96 lines
2.3 KiB
Plaintext
96 lines
2.3 KiB
Plaintext
// Copyright David Abrahams 2001.
|
|
// 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)
|
|
#ifndef FORWARD_DWA20011215_HPP
|
|
# define FORWARD_DWA20011215_HPP
|
|
|
|
# include <boost/mpl/if.hpp>
|
|
# include <boost/type_traits/is_scalar.hpp>
|
|
# include <boost/type_traits/add_const.hpp>
|
|
# include <boost/type_traits/add_reference.hpp>
|
|
# include <boost/ref.hpp>
|
|
# include <boost/python/detail/value_arg.hpp>
|
|
# include <boost/python/detail/copy_ctor_mutates_rhs.hpp>
|
|
# include <boost/mpl/or.hpp>
|
|
|
|
namespace boost { namespace python { namespace objects {
|
|
|
|
// Very much like boost::reference_wrapper<T>, except that in this
|
|
// case T can be a reference already without causing a
|
|
// reference-to-reference error.
|
|
template <class T>
|
|
struct reference_to_value
|
|
{
|
|
typedef typename add_reference<typename add_const<T>::type>::type reference;
|
|
|
|
reference_to_value(reference x) : m_value(x) {}
|
|
reference get() const { return m_value; }
|
|
private:
|
|
reference m_value;
|
|
};
|
|
|
|
// A little metaprogram which selects the type to pass through an
|
|
// intermediate forwarding function when the destination argument type
|
|
// is T.
|
|
template <class T>
|
|
struct forward
|
|
: mpl::if_<
|
|
mpl::or_<python::detail::copy_ctor_mutates_rhs<T>, is_scalar<T> >
|
|
, T
|
|
, reference_to_value<T>
|
|
>
|
|
{
|
|
};
|
|
|
|
template<typename T>
|
|
struct unforward
|
|
{
|
|
typedef typename unwrap_reference<T>::type& type;
|
|
};
|
|
|
|
template<typename T>
|
|
struct unforward<reference_to_value<T> >
|
|
{
|
|
typedef T type;
|
|
};
|
|
|
|
template <typename T>
|
|
struct unforward_cref
|
|
: python::detail::value_arg<
|
|
typename unwrap_reference<T>::type
|
|
>
|
|
{
|
|
};
|
|
|
|
template<typename T>
|
|
struct unforward_cref<reference_to_value<T> >
|
|
: add_reference<typename add_const<T>::type>
|
|
{
|
|
};
|
|
|
|
|
|
template <class T>
|
|
typename reference_to_value<T>::reference
|
|
do_unforward(reference_to_value<T> const& x, int)
|
|
{
|
|
return x.get();
|
|
}
|
|
|
|
template <class T>
|
|
typename reference_wrapper<T>::type&
|
|
do_unforward(reference_wrapper<T> const& x, int)
|
|
{
|
|
return x.get();
|
|
}
|
|
|
|
template <class T>
|
|
T const& do_unforward(T const& x, ...)
|
|
{
|
|
return x;
|
|
}
|
|
|
|
}}} // namespace boost::python::objects
|
|
|
|
#endif // FORWARD_DWA20011215_HPP
|