is_functor_argument_immutable.h

/*  This file is part of the Vc library. {{{
Copyright © 2014-2016 Matthias Kretz <kretz@kde.org>
 
Redistribution and use in source and binary forms, with or without
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      notice, this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in the
      documentation and/or other materials provided with the distribution.
    * Neither the names of contributing organizations nor the
      names of its contributors may be used to endorse or promote products
      derived from this software without specific prior written permission.
 
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE FOR ANY
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}}}*/
 
#ifndef VC_TRAITS_IS_FUNCTOR_ARGUMENT_IMMUTABLE_H_
#define VC_TRAITS_IS_FUNCTOR_ARGUMENT_IMMUTABLE_H_
 
namespace Vc_VERSIONED_NAMESPACE
{
namespace Traits
{
namespace is_functor_argument_immutable_impl
{
template <typename F, typename A> std::true_type   test(void (F::*)(A));
template <typename F, typename A> std::true_type   test(void (F::*)(A) const);
template <typename F, typename A> std::is_const<A> test(void (F::*)(A &));
template <typename F, typename A> std::is_const<A> test(void (F::*)(A &) const);
template <typename F, typename A> std::is_const<A> test(void (F::*)(A &&));
template <typename F, typename A> std::is_const<A> test(void (F::*)(A &&) const);
 
struct dummy {};
 
// generate a true_type for template operator() members in F that are callable with a
// 'const A &' argument even if the template parameter to operator() is fixed to 'A'.
template <
    typename F, typename A,
#ifdef Vc_MSVC
// MSVC fails if the template keyword is used to *correctly* tell the compiler that <A> is
// an explicit template instantiation of operator()
#define Vc_TEMPLATE_
#else
#define Vc_TEMPLATE_ template
#endif
    typename MemberPtr = decltype(&F::Vc_TEMPLATE_ operator()<A>)>
decltype(is_functor_argument_immutable_impl::test(std::declval<MemberPtr>())) test2(int);
#undef Vc_TEMPLATE_
 
// generate a true_type for non-template operator() members in F that are callable with a
// 'const A &' argument.
template <typename F, typename A>
decltype(
    is_functor_argument_immutable_impl::test(std::declval<decltype(&F::operator())>()))
test2(float);
 
template <typename A> std::true_type   test3(void(*)(A));
template <typename A> std::is_const<A> test3(void(*)(A &));
template <typename A> std::is_const<A> test3(void(*)(A &&));
 
}  // namespace is_functor_argument_immutable_impl
 
template <typename F, typename A, bool = std::is_function<F>::value>
struct is_functor_argument_immutable;
template <typename F, typename A>
struct is_functor_argument_immutable<F, A, false>
    : decltype(is_functor_argument_immutable_impl::test2<
                      typename std::remove_reference<F>::type, A>(int())) {
};
template <typename F, typename A>
struct is_functor_argument_immutable<F, A, true>
    : decltype(is_functor_argument_immutable_impl::test3(std::declval<F>())) {
};
 
}  // namespace Traits
}  // namespace Vc
 
#endif  // VC_TRAITS_IS_FUNCTOR_ARGUMENT_IMMUTABLE_H_
 
// vim: foldmethod=marker