net.sf.saxon.expr.flwor

Class WindowClausePull

java.lang.Object

net.sf.saxon.expr.flwor.TuplePull

net.sf.saxon.expr.flwor.WindowClausePull

public class WindowClausePull
extends TuplePull

Implement a sliding or tumbling window clause of a FLWOR expression in tuple-pull mode. The entire window processing is activated once for each input tuple, and it generates one output tuple for each identified window.

Constructor Summary

Constructors

Constructor and Description
WindowClausePull(TuplePull source, WindowClause windowClause, XPathContext context)

Method Summary

Modifier and Type	Method and Description
void	close() Close the tuple stream, indicating that no more tuples will be supplied
boolean	nextTuple(XPathContext context) Move on to the next tuple.
void	processWindow(WindowClause.Window w, XPathContext context) Despatch a window to the output tuple stream.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

WindowClausePull

public WindowClausePull(TuplePull source,
                        WindowClause windowClause,
                        XPathContext context)

Method Detail

nextTuple

public boolean nextTuple(XPathContext context)
                  throws XPathException

Move on to the next tuple. Before returning, this method must set all the variables corresponding to the "returned" tuple in the local stack frame associated with the context object

Specified by:

nextTuple in class TuplePull

Parameters:

context - the dynamic evaluation context

Returns:

true if another tuple has been generated; false if the tuple stream is exhausted. If the method returns false, the values of the local variables corresponding to this tuple stream are undefined.

Throws:

XPathException

processWindow

public void processWindow(WindowClause.Window w,
                          XPathContext context)
                   throws XPathException

Despatch a window to the output tuple stream. This essentially means setting the relevant local variables on the context stack from information held in the window object.

Parameters:

w - the window to be despatched

context - the dynamic evaluation context

Throws:

XPathException - if anything goes wrong

close

public void close()

Close the tuple stream, indicating that no more tuples will be supplied

Overrides:

close in class TuplePull