Class DocumentOrderIterator

  • All Implemented Interfaces:
    Sortable, SequenceIterator

    public final class DocumentOrderIterator
    extends java.lang.Object
    implements SequenceIterator, Sortable
    DocumentOrderIterator takes as input an iteration of nodes in any order, and returns as output an iteration of the same nodes in document order, eliminating any duplicates.
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void close()
      Close the iterator.
      int compare​(int a, int b)
      Compare two nodes in document sequence (needed to implement the Sortable interface)
      Item current()
      Get the current value in the sequence (the one returned by the most recent call on next()).
      SequenceIterator getAnother()
      Get another SequenceIterator that iterates over the same items as the original, but which is repositioned at the start of the sequence.
      int getProperties()
      Get properties of this iterator, as a bit-significant integer.
      Item next()
      Get the next item in the sequence.
      int position()
      Get the current position.
      void swap​(int a, int b)
      Swap two nodes (needed to implement the Sortable interface)
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Method Detail

      • compare

        public int compare​(int a,
                           int b)
        Compare two nodes in document sequence (needed to implement the Sortable interface)
        Specified by:
        compare in interface Sortable
        Returns:
        <0 if obj[a]0 if obj[a]>obj[b]
      • swap

        public void swap​(int a,
                         int b)
        Swap two nodes (needed to implement the Sortable interface)
        Specified by:
        swap in interface Sortable
      • next

        public Item next()
                  throws XPathException
        Description copied from interface: SequenceIterator
        Get the next item in the sequence. This method changes the state of the iterator, in particular it affects the result of subsequent calls of position() and current().
        Specified by:
        next in interface SequenceIterator
        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.
        Throws:
        XPathException - if an error occurs retrieving the next item
      • current

        public Item current()
        Description copied from interface: SequenceIterator
        Get the current value in the sequence (the one returned by the most recent call on next()). This will be null before the first call of next(). This method does not change the state of the iterator.
        Specified by:
        current in interface SequenceIterator
        Returns:
        the current item, the one most recently returned by a call on next(). Returns null if next() has not been called, or if the end of the sequence has been reached.
      • position

        public int position()
        Description copied from interface: SequenceIterator
        Get the current position. This will usually be zero before the first call on next(), otherwise it will be the number of times that next() has been called. Once next() has returned null, the preferred action is for subsequent calls on position() to return -1, but not all existing implementations follow this practice. (In particular, the EmptyIterator is stateless, and always returns 0 as the value of position(), whether or not next() has been called.)

        This method does not change the state of the iterator.

        Specified by:
        position in interface SequenceIterator
        Returns:
        the current position, the position of the item returned by the most recent call of next(). This is 1 after next() has been successfully called once, 2 after it has been called twice, and so on. If next() has never been called, the method returns zero. If the end of the sequence has been reached, the value returned will always be <= 0; the preferred value is -1.
      • close

        public void close()
        Description copied from interface: SequenceIterator
        Close the iterator. This indicates to the supplier of the data that the client does not require any more items to be delivered by the iterator. This may enable the supplier to release resources. After calling close(), no further calls on the iterator should be made; if further calls are made, the effect of such calls is undefined.

        (Currently, closing an iterator is important only when the data is being "pushed" in another thread. Closing the iterator terminates that thread and means that it needs to do no additional work. Indeed, failing to close the iterator may cause the push thread to hang waiting for the buffer to be emptied.)

        Specified by:
        close in interface SequenceIterator
      • getAnother

        public SequenceIterator getAnother()
                                    throws XPathException
        Description copied from interface: SequenceIterator
        Get another SequenceIterator that iterates over the same items as the original, but which is repositioned at the start of the sequence.

        This method allows access to all the items in the sequence without disturbing the current position of the iterator. Internally, its main use is in evaluating the last() function.

        This method does not change the state of the iterator.

        Specified by:
        getAnother in interface SequenceIterator
        Returns:
        a SequenceIterator that iterates over the same items, positioned before the first item
        Throws:
        XPathException - if any error occurs