Relationship.h

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/*
 * This file is part of sphgeom.
 *
 * Developed for the LSST Data Management System.
 * This product includes software developed by the LSST Project
 * (http://www.lsst.org).
 * See the COPYRIGHT file at the top-level directory of this distribution
 * for details of code ownership.
 *
 * This software is dual licensed under the GNU General Public License and also
 * under a 3-clause BSD license. Recipients may choose which of these licenses
 * to use; please see the files gpl-3.0.txt and/or bsd_license.txt,
 * respectively.  If you choose the GPL option then the following text applies
 * (but note that there is still no warranty even if you opt for BSD instead):
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
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 */
 
#ifndef LSST_SPHGEOM_RELATIONSHIP_H_
#define LSST_SPHGEOM_RELATIONSHIP_H_
 
#include <bitset>
 
 
namespace lsst {
namespace sphgeom {
 
using Relationship = std::bitset<3>;
 
static constexpr Relationship DISJOINT(1);
 
static constexpr Relationship INTERSECTS(0);
 
static constexpr Relationship CONTAINS(2);
 
static constexpr Relationship WITHIN(4);
 
inline Relationship invert(Relationship r) {
    // If A is disjoint from B, then B is disjoint from A. But if A contains B
    // then B is within A, so the corresponding bits must be swapped.
    return (r & DISJOINT) | ((r & CONTAINS) << 1) | ((r & WITHIN) >> 1);
}
 
}} // namespace lsst::sphgeom
 
#endif // LSST_SPHGEOM_RELATIONSHIP_H_