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TableQuantumDesc.h
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//# TableQuantumDesc.h: Defines a Quantum column in a Table.
//# Copyright (C) 1997,1998,1999,2000,2001
//# 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 MEASURES_TABLEQUANTUMDESC_H
#define MEASURES_TABLEQUANTUMDESC_H
//# Includes
#include <casacore/casa/aips.h>
#include <casacore/casa/Arrays/Vector.h>
#include <casacore/casa/BasicSL/String.h>
namespace casacore { //# NAMESPACE CASACORE - BEGIN
//# Forward Declarations
class TableDesc;
class Table;
class TableRecord;
class TableColumn;
class Unit;
// <summary>
// A class for defining Quantum columns in Tables.
// </summary>
// <use visibility=export>
// <reviewed reviewer="Bob Garwood" date="1999/12/23" tests="tTableQuantum.cc">
// </reviewed>
// <prerequisite>
//# Classes you should understand before using this one.
// <li> <linkto class=Table>Table</linkto>
// <li> <linkto class=Quantum>Quantum</linkto>
// </prerequisite>
// <synopsis>
// A TableQuantumDesc object is used to define a Quantum column in a Table.
// The use of this object and the associated Scalar- and ArrayQuantColumn
// objects make it possible to store (and retrieve) Quanta in Tables.<br>
//
// TableQuantumDesc objects are analogous to ColumnDesc objects in that they
// add information, describing the characteristics of a column, to the Table
// Descriptor before the Table is created. However, rather than
// replacing the use of a ColumnDesc object, a TableQuantumDesc is
// used in conjunction with a ColumnDesc in the definition of
// Quantum columns.<br>
//
// <note role=caution>
// A good understanding of the Table system is essential
// before attempting to use this class.
// </note>
//
// Defining a Quantum column requires the following steps:
// <ol>
// <li> Use a normal Scalar- or ArrayColumnDesc to define a column to use for
// the Quanta.
// <li> If needed (see
// <A HREF="#TableQuantumDesc:Quantum Units">below</A>) define a column
// for the Quantum Units.
// <li> Add the columns to the Table Descriptor.
// <li> Declare a TableQuantumDesc to associate the column defined in step 1
// and the Unit column from step 2 and update the Table Descriptor.
// <li> Setup and create the Table.
// </ol>
// It is also possible to define a Quantum column after the table is created.
// which is useful when columns (to be used for quanta) are added to
// an already existing table. <br>
//
// The type of the quantum columns must match the type of the underlying
// Quanta that are to be stored in the column. Hence, for a column of
// Quantum&lt;Complex&gt; a ScalarColumnDesc&lt;Complex&gt; must be used.<br>
//
// As with standard Table Columns Quanta can be stored in Scalar and Array
// columns. This must be specified in advance by using either a
// Scalar- or ArrayColumnDesc.<br>
//
// After the Table has be created a Quantum column can be accessed for writing
// and reading of Quanta via the
// <linkto class="ScalarQuantColumn">(RO)ScalarQuantColumn&lt;T&gt;</linkto>
// and
// <linkto class="ArrayQuantColumn">(RO)ArrayQuantColumn&lt;T&gt;</linkto>
// objects.
//
// <ANCHOR NAME="TableQuantumDesc:Quantum Units">
// <h3>Quantum Units</h3></ANCHOR>
// The treatment of the Unit component of a Quantum in the TableQuantumDesc
// class varies depending on your needs. The main consideration
// is whether the Quanta to be stored in a specific column are to have the
// same Unit or whether their Units could differ. In the simple case,
// where the
// Quanta have the same unit, a TableQuantumDesc is declared with the
// Unit value specified as a parameter. The following defines a Quantum
// column with units "deg":
//
// <srcblock>
// ScalarColumnDesc<Double> scd("QuantumCol");
// ...
// // defines QuantumCol as a Quantum column with fix Units "deg"
// TableQuantumDesc tqd(td, "QuantumCol", Unit("deg"));
// </srcblock>
//
// This constructor stores the value for the Unit as a
// column keyword. In situations, however, where it is necessary to
// store a distinct Unit with each Quantum, it is necessary to define
// an additional column for storing the Unit component of each Quantum.
