Double comparison == in table select expression tree. More...

#include <ExprLogicNode.h>

Inheritance diagram for casa::TableExprNodeEQDouble:

Public Member Functions
	TableExprNodeEQDouble (const TableExprNodeRep &)
	~TableExprNodeEQDouble ()
Bool	getBool (const TableExprId &id)
	Is the expression a column aggregate function?
void	ranges (Block< TableExprRange > &)
	Convert the tree to a number of range vectors which at least select the same things.

Detailed Description

Double comparison == in table select expression tree.

Intended use:

Internal

Review Status

Reviewed By:: UNKNOWN
Date Reviewed:: before2004/08/25

Prerequisite

TableExprNode

Synopsis

This class represents an == comparison in a table select expression tree. This is defined for all data types. Only the Bool get function is defined, because the result of a compare is always a Bool.

Definition at line 130 of file ExprLogicNode.h.

Constructor & Destructor Documentation

casa::TableExprNodeEQDouble::TableExprNodeEQDouble ( const TableExprNodeRep & )

casa::TableExprNodeEQDouble::~TableExprNodeEQDouble ( )

Member Function Documentation

Bool casa::TableExprNodeEQDouble::getBool ( const TableExprId & id ) [virtual]

Is the expression a column aggregate function?

virtual Bool isAggregate() const; Get a scalar value for this node in the given row. The appropriate functions are implemented in the derived classes and will usually invoke the get in their children and apply the operator on the resulting values.

Reimplemented from casa::TableExprNodeRep.

void casa::TableExprNodeEQDouble::ranges ( Block< TableExprRange > & ) [virtual]

Convert the tree to a number of range vectors which at least select the same things.

This function is very useful to convert the expression to some intervals covering the select expression. This can be used to do a rough fast selection via an index and do the the slower final selection on that much smaller subset. The function can only convert direct comparisons of columns with constants (via ==, !=, >, >=, < or <=) and their combinations using && or ||.