Class EmptyIterator

java.lang.Object
net.sf.saxon.tree.iter.EmptyIterator
All Implemented Interfaces:
Closeable, AutoCloseable, LastPositionFinder, AtomizedValueIterator, SequenceIterator, GroundedIterator, LookaheadIterator, ReversibleIterator, UnfailingIterator

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.
  • Constructor Details

    • EmptyIterator

      protected EmptyIterator()
      Protected constructor
  • Method Details

    • 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)
    • emptyIterator

      public static EmptyIterator emptyIterator()
    • nextAtomizedValue

      public AtomicSequence nextAtomizedValue()
      Deliver the atomic value that is next in the atomized result
      Specified by:
      nextAtomizedValue in interface AtomizedValueIterator
      Returns:
      the next atomic value
    • next

      public Item next()
      Get the next item.
      Specified by:
      next in interface SequenceIterator
      Specified by:
      next in interface UnfailingIterator
      Returns:
      the next item. For the EmptyIterator this is always null.
    • getLength

      public int getLength()
      Get the position of the last item in the sequence.
      Specified by:
      getLength in interface LastPositionFinder
      Returns:
      the position of the last item in the sequence, always zero in this implementation
    • getReverseIterator

      public EmptyIterator getReverseIterator()
      Get another iterator over the same items, in reverse order.
      Specified by:
      getReverseIterator in interface ReversibleIterator
      Returns:
      a reverse iterator over an empty sequence (in practice, it returns the same iterator each time)
    • getProperties

      public EnumSet<SequenceIterator.Property> getProperties()
      Get properties of this iterator, as a bit-significant integer.
      Specified by:
      getProperties in interface SequenceIterator
      Returns:
      the properties of this iterator. This will be some combination of properties such as SequenceIterator.Property.GROUNDED, SequenceIterator.Property.LAST_POSITION_FINDER, and SequenceIterator.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.
    • 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:
      materialize in interface GroundedIterator
      Specified by:
      materialize in interface SequenceIterator
      Returns:
      the corresponding Value
    • getResidue

      public GroundedValue 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 interface GroundedIterator
      Returns:
      the corresponding Value
    • 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 interface LookaheadIterator
      Returns:
      true if there are more nodes
    • ofNodes

      public static AxisIterator ofNodes()
      Static method to get an empty AxisIterator
    • ofAtomic

      public static <T extends AtomicValue> AtomicIterator<T> ofAtomic()
      Static method to get an empty AtomicIterator