TaQLNodeResult.h

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// # TaQLNodeResult.h: Classes holding the result of a node tree visit
// # Copyright (C) 2005
// # 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 TABLES_TAQLNODERESULT_H
#define TABLES_TAQLNODERESULT_H
 
// # Includes
#include <casacore/casa/aips.h>
#include <memory>
 
namespace casacore {  // # NAMESPACE CASACORE - BEGIN
 
// <summary>
// Abstract base class to hold the result of a visit to the node tree.
// </summary>
 
// <use visibility=local>
 
// <reviewed reviewer="" date="" tests="tTableGram">
// </reviewed>
 
// <prerequisite>
// # Classes you should understand before using this one.
//   <li> <linkto class=TaQLNodeVisitor>TaQLNodeVisitor</linkto>
//   <li> Note 199 describing
//        <a href="../notes/199.html">
//        TaQL</a>
// </prerequisite>
 
// <synopsis>
// TaQLNodeResultRep is the abstract base class for classes holding
// values filled by visitors to the raw TaQL parse tree. Visitors are
// classes derived from <linkto class=TaQLNodeVisitor>TaQLNodeVisitor</linkto>
// which traverse the parse tree.
// TaQLNodeResultRep is the counted referenced letter class in the envelope
// class <linkto class=TaQLNodeResult>TaQLNodeResult</linkto>.
// </synopsis>
 
class TaQLNodeResultRep {
 public:
  // Default constructor.
  TaQLNodeResultRep() {}
 
  // Destructor.
  virtual ~TaQLNodeResultRep() = default;
 
  // Letter objects cannot be copied.
  // <group>
  TaQLNodeResultRep(const TaQLNodeResultRep&) = delete;
  TaQLNodeResultRep& operator=(const TaQLNodeResultRep&) = delete;
  // </group>
};
 
// <summary>
// Envelope class to hold the result of a visit to the node tree.
// </summary>
 
// <use visibility=local>
 
// <reviewed reviewer="" date="" tests="tTableGram">
// </reviewed>
 
// <prerequisite>
// # Classes you should understand before using this one.
//   <li> <linkto class=TaQLNodeVisitor>TaQLNodeVisitor</linkto>
//   <li> Note 199 describing
//        <a href="../notes/199.html">
//        TaQL</a>
// </prerequisite>
 
// <synopsis>
// TaQLNodeResult is the envelope class for classes holding
// values filled by visitors to the raw TaQL parse tree. Visitors are
// classes derived from <linkto class=TaQLNodeVisitor>TaQLNodeVisitor</linkto>
// which traverse the parse tree.
// The counted referenced letter base class for the envelope is
// class <linkto class=TaQLNodeResultRep>TaQLNodeResultRep</linkto>.
// </synopsis>
class TaQLNodeResult {
 public:
  // Default constructor has no letter.
  TaQLNodeResult() {}
 
  // Wrap the given pointer in a shared_ptr.
  TaQLNodeResult(TaQLNodeResultRep* rep) : itsRep(rep) {}
 
  // Does the envelope hold a letter?
  Bool isValid() const { return itsRep.get(); }
 
  // Get the actual underlying object.
  const TaQLNodeResultRep& getRep() const { return *(itsRep.get()); }
 
 private:
  std::shared_ptr<TaQLNodeResultRep> itsRep;
};
 
}  // namespace casacore
 
#endif