389a23c538
Resolves #148131 - Unlock `std::optional<T&>` implementation - Allow instantiations of `optional<T(&)(...)>` and `optional<T(&)[]>` but disables `value_or()` and `optional::iterator` + all `iterator` related functions - Update documentation - Update tests
100 lines
2.8 KiB
C++
100 lines
2.8 KiB
C++
//===----------------------------------------------------------------------===//
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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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// <optional>
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// template<class F> constexpr optional or_else(F&&) &&;
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// template<class F> constexpr optional or_else(F&&) const&;
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#include "MoveOnly.h"
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#include <cassert>
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#include <optional>
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struct NonMovable {
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NonMovable() = default;
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NonMovable(NonMovable&&) = delete;
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};
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template <class Opt, class F>
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concept has_or_else = requires(Opt&& opt, F&& f) {
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{std::forward<Opt>(opt).or_else(std::forward<F>(f))};
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};
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template <class T>
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std::optional<T> return_optional() {}
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static_assert(has_or_else<std::optional<int>&, decltype(return_optional<int>)>);
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static_assert(has_or_else<std::optional<int>&&, decltype(return_optional<int>)>);
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static_assert(!has_or_else<std::optional<MoveOnly>&, decltype(return_optional<MoveOnly>)>);
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static_assert(has_or_else<std::optional<MoveOnly>&&, decltype(return_optional<MoveOnly>)>);
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static_assert(!has_or_else<std::optional<NonMovable>&, decltype(return_optional<NonMovable>)>);
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static_assert(!has_or_else<std::optional<NonMovable>&&, decltype(return_optional<NonMovable>)>);
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std::optional<int> take_int(int) { return 0; }
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void take_int_return_void(int) {}
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static_assert(!has_or_else<std::optional<int>, decltype(take_int)>);
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static_assert(!has_or_else<std::optional<int>, decltype(take_int_return_void)>);
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static_assert(!has_or_else<std::optional<int>, int>);
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constexpr bool test() {
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{
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std::optional<int> opt;
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assert(opt.or_else([] { return std::optional<int>{0}; }) == 0);
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opt = 1;
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opt.or_else([] {
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assert(false);
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return std::optional<int>{};
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});
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}
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{
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std::optional<MoveOnly> opt;
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opt = std::move(opt).or_else([] { return std::optional<MoveOnly>{MoveOnly{}}; });
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std::move(opt).or_else([] {
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assert(false);
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return std::optional<MoveOnly>{};
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});
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}
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#if TEST_STD_VER >= 26
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{
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int i = 2;
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std::optional<int&> opt;
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assert(opt.or_else([&] { return std::optional<int&>{i}; }) == i);
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int j = 3;
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opt = j;
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opt.or_else([] {
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assert(false);
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return std::optional<int&>{};
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});
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assert(opt == j);
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}
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{
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int i = 2;
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std::optional<int&> opt;
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assert(std::move(opt).or_else([&] { return std::optional<int&>{i}; }) == i);
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int j = 3;
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opt = j;
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std::move(opt).or_else([] {
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assert(false);
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return std::optional<int&>{};
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});
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assert(opt == j);
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}
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#endif
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return true;
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}
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int main(int, char**) {
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test();
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static_assert(test());
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return 0;
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}
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