RegularFileIO.h

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// # RegularFileIO.h: Class for IO on a regular file
// # Copyright (C) 1996,1997,1999,2001,2002
// # 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_REGULARFILEIO_H
#define CASA_REGULARFILEIO_H
 
// # Includes
#include <casacore/casa/aips.h>
#include <casacore/casa/IO/FilebufIO.h>
#include <casacore/casa/OS/RegularFile.h>
 
namespace casacore {  // # NAMESPACE CASACORE - BEGIN
 
// <summary>
// Class for IO on a regular file.
// </summary>
 
// <use visibility=export>
 
// <reviewed reviewer="Friso Olnon" date="1996/11/06" tests="tByteIO" demos="">
// </reviewed>
 
// <prerequisite>
//    <li> <linkto class=FilebufIO>FilebufIO</linkto> class
// </prerequisite>
 
// <synopsis>
// This class is a specialization of class
// <linkto class=ByteIO>ByteIO</linkto>. It uses a
// <linkto class=RegularFile>regular file</linkto> as the data store.
// <p>
// The class is derived from <linkto class=FilebufIO>FilebufIO</linkto>,
// which contains all functions to access the file. The description of
// this class explains the use of the <src>filebufSize</src> argument
// in the constructor.
// </synopsis>
 
// <example>
// <srcblock>
//    // Create a file (which should not exist yet).
//    RegularFileIO regio (RegularFile("file.name"), ByteIO::NewNoReplace);
//    // Use that as the sink of AipsIO.
//    AipsIO stream (&regio);
//    // Write values.
//    stream << (Int)10;
//    stream << True;
//    // Seek to beginning of file and read data in.
//    stream.setpos (0);
//    Int vali;
//    Bool valb;
//    stream >> vali >> valb;
// </srcblock>
// </example>
 
class RegularFileIO : public FilebufIO {
 public:
  // Create an IO stream object for a regular file with the given name.
  // The ByteIO option determines if the file will be created
  // or opened for input and/or output.
  // <br>
  // The argument <src>filebufSize</src> defines the length of
  // the internal buffer in the underlying <linkto class=FilebufIO>
  // FilebufIO</linkto> object. A zero length uses an appropriate default.
  explicit RegularFileIO(const RegularFile& regularFile, ByteIO::OpenOption = ByteIO::Old,
                         uInt filebufSize = 0);
 
  ~RegularFileIO();
 
  // Reopen the underlying file for read/write access.
  // Nothing will be done if the stream is writable already.
  // Otherwise it will be reopened and an exception will be thrown
  // if it is not possible to reopen it for read/write access.
  virtual void reopenRW();
 
  // Get the file name of the file attached.
  virtual String fileName() const;
 
  // Convenience function to open or create a file.
  // Optionally it is checked if the file does not exist yet.
  // If useODirect=True and if supported by the OS, the file will be opened
  // with O_DIRECT which bypasses the kernel's file cache for more predictable
  // I/O behaviour. It requires the size and the alignment of the data to be
  // read/written to be a multiple of the the disk's logical block size.
  // It returns the file descriptor.
  static int openCreate(const RegularFile& file, ByteIO::OpenOption, Bool useODirect = False);
 
 private:
  OpenOption itsOption;
  RegularFile itsRegularFile;
 
  // Copy constructor, should not be used.
  RegularFileIO(const RegularFileIO& that);
 
  // Assignment, should not be used.
  RegularFileIO& operator=(const RegularFileIO& that);
};
 
}  // namespace casacore
 
#endif