ScalarColumn.h

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// # SclarColumn.h: access to a scalar table column with arbitrary data type
// # Copyright (C) 1994,1995,1996,1997,1998
// # 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
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// #                        Charlottesville, VA 22903-2475 USA
 
#ifndef TABLES_SCALARCOLUMN_H
#define TABLES_SCALARCOLUMN_H
 
// # Includes
#include <casacore/casa/aips.h>
#include <casacore/casa/Arrays/ArrayFwd.h>
#include <casacore/tables/Tables/TableColumn.h>
#include <casacore/tables/Tables/ColumnCache.h>
 
namespace casacore {  // # NAMESPACE CASACORE - BEGIN
 
// # Forward Declarations
class BaseColumn;
class RefRows;
class String;
 
// <summary>
// Access to a scalar table column with arbitrary data type
// </summary>
 
// <use visibility=export>
 
// <reviewed reviewer="dschieb" date="1994/08/10" tests="none">
// </reviewed>
 
// <prerequisite>
//   <li> Table
//   <li> TableColumn
// </prerequisite>
 
// <etymology>
// ScalarColumn<T> gives read and write access to a column in a table
// containing a scalar with data type T.
// </etymology>
 
// <synopsis>
// The class ScalarColumn allows read and write access to a column
// containing scalar values with an arbitrary data type.
// It is possible to get the data in an individual cell (i.e. table row)
// and to get the column as a whole.
//
// A default constructor is defined to allow construction of an array
// of ScalarColumn objects. However, this constructs an object not
// referencing a column. Functions like get, etc. will fail (i.e. result
// in a segmentation fault) when used on such objects. The functions
// isNull and throwIfNull can be used to test on this.
// The functions attach and reference can fill in the object.
// </synopsis>
 
// <example>
// See module <linkto module="Tables#open">Tables</linkto>.
// </example>
 
template <class T>
class ScalarColumn : public TableColumn {
 public:
  // The default constructor creates a null object, i.e. it
  // does not reference a table column.
  // The sole purpose of this constructor is to allow construction
  // of an array of ScalarColumn objects.
  // The functions reference and attach can be used to make a null object
  // reference a column.
  // Note that get functions, etc. will cause a segmentation fault
  // when operating on a null object. It was felt it was too expensive
  // to test on null over and over again. The user should use the isNull
  // or throwIfNull function in case of doubt.
  ScalarColumn();
 
  // Construct for the given column in the given table.
  ScalarColumn(const Table&, const String& columnName);
 
  // Construct from the given table column.
  // This constructor is useful if first a table column was constructed,
  // its type is determined and thereafter used to construct the
  // correct column object.
  explicit ScalarColumn(const TableColumn&);
 
  // Copy constructor (reference semantics).
  ScalarColumn(const ScalarColumn<T>&);
 
  ~ScalarColumn();
 
  // Clone the object.
  virtual TableColumn* clone() const;
 
  // Assignment uses reference semantics, thus works the same
  // as function reference.
  ScalarColumn<T>& operator=(const ScalarColumn<T>&);
 
  // Change the reference to another column.
  // This is in fact an assignment operator with reference semantics.
  // It removes the reference to the current column and creates
  // a reference to the column referenced in the other object.
  // It will handle null objects correctly.
  void reference(const ScalarColumn<T>&);
 
  // Attach a column to the object.
  // This is in fact only a shorthand for
  // <br><src> reference (ScalarColumn<T> (table, columnName)); </src>
  void attach(const Table& table, const String& columnName) {
    reference(ScalarColumn<T>(table, columnName));
  }
 
  // Get the data from a particular cell (i.e. table row).
  // The row numbers count from 0 until #rows-1.
  // <group>
  void get(rownr_t rownr, T& value) const {
    TABLECOLUMNCHECKROW(rownr);
    Int off = colCachePtr_p->offset(rownr);
    if (off >= 0) {
      value = ((T*)(colCachePtr_p->dataPtr()))[off];
    } else {
      baseColPtr_p->get(rownr, &value);
    }
  }
  T get(rownr_t rownr) const {
    T value;
    get(rownr, value);
    return value;
  }
  T operator()(rownr_t rownr) const {
    T value;
    get(rownr, value);
    return value;
  }
  // </group>
 
  // Get the vector of all values in the column.
  // According to the assignment rules of class Array, the destination
  // vector must be empty or its length must be the number of cells
  // in the column (i.e. the number of rows in the table).
  void getColumn(Vector<T>& vec, Bool resize = False) const;
 
  // Get the vector of all values in the column.
  Vector<T> getColumn() const;
 
