721e94dcf1
Based on tracked types being nothrow copy and move construtible. Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
86 lines
2.0 KiB
C++
86 lines
2.0 KiB
C++
/*
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* Copyright (C) 2018-present ScyllaDB
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*/
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/*
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* SPDX-License-Identifier: AGPL-3.0-or-later
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*/
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#pragma once
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#include <functional>
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#include <limits>
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#include <optional>
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namespace detail {
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template<typename T, typename Comparator>
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requires std::is_nothrow_copy_constructible_v<T> && std::is_nothrow_move_constructible_v<T>
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class extremum_tracker {
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T _default_value;
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std::optional<T> _value;
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public:
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explicit extremum_tracker(const T& default_value) noexcept
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: _default_value(default_value)
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{}
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void update(const T& value) noexcept {
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if (!_value || Comparator{}(value, *_value)) {
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_value = value;
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}
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}
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void update(const extremum_tracker& other) noexcept {
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if (other._value) {
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update(*other._value);
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}
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}
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const T& get() const noexcept {
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return _value ? *_value : _default_value;
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}
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};
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} // namespace detail
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template <typename T>
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using min_tracker = detail::extremum_tracker<T, std::less<T>>;
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template <typename T>
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using max_tracker = detail::extremum_tracker<T, std::greater<T>>;
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template <typename T>
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requires std::is_nothrow_copy_constructible_v<T> && std::is_nothrow_move_constructible_v<T>
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class min_max_tracker {
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min_tracker<T> _min_tracker;
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max_tracker<T> _max_tracker;
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public:
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min_max_tracker() noexcept
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: _min_tracker(std::numeric_limits<T>::min())
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, _max_tracker(std::numeric_limits<T>::max())
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{}
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min_max_tracker(const T& default_min, const T& default_max) noexcept
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: _min_tracker(default_min)
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, _max_tracker(default_max)
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{}
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void update(const T& value) noexcept {
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_min_tracker.update(value);
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_max_tracker.update(value);
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}
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void update(const min_max_tracker<T>& other) noexcept {
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_min_tracker.update(other._min_tracker);
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_max_tracker.update(other._max_tracker);
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}
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const T& min() const noexcept {
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return _min_tracker.get();
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}
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const T& max() const noexcept {
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return _max_tracker.get();
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}
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};
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