81 lines
2.3 KiB
C++
81 lines
2.3 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Copyright 2024 Bloomberg Finance L.P.
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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// UNSUPPORTED: c++03 || c++11 || c++14 || c++17 || c++20
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// ADDITIONAL_COMPILE_FLAGS: -freflection
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// ADDITIONAL_COMPILE_FLAGS: -Wno-inconsistent-missing-override
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// <experimental/reflection>
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//
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// [reflection]
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//
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// RUN: %{build}
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// RUN: %{exec} %t.exe > %t.stdout
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#include <meta>
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#include <array>
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#include <print>
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#include <ranges>
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#include <tuple>
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consteval auto struct_to_tuple_type(std::meta::info type) -> std::meta::info {
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constexpr auto remove_cvref = [](std::meta::info r) consteval {
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return substitute(^^std::remove_cvref_t, {r});
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};
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constexpr auto ctx = std::meta::access_context::current();
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return substitute(^^std::tuple,
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nonstatic_data_members_of(type, ctx)
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| std::views::transform(std::meta::type_of)
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| std::views::transform(remove_cvref)
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| std::ranges::to<std::vector>());
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}
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template <typename To, typename From, std::meta::info... members>
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constexpr auto struct_to_tuple_helper(From const& from) -> To {
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return To(from.[:members:]...);
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}
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template<typename From>
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consteval auto get_struct_to_tuple_helper() {
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using To = [: struct_to_tuple_type(^^From) :];
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std::vector args = {^^To, ^^From};
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constexpr auto ctx = std::meta::access_context::current();
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for (auto mem : nonstatic_data_members_of(^^From, ctx)) {
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args.push_back(reflect_constant(mem));
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}
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return extract<To(*)(From const&)>(substitute(^^struct_to_tuple_helper,
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args));
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}
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template <typename From>
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constexpr auto struct_to_tuple(From const& from) {
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return get_struct_to_tuple_helper<From>()(from);
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}
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struct S { bool i; int j; int k; };
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int main() {
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{
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constexpr S s = {true, 55, 66};
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constexpr auto t = struct_to_tuple(s);
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std::println("({}, {}, {})", get<0>(t), get<1>(t), get<2>(t));
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}
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{
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auto t = struct_to_tuple<S>({false, 11, 22});
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std::println("({}, {}, {})", get<0>(t), get<1>(t), get<2>(t));
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}
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}
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