  // Get the vector of a range of values in the column.
  // The Slicer object can be used to specify start, end (or length),
  // and stride of the rows to get.
  // According to the assignment rules of class Array, the destination
  // vector must be empty or its length must be the number of cells
  // in the column (i.e. the number of rows in the slicer).
  void getColumnRange(const Slicer& rowRange, Vector<T>& vec, Bool resize = False) const;
 
  // Get the vector of a range of values in the column.
  // The Slicer object can be used to specify start, end (or length),
  // and stride of the rows to get..
  Vector<T> getColumnRange(const Slicer& rowRange) const;
 
  // Get the vector of some values in the column.
  // The Slicer object can be used to specify start, end (or length),
  // and stride of the rows to get.
  // According to the assignment rules of class Array, the destination
  // vector must be empty or its length must be the number of cells
  // in the column (i.e. the number of rows in the RefRows object).
  void getColumnCells(const RefRows& rownrs, Vector<T>& vec, Bool resize = False) const;
 
  // Get the vector of some values in the column.
  Vector<T> getColumnCells(const RefRows& rownrs) const;
 
  // Put the value in a particular cell (i.e. table row).
  // The row numbers count from 0 until #rows-1.
  void put(rownr_t rownr, const T& value) {
    TABLECOLUMNCHECKROW(rownr);
    checkWritable();
    baseColPtr_p->put(rownr, &value);
  }
 
  // Copy the value of a cell of that column to a cell of this column.
  // The data types of both columns must be the same.
  // <group>
  // Use the same row numbers for both cells.
  void put(rownr_t rownr, const ScalarColumn<T>& that) { put(rownr, that, rownr); }
  // Use possibly different row numbers for that (i.e. input) and
  // and this (i.e. output) cell.
  void put(rownr_t thisRownr, const ScalarColumn<T>& that, rownr_t thatRownr);
  // </group>
 
  // Copy the value of a cell of that column to a cell of this column.
  // This function uses a generic TableColumn object as input.
  // If possible the data will be promoted to the data type of this column.
  // Otherwise an exception is thrown.
  // <group>
  // Use the same row numbers for both cells.
  void put(rownr_t rownr, const TableColumn& that, Bool = False) { put(rownr, that, rownr); }
  // Use possibly different row numbers for that (i.e. input) and
  // and this (i.e. output) cell.
  void put(rownr_t thisRownr, const TableColumn& that, rownr_t thatRownr, Bool = False);
  // </group>
 
  // Put the vector of all values in the column.
  // The length of the vector must be the number of cells in the column
  // (i.e. the number of rows in the table).
  void putColumn(const Vector<T>& vec);
 
  // Put the vector of a range of values in the column.
  // The Slicer object can be used to specify start, end (or length),
  // and stride of the rows to put.
  // The length of the vector must be the number of cells in the slice.
  void putColumnRange(const Slicer& rowRange, const Vector<T>& vec);
 
  // Put the vector of some values in the column.
  // The length of the vector must be the number of cells in the RefRows
  // object.
  void putColumnCells(const RefRows& rownrs, const Vector<T>& vec);
 
  // Put the same value in all cells of the column.
  void fillColumn(const T& value);
 
  // Put the contents of a column with the same data type into this column.
  // To put the contents of a column with a different data type into
  // this column, the function TableColumn::putColumn can be used
  // (provided the data type promotion is possible).
  // In fact, this function is an assignment operator with copy semantics.
  void putColumn(const ScalarColumn<T>& that);
 
 private:
  // Check if the data type matches the column data type.
  void checkDataType() const;
};
 
// # Explicitly instantiate these templates in ScalarColumn_tmpl.cc
extern template class ScalarColumn<Bool>;
extern template class ScalarColumn<Char>;
extern template class ScalarColumn<Short>;
extern template class ScalarColumn<uShort>;
extern template class ScalarColumn<Int>;
extern template class ScalarColumn<uInt>;
extern template class ScalarColumn<Int64>;
extern template class ScalarColumn<Float>;
extern template class ScalarColumn<Double>;
extern template class ScalarColumn<Complex>;
extern template class ScalarColumn<DComplex>;
extern template class ScalarColumn<String>;
 
}  // namespace casacore
 
// # Make old name ROScalarColumn still available.
#define ROScalarColumn ScalarColumn
 
#ifndef CASACORE_NO_AUTO_TEMPLATES
#include <casacore/tables/Tables/ScalarColumn.tcc>
#endif  // # CASACORE_NO_AUTO_TEMPLATES
#endif