Abstract base class for classes calculating an aggregated group result. More...

#include <ExprGroup.h>

Inheritance diagram for casacore::TableExprGroupFuncBase:

Public Member Functions
	TableExprGroupFuncBase (TableExprNodeRep *node)
	Construct from the TaQL aggregation node. More...

virtual	~TableExprGroupFuncBase ()

virtual Bool	isLazy () const
	Does the aggregate function use lazy semantics? The default implementation returns False. More...

uInt	seqnr () const
	Get the function's sequence nr. More...

void	setSeqnr (uInt seqnr)
	Set the function's sequence nr. More...

virtual void	apply (const TableExprId &id)=0
	Get the operand's value for the given row and apply it to the aggregation. More...

virtual void	finish ()
	If needed, finish the aggregation. More...

virtual CountedPtr< vector < TableExprId > >	getIds () const
	Get the assembled TableExprIds of a group. More...

virtual Bool	getBool (const vector< TableExprId > &=vector< TableExprId >())
	Get the aggregated value. More...

virtual Int64	getInt (const vector< TableExprId > &=vector< TableExprId >())

virtual Double	getDouble (const vector< TableExprId > &=vector< TableExprId >())

virtual DComplex	getDComplex (const vector< TableExprId > &=vector< TableExprId >())

virtual MVTime	getDate (const vector< TableExprId > &=vector< TableExprId >())

virtual String	getString (const vector< TableExprId > &=vector< TableExprId >())

virtual MArray< Bool >	getArrayBool (const vector< TableExprId > &=vector< TableExprId >())

virtual MArray< Int64 >	getArrayInt (const vector< TableExprId > &=vector< TableExprId >())

virtual MArray< Double >	getArrayDouble (const vector< TableExprId > &=vector< TableExprId >())

virtual MArray< DComplex >	getArrayDComplex (const vector< TableExprId > &=vector< TableExprId >())

virtual MArray< MVTime >	getArrayDate (const vector< TableExprId > &=vector< TableExprId >())

virtual MArray< String >	getArrayString (const vector< TableExprId > &=vector< TableExprId >())

Protected Attributes
TableExprNodeRep *	itsNode

TableExprNodeRep *	itsOperand

uInt	itsSeqnr

Private Member Functions
	TableExprGroupFuncBase (const TableExprGroupFuncBase &)
	Copying is not needed, thus not allowed. More...

TableExprGroupFuncBase &	operator= (const TableExprGroupFuncBase &)

Detailed Description

Abstract base class for classes calculating an aggregated group result.

Intended use:

Internal

Review Status

Test programs:: tExprGroup

Synopsis

The GROUPBY clause divides a table into groups for which aggregated results can be calculated like the mean or minimum. These results are calculated in classes derived from this abstract base class.
There is one such function object per aggregation per group. All aggregation objects of a group are combined in a std::vector. This vector is mapped to a TableExprGroupKeySet object to keep track of all groups and aggregations.
There are two types of aggregation function classes.

Immediate classes implement the 'apply' function to immediately apply the operand's value in the aggregation. Such classes do not keep the operand's values.
Lazy classes do not need the 'apply' function. Instead they read all values of the group in the 'getXXX' function and do the aggregation. Such classes are meant for aggregation functions like 'median' that need to keep all values. When applying it immediately, all groups need to keep their values which might need too much memory. Lazy classes need the values of only one group at a time, but have the disadvantage that reading the values from the table might be done in a non-sequential order.

Most derived classes are immediate classes.

Definition at line 201 of file ExprGroup.h.

Constructor & Destructor Documentation

casacore::TableExprGroupFuncBase::TableExprGroupFuncBase ( TableExprNodeRep * node )

explicit

Construct from the TaQL aggregation node.

It keeps the operand of the aggregation node.

virtual casacore::TableExprGroupFuncBase::~TableExprGroupFuncBase ( )

virtual

casacore::TableExprGroupFuncBase::TableExprGroupFuncBase ( const TableExprGroupFuncBase & )

private

Copying is not needed, thus not allowed.

Member Function Documentation

virtual void casacore::TableExprGroupFuncBase::apply ( const TableExprId & id )

pure virtual

Get the operand's value for the given row and apply it to the aggregation.

This function should not be called for lazy classes.

virtual void casacore::TableExprGroupFuncBase::finish ( )

virtual

If needed, finish the aggregation.

By default nothing is done.

virtual MArray<Bool> casacore::TableExprGroupFuncBase::getArrayBool ( const vector< TableExprId > & = vector< TableExprId >() )

virtual

Reimplemented in casacore::TableExprGroupFuncArrayBool, casacore::TableExprGroupAggr, and casacore::TableExprGroupFirst.

virtual MArray<MVTime> casacore::TableExprGroupFuncBase::getArrayDate ( const vector< TableExprId > & = vector< TableExprId >() )

virtual

Reimplemented in casacore::TableExprGroupFuncArrayDate, casacore::TableExprGroupAggr, and casacore::TableExprGroupFirst.

virtual MArray<DComplex> casacore::TableExprGroupFuncBase::getArrayDComplex ( const vector< TableExprId > & = vector< TableExprId >() )

virtual

Reimplemented in casacore::TableExprGroupFuncArrayDComplex, casacore::TableExprGroupAggr, and casacore::TableExprGroupFirst.

virtual MArray<Double> casacore::TableExprGroupFuncBase::getArrayDouble ( const vector< TableExprId > & = vector< TableExprId >() )

virtual

Reimplemented in casacore::TableExprGroupFuncArrayDouble, casacore::TableExprGroupAggr, and casacore::TableExprGroupFirst.

virtual MArray<Int64> casacore::TableExprGroupFuncBase::getArrayInt ( const vector< TableExprId > & = vector< TableExprId >() )

virtual

Reimplemented in casacore::TableExprGroupHistBase, casacore::TableExprGroupFuncArrayInt, casacore::TableExprGroupAggr, casacore::TableExprGroupRowid, and casacore::TableExprGroupFirst.

virtual MArray<String> casacore::TableExprGroupFuncBase::getArrayString ( const vector< TableExprId > & = vector< TableExprId >() )

virtual

Reimplemented in casacore::TableExprGroupFuncArrayString, casacore::TableExprGroupAggr, and casacore::TableExprGroupFirst.

virtual Bool casacore::TableExprGroupFuncBase::getBool ( const vector< TableExprId > & = vector< TableExprId >() )

virtual

Get the aggregated value.

Immediate classes can return the already calculated value, while lazy classes will get the values of all rows given by the TableExprIds and do the aggregation.

Reimplemented in casacore::TableExprGroupFuncBool, and casacore::TableExprGroupFirst.

virtual MVTime casacore::TableExprGroupFuncBase::getDate ( const vector< TableExprId > & = vector< TableExprId >() )