net.sf.saxon.expr.flwor
Class OrderByClausePull

java.lang.Object
  net.sf.saxon.expr.flwor.TuplePull
      net.sf.saxon.expr.flwor.OrderByClausePull

All Implemented Interfaces:

Sortable

public class OrderByClausePull
extends TuplePull
implements Sortable

Represents the tuple stream delivered by an "order by" clause. This sorts the tuple stream supplied as its input, and outputs the same tuples but in sorted order.

Field Summary

protected AtomicComparer[]

comparers

Constructor Summary

OrderByClausePull(TuplePull base, TupleExpression tupleExpr, OrderByClause orderBy, XPathContext context)

Method Summary

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
int	compare(int a, int b) Compare two objects within this Sortable, identified by their position.
boolean	nextTuple(XPathContext context) Move on to the next tuple.
void	swap(int a, int b) Swap two objects within this Sortable, identified by their position.

Methods inherited from class java.lang.Object

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

Field Detail

comparers

protected AtomicComparer[] comparers

Constructor Detail

OrderByClausePull

public OrderByClausePull(TuplePull base,
                         TupleExpression tupleExpr,
                         OrderByClause orderBy,
                         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

compare

public int compare(int a,
                   int b)

Compare two objects within this Sortable, identified by their position.

Specified by:

compare in interface Sortable

Returns:

<0 if obj[a]0 if obj[a]>obj[b]

swap

public void swap(int a,
                 int b)

Swap two objects within this Sortable, identified by their position.

Specified by:

swap in interface Sortable

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

Overrides:

close in class TuplePull