com.icl.saxon.expr
Class DifferenceEnumeration

java.lang.Object
  com.icl.saxon.expr.DifferenceEnumeration

All Implemented Interfaces:

NodeEnumeration

public class DifferenceEnumeration

extends java.lang.Object

implements NodeEnumeration

An enumeration representing a nodeset that is an intersection of two other NodeSets. There is currently no operator in XPath to create such an expression, but it is used by the extension function difference(). The code is derived from the analagous UnionEnumeration, an inner class of UnionExpression.

Constructor Summary

DifferenceEnumeration(NodeEnumeration p1, NodeEnumeration p2, Controller controller)
Form an enumeration of the difference of two nodesets, that is, the nodes that are in p1 and that are not in p2.

Method Summary

boolean	hasMoreElements() Determine whether there are more nodes to come.
boolean	isPeer() Determine whether the nodes returned by this enumeration are known to be peers, that is, no node is a descendant or ancestor of another node.
boolean	isReverseSorted() Determine whether the nodes returned by this enumeration are known to be in reverse document order.
boolean	isSorted() Determine whether the nodes returned by this enumeration are known to be in document order
NodeInfo	nextElement() Get the next node in sequence.

Methods inherited from class java.lang.Object

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

Constructor Detail

DifferenceEnumeration

public DifferenceEnumeration(NodeEnumeration p1,
                             NodeEnumeration p2,
                             Controller controller)
                      throws XPathException

Form an enumeration of the difference of two nodesets, that is, the nodes that are in p1 and that are not in p2.

Parameters:

p1 - the first operand

p2 - the second operand

Method Detail

hasMoreElements

public boolean hasMoreElements()

Description copied from interface: NodeEnumeration

Determine whether there are more nodes to come.
(Note the term "Element" is used here in the sense of the standard Java Enumeration class, it has nothing to do with XML elements).

Specified by:

hasMoreElements in interface NodeEnumeration

Returns:

true if there are more nodes

nextElement

public NodeInfo nextElement()
                     throws XPathException

Description copied from interface: NodeEnumeration

Get the next node in sequence.
(Note the term "Element" is used here in the sense of the standard Java Enumeration class, it has nothing to do with XML elements).

Specified by:

nextElement in interface NodeEnumeration

Returns:

the next NodeInfo

Throws:

XPathException

isSorted

public boolean isSorted()

Description copied from interface: NodeEnumeration

Determine whether the nodes returned by this enumeration are known to be in document order

Specified by:

isSorted in interface NodeEnumeration

Returns:

true if the nodes are guaranteed to be in document order.

isReverseSorted

public boolean isReverseSorted()

Description copied from interface: NodeEnumeration

Determine whether the nodes returned by this enumeration are known to be in reverse document order.

Specified by:

isReverseSorted in interface NodeEnumeration

Returns:

true if the nodes are guaranteed to be in document order.

isPeer

public boolean isPeer()

Description copied from interface: NodeEnumeration

Determine whether the nodes returned by this enumeration are known to be peers, that is, no node is a descendant or ancestor of another node. This significance of this property is that if a peer enumeration is applied to each node in a set derived from another peer enumeration, and if both enumerations are sorted, then the result is also sorted.

Specified by:

isPeer in interface NodeEnumeration