net.sf.saxon.functions

Class DistinctValues.DistinctIterator

java.lang.Object

net.sf.saxon.functions.DistinctValues.DistinctIterator

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, SequenceIterator<AtomicValue>

Enclosing class:

DistinctValues

public static class DistinctValues.DistinctIterator
extends java.lang.Object
implements SequenceIterator<AtomicValue>

Iterator class to return the distinct values in a sequence

Field Summary

Fields inherited from interface net.sf.saxon.om.SequenceIterator

ATOMIZING, GROUNDED, LAST_POSITION_FINDER, LOOKAHEAD

Constructor Summary

Constructors

Constructor and Description
DistinctIterator(SequenceIterator<? extends AtomicValue> base, StringCollator collator, XPathContext context) Create an iterator over the distinct values in a sequence

Method Summary

Modifier and Type	Method and Description
void	close() Close the iterator.
int	getProperties() Get properties of this iterator, as a bit-significant integer.
AtomicValue	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

Methods inherited from interface net.sf.saxon.om.SequenceIterator

forEachOrFail, materialize

Constructor Detail

DistinctIterator

public DistinctIterator(SequenceIterator<? extends AtomicValue> base,
                        StringCollator collator,
                        XPathContext context)

Create an iterator over the distinct values in a sequence

Parameters:

base - the input sequence. This must return atomic values only.

collator - The comparer used to obtain comparison keys from each value; these comparison keys are themselves compared using equals().

context - the XPath dynamic context

Method Detail

next

public AtomicValue next()
                 throws XPathException

Get the next item in the sequence.

Specified by:

next in interface SequenceIterator<AtomicValue>

Returns:

the next item, or null if there are no more items.

Throws:

XPathException - if an error occurs retrieving the next item

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.

Specified by:

close in interface java.io.Closeable

Specified by:

close in interface java.lang.AutoCloseable

Specified by:

close in interface SequenceIterator<AtomicValue>

getProperties

public int getProperties()

Get properties of this iterator, as a bit-significant integer.

Specified by:

getProperties in interface SequenceIterator<AtomicValue>

Returns:

the properties of this iterator. This will be some combination of properties such as SequenceIterator.GROUNDED, SequenceIterator.LAST_POSITION_FINDER, and SequenceIterator.LOOKAHEAD. It is always acceptable to return the value zero, indicating that there are no known special properties. It is acceptable for the properties of the iterator to change depending on its state.