blob: 3954d46ab4ffa7b2c1ac2db171b5493a0e0a41bf [file] [log] [blame]
#pragma once
#include <cstddef>
#include <tuple>
#include <utility>
namespace phosphor
{
namespace dbus
{
namespace monitoring
{
/** @brief A tuple of references. */
template <typename... T>
using TupleOfRefs = std::tuple<std::reference_wrapper<T>...>;
namespace detail
{
/** @brief Less than implementation for tuples of references. */
template <size_t size, size_t i, typename T, typename U>
struct TupleOfRefsLess
{
static constexpr bool compare(const T& l, const U& r)
{
if (std::get<i>(l).get() < std::get<i>(r).get())
{
return true;
}
if (std::get<i>(r).get() < std::get<i>(l).get())
{
return false;
}
return TupleOfRefsLess<size, i + 1, T, U>::compare(l, r);
}
};
/** @brief Less than specialization for tuple element sizeof...(tuple) +1. */
template <size_t size, typename T, typename U>
struct TupleOfRefsLess<size, size, T, U>
{
static constexpr bool compare(const T& l, const U& r)
{
return false;
}
};
} // namespace detail
/** @brief Less than comparison for tuples of references. */
struct TupleOfRefsLess
{
template <typename... T, typename... U>
constexpr bool operator()(const TupleOfRefs<T...>& l,
const TupleOfRefs<U...>& r) const
{
static_assert(sizeof...(T) == sizeof...(U),
"Cannot compare tuples of different lengths.");
return detail::TupleOfRefsLess<sizeof...(T), 0, TupleOfRefs<T...>,
TupleOfRefs<U...>>::compare(l, r);
}
};
} // namespace monitoring
} // namespace dbus
} // namespace phosphor