Package net.sf.saxon.tree.iter
Class EmptyIterator
java.lang.Object
net.sf.saxon.tree.iter.EmptyIterator
- All Implemented Interfaces:
Closeable
,AutoCloseable
,LastPositionFinder
,AtomizedValueIterator
,SequenceIterator
,GroundedIterator
,LookaheadIterator
,ReversibleIterator
,UnfailingIterator
public class EmptyIterator
extends Object
implements SequenceIterator, ReversibleIterator, LastPositionFinder, GroundedIterator, LookaheadIterator, UnfailingIterator, AtomizedValueIterator
EmptyIterator: an iterator over an empty sequence. Since such an iterator has no state,
only one instance is required; therefore a singleton instance is available via the static
getInstance() method.
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Nested Class Summary
Nested classes/interfaces inherited from interface net.sf.saxon.om.SequenceIterator
SequenceIterator.Property
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionstatic EmptyIterator
static EmptyIterator
Get an EmptyIterator, an iterator over an empty sequence.int
Get the position of the last item in the sequence.Get properties of this iterator, as a bit-significant integer.Return a GroundedValue containing all the remaining items in the sequence returned by this SequenceIterator, starting at the current position.Get another iterator over the same items, in reverse order.boolean
hasNext()
Determine whether there are more items to come.Return a Value containing all the items in the sequence returned by this SequenceIterator.next()
Get the next item.Deliver the atomic value that is next in the atomized resultstatic <T extends AtomicValue>
AtomicIterator<T>ofAtomic()
Static method to get an empty AtomicIteratorstatic AxisIterator
ofNodes()
Static method to get an empty AxisIteratorMethods 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
close, forEachOrFail
Methods inherited from interface net.sf.saxon.tree.iter.UnfailingIterator
forEach, toList
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Constructor Details
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EmptyIterator
protected EmptyIterator()Protected constructor
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Method Details
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getInstance
Get an EmptyIterator, an iterator over an empty sequence.- Returns:
- an EmptyIterator (in practice, this always returns the same one)
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emptyIterator
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nextAtomizedValue
Deliver the atomic value that is next in the atomized result- Specified by:
nextAtomizedValue
in interfaceAtomizedValueIterator
- Returns:
- the next atomic value
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next
Get the next item.- Specified by:
next
in interfaceSequenceIterator
- Specified by:
next
in interfaceUnfailingIterator
- Returns:
- the next item. For the EmptyIterator this is always null.
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getLength
public int getLength()Get the position of the last item in the sequence.- Specified by:
getLength
in interfaceLastPositionFinder
- Returns:
- the position of the last item in the sequence, always zero in this implementation
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getReverseIterator
Get another iterator over the same items, in reverse order.- Specified by:
getReverseIterator
in interfaceReversibleIterator
- Returns:
- a reverse iterator over an empty sequence (in practice, it returns the same iterator each time)
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getProperties
Get properties of this iterator, as a bit-significant integer.- Specified by:
getProperties
in interfaceSequenceIterator
- Returns:
- the properties of this iterator. This will be some combination of
properties such as
SequenceIterator.Property.GROUNDED
,SequenceIterator.Property.LAST_POSITION_FINDER
, andSequenceIterator.Property.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.
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materialize
Return a Value containing all the items in the sequence returned by this SequenceIterator. This should be an "in-memory" value, not a Closure.- Specified by:
materialize
in interfaceGroundedIterator
- Specified by:
materialize
in interfaceSequenceIterator
- Returns:
- the corresponding Value
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getResidue
Description copied from interface:GroundedIterator
Return a GroundedValue containing all the remaining items in the sequence returned by this SequenceIterator, starting at the current position. This should be an "in-memory" value, not a Closure. This method does not change the state of the iterator (in particular, it does not consume the iterator).- Specified by:
getResidue
in interfaceGroundedIterator
- Returns:
- the corresponding Value
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hasNext
public 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 interfaceLookaheadIterator
- Returns:
- true if there are more nodes
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ofNodes
Static method to get an empty AxisIterator -
ofAtomic
Static method to get an empty AtomicIterator
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