Class SortedIterator

java.lang.Object
net.sf.saxon.expr.sort.SortedIterator
All Implemented Interfaces:
Closeable, AutoCloseable, LastPositionFinder, SequenceIterator, LookaheadIterator
Direct Known Subclasses:
SortedGroupIterator

public class SortedIterator extends Object implements SequenceIterator, LastPositionFinder, LookaheadIterator
Class to do a sorted iteration
  • Field Details

  • Constructor Details

    • SortedIterator

      protected SortedIterator()
