Package net.sf.saxon.expr.flwor

Class TuplePull

java.lang.Object

net.sf.saxon.expr.flwor.TuplePull

Direct Known Subclasses:

CountClausePull, DiagnosticClausePull, ForClausePull, GroupByClausePull, LetClausePull, OrderByClausePull, SingularityPull, TraceClausePull, WhereClausePull, WhileClausePull, WindowClausePull

public abstract class TuplePull
extends Object

Abtract class representing a tuple stream (used to evaluate a FLWOR expression) in pull mode (where the consumer of tuples activates the provider of those tuples)

Constructor Summary

Constructors

Constructor	Description
TuplePull()

Method Summary

Modifier and Type	Method	Description
void	close()	Close the tuple stream, indicating that although not all tuples have been read, no further tuples are required and resources can be released
abstract boolean	nextTuple(XPathContext context)	Move on to the next tuple.

Methods inherited from class java.lang.Object

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

Constructor Details

TuplePull

public TuplePull()

Method Details

nextTuple

public abstract 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

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 - if any error occurs

close

public void close()

Close the tuple stream, indicating that although not all tuples have been read, no further tuples are required and resources can be released