ExprRange.h

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// # ExprRange.h: Select range of a column in an select expression
// # Copyright (C) 1994,1995,1999
// # 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_EXPRRANGE_H
#define TABLES_EXPRRANGE_H
 
// # Includes
#include <casacore/casa/aips.h>
#include <casacore/casa/Arrays/Vector.h>
 
namespace casacore {  // # NAMESPACE CASACORE - BEGIN
 
// # Forward Declarations
class TableColumn;
 
// <summary>
// Select range of a column in an select expression
// </summary>
 
// <use visibility=local>
 
// <reviewed reviewer="UNKNOWN" date="before2004/08/25" tests="">
// </reviewed>
 
// <prerequisite>
// # Classes you should understand before using this one.
//   <li> TableExprNode
// </prerequisite>
 
// <etymology>
// TableExprRange represents the ranges of a column as specified in
// a table select expression.
// </etymology>
 
// <synopsis>
// TableExprRange holds the ranges of values for a column as specified
// in a table select expression.
// It traverses the expression tree and composes the hull of the values.
// Only double values are taken into account.
// It can handle operators &&, ||, ==, >, >=, <, <=, !.
// It can handle a comparison operator only for a column with a constant.
// Other operators and expressions are non-convertable.
//
// The ranges function in class TableExprNode returns a Block
// of TableExprRange objects which contains the ranges for each
// (applicable) column used in the expression.
// </synopsis>
 
// <motivation>
// TableExprRange gives great possibilities in optimizing a table
// selection. It allows to get a rough estimate of the values needed
// for a column which can be used to do a fast preselect using an index.
// </motivation>
 
// <todo asof="$DATE:$">
// # A List of bugs, limitations, extensions or planned refinements.
//   <li> Support other data types than double
//   <li> Recognize that 2*COL<3 is equal to COL<3/2
// </todo>
 
class TableExprRange {
 public:
  // Default constructor (needed for Block<TableExprRange>).
  TableExprRange();
 
  // Construct from a column and a single constant range.
  TableExprRange(const TableColumn&, double stval, double endval);
 
  // Copy constructor.
  TableExprRange(const TableExprRange&);
 
  ~TableExprRange();
 
  // Assignment operator (copy semantics).
  TableExprRange& operator=(const TableExprRange&);
 
  // Return the vector of start values.
  // Together with the equally sized vector of end values, this forms
  // the ranges for the column (which can be acquired using getColumn).
  const Vector<double>& start() const;
 
  // Return the vector of end values.
  // Together with the equally sized vector of start values, this forms
  // the ranges for the column (which can be acquired using getColumn).
  const Vector<double>& end() const;
 
  // Return the column object.
  const TableColumn& getColumn() const;
 
  //*display 4
  // Mix with another range for an AND expression.
  void mixAnd(const TableExprRange&);
 
  //*display 4
  // Mix with another range for an OR expression.
  void mixOr(const TableExprRange&);
 
 private:
  Vector<double> sval_p;     // # start values
  Vector<double> eval_p;     // # end values
  TableColumn* tabColPtr_p;  // # pointer to column
};
 
inline const Vector<double>& TableExprRange::start() const { return sval_p; }
inline const Vector<double>& TableExprRange::end() const { return eval_p; }
 
}  // namespace casacore
 
#endif