Danny Robson
5a7613d3f3
This allows more flexibility in some client code (eg, calling this to sort compound objects like region).
52 lines
1.3 KiB
C++
52 lines
1.3 KiB
C++
/*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*
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* Copyright 2019 Danny Robson <danny@nerdcruft.net>
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*/
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#pragma once
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#include "base.hpp"
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#include <compare>
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#include <cstddef>
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///////////////////////////////////////////////////////////////////////////////
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namespace cruft::coord {
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/// A StrictWeakOrder over coordinate types.
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///
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/// The comparison operates across successive elements of the two
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/// coordinates.
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template <typename CoordT>
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std::weak_ordering
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element_ordering (
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CoordT const &a,
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CoordT const &b
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) noexcept {
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for (std::size_t i = 0; i < CoordT::elements; ++i)
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if (auto cmp = a[i] <=> b[i]; cmp != 0)
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return cmp;
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return std::weak_ordering::equivalent;
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}
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/// A StrictWeakOrder over coordinate types.
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///
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/// Deduction is deferred until the function is called, in the same way
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/// that std::less<> operates.
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template <typename = void>
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struct ordering {
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template <typename CoordT>
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bool
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operator() (CoordT const &a, CoordT const &b) const noexcept
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{
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return element_ordering<CoordT> (a, b) < 0;
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}
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};
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}
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