Class GroupMatchingIterator

java.lang.Object
net.sf.saxon.expr.sort.GroupMatchingIterator
All Implemented Interfaces:
Closeable, AutoCloseable, LastPositionFinder, GroupIterator, SequenceIterator, LookaheadIterator
Direct Known Subclasses:
GroupEndingIterator, GroupStartingIterator

public abstract class GroupMatchingIterator extends Object implements LookaheadIterator, LastPositionFinder, GroupIterator
A GroupMatchingIterator contains code shared between GroupStartingIterator and GroupEndingIterator
  • Field Details

    • select

      protected Expression select
    • population

      protected FocusIterator population
    • pattern

      protected Pattern pattern
    • baseContext

      protected XPathContext baseContext
    • runningContext

      protected XPathContext runningContext
    • currentMembers

      protected List<Item> currentMembers
    • next

      protected Item next
    • current

      protected Item current
    • position

      protected int position
  • Constructor Details

    • GroupMatchingIterator

      public GroupMatchingIterator()
  • Method Details

    • advance

      protected abstract void advance() throws XPathException
      Throws:
      XPathException
    • getCurrentGroupingKey

      public AtomicSequence getCurrentGroupingKey()
      Description copied from interface: GroupIterator
      Get the grouping key of the current group
      Specified by:
      getCurrentGroupingKey in interface GroupIterator
      Returns:
      the current grouping key in the case of group-by or group-adjacent, or null in the case of group-starting-with and group-ending-with
    • iterateCurrentGroup

      public SequenceIterator iterateCurrentGroup()
      Description copied from interface: GroupIterator
      Get an iterator over the members of the current group, in population order. This must always be a clean iterator, that is, an iterator that starts at the first item of the group.
      Specified by:
      iterateCurrentGroup in interface GroupIterator
      Returns:
      an iterator over all the members of the current group, in population order.
    • hasNext

      public boolean hasNext()
      Description copied from interface: LookaheadIterator
      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.

      This method must not be called unless the result of getProperties() on the iterator includes the property SequenceIterator.Property.LOOKAHEAD

      Specified by:
      hasNext in interface LookaheadIterator
      Returns:
      true if there are more items in the sequence
    • 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.
      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
    • 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
    • getProperties

      public EnumSet<SequenceIterator.Property> getProperties()
      Description copied from interface: SequenceIterator
      Get properties of this iterator.
      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 default value EnumSet.noneOf(Property.class), indicating that there are no known special properties. It is acceptable (though unusual) for the properties of the iterator to change depending on its state.