vectormap.h

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// The libMesh Finite Element Library.
// Copyright (C) 2002-2025 Benjamin S. Kirk, John W. Peterson, Roy H. Stogner

// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.

// This library 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
// Lesser General Public License for more details.

// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA



#ifndef LIBMESH_VECTORMAP_H
#define LIBMESH_VECTORMAP_H

// C++ Includes   -----------------------------------
#include <vector>
#include <algorithm>

// libMesh includes
#include "libmesh/libmesh_common.h"


namespace libMesh
{

template <typename Key, typename Tp>
class vectormap : public std::vector<std::pair<Key, Tp>>
{

public:

  typedef Key                                   key_type;
  typedef Tp                                    mapped_type;
  typedef std::pair<Key, Tp>                    value_type;
  typedef std::vector<value_type>               vector_type;
  typedef typename vector_type::difference_type difference_type;
  typedef typename vector_type::iterator        iterator;
  typedef typename vector_type::const_iterator  const_iterator;

private:

  struct FirstOrder
  {
    bool operator()(const value_type & lhs,
                    const value_type & rhs) const
    { return lhs.first < rhs.first; }
  };

  struct FirstCompare
  {
    bool operator()(const value_type & lhs,
                    const value_type & rhs) const
    { return lhs.first == rhs.first; }
  };

public:

  vectormap() :
    _sorted(false)
  {}

  vectormap(const vectormap<Key,Tp> & other) :
    std::vector<std::pair<Key, Tp>> (other),
    _sorted(other._sorted)
  {}

  void insert (const value_type & x)
  {
    _sorted = false;
    this->push_back(x);
  }

  template<class... Args>
  void emplace(Args&&... args)
  {
    _sorted = false;
    this->emplace_back(args...);
  }

  void sort()
  {
    std::sort (this->begin(), this->end(), FirstOrder());

    this->erase (std::unique (this->begin(), this->end(), FirstCompare()), this->end());

    _sorted = true;
  }

  const Tp & operator[](const key_type & key) const
  {
    if (!_sorted)
      const_cast<vectormap<Key, Tp> *>(this)->sort();

    libmesh_assert (_sorted);

    value_type to_find;
    to_find.first = key;

    const_iterator lower_bound = std::lower_bound (this->begin(), this->end(), to_find, FirstOrder());

    libmesh_error_msg_if(lower_bound == this->end() || lower_bound->first != key,
                         "Error in vectormap::operator[], key not found. "
                         "If you are searching for values you aren't sure exist, try vectormap::find() instead.");

    return lower_bound->second;
  }

  iterator find (const key_type & key)
  {
    if (!_sorted)
      this->sort();

    libmesh_assert (_sorted);

    value_type to_find;
    to_find.first = key;

    iterator lb = std::lower_bound (this->begin(), this->end(), to_find, FirstOrder());

    // If we didn't find the key, return end()
    if (lb == this->end() || lb->first != key)
      return this->end();

    return lb;
  }

  const_iterator find (const key_type & key) const
  {
    // This function isn't really const, we might have to sort the
    // underlying container before we can search in it.
    if (!_sorted)
      const_cast<vectormap<Key, Tp> *>(this)->sort();

    libmesh_assert (_sorted);

    value_type to_find;
    to_find.first = key;

    const_iterator lb = std::lower_bound (this->begin(), this->end(), to_find, FirstOrder());

    // If we didn't find the key, return end()
    if (lb == this->end() || lb->first != key)
      return this->end();

    return lb;
  }

  difference_type
  count (const key_type & key) const
  {
    if (!_sorted)
      const_cast<vectormap<Key, Tp> *>(this)->sort();

    libmesh_assert (_sorted);

    value_type to_find;
    to_find.first = key;

    const_iterator lb = std::lower_bound (this->begin(), this->end(), to_find, FirstOrder());

    // If we didn't find the key, the count is 0.
    if (lb == this->end() || lb->first != key)
      return 0;

    return 1;
  }


private:

  bool _sorted;
};

} // namespace libMesh

#endif // LIBMESH_VECTORMAP_H