- All Implemented Interfaces:
public class UntypedAtomizingIterator extends java.lang.Object implements SequenceIterator, LastPositionFinder, LookaheadIteratorAtomizingIterator returns the atomization of an underlying sequence supplied as an iterator. We use a specialist class rather than a general-purpose MappingIterator for performance, especially as the relationship of items in the result sequence to those in the base sequence is often one-to-one.
This UntypedAtomizingIterator is used only when it is known that the input sequence consists entirely of nodes, and that all nodes will be untyped.
All Methods Instance Methods Concrete Methods Modifier and Type Method Description
close()Close the iterator.
getLength()Get the last position (that is, the number of items in the sequence).
hasNext()Determine whether there are more items to come.
next()Get the next item in the sequence.
supportsGetLength()Ask whether this iterator supports use of the
supportsHasNext()Ask whether the hasNext() method can be called.
public UntypedAtomizingIterator(SequenceIterator base)Construct an AtomizingIterator that will atomize the values returned by the base iterator.
base- the base iterator
public AtomicValue next()Description copied from interface:
SequenceIteratorGet the next item in the sequence. This method changes the state of the iterator.
- Specified by:
- 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.
public void close()Description copied from interface:
SequenceIteratorClose 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
$varis passed to a user-written function, the function may access
$varonly; we have no way of knowing whether further items will be read. For this reason, any
SequenceIteratorthat holds resources which need to be closed should use the
Cleaner, and resources held by a
SequenceIteratorshould be registered with the
Cleaner; if the
SequenceIteratoris then garbage-collected without being closed, the
Cleanerwill ensure that the underlying resources are closed. (An example of a
SequenceIteratorthat uses this mechanism is the
public boolean supportsGetLength()Ask whether this iterator supports use of the
getLength()method. This method should always be called before calling
getLength(), because an iterator that implements this interface may support use of
getLength()in some situations and not in others
public int getLength()Description copied from interface:
LastPositionFinderGet the last position (that is, the number of items in the sequence). This method is non-destructive: it does not change the state of the iterator. The result is undefined if the next() method of the iterator has already returned null. This method must not be called unless the
LastPositionFinder.supportsGetLength()has been called and has returned true.
public boolean supportsHasNext()Description copied from interface:
LookaheadIteratorAsk whether the hasNext() method can be called. This method must be called before calling hasNext(), because some iterators implement this interface, but only support look-ahead under particular circumstances (this is usually because they delegate to another iterator)
public boolean hasNext()Description copied from interface:
LookaheadIteratorDetermine whether there are more items to come. Note that this operation is stateless and it is not necessary (or usual) to call it before calling next(). It is used only when there is an explicit need to tell if we are at the last element.
This method must not be called unless the result of