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// Copyright (C) 2009-2012 Lorenzo Caminiti
// Distributed under the Boost Software License, Version 1.0
// (see accompanying file LICENSE_1_0.txt or a copy at
// http://www.boost.org/LICENSE_1_0.txt)
// Home at http://www.boost.org/libs/functional/overloaded_function
#ifndef BOOST_FUNCTIONAL_OVERLOADED_FUNCTION_DETAIL_FUNCTION_TYPE_HPP_
#define BOOST_FUNCTIONAL_OVERLOADED_FUNCTION_DETAIL_FUNCTION_TYPE_HPP_
#include <boost/function_types/is_function.hpp>
#include <boost/function_types/is_function_pointer.hpp>
#include <boost/function_types/is_function_reference.hpp>
#include <boost/function_types/function_type.hpp>
#include <boost/function_types/parameter_types.hpp>
#include <boost/function_types/result_type.hpp>
#include <boost/type_traits/remove_pointer.hpp>
#include <boost/type_traits/remove_reference.hpp>
#include <boost/function.hpp>
#include <boost/mpl/if.hpp>
#include <boost/mpl/identity.hpp>
#include <boost/mpl/pop_front.hpp>
#include <boost/mpl/push_front.hpp>
#include <boost/typeof/typeof.hpp>
// Do not use namespace ::detail because overloaded_function is already a class.
namespace boost { namespace overloaded_function_detail {
// Requires: F is a monomorphic functor (i.e., has non-template `operator()`).
// Returns: F's function type `result_type (arg1_type, arg2_type, ...)`.
// It does not assume F typedef result_type, arg1_type, ... but needs typeof.
template<typename F>
class functor_type {
// NOTE: clang does not accept extra parenthesis `&(...)`.
typedef BOOST_TYPEOF_TPL(&F::operator()) call_ptr;
public:
typedef
typename boost::function_types::function_type<
typename boost::mpl::push_front<
typename boost::mpl::pop_front< // Remove functor type (1st).
typename boost::function_types::parameter_types<
call_ptr>::type
>::type
, typename boost::function_types::result_type<call_ptr>::type
>::type
>::type
type;
};
// NOTE: When using boost::function in Boost.Typeof emulation mode, the user
// has to register boost::functionN instead of boost::function in oder to
// do TYPEOF(F::operator()). That is confusing, so boost::function is handled
// separately so it does not require any Boost.Typeof registration at all.
template<typename F>
struct functor_type< boost::function<F> > {
typedef F type;
};
// Requires: F is a function type, pointer, reference, or monomorphic functor.
// Returns: F's function type `result_type (arg1_type, arg2_type, ...)`.
template<typename F>
struct function_type {
typedef
typename boost::mpl::if_<boost::function_types::is_function<F>,
boost::mpl::identity<F>
,
typename boost::mpl::if_<boost::function_types::
is_function_pointer<F>,
boost::remove_pointer<F>
,
typename boost::mpl::if_<boost::function_types::
is_function_reference<F>,
boost::remove_reference<F>
, // Else, requires that F is a functor.
functor_type<F>
>::type
>::type
>::type
::type type;
};
} } // namespace
#endif // #include guard
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