Class SingletonIterator<T extends Item>

java.lang.Object
net.sf.saxon.tree.iter.SingletonIterator<T>
All Implemented Interfaces:
Closeable, AutoCloseable, LastPositionFinder, SequenceIterator, GroundedIterator, LookaheadIterator, ReversibleIterator, UnfailingIterator
Direct Known Subclasses:
SingleAtomicIterator

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

    • gone

      boolean gone
  • Constructor Details

    • SingletonIterator

      public SingletonIterator(T value)
      Private constructor: external classes should use the factory method
      Parameters:
      value - the item to iterate over
  • Method Details

    • makeIterator

      public static <T extends Item> UnfailingIterator makeIterator(T item)
      Factory method.
      Parameters:
      item - the item to iterate over
      Returns:
      a SingletonIterator over the supplied item, or an EmptyIterator if the supplied item is null.
    • rawIterator

      public static <T extends Item> SingletonIterator<T> rawIterator(T item)
      Factory method for use when it is known the item will not be null
      Parameters:
      item - the item to iterate over; must not be null
      Returns:
      a SingletonIterator over the supplied item
    • 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 items
    • next

      public 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

      public 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
    • getReverseIterator

      public SingletonIterator<T> getReverseIterator()
      Description copied from interface: ReversibleIterator
      Get a new SequenceIterator that returns the same items in reverse order. If this SequenceIterator is an AxisIterator, then the returned SequenceIterator must also be an AxisIterator.
      Specified by:
      getReverseIterator in interface ReversibleIterator
      Returns:
      an iterator over the items in reverse order
    • getValue

      public T getValue()
    • materialize

      public GroundedValue materialize()
      Return a Value containing all the items in the sequence returned by this SequenceIterator
      Specified by:
      materialize in interface GroundedIterator
      Specified by:
      materialize in interface SequenceIterator
      Returns:
      the corresponding Value. If the value is a closure or a function call package, it will be evaluated and expanded.
    • 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
    • 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.