/*
* Copyright (c) 2018 Jaroslav Jindrak
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* 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.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef LIBCPP_BITS_FUNCTION_CONDITIONAL_FUNCTION_TYPEDEFS
#define LIBCPP_BITS_FUNCTION_CONDITIONAL_FUNCTION_TYPEDEFS
namespace std::aux
{
/**
* Note: Some types with possible function-like behavior
* (e.g. function, reference_wrapper, aux::mem_fn_t)
* have to define a type argument type or two types
* first_argument_type and second_argument_type when
* their invocation takes one or two arguments, respectively.
*
* The easiest way to conditionally define a type is using
* inheritance and the types below serve exactly for that
* purpose.
*
* If we have a type that is specialized as R(Args...)
* for some return type R and argument types Args...,
* we can simply (publicly) inherit from
* conditional_function_typedefs<Args...>. If it is
* templated by some generic type T, we can inherit from
* conditional_function_typedefs<remove_cv_t<remove_reference_t<T>>>
* so that the correct type below gets chosen.
*/
template<class... Args>
struct conditional_function_typedefs
{ /* DUMMY BODY */ };
template<class A>
struct conditional_function_typedefs<A>
{
using argument_type = A;
};
template<class A1, class A2>
struct conditional_function_typedefs<A1, A2>
{
using first_argument_type = A1;
using second_argument_type = A2;
};
template<class R, class... Args>
struct conditional_function_typedefs<R(Args...)>
: conditional_function_typedefs<Args...>
{ /* DUMMY BODY */ };
}
#endif