data_type.h

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// The TIMPI Message-Passing Parallelism 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 TIMPI_DATA_TYPE_H
#define TIMPI_DATA_TYPE_H

// TIMPI includes
#include "timpi/timpi_call_mpi.h"

namespace TIMPI
{

#ifdef TIMPI_HAVE_MPI
//-------------------------------------------------------------------
typedef MPI_Datatype data_type;

#else

// These shouldn't actually be needed, but must be
// unique types for function overloading to work
// properly.
struct data_type    { /* unsigned int t; */ };

#endif // TIMPI_HAVE_MPI



//-------------------------------------------------------------------
class DataType
{
public:
  DataType () = default;
  DataType (const DataType & other) = default;
  DataType (DataType && other) = default;
  static const bool is_fixed_type = true;

  DataType (const data_type & type) :
    _datatype(type)
  {}

  DataType (const DataType & other, unsigned int count)
  {
    // FIXME - if we nest an inner type here will we run into bug
    // https://github.com/libMesh/libmesh/issues/631 again?
    timpi_call_mpi(MPI_Type_contiguous(count, other._datatype, &_datatype));
    ignore(other, count); // ifndef TIMPI_HAVE_MPI
    this->commit();
  }

  virtual ~DataType () = default;

  DataType & operator = (const DataType & other) = default;
  DataType & operator = (DataType && other) = default;

  DataType & operator = (const data_type & type)
  { _datatype = type; return *this; }

  operator const data_type & () const
  { return _datatype; }

  operator data_type & ()
  { return _datatype; }

  //     operator data_type const * () const
  //     { return &_datatype; }

  //     operator data_type * ()
  //     { return &_datatype; }

  void commit ()
  {
    timpi_call_mpi
      (MPI_Type_commit (&_datatype));
  }

  void free ()
  {
    timpi_call_mpi
      (MPI_Type_free (&_datatype));
  }

protected:

  data_type _datatype;
};

class NotADataType
{
public:
  NotADataType () = default;
  NotADataType (const NotADataType & other) = default;
  NotADataType (NotADataType && other) = default;
  ~NotADataType () = default;
  NotADataType & operator = (const NotADataType & other) = default;
  NotADataType & operator = (NotADataType && other) = default;

  static const bool is_fixed_type = false;
};

template <bool>
struct MaybeADataType {
  typedef DataType type;
};

template <>
struct MaybeADataType<false>
{
  typedef NotADataType type;
};

} // namespace TIMPI

#endif // TIMPI_DATA_TYPE_H