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37 lines
1.1 KiB
37 lines
1.1 KiB
#pragma once
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#include <utility>
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#include "exopt.h"
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#define _EO_CONSTANT_VALUE(X) ([] { \
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struct { \
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typedef decltype(X) comptime_constant_t; \
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consteval operator comptime_constant_t() const noexcept { return (X); } \
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} inner; \
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return inner; \
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}())
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namespace exopt { namespace util [[gnu::visibility("internal")]] {
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template<typename T, typename U>
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concept comptime = std::convertible_to<T, U> and requires{
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typename T::comptime_constant_t;
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};
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constexpr auto comptime_value(auto value) noexcept {
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using U = decltype(value);
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struct inner {
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typedef U comptime_constant_t;
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consteval operator comptime_constant_t() const noexcept { return std::move(value); }
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U value;
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constexpr inner(std::add_rvalue_reference_t<U> m) noexcept : value(std::move(m)) {}
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constexpr ~inner() = default;
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};
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return inner{ std::move(value) };
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}
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static_assert(comptime_value(std::string_view{"hello"}.size()) == 5, "Bad comptime_value()");
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static_assert(_EO_CONSTANT_VALUE(std::string_view{"hello world"}) == std::string_view{"hello world"}, "Bad CONSTANT_VALUE()");
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} }
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