Class TailExpression.TailIterator

java.lang.Object
net.sf.saxon.expr.TailExpression.TailIterator
All Implemented Interfaces:
LastPositionFinder, LookaheadIterator, SequenceIterator
Enclosing class:
TailExpression

public static class TailExpression.TailIterator extends Object implements SequenceIterator, LastPositionFinder, LookaheadIterator
  • Constructor Details

  • Method Details

    • 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 invalid input: '<'= 0; the preferred value is -1.
    • 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 bit setting SequenceIterator.LOOKAHEAD

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

      public int getLastPosition() throws XPathException
      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.LAST_POSITION_FINDER
      Specified by:
      getLastPosition in interface LastPositionFinder
      Throws:
      XPathException
    • 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
    • getProperties

      public int 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.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.