Package net.sf.saxon.expr.sort

Class DocumentOrderIterator

java.lang.Object
net.sf.saxon.expr.sort.DocumentOrderIterator
All Implemented Interfaces:
Closeable, AutoCloseable, Sortable, SequenceIterator<NodeInfo>
public final class DocumentOrderIterator extends Object implements SequenceIterator<NodeInfo>, 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. An error occurs if the input sequence contains items that are not nodes.

  • Constructor Details

    • DocumentOrderIterator

      public DocumentOrderIterator(SequenceIterator<?> base, ItemOrderComparer comparer) throws XPathException
      Iterate over a sequence in document order.
      Parameters:
      base - the input sequence to be sorted
      comparer - the comparer used for comparing node positions
      Throws:
      XPathException - if the input sequence cannot be evaluated, or if it contains an item that is not a node

  • Method Details

    • 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]<obj[b], 0 if obj[a]=obj[b], >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 NodeInfo next() throws XPathException
      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<NodeInfo>
      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

    • getProperties

      public int getProperties()
      Get properties of this iterator, as a bit-significant integer.
      Specified by:
      getProperties in interface SequenceIterator<NodeInfo>
      Returns:
      the properties of this iterator. This will be some combination of properties such as SequenceIterator.GROUNDED, SequenceIterator.LAST_POSITION_FINDER, and SequenceIterator.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.

    • 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.

      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Closeable
      Specified by:
      close in interface SequenceIterator<NodeInfo>