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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
+