// Copyright 2019 Hans Dembinski
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//
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// Distributed under the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE_1_0.txt
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// or copy at http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_HISTOGRAM_DETAIL_OPTIONAL_INDEX_HPP
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#define BOOST_HISTOGRAM_DETAIL_OPTIONAL_INDEX_HPP
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#include <cassert>
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#include <cstdint>
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namespace boost {
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namespace histogram {
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namespace detail {
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constexpr auto invalid_index = ~static_cast<std::size_t>(0);
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// integer with a persistent invalid state, similar to NaN
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struct optional_index {
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std::size_t value;
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optional_index& operator=(std::size_t x) noexcept {
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value = x;
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return *this;
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}
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optional_index& operator+=(std::intptr_t x) noexcept {
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assert(x >= 0 || static_cast<std::size_t>(-x) <= value);
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if (value != invalid_index) { value += x; }
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return *this;
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}
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optional_index& operator+=(const optional_index& x) noexcept {
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if (value != invalid_index) return operator+=(x.value);
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value = invalid_index;
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return *this;
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}
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operator std::size_t() const noexcept { return value; }
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friend bool operator<=(std::size_t x, optional_index idx) noexcept {
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return x <= idx.value;
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}
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};
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constexpr inline bool is_valid(const std::size_t) noexcept { return true; }
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inline bool is_valid(const optional_index x) noexcept { return x.value != invalid_index; }
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} // namespace detail
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} // namespace histogram
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} // namespace boost
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#endif
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