82 #endif // #ifndef BOOST_NO_SFINAE //------------------------------------------//
83
84 //------------------Definition of unwrap--------------------------------------//
85
86 template<typename T>
87 typename unwrapped_type<T>::type&
unwrap(const reference_wrapper<T> & ref)88 unwrap(const reference_wrapper<T>& ref) { return ref.get(); }
89
90 template<typename T>
unwrap(T & t)91 typename unwrapped_type<T>::type& unwrap(T& t) { return t; }
92
93 template<typename T>
unwrap(const T & t)94 const typename unwrapped_type<T>::type& unwrap(const T& t) { return t; }
95
96 } } } // End namespaces detail, iostreams, boost.
97
98 #endif // #ifndef BOOST_IOSTREAMS_DETAIL_WRAP_UNWRAP_HPP_INCLUDED
99