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// Copyright (c) 2009-2020 Vladimir Batov.
// Use, modification and distribution are subject to the Boost Software License,
// Version 1.0. See http://www.boost.org/LICENSE_1_0.txt.
#ifndef BOOST_CONVERT_IS_CALLABLE_HPP
#define BOOST_CONVERT_IS_CALLABLE_HPP
#include <boost/convert/detail/has_member.hpp>
namespace boost { namespace cnv { namespace detail
{
using yes_type = ::boost::type_traits::yes_type;
using no_type = ::boost::type_traits:: no_type;
struct not_found {};
struct void_return_substitute {};
// The overloaded comma operator only kicks in for U != void essentially short-circuiting
// itself ineffective. Otherwise, when U=void, the standard op,() kicks in and returns
// 'void_return_substitute'.
template<typename U> U const& operator, (U const&, void_return_substitute);
template<typename U> U& operator, (U&, void_return_substitute);
template <typename src, typename dst> struct match_const { using type = dst; };
template <typename src, typename dst> struct match_const<src const, dst> { using type = dst const; };
template<typename T, typename return_type>
struct redirect
{
static no_type test (...);
static yes_type test (return_type);
};
template<typename T>
struct redirect<T, void>
{
static yes_type test (...);
static no_type test (not_found);
};
}}}
// No-args case needs to be implemented differently and has not been implemented yet.
// template <typename R>
// struct check<true, R ()>
// C1. Need to find some unique/ugly names so that they do not clash if this macro is
// used inside some other template class;
// C2. Body of the function is not actually used anywhere.
// However, Intel C++ compiler treats it as an error. So, we provide the body.
#define BOOST_DECLARE_IS_CALLABLE(__trait_name__, __member_name__) \
\
template <typename __boost_is_callable_T__, typename __boost_is_callable_signature__> \
class __trait_name__ \
{ \
using class_type = __boost_is_callable_T__; /*C1*/ \
using signature = __boost_is_callable_signature__; /*C1*/ \
using not_found = boost::cnv::detail::not_found; \
\
BOOST_DECLARE_HAS_MEMBER(has_member, __member_name__); \
\
struct mixin : class_type \
{ \
using class_type::__member_name__; \
not_found __member_name__(...) const { return not_found(); /*C2*/} \
}; \
using mixin_ptr = typename boost::cnv::detail::match_const<class_type, mixin>::type*; \
\
template <bool has, typename F> struct check { static bool const value = false; }; \
\
template <typename Arg1, typename R> \
struct check<true, R (Arg1)> \
{ \
using a1 = typename boost::decay<Arg1>::type*; \
\
static bool BOOST_CONSTEXPR_OR_CONST value = \
sizeof(boost::type_traits::yes_type) == \
sizeof(boost::cnv::detail::redirect<class_type, R>::test( \
(mixin_ptr(0)->__member_name__(*a1(0)), \
boost::cnv::detail::void_return_substitute()))); \
}; \
template <typename Arg1, typename Arg2, typename R> \
struct check<true, R (Arg1, Arg2)> \
{ \
using a1 = typename boost::decay<Arg1>::type*; \
using a2 = typename boost::decay<Arg2>::type*; \
\
static bool BOOST_CONSTEXPR_OR_CONST value = \
sizeof(boost::type_traits::yes_type) == \
sizeof(boost::cnv::detail::redirect<class_type, R>::test( \
(mixin_ptr(0)->__member_name__(*a1(0), *a2(0)), \
boost::cnv::detail::void_return_substitute()))); \
}; \
\
public: \
\
/* Check the existence of __member_name__ first, then the signature. */ \
static bool BOOST_CONSTEXPR_OR_CONST value = check<has_member<class_type>::value, signature>::value; \
}
#endif // BOOST_CONVERT_IS_CALLABLE_HPP
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