//----------------------------------------------------------------------------- | |
// boost variant/detail/generic_result_type.hpp header file | |
// See http://www.boost.org for updates, documentation, and revision history. | |
//----------------------------------------------------------------------------- | |
// | |
// Copyright (c) 2003 | |
// Eric Friedman | |
// | |
// 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 BOOST_VARIANT_DETAIL_GENERIC_RESULT_TYPE_HPP | |
#define BOOST_VARIANT_DETAIL_GENERIC_RESULT_TYPE_HPP | |
#include "boost/config.hpp" | |
////////////////////////////////////////////////////////////////////////// | |
// (workaround) macro BOOST_VARIANT_AUX_GENERIC_RESULT_TYPE | |
// | |
// On compilers with BOOST_NO_VOID_RETURNS, this macro provides a route | |
// to a single syntax for dealing with template functions that may (but | |
// not necessarily) return nothing (i.e. void). | |
// | |
// BOOST_VARIANT_AUX_RETURN_VOID provided for compilers w/ (erroneous?) | |
// warnings about non-void functions not returning a value. | |
// | |
#if !defined(BOOST_NO_VOID_RETURNS) | |
#define BOOST_VARIANT_AUX_GENERIC_RESULT_TYPE(T) \ | |
T \ | |
/**/ | |
#define BOOST_VARIANT_AUX_RETURN_VOID \ | |
/**/ | |
#define BOOST_VARIANT_AUX_RETURN_VOID_TYPE \ | |
void \ | |
/**/ | |
#else // defined(BOOST_NO_VOID_RETURNS) | |
namespace boost { | |
namespace detail { namespace variant { | |
struct fake_return_void | |
{ | |
fake_return_void() | |
{ | |
} | |
template <typename T> | |
fake_return_void(const T&) | |
{ | |
} | |
}; | |
template <typename T> | |
struct no_void_returns_helper | |
{ | |
typedef T type; | |
}; | |
template <> | |
struct no_void_returns_helper<void> | |
{ | |
typedef fake_return_void type; | |
}; | |
}} // namespace detail::variant | |
} // namespace boost | |
#define BOOST_VARIANT_AUX_GENERIC_RESULT_TYPE(T) \ | |
BOOST_DEDUCED_TYPENAME \ | |
::boost::detail::variant::no_void_returns_helper< T >::type \ | |
/**/ | |
#define BOOST_VARIANT_AUX_RETURN_VOID \ | |
return ::boost::detail::variant::fake_return_void() \ | |
/**/ | |
#define BOOST_VARIANT_AUX_RETURN_VOID_TYPE \ | |
::boost::detail::variant::fake_return_void | |
#endif // BOOST_NO_VOID_RETURNS workaround | |
#endif // BOOST_VARIANT_DETAIL_GENERIC_RESULT_TYPE_HPP |