Package net.sf.saxon.tree.iter
Class EmptyIterator
- java.lang.Object
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- net.sf.saxon.tree.iter.EmptyIterator
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- All Implemented Interfaces:
java.io.Closeable,java.lang.AutoCloseable,LastPositionFinder,AtomizedValueIterator,SequenceIterator,GroundedIterator,LookaheadIterator,ReversibleIterator,UnfailingIterator
public class EmptyIterator extends java.lang.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
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Nested classes/interfaces inherited from interface net.sf.saxon.om.SequenceIterator
SequenceIterator.Property
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Constructor Summary
Constructors Modifier Constructor Description protectedEmptyIterator()Protected constructor
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description static EmptyIteratoremptyIterator()static EmptyIteratorgetInstance()Get an EmptyIterator, an iterator over an empty sequence.intgetLength()Get the position of the last item in the sequence.java.util.EnumSet<SequenceIterator.Property>getProperties()Get properties of this iterator, as a bit-significant integer.GroundedValuegetResidue()Return a GroundedValue containing all the remaining items in the sequence returned by this SequenceIterator, starting at the current position.EmptyIteratorgetReverseIterator()Get another iterator over the same items, in reverse order.booleanhasNext()Determine whether there are more items to come.GroundedValuematerialize()Return a Value containing all the items in the sequence returned by this SequenceIterator.Itemnext()Get the next item.AtomicSequencenextAtomizedValue()Deliver the atomic value that is next in the atomized resultstatic <T extends AtomicValue>
AtomicIterator<T>ofAtomic()Static method to get an empty AtomicIteratorstatic AxisIteratorofNodes()Static method to get an empty AxisIterator-
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
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Methods inherited from interface net.sf.saxon.om.SequenceIterator
close, forEachOrFail
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Methods inherited from interface net.sf.saxon.tree.iter.UnfailingIterator
forEach, toList
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Method Detail
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getInstance
public static EmptyIterator 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
public static EmptyIterator emptyIterator()
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nextAtomizedValue
public AtomicSequence nextAtomizedValue()
Deliver the atomic value that is next in the atomized result- Specified by:
nextAtomizedValuein interfaceAtomizedValueIterator- Returns:
- the next atomic value
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next
public Item next()
Get the next item.- Specified by:
nextin interfaceSequenceIterator- Specified by:
nextin 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:
getLengthin interfaceLastPositionFinder- Returns:
- the position of the last item in the sequence, always zero in this implementation
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getReverseIterator
public EmptyIterator getReverseIterator()
Get another iterator over the same items, in reverse order.- Specified by:
getReverseIteratorin interfaceReversibleIterator- Returns:
- a reverse iterator over an empty sequence (in practice, it returns the same iterator each time)
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getProperties
public java.util.EnumSet<SequenceIterator.Property> getProperties()
Get properties of this iterator, as a bit-significant integer.- Specified by:
getPropertiesin 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
public GroundedValue 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:
materializein interfaceGroundedIterator- Specified by:
materializein interfaceSequenceIterator- Returns:
- the corresponding Value
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getResidue
public GroundedValue getResidue()
Description copied from interface:GroundedIteratorReturn 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:
getResiduein 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:
hasNextin interfaceLookaheadIterator- Returns:
- true if there are more nodes
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ofNodes
public static AxisIterator ofNodes()
Static method to get an empty AxisIterator
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ofAtomic
public static <T extends AtomicValue> AtomicIterator<T> ofAtomic()
Static method to get an empty AtomicIterator
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