// The TableQuantumDesc constructor for this takes the name of
// the Unit column as
// a parameter. Hence an additional column must be defined for storing the
// Units and its type must be string. The following
// example shows how to set up a Quantum column with support for Quantum
// unit variability:
//
// <srcblock>
// // the quanta values stored here
// ScalarColumnDesc<Double> scd("QuantumCol");
// // a String column for the Units
// ScalarColumnDesc<String> scd("QuantumUnitCol");
// ...
// TableQuantumDesc tqd(td, "QuantumCol", "QuantumUnitCol");
// </srcblock>
//
// One further consideration is that for Array Quantum Columns it is
// necessary to
// decide on a level of granularity for the Unit storage you would like.
// In Array Quantum columns it is possible to store a distinct Unit per row or
// per array element per row. This distinction is established when the
// Unit column is declared. Defining a ScalarColumn for Units specifies per
// row variability, that is, each row in an array column of Quanta will
// have the same unit. Alternatively, use of an ArrayColumn for the Unit
// column
// specifies that every Quantum stored will have its unit stored as well.
// In both cases the Unit column's type must be String. The following
// defines an Array Quantum Column with per row Unit storage:
//
// <srcblock>
// // for the Quanta values
// ArrayColumnDesc<Double> scd("ArrayQuantumCol");
// // per row storage of units
// ScalarColumnDesc<String> scd("QuantumUnitCol");
// ...
// TableQuantumDesc tqd(td, "ArrayQuantumCol", "QuantumUnitCol");
// </srcblock>
//
// And finally, an array Quantum Column with an Array Unit Column:
//
// <srcblock>
// // for Quanta values
// ArrayColumnDesc<Double> scd("ArrayQuantumCol");
// // per element storage of Units
// ArrayColumnDesc<String> scd("ArrayUnitCol");
// ...
// TableQuantumDesc tqd(td, "ArrayQuantumCol", "ArrayUnitCol");
// </srcblock>
//
//
// After constructing an TableQuantumDesc object use of the write() member
// updates the Table Descriptor or Table object.
// <linkto class="ScalarQuantColumn">(RO)ScalarQuantColumn&lt;T&gt;</linkto>
// and
// <linkto class="ArrayQuantColumn">(RO)ArrayQuantColumn&lt;T&gt;</linkto>
// are subsequently used to read-only and read/write access the Quantum
// Columns.
// </synopsis>
//
// <example>
// <srcblock>
// // create a table descriptor as normal
// TableDesc td("measTD", "1", TableDesc::New);
// td.comment() = "A table containing measures and quantums";
//
// // This example sets up a Quantum<Complex> column but any valid Quantum
// // type can be specified. However, the type of the Quantums to be
// // stored must match the type of the underlying table column.
// ScalarColumnDesc<Complex> tcdQCplx("Quant", "A quantum complex column");
//
// // For a Quantum array column an ArrayColumnDesc is first defined
// ArrayColumnDesc<Double> tcdQDoub("QuantArray", "A quantum array col");
//
// // The QuantumArray column has variable units. A string is needed
// // for these. This could be done in two ways depending on what is
// // wanted. Units can vary per element of array per row or
// // just per row. In the first instance an ArrayColumn<String> would be
// // require. Here we want to vary units only per row.
// ScalarColumnDesc<String> tcdUnits("VarQuantUnits", "Quantum units");
//
// // Add the columns to the Table Descriptor
// td.addColumn(tcdQplx);
// td.addColumn(tcdQDoub);
// td.addColumn(tcdUnits);
//
// // Create the TableQuantumDesc with units "deg" and an Array Quantum
// // Column with per row Unit granularity
// TableQuantumDesc tqdS(td, "Quant", unit("deg"));
// TableQuantumDesc tqdA(td, "QuantArray", "VarQuantUnits");
//
// // Update the Table Descriptor
// tqdA.write(td);
// tqdS.write(td);
//
// // Setup and create the new table as usual.
// SetupNewTable newtab("mtab", td, Table::New);
// Table qtab(newtab);
//
// // Now ScalarQuantColumn and ArrayQuantColumn objects could be
// // constructed to access the columns...
// </srcblock>
// Note that writing the Quantum description could also be done
// after the table is created. It is meaningless in this case, but
// it is useful when columns (to be used for quanta) are added to
// an already existing table.
// be used as
// <srcblock>
// // Setup and create the new table as usual.
// SetupNewTable newtab("mtab", td, Table::New);
// Table qtab(newtab);
//
// // Update the Table Descriptor
// tqdA.write(qtab);
// tqdS.write(qtab);
// </srcblock>
// </example>
// <motivation>
// This class assists in the definition of a Quantum Table Column.
// </motivation>
// <thrown>
// <li>AipsError during construction if the column doesn't exist.
// <li>AipsError during construction if the unit's column doesn't
// exist (when variable units).
// <li>AipsError during construction if the type of the variable unit's
// column is not String.
// <li>AipsError during a reconstruct if the column doesn't have a Unit.
// </thrown>
//# <todo asof="$DATE:$">
//# A List of bugs, limitations, extensions or planned refinements.
//# </todo>
class TableQuantumDesc
{
public:
// Constructs a Quantum column descriptor with null units (Unit == "").
// The column should have already been added to the TableDesc.
// An exception is thrown if the column doesn't exist.
TableQuantumDesc (const TableDesc& td, const String& column);
// Constructs a Quantum column descriptor with the specified Quantum unit.
// The column should have already been added to the TableDesc.
// An exception is thrown if the column doesn't exist.
TableQuantumDesc (const TableDesc& td, const String& column, const Unit&);
// Constructs a Quantum column descriptor with the specified Quantum units.
// The column should have already been added to the TableDesc.
// An exception is thrown if the column doesn't exist.
// <group>
TableQuantumDesc (const TableDesc& td, const String& column,
const Vector<String>& unitNames);
TableQuantumDesc (const TableDesc& td, const String& column,
const Vector<Unit>&);
// </group>
// Constructs a Quantum column descriptor with variable units stored in
// unitCol. Both the quantum and unit column should exist in the
// TableDesc.
//# Note that the Char* constructor is needed, otherwise the compiler
//# cannot choose between String and Unit.
//<group>
TableQuantumDesc (const TableDesc& td, const String& column,
const String& unitCol);
TableQuantumDesc (const TableDesc& td, const String& column,
const Char* unitCol);
//</group>
// Copy constructor (copy semantics).
TableQuantumDesc (const TableQuantumDesc& that);
~TableQuantumDesc();
// Reconstructs a previously constructed TableQuantumDesc.
static TableQuantumDesc* reconstruct (const TableDesc& td,
const String& column);
// Assignment.
TableQuantumDesc& operator= (const TableQuantumDesc& that);
// Returns the Quantum column descriptor's units. A empty vector is
// returned if units have not been specified. This could be because the null
// unit constructor was used or because the units are variable.
const Vector<String>& getUnits() const
{ return itsUnitsName; }
// Returns True if descriptor set for variable units (one per row)
Bool isUnitVariable() const
{ return (! itsUnitsColName.empty()); }
// Returns the name of the quantum column.
const String& columnName() const
{ return itsColName; }
// Returns the name of the units column (an empty String is returned
// if the units are not variable).
const String& unitColumnName() const
{ return itsUnitsColName; }
// Makes the TableQuantumDesc persistent (updates the Table Descriptor).
// <group>
void write (TableDesc&);
void write (Table&);
// </group>
// Does this column contain table quanta?
static Bool hasQuanta (const TableColumn& column);
private:
// Name of column which stores the Quantum's values.
String itsColName;
// The Quantum's unit as a string.
Vector<String> itsUnitsName;
// Name of units column if units are variable.
String itsUnitsColName;
// Write the actual keywords.
void writeKeys (TableRecord& columnKeyset);
// Throw an exception if the quantum column doesn't exist.
void checkColumn (const TableDesc& td) const;
// Throw an exception if the variable units column isn't a string column.
void checkUnitsColumn (const TableDesc& td) const;
};
} //# NAMESPACE CASACORE - END
#endif
casacore::String
String: the storage and methods of handling collections of characters.
Definition String.h:223
casacore::TableColumn
Definition TableColumn.h:97
casacore::TableDesc
Definition TableDesc.h:189
casacore::TableQuantumDesc::TableQuantumDesc
TableQuantumDesc(const TableDesc &td, const String &column, const String &unitCol)
Constructs a Quantum column descriptor with variable units stored in unitCol.
casacore::TableQuantumDesc::itsUnitsName
Vector< String > itsUnitsName
The Quantum's unit as a string.
Definition TableQuantumDesc.h:342
casacore::TableQuantumDesc::writeKeys
void writeKeys(TableRecord &columnKeyset)
Write the actual keywords.
casacore::TableQuantumDesc::itsUnitsColName
String itsUnitsColName
Name of units column if units are variable.
Definition TableQuantumDesc.h:344
casacore::TableQuantumDesc::write
void write(TableDesc &)
Makes the TableQuantumDesc persistent (updates the Table Descriptor).
casacore::TableQuantumDesc::hasQuanta
static Bool hasQuanta(const TableColumn &column)
Does this column contain table quanta?
casacore::TableQuantumDesc::write
void write(Table &)
casacore::TableQuantumDesc::TableQuantumDesc
TableQuantumDesc(const TableDesc &td, const String &column, const Char *unitCol)
casacore::TableQuantumDesc::operator=
TableQuantumDesc & operator=(const TableQuantumDesc &that)
Assignment.
casacore::TableQuantumDesc::getUnits
const Vector< String > & getUnits() const
Returns the Quantum column descriptor's units.
Definition TableQuantumDesc.h:313
casacore::TableQuantumDesc::TableQuantumDesc
TableQuantumDesc(const TableDesc &td, const String &column, const Unit &)
Constructs a Quantum column descriptor with the specified Quantum unit.
casacore::TableQuantumDesc::unitColumnName
const String & unitColumnName() const
Returns the name of the units column (an empty String is returned if the units are not variable).
Definition TableQuantumDesc.h:326
casacore::TableQuantumDesc::itsColName
String itsColName
Name of column which stores the Quantum's values.
Definition TableQuantumDesc.h:340
casacore::TableQuantumDesc::TableQuantumDesc
TableQuantumDesc(const TableQuantumDesc &that)
Copy constructor (copy semantics).
casacore::TableQuantumDesc::columnName
const String & columnName() const
Returns the name of the quantum column.
Definition TableQuantumDesc.h:321
casacore::TableQuantumDesc::checkUnitsColumn
void checkUnitsColumn(const TableDesc &td) const
Throw an exception if the variable units column isn't a string column.
casacore::TableQuantumDesc::~TableQuantumDesc
~TableQuantumDesc()
casacore::TableQuantumDesc::TableQuantumDesc
TableQuantumDesc(const TableDesc &td, const String &column, const Vector< String > &unitNames)
Constructs a Quantum column descriptor with the specified Quantum units.
casacore::TableQuantumDesc::checkColumn
void checkColumn(const TableDesc &td) const
Throw an exception if the quantum column doesn't exist.
casacore::TableQuantumDesc::TableQuantumDesc
TableQuantumDesc(const TableDesc &td, const String &column)
Constructs a Quantum column descriptor with null units (Unit == "").
casacore::TableQuantumDesc::reconstruct
static TableQuantumDesc * reconstruct(const TableDesc &td, const String &column)
Reconstructs a previously constructed TableQuantumDesc.
casacore::TableQuantumDesc::TableQuantumDesc
TableQuantumDesc(const TableDesc &td, const String &column, const Vector< Unit > &)
casacore::TableQuantumDesc::isUnitVariable
Bool isUnitVariable() const
Returns True if descriptor set for variable units (one per row).
Definition TableQuantumDesc.h:317
casacore::TableRecord
Definition TableRecord.h:183
casacore::Table
Definition Table.h:157
casacore::Unit
Definition Unit.h:187
casacore::Vector
Definition Vector.h:82
casacore
this file contains all the compiler specific defines
Definition mainpage.dox:28
casacore::Bool
bool Bool
Define the standard types used by Casacore.
Definition aipstype.h:40
casacore::Char
char Char
Definition aipstype.h:44