Package net.sf.saxon.tree.wrapper

Class VirtualCopy.VirtualCopier

java.lang.Object

net.sf.saxon.tree.wrapper.VirtualCopy.VirtualCopier

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, SequenceIterator, AxisIterator

Enclosing class:

VirtualCopy

protected static class VirtualCopy.VirtualCopier
extends java.lang.Object
implements AxisIterator

VirtualCopier implements the XPath axes as applied to a VirtualCopy node. It works by applying the requested axis to the node of which this is a copy. There are two complications: firstly, all nodes encountered must themselves be (virtually) copied to give them a new identity. Secondly, axes that stray outside the subtree rooted at the original copied node must be truncated.

Field Summary

Fields

Modifier and Type	Field	Description
protected AxisIterator	base
protected VirtualCopy	node
protected boolean	testInclusion

Constructor Summary

Constructors

Constructor	Description
VirtualCopier(VirtualCopy node, AxisIterator base, VirtualCopy parent, boolean testInclusion)

Method Summary

Modifier and Type	Method	Description
void	close()	Close the iterator.
NodeInfo	next()	Get the next item in the sequence.

Methods inherited from class java.lang.Object

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

Field Detail

node

protected VirtualCopy node

base

protected AxisIterator base

testInclusion

protected boolean testInclusion

Constructor Detail

VirtualCopier

public VirtualCopier(VirtualCopy node,
                     AxisIterator base,
                     VirtualCopy parent,
                     boolean testInclusion)

Method Detail

next

public NodeInfo next()

Get the next item in the sequence.

Specified by:

next in interface AxisIterator

Specified by:

next in interface SequenceIterator

Returns:

the next Item. If there are no more nodes, return null.

close

public void close()

Description copied from interface: SequenceIterator

Close the iterator. This indicates to the supplier of the data that the client does not require any more items to be delivered by the iterator. This may enable the supplier to release resources. After calling close(), no further calls on the iterator should be made; if further calls are made, the effect of such calls is undefined.

For example, the iterator returned by the unparsed-text-lines() function has a close() method that causes the underlying input stream to be closed, whether or not the file has been read to completion.

Closing an iterator is important when the data is being "pushed" in another thread. Closing the iterator terminates that thread and means that it needs to do no additional work. Indeed, failing to close the iterator may cause the push thread to hang waiting for the buffer to be emptied.

Closing an iterator is not necessary if the iterator is read to completion: if a call on SequenceIterator.next() returns null, the iterator will be closed automatically. An explicit call on SequenceIterator.close() is needed only when iteration is abandoned prematurely.

It is not possible to guarantee that an iterator that is not read to completion or will be closed. For example, if a lazy-evaluated variable $var is passed to a user-written function, the function may access $var[1] only; we have no way of knowing whether further items will be read. For this reason, any SequenceIterator that holds resources which need to be closed should use the Cleaner mechanism. The Configuration holds a Cleaner, and resources held by a SequenceIterator should be registered with the Cleaner; if the SequenceIterator is then garbage-collected without being closed, the Cleaner will ensure that the underlying resources are closed. (An example of a SequenceIterator that uses this mechanism is the UnparsedTextIterator).

Specified by:

close in interface java.lang.AutoCloseable

Specified by:

close in interface java.io.Closeable

Specified by:

close in interface SequenceIterator