Brad Bishop | 186aa67 | 2017-05-15 22:27:57 -0400 | [diff] [blame] | 1 | #pragma once |
| 2 | |
| 3 | #include <tuple> |
| 4 | #include <utility> |
| 5 | |
| 6 | namespace phosphor |
| 7 | { |
| 8 | namespace dbus |
| 9 | { |
| 10 | namespace monitoring |
| 11 | { |
| 12 | |
| 13 | /** @brief A tuple of references. */ |
| 14 | template <typename... T> |
| 15 | using TupleOfRefs = std::tuple<std::reference_wrapper<T>...>; |
| 16 | |
| 17 | namespace detail |
| 18 | { |
| 19 | /** @brief Less than implementation for tuples of references. */ |
Brad Bishop | d1eac88 | 2018-03-29 10:34:05 -0400 | [diff] [blame] | 20 | template <size_t size, size_t i, typename T, typename U> struct TupleOfRefsLess |
Brad Bishop | 186aa67 | 2017-05-15 22:27:57 -0400 | [diff] [blame] | 21 | { |
| 22 | static constexpr bool compare(const T& l, const U& r) |
| 23 | { |
| 24 | if (std::get<i>(l).get() < std::get<i>(r).get()) |
| 25 | { |
| 26 | return true; |
| 27 | } |
| 28 | if (std::get<i>(r).get() < std::get<i>(l).get()) |
| 29 | { |
| 30 | return false; |
| 31 | } |
Brad Bishop | d1eac88 | 2018-03-29 10:34:05 -0400 | [diff] [blame] | 32 | return TupleOfRefsLess<size, i + 1, T, U>::compare(l, r); |
Brad Bishop | 186aa67 | 2017-05-15 22:27:57 -0400 | [diff] [blame] | 33 | } |
| 34 | }; |
| 35 | |
| 36 | /** @brief Less than specialization for tuple element sizeof...(tuple) +1. */ |
| 37 | template <size_t size, typename T, typename U> |
| 38 | struct TupleOfRefsLess<size, size, T, U> |
| 39 | { |
| 40 | static constexpr bool compare(const T& l, const U& r) |
| 41 | { |
| 42 | return false; |
| 43 | } |
| 44 | }; |
| 45 | } // namespace detail |
| 46 | |
| 47 | /** @brief Less than comparison for tuples of references. */ |
| 48 | struct TupleOfRefsLess |
| 49 | { |
| 50 | template <typename... T, typename... U> |
Brad Bishop | d1eac88 | 2018-03-29 10:34:05 -0400 | [diff] [blame] | 51 | constexpr bool operator()(const TupleOfRefs<T...>& l, |
| 52 | const TupleOfRefs<U...>& r) const |
Brad Bishop | 186aa67 | 2017-05-15 22:27:57 -0400 | [diff] [blame] | 53 | { |
| 54 | static_assert(sizeof...(T) == sizeof...(U), |
| 55 | "Cannot compare tuples of different lengths."); |
Brad Bishop | d1eac88 | 2018-03-29 10:34:05 -0400 | [diff] [blame] | 56 | return detail::TupleOfRefsLess<sizeof...(T), 0, TupleOfRefs<T...>, |
| 57 | TupleOfRefs<U...>>::compare(l, r); |
Brad Bishop | 186aa67 | 2017-05-15 22:27:57 -0400 | [diff] [blame] | 58 | } |
| 59 | }; |
| 60 | |
| 61 | } // namespace monitoring |
| 62 | } // namespace dbus |
| 63 | } // namespace phosphor |