Package net.sf.saxon.functions

Class DistinctValues.DistinctIterator

  • All Implemented Interfaces:
    java.io.Closeable, java.lang.AutoCloseable, SequenceIterator
    Enclosing class:
    DistinctValues
    public static class DistinctValues.DistinctIterator
extends java.lang.Object
implements SequenceIterator
    Iterator class to return the distinct values in a sequence

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void close()
      Close the iterator.
      void discharge()
      Calling this method instructs the iterator to release any resources it holds, while still remaining able to deliver the remaining items in the sequence.
      AtomicValue next()
      Get the next item in the sequence.

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Constructor Detail

      • DistinctIterator

        public DistinctIterator​(SequenceIterator base,
                        StringCollator collator,
                        XPathContext context)
        Create an iterator over the distinct values in a sequence
        Parameters:
        base - the input sequence. This must return atomic values only.
        collator - The comparer used to obtain comparison keys from each value; these comparison keys are themselves compared using equals().
        context - the XPath dynamic context

    • Method Detail

      • next

        public AtomicValue next()
        Get the next item in the sequence.
        Specified by:
        next in interface SequenceIterator
        Returns:
        the next item, or null if there are no more items.

      • 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.

        For example, the iterator returned by the unparsed-text-lines() function has a close() method that causes the underlying input stream to be closed, whether or not the file has been read to completion.

        Closing an iterator is important 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.

        Closing an iterator is not necessary if the iterator is read to completion: if a call on SequenceIterator.next() returns null, the iterator will be closed automatically. An explicit call on SequenceIterator.close() is needed only when iteration is abandoned prematurely.

        Specified by:
        close in interface java.lang.AutoCloseable
        Specified by:
        close in interface java.io.Closeable
        Specified by:
        close in interface SequenceIterator

      • discharge

        public void discharge()
        Description copied from interface: SequenceIterator
        Calling this method instructs the iterator to release any resources it holds, while still remaining able to deliver the remaining items in the sequence. This may require the iterator to calculate the rest of the sequence eagerly. The method is called by a client if it anticipates that it might not read the iterator to completion, but it cannot guarantee that SequenceIterator.close() will be called when no more items are needed.
        Specified by:
        discharge in interface SequenceIterator