89 lines
2.4 KiB
C++
89 lines
2.4 KiB
C++
/*
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* Copyright 2022 CM4all GmbH
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* All rights reserved.
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*
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* author: Max Kellermann <mk@cm4all.com>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* - Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* - Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#pragma once
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#include <cassert>
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#include <cstddef>
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template<bool enable> class OptionalCounter;
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template<>
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class OptionalCounter<false>
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{
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public:
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constexpr void reset() noexcept {}
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constexpr auto &operator++() noexcept { return *this; }
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constexpr auto &operator--() noexcept { return *this; }
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constexpr auto &operator+=(std::size_t) noexcept { return *this; }
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constexpr auto &operator-=(std::size_t) noexcept { return *this; }
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};
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template<>
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class OptionalCounter<true>
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{
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std::size_t value = 0;
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public:
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constexpr operator std::size_t() const noexcept {
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return value;
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}
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constexpr void reset() noexcept {
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value = 0;
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}
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constexpr auto &operator++() noexcept {
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++value;
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return *this;
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}
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constexpr auto &operator--() noexcept {
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assert(value > 0);
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--value;
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return *this;
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}
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constexpr auto &operator+=(std::size_t n) noexcept {
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value += n;
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return *this;
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}
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constexpr auto &operator-=(std::size_t n) noexcept {
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assert(value >= n);
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value -= n;
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return *this;
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}
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};
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