localkey.hh

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// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
// vi: set et ts=4 sw=2 sts=2:
// SPDX-FileCopyrightInfo: Copyright © DUNE Project contributors, see file LICENSE.md in module root
// SPDX-License-Identifier: LicenseRef-GPL-2.0-only-with-DUNE-exception
#ifndef DUNE_LOCALKEY_HH
#define DUNE_LOCALKEY_HH

#include <array>
#include <cstddef>
#include <ostream>

namespace Dune
{
  class LocalKey
  {
  public:

    enum {
      intersectionCodim=666
    };

    constexpr LocalKey () noexcept
      : values_{}
    {}

    constexpr LocalKey (unsigned int s, unsigned int c, unsigned int i) noexcept
      : values_{s,c,i}
    {}

    [[nodiscard]]
    constexpr unsigned int subEntity () const noexcept
    {
      return values_[0];
    }

    [[nodiscard]]
    constexpr unsigned int codim () const noexcept
    {
      return values_[1];
    }

    [[nodiscard]]
    constexpr unsigned int index () const noexcept
    {
      return values_[2];
    }

    constexpr void index (unsigned int i) noexcept
    {
      values_[2] = i;
    }

    [[nodiscard]]
    bool operator< (const LocalKey& other) const noexcept
    {
      return values_ < other.values_;
    }

    friend std::ostream& operator<< (std::ostream& s, const LocalKey& localKey)
    {
      return s << "[ subEntity: " << localKey.subEntity()
             << ", codim: " << localKey.codim()
             << ", index: " << localKey.index() << " ]";
    }

  private:

    // We use an array to store the values in order to be able to use the array::operator< implementation
    std::array<unsigned int,3> values_;

  };

}
#endif