HDF5Object.h

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// # HDF5Object.h: An abstract base class representing an HDF5 object
// # Copyright (C) 2008
// # Associated Universities, Inc. Washington DC, USA.
// #
// # This library is free software; you can redistribute it and/or modify it
// # under the terms of the GNU Library General Public License as published by
// # the Free Software Foundation; either version 2 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 Library General Public
// # License for more details.
// #
// # You should have received a copy of the GNU Library General Public License
// # along with this library; if not, write to the Free Software Foundation,
// # Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
// #
// # Correspondence concerning AIPS++ should be addressed as follows:
// #        Internet email: casa-feedback@nrao.edu.
// #        Postal address: AIPS++ Project Office
// #                        National Radio Astronomy Observatory
// #                        520 Edgemont Road
// #                        Charlottesville, VA 22903-2475 USA
 
#ifndef CASA_HDF5OBJECT_H
#define CASA_HDF5OBJECT_H
 
// # Includes
#include <casacore/casa/aips.h>
#include <casacore/casa/BasicSL/String.h>
 
// # Define hid_t and hsize_t if not defined (thus if HDF5 disabled).
// # They should be the same as used by HDF5.
// # This is checked by functions check_hid_t and check_hsize_t.
#ifdef HAVE_HDF5
#include <hdf5.h>
#else
typedef int64_t hid_t;
typedef casacore::uInt64 hsize_t;
#endif
 
namespace casacore {  // # NAMESPACE CASACORE - BEGIN
 
// <summary>
// An abstract base class representing an HDF5 object
// </summary>
 
// <use visibility=export>
 
// <reviewed reviewer="" date="" tests="tHDF5Dataset.cc">
// </reviewed>
 
// <synopsis>
// This class wraps a basic HDF5 object. It offers several benefits:
// <ul>
//  <li> The most important is resource management. In case of an exception,
//       the object's hid will automatically be closed by the destructor.
//  <li> It acts as the base class for the basic objects file, group,
//       and dataset.
//  <li> An HDF5 hid is a kind of pointer and should not be copied.
//       These classes forbid making a copy, but make it possible to use
//       them in a shared pointer context.
// </ul>
// </synopsis>
 
class HDF5Object {
 public:
  // Default constructor sets to invalid hid.
  HDF5Object() : itsHid(-1) {}
 
  // The destructor in a derived class should close the hid appropriately.
  virtual ~HDF5Object();
 
  // Copy constructor cannot be used because a HID cannot be copied.
  HDF5Object(const HDF5Object&) = delete;
 
  // Assignment cannot be used because a HID cannot be copied .
  HDF5Object& operator=(const HDF5Object&) = delete;
 
  // Check if there is HDF5 support compiled in.
  static Bool hasHDF5Support();
 
  // Close the hid if valid.
  virtual void close() = 0;
 
  // Is it a valid hid?
  bool isValid() const { return itsHid >= 0; }
 
  // Get the hid.
  hid_t getHid() const { return itsHid; }
 
  // Convert automatically to hid_t.
  operator hid_t() const { return itsHid; }
 
  // Get or set the name.
  // <group>
  void setName(const String& name) { itsName = name; }
  const String& getName() const { return itsName; }
  // </group>
 
  // If no HDF5, throw an exception that HDF5 is not supported.
  static void throwNoHDF5();
 
 protected:
  // Set the hid.
  void setHid(hid_t hid) { itsHid = hid; }
 
  // Clear the hid (set to invalid).
  void clearHid() { itsHid = -1; }
 
 private:
  // # Data members
  // # Define a union to ensure that the object always uses 64 bits, even
  // # for older HDF5 versions where hid_t is a 32 bit integer.
  union {
    hid_t itsHid;
    int64_t itsDummyHid;
  };
  String itsName;
};
 
}  // namespace casacore
 
#endif