| //===----------------------------------------------------------------------===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| |
| // <algorithm> |
| |
| // UNSUPPORTED: c++03, c++11, c++14, c++17 |
| |
| // template<class T, class Proj = identity, |
| // indirect_strict_weak_order<projected<const T*, Proj>> Comp = ranges::less> |
| // constexpr const T& |
| // ranges::clamp(const T& v, const T& lo, const T& hi, Comp comp = {}, Proj proj = {}); |
| |
| #include <algorithm> |
| #include <cassert> |
| #include <concepts> |
| #include <functional> |
| #include <utility> |
| |
| template <class T, class Comp = std::ranges::less, class Proj = std::identity> |
| concept HasClamp = |
| requires(T&& val, T&& low, T&& high, Comp&& comp, Proj&& proj) { |
| std::ranges::clamp(std::forward<T>(val), std::forward<T>(low), std::forward<T>(high), |
| std::forward<Comp>(comp), std::forward<Proj>(proj)); |
| }; |
| |
| struct NoComp {}; |
| struct CreateNoComp { |
| auto operator()(int) const { return NoComp(); } |
| }; |
| |
| static_assert(HasClamp<int, std::ranges::less, std::identity>); |
| static_assert(!HasClamp<NoComp>); |
| static_assert(!HasClamp<int, NoComp>); |
| static_assert(!HasClamp<int, std::ranges::less, CreateNoComp>); |
| |
| constexpr bool test() { |
| { // low < val < high |
| int val = 2; |
| int low = 1; |
| int high = 3; |
| std::same_as<const int&> decltype(auto) ret = std::ranges::clamp(val, low, high); |
| assert(ret == 2); |
| assert(&ret == &val); |
| } |
| |
| { // low > val < high |
| assert(std::ranges::clamp(10, 20, 30) == 20); |
| } |
| |
| { // low < val > high |
| assert(std::ranges::clamp(15, 5, 10) == 10); |
| } |
| |
| { // low == val == high |
| int val = 10; |
| assert(&std::ranges::clamp(val, 10, 10) == &val); |
| } |
| |
| { // Check that a custom comparator works. |
| assert(std::ranges::clamp(10, 30, 20, std::ranges::greater{}) == 20); |
| } |
| |
| { // Check that a custom projection works. |
| struct S { |
| int i; |
| |
| constexpr const int& lvalue_proj() const { return i; } |
| constexpr int prvalue_proj() const { return i; } |
| }; |
| |
| struct Comp { |
| constexpr bool operator()(const int& lhs, const int& rhs) const { return lhs < rhs; } |
| constexpr bool operator()(int&& lhs, int&& rhs) const { return lhs > rhs; } |
| }; |
| |
| auto val = S{10}; |
| auto low = S{20}; |
| auto high = S{30}; |
| // Check that the value category of the projection return type is preserved. |
| assert(&std::ranges::clamp(val, low, high, Comp{}, &S::lvalue_proj) == &low); |
| assert(&std::ranges::clamp(val, high, low, Comp{}, &S::prvalue_proj) == &low); |
| } |
| |
| { // Check that the implementation doesn't cause double moves (which could result from calling the projection on |
| // `value` once and then forwarding the result into the comparator). |
| struct CheckDoubleMove { |
| int i; |
| bool moved = false; |
| |
| constexpr explicit CheckDoubleMove(int set_i) : i(set_i) {} |
| constexpr CheckDoubleMove(const CheckDoubleMove&) = default; |
| constexpr CheckDoubleMove(CheckDoubleMove&& rhs) noexcept : i(rhs.i) { |
| assert(!rhs.moved); |
| rhs.moved = true; |
| } |
| }; |
| |
| auto val = CheckDoubleMove{20}; |
| auto low = CheckDoubleMove{10}; |
| auto high = CheckDoubleMove{30}; |
| |
| auto moving_comp = [](CheckDoubleMove lhs, CheckDoubleMove rhs) { return lhs.i < rhs.i; }; |
| auto prvalue_proj = [](const CheckDoubleMove& x) -> CheckDoubleMove { return x; }; |
| assert(&std::ranges::clamp(val, low, high, moving_comp, prvalue_proj) == &val); |
| } |
| |
| return true; |
| } |
| |
| int main(int, char**) { |
| test(); |
| static_assert(test()); |
| |
| return 0; |
| } |