utility.hpp

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//   ___ __  __ ___ 
//  / __|  \/  | _ \ GMP(Generative Metaprogramming)
// | (_ | |\/| |  _/ version 0.2.0
//  \___|_|  |_|_|   https://github.com/lkimuk/gmp
//
// SPDX-FileCopyrightText: 2023-2026 Miles Li <https://www.cppmore.com/>
// SPDX-License-Identifier: MIT
//
// This file is part of the GMP (Generative Metaprogramming) library.
// Full project source: https://github.com/lkimuk/gmp
 
#ifndef GMP_META_UTILITY_HPP_
#define GMP_META_UTILITY_HPP_
 
namespace gmp {
 
template<auto>
struct constant_arg_t {
    explicit constant_arg_t() = default;
};
 
template<auto V>
inline constexpr constant_arg_t<V> constant_arg{};
 
struct any { template<typename T> operator T() const; };
 
namespace detail {
 
template<typename T>
struct wrapper {
    const T value{};
    static const wrapper<T> long_lifetime_obj;
 
    wrapper() = default;
    wrapper(const wrapper&) = delete;
    wrapper& operator=(const wrapper&) = delete;
    wrapper& operator=(wrapper&&) = delete;
};
 
template<typename T>
const wrapper<T> wrapper<T>::long_lifetime_obj{};
 
} // namespace detail
 
template<typename T>
consteval const T& as_value() noexcept {
    return detail::wrapper<T>::long_lifetime_obj.value;
}
 
} // namespace gmp
 
#endif // GMP_META_UTILITY_HPP_