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// (C) Copyright 2008 CodeRage, LLC (turkanis at coderage dot com)
// (C) Copyright 2003-2007 Jonathan Turkanis
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.)
// See http://www.boost.org/libs/iostreams for documentation.
#ifndef BOOST_IOSTREAMS_DETAIL_WRAP_UNWRAP_HPP_INCLUDED
#define BOOST_IOSTREAMS_DETAIL_WRAP_UNWRAP_HPP_INCLUDED
#if defined(_MSC_VER) && (_MSC_VER >= 1020)
# pragma once
#endif
#include <boost/config.hpp> // SFINAE, MSVC.
#include <boost/detail/workaround.hpp>
#include <boost/iostreams/detail/enable_if_stream.hpp>
#include <boost/iostreams/traits_fwd.hpp> // is_std_io.
#include <boost/mpl/bool.hpp>
#include <boost/mpl/identity.hpp>
#include <boost/mpl/eval_if.hpp>
#include <boost/mpl/if.hpp>
#include <boost/ref.hpp>
namespace boost { namespace iostreams { namespace detail {
//------------------Definition of wrap/unwrap traits--------------------------//
template<typename T>
struct wrapped_type
: mpl::if_<is_std_io<T>, reference_wrapper<T>, T>
{ };
template<typename T>
struct unwrapped_type
: unwrap_reference<T>
{ };
template<typename T>
struct unwrap_ios
: mpl::eval_if<
is_std_io<T>,
unwrap_reference<T>,
mpl::identity<T>
>
{ };
//------------------Definition of wrap----------------------------------------//
#ifndef BOOST_NO_SFINAE //----------------------------------------------------//
template<typename T>
inline T wrap(const T& t BOOST_IOSTREAMS_DISABLE_IF_STREAM(T))
{ return t; }
template<typename T>
inline typename wrapped_type<T>::type
wrap(T& t BOOST_IOSTREAMS_ENABLE_IF_STREAM(T)) { return boost::ref(t); }
#else // #ifndef BOOST_NO_SFINAE //-------------------------------------------//
template<typename T>
inline typename wrapped_type<T>::type // BCC 5.x needs namespace qualification.
wrap_impl(const T& t, mpl::true_) { return boost::ref(const_cast<T&>(t)); }
template<typename T>
inline typename wrapped_type<T>::type // BCC 5.x needs namespace qualification.
wrap_impl(T& t, mpl::true_) { return boost::ref(t); }
template<typename T>
inline typename wrapped_type<T>::type
wrap_impl(const T& t, mpl::false_) { return t; }
template<typename T>
inline typename wrapped_type<T>::type
wrap_impl(T& t, mpl::false_) { return t; }
template<typename T>
inline typename wrapped_type<T>::type
wrap(const T& t) { return wrap_impl(t, is_std_io<T>()); }
template<typename T>
inline typename wrapped_type<T>::type
wrap(T& t) { return wrap_impl(t, is_std_io<T>()); }
#endif // #ifndef BOOST_NO_SFINAE //------------------------------------------//
//------------------Definition of unwrap--------------------------------------//
#if !BOOST_WORKAROUND(BOOST_MSVC, < 1310) //----------------------------------//
template<typename T>
typename unwrapped_type<T>::type&
unwrap(const reference_wrapper<T>& ref) { return ref.get(); }
template<typename T>
typename unwrapped_type<T>::type& unwrap(T& t) { return t; }
template<typename T>
const typename unwrapped_type<T>::type& unwrap(const T& t) { return t; }
#else // #if !BOOST_WORKAROUND(BOOST_MSVC, < 1310) //-------------------------//
// Since unwrap is a potential bottleneck, we avoid runtime tag dispatch.
template<bool IsRefWrap>
struct unwrap_impl;
template<>
struct unwrap_impl<true> {
template<typename T>
static typename unwrapped_type<T>::type& unwrap(const T& t)
{ return t.get(); }
};
template<>
struct unwrap_impl<false> {
template<typename T>
static typename unwrapped_type<T>::type& unwrap(const T& t)
{ return const_cast<T&>(t); }
};
template<typename T>
typename unwrapped_type<T>::type&
unwrap(const T& t)
{ return unwrap_impl<is_reference_wrapper<T>::value>::unwrap(t); }
#endif // #if !BOOST_WORKAROUND(BOOST_MSVC, < 1310) //------------------------//
} } } // End namespaces detail, iostreams, boost.
#endif // #ifndef BOOST_IOSTREAMS_DETAIL_WRAP_UNWRAP_HPP_INCLUDED
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