Class ReverseRangeIterator

java.lang.Object
net.sf.saxon.expr.ReverseRangeIterator
All Implemented Interfaces:
Closeable, AutoCloseable, LastPositionFinder, SequenceIterator, AtomicIterator<IntegerValue>, LookaheadIterator, ReversibleIterator, UnfailingIterator

public class ReverseRangeIterator extends Object implements AtomicIterator<IntegerValue>, ReversibleIterator, LastPositionFinder, LookaheadIterator
Iterator that produces numeric values in a monotonic sequence, ascending or descending. Although a range expression (N to M) is always in ascending order, applying the reverse() function will produce a RangeIterator that works in descending order.
  • Field Details

    • start

      long start
    • currentValue

      long currentValue
    • limit

      long limit
  • Constructor Details

    • ReverseRangeIterator

      public ReverseRangeIterator(long start, long end) throws XPathException
      Create an iterator over a range of integers in monotonic descending order
      Parameters:
      start - the first integer to be delivered (the highest in the range)
      end - the last integer to be delivered (the lowest in the range). Must be <= start
      Throws:
      XPathException - if the values are inconsistent or if the length is greater than 2^31
  • Method Details

    • 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 IntegerValue next()
      Description copied from interface: AtomicIterator
      Get the next atomic value in the sequence.
      Specified by:
      next in interface AtomicIterator<IntegerValue>
      Specified by:
      next in interface SequenceIterator
      Specified by:
      next in interface UnfailingIterator
      Returns:
      the next Item. If there are no more items, return null.
    • 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
    • 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.
    • getReverseIterator

      public AtomicIterator 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