net.sf.saxon.tree.iter

Interface ConstrainedIterator<T extends Item>

All Superinterfaces:

java.lang.AutoCloseable, java.io.Closeable, GroundedIterator, LastPositionFinder, LookaheadIterator, ReversibleIterator, SequenceIterator, UnfailingIterator

public interface ConstrainedIterator<T extends Item>
extends SequenceIterator, UnfailingIterator, ReversibleIterator, LastPositionFinder, GroundedIterator, LookaheadIterator

SingletonIterator: an iterator over a sequence of zero or one values

Nested Class Summary

Nested classes/interfaces inherited from interface net.sf.saxon.om.SequenceIterator

SequenceIterator.Property

Method Summary

Modifier and Type	Method and Description
int	getLength() Get the last position (that is, the number of items in the sequence).
boolean	hasNext() Determine whether there are more items to come.
GroundedValue	materialize() Create a GroundedValue (a sequence materialized in memory) containing all the values delivered by this SequenceIterator.
T	next() Get the next item in the sequence.

Methods inherited from interface net.sf.saxon.tree.iter.UnfailingIterator

forEach, toList

Methods inherited from interface net.sf.saxon.tree.iter.ReversibleIterator

getReverseIterator

Methods inherited from interface net.sf.saxon.tree.iter.GroundedIterator

getResidue

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

close, forEachOrFail, getProperties

Method Detail

hasNext

boolean hasNext()

Determine 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.

Specified by:

hasNext in interface LookaheadIterator

Returns:

true if there are more items

next

T 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 UnfailingIterator

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.

getLength

int getLength()

Description copied from interface: LastPositionFinder

Get 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 result of getProperties() on the iterator includes the bit setting SequenceIterator.Property.LAST_POSITION_FINDER

Specified by:

getLength in interface LastPositionFinder

Returns:

the number of items in the sequence

materialize

GroundedValue materialize()

Description copied from interface: SequenceIterator

Create a GroundedValue (a sequence materialized in memory) containing all the values delivered by this SequenceIterator. The method must only be used when the SequenceIterator is positioned at the start. If it is not positioned at the start, then it is implementation-dependant whether the returned sequence contains all the nodes delivered by the SequenceIterator from the beginning, or only those delivered starting at the current position.

It is implementation-dependant whether this method consumes the SequenceIterator. (More specifically, in the current implementation: if the iterator is backed by a GroundedValue, then that value is returned and the iterator is not consumed; otherwise, the iterator is consumed and the method returns the remaining items after the current position only).

Specified by:

materialize in interface GroundedIterator

Specified by:

materialize in interface SequenceIterator

Returns:

a sequence containing all the items delivered by this SequenceIterator.