core/ref.hpp

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#ifndef BOOST_CORE_REF_HPP
#define BOOST_CORE_REF_HPP
 
// MS compatible compilers support #pragma once
 
#if defined(_MSC_VER) && (_MSC_VER >= 1020)
# pragma once
#endif
 
#include <boost/config.hpp>
#include <boost/utility/addressof.hpp>
#include <boost/detail/workaround.hpp>
 
//
//  ref.hpp - ref/cref, useful helper functions
//
//  Copyright (C) 1999, 2000 Jaakko Jarvi (jaakko.jarvi@cs.utu.fi)
//  Copyright (C) 2001, 2002 Peter Dimov
//  Copyright (C) 2002 David Abrahams
//
//  Copyright (C) 2014 Glen Joseph Fernandes
//  glenfe at live dot com
//  Copyright (C) 2014 Agustin Berge
//
// 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/core/doc/html/core/ref.html for documentation.
//
 
namespace boost
{
 
#if defined( BOOST_MSVC ) && BOOST_WORKAROUND( BOOST_MSVC, == 1600 )
 
    struct ref_workaround_tag {};
 
#endif
 
// reference_wrapper
 
template<class T> class reference_wrapper
{
public:
    typedef T type;
 
    BOOST_FORCEINLINE explicit reference_wrapper(T& t): t_(boost::addressof(t)) {}
 
#if defined( BOOST_MSVC ) && BOOST_WORKAROUND( BOOST_MSVC, == 1600 )
 
    BOOST_FORCEINLINE explicit reference_wrapper( T & t, ref_workaround_tag ): t_( boost::addressof( t ) ) {}
 
#endif
 
#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
 
    BOOST_DELETED_FUNCTION(reference_wrapper(T&& t))
public:
#endif
 
    BOOST_FORCEINLINE operator T& () const { return *t_; }
 
    BOOST_FORCEINLINE T& get() const { return *t_; }
 
    BOOST_FORCEINLINE T* get_pointer() const { return t_; }
 
private:
 
    T* t_;
};
 
// ref
 
#if defined( __BORLANDC__ ) && BOOST_WORKAROUND( __BORLANDC__, BOOST_TESTED_AT(0x581) )
#  define BOOST_REF_CONST
#else
#  define BOOST_REF_CONST const
#endif
 
template<class T> BOOST_FORCEINLINE reference_wrapper<T> BOOST_REF_CONST ref( T & t )
{
#if defined( BOOST_MSVC ) && BOOST_WORKAROUND( BOOST_MSVC, == 1600 )
 
    return reference_wrapper<T>( t, ref_workaround_tag() );
 
#else
 
    return reference_wrapper<T>( t );
 
#endif
}
 
// cref
 
template<class T> BOOST_FORCEINLINE reference_wrapper<T const> BOOST_REF_CONST cref( T const & t )
{
    return reference_wrapper<T const>(t);
}
 
#undef BOOST_REF_CONST
 
#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
 
#if defined(BOOST_NO_CXX11_DELETED_FUNCTIONS)
#  define BOOST_REF_DELETE
#else
#  define BOOST_REF_DELETE = delete
#endif
 
template<class T> void ref(T const&&) BOOST_REF_DELETE;
 
template<class T> void cref(T const&&) BOOST_REF_DELETE;
 
#undef BOOST_REF_DELETE
 
#endif
 
// is_reference_wrapper
 
template<typename T> struct is_reference_wrapper
{
    BOOST_STATIC_CONSTANT( bool, value = false );
};
 
template<typename T> struct is_reference_wrapper< reference_wrapper<T> >
{
    BOOST_STATIC_CONSTANT( bool, value = true );
};
 
#if !defined(BOOST_NO_CV_SPECIALIZATIONS)
 
template<typename T> struct is_reference_wrapper< reference_wrapper<T> const >
{
    BOOST_STATIC_CONSTANT( bool, value = true );
};
 
template<typename T> struct is_reference_wrapper< reference_wrapper<T> volatile >
{
    BOOST_STATIC_CONSTANT( bool, value = true );
};
 
template<typename T> struct is_reference_wrapper< reference_wrapper<T> const volatile >
{
    BOOST_STATIC_CONSTANT( bool, value = true );
};
 
#endif // !defined(BOOST_NO_CV_SPECIALIZATIONS)
 
// unwrap_reference
 
template<typename T> struct unwrap_reference
{
    typedef T type;
};
 
template<typename T> struct unwrap_reference< reference_wrapper<T> >
{
    typedef T type;
};
 
#if !defined(BOOST_NO_CV_SPECIALIZATIONS)
 
template<typename T> struct unwrap_reference< reference_wrapper<T> const >
{
    typedef T type;
};
 
template<typename T> struct unwrap_reference< reference_wrapper<T> volatile >
{
    typedef T type;
};
 
template<typename T> struct unwrap_reference< reference_wrapper<T> const volatile >
{
    typedef T type;
};
 
#endif // !defined(BOOST_NO_CV_SPECIALIZATIONS)
 
// unwrap_ref
 
template<class T> BOOST_FORCEINLINE typename unwrap_reference<T>::type& unwrap_ref( T & t )
{
    return t;
}
 
// get_pointer
 
template<class T> BOOST_FORCEINLINE T* get_pointer( reference_wrapper<T> const & r )
{
    return r.get_pointer();
}
} // namespace boost
 
#endif // #ifndef BOOST_CORE_REF_HPP