Class FilterIterator

java.lang.Object
net.sf.saxon.expr.FilterIterator
All Implemented Interfaces:
SequenceIterator
Direct Known Subclasses:
FilterIterator.Leading, FilterIterator.NonNumeric

public class FilterIterator extends Object implements SequenceIterator
A FilterIterator filters an input sequence using a filter expression. Note that a FilterIterator is not used where the filter is a constant number (PositionFilter is used for this purpose instead), so this class does no optimizations for numeric predicates.
  • Field Details

  • Constructor Details

    • FilterIterator

      public FilterIterator(SequenceIterator base, Expression filter, XPathContext context)
      Constructor
      Parameters:
      base - An iteration of the items to be filtered
      filter - The expression defining the filter predicate
      context - The context in which the expression is being evaluated
  • Method Details

    • setFilterIsSingletonBoolean

      public void setFilterIsSingletonBoolean(boolean isBoolean)
    • next

      public Item next() throws XPathException
      Get the next item if there is one
      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
    • getNextMatchingItem

      protected Item getNextMatchingItem() throws XPathException
      Get the next node that matches the filter predicate if there is one, or null if not.
      Throws:
      XPathException
    • matches

      protected boolean matches() throws XPathException
      Determine whether the context item matches the filter predicate
      Throws:
      XPathException
    • 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.
    • getAnother

      public SequenceIterator getAnother() throws XPathException
      Get another iterator to return the same nodes
      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.