net.sf.saxon.tree.wrapper

Class WrappingIterator

java.lang.Object

net.sf.saxon.tree.wrapper.WrappingIterator

All Implemented Interfaces:

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

public class WrappingIterator
extends java.lang.Object
implements AxisIterator

A WrappingIterator delivers wrappers for the nodes delivered by its underlying iterator. It is used when no whitespace stripping is actually needed, e.g. for the attribute axis. But we still need to create wrappers, so that further iteration remains in the virtual layer rather than switching to the real nodes.

Constructor Summary

Constructors

Constructor and Description
WrappingIterator(AxisIterator base, WrappingFunction function, VirtualNode parent) Create a WrappingIterator

Method Summary

Modifier and Type	Method and Description
void	close() Close the iterator.
NodeInfo	current()
void	discharge() Calling this method instructs the iterator to release any resources it holds, while still remaining able to deliver the remaining items in the sequence.
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

Constructor Detail

WrappingIterator

public WrappingIterator(AxisIterator base,
                        WrappingFunction function,
                        VirtualNode parent)

Create a WrappingIterator

Parameters:

base - The underlying iterator

function - The wrapping function

parent - If all the nodes to be wrapped have the same parent, it can be specified here. Otherwise specify null.

Method Detail

next

public NodeInfo next()

Description copied from interface: SequenceIterator

Get the next item in the sequence. This method changes the state of the iterator.

Specified by:

next in interface SequenceIterator

Specified by:

next in interface AxisIterator

Returns:

the next item, or null if there are no more items. Once a call on next() has returned null, no further calls should be made. The preferred action for an iterator if subsequent calls on next() are made is to return null again, and all implementations within Saxon follow this rule.

current

public NodeInfo current()

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.

Specified by:

close in interface java.io.Closeable

Specified by:

close in interface java.lang.AutoCloseable

Specified by:

close in interface SequenceIterator

discharge

public void discharge()

Description copied from interface: SequenceIterator

Calling this method instructs the iterator to release any resources it holds, while still remaining able to deliver the remaining items in the sequence. This may require the iterator to calculate the rest of the sequence eagerly. The method is called by a client if it anticipates that it might not read the iterator to completion, but it cannot guarantee that SequenceIterator.close() will be called when no more items are needed.

Specified by:

discharge in interface SequenceIterator