RecordFieldId.h

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// # RecordFieldId.h: The identification of a record field
// # Copyright (C) 1995,1996
// # 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_RECORDFIELDID_H
#define CASA_RECORDFIELDID_H
 
// # Includes
#include <casacore/casa/aips.h>
#include <casacore/casa/BasicSL/String.h>
 
namespace casacore {  // # NAMESPACE CASACORE - BEGIN
 
// # Forward Declarations
class RecordInterface;
 
// <summary>
// The identification of a record field.
// </summary>
 
// <use visibility=export>
// <reviewed reviewer="Mark Wieringa" date="1996/04/15" tests="tRecord">
// </reviewed>
 
// <prerequisite>
//   <li> <linkto class="RecordInterface">RecordInterface</linkto>.
// </prerequisite>
 
// <etymology>
// RecordFieldId gives the identification of a field in a record.
// </etymology>
 
// <synopsis>
// This class provides the user to identify a field in a record.
// Identification can be done by means of the field name or by means
// of its field number.
// <br>For the programmer the most convenient way is probably the name,
// because that is the natural identification.
// However, identification by means of field number is much faster
// and could be used when it is known.
// </synopsis>
 
// <example>
// <srcblock>
// void someFunc (const Record& record)
// {
//     float value1 = record.asfloat ("name");     // identify by name
//     float value2 = record.asfloat (0);          // identify by number
// }
// </srcBlock>
// </example>
 
// <motivation>
// This class makes it possible that many functions in Record classes
// have to be defined only once. The constructors of RecordFieldId
// make it possible that a number and a string are automatically
// converted, so the user does not have to instantiate a RecordFieldId
// object explicitly.
// </motivation>
 
// # <todo asof="1996/03/12">
// # </todo>
 
class RecordFieldId {
 public:
  // Construct it from a field number.
  RecordFieldId(Int fieldNumber);
 
  // Construct it from a field name.
  // <group>
  RecordFieldId(const String& name);
  RecordFieldId(const std::string& name);
  RecordFieldId(const Char* name);
  // </group>
 
  // Get the field number.
  Int fieldNumber() const;
 
  // Get the field name.
  const String& fieldName() const;
 
  // Is the id given by name?
  Bool byName() const;
 
 private:
  Bool byName_p;
  Int number_p;
  String name_p;
};
 
inline RecordFieldId::RecordFieldId(Int fieldNumber) : byName_p(False), number_p(fieldNumber) {}
 
inline RecordFieldId::RecordFieldId(const String& fieldName)
    : byName_p(True), number_p(-1), name_p(fieldName) {}
 
inline RecordFieldId::RecordFieldId(const std::string& fieldName)
    : byName_p(True), number_p(-1), name_p(fieldName) {}
 
inline RecordFieldId::RecordFieldId(const Char* fieldName)
    : byName_p(True), number_p(-1), name_p(fieldName) {}
 
inline Int RecordFieldId::fieldNumber() const { return number_p; }
 
inline const String& RecordFieldId::fieldName() const { return name_p; }
 
inline Bool RecordFieldId::byName() const { return byName_p; }
 
}  // namespace casacore
 
#endif