mirror of
https://github.com/boostorg/hof.git
synced 2026-02-01 08:32:12 +00:00
71 lines
1.8 KiB
C++
71 lines
1.8 KiB
C++
/*=============================================================================
|
|
Copyright (c) 2015 Paul Fultz II
|
|
constexpr_deduce.h
|
|
Distributed under the Boost Software License, Version 1.0. (See accompanying
|
|
file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
|
|
==============================================================================*/
|
|
|
|
#ifndef FIT_GUARD_FUNCTION_CONSTEXPR_DEDUCE_H
|
|
#define FIT_GUARD_FUNCTION_CONSTEXPR_DEDUCE_H
|
|
|
|
|
|
#ifndef FIT_NO_UNIQUE_STATIC_LAMBDA_FUNCTION_ADDR
|
|
#if defined(_MSC_VER)
|
|
#define FIT_NO_UNIQUE_STATIC_LAMBDA_FUNCTION_ADDR 1
|
|
#else
|
|
#define FIT_NO_UNIQUE_STATIC_LAMBDA_FUNCTION_ADDR 0
|
|
#endif
|
|
#endif
|
|
|
|
#define FIT_CONST_FOLD(x) (__builtin_constant_p(x) ? (x) : (x))
|
|
|
|
namespace fit {
|
|
|
|
namespace detail {
|
|
|
|
struct constexpr_deduce
|
|
{
|
|
constexpr constexpr_deduce()
|
|
{}
|
|
template<class F>
|
|
constexpr operator F() const
|
|
{
|
|
return F();
|
|
}
|
|
};
|
|
|
|
template<class T>
|
|
struct constexpr_deduce_unique
|
|
{
|
|
constexpr constexpr_deduce_unique()
|
|
{}
|
|
#if FIT_NO_UNIQUE_STATIC_LAMBDA_FUNCTION_ADDR
|
|
template<class F>
|
|
constexpr operator F() const
|
|
{
|
|
// static_assert(std::is_default_constructible<F>::value, "Function not default constructible");
|
|
return F();
|
|
}
|
|
#else
|
|
template<class F>
|
|
constexpr operator const F&() const
|
|
{
|
|
static_assert(FIT_IS_EMPTY(F), "Function or lambda expression must be empty");
|
|
return FIT_CONST_FOLD(reinterpret_cast<const F&>(static_const_var<T>()));
|
|
}
|
|
#endif
|
|
};
|
|
|
|
}} // namespace fit
|
|
|
|
#define FIT_DETAIL_CONSTEXPR_DEDUCE true ? fit::detail::constexpr_deduce() :
|
|
#define FIT_DETAIL_CONSTEXPR_DEDUCE_UNIQUE(T) true ? fit::detail::constexpr_deduce_unique<T>() :
|
|
|
|
#ifdef _MSC_VER
|
|
#define FIT_DETAIL_MSVC_CONSTEXPR_DEDUCE FIT_DETAIL_CONSTEXPR_DEDUCE
|
|
#else
|
|
#define FIT_DETAIL_MSVC_CONSTEXPR_DEDUCE
|
|
#endif
|
|
|
|
#endif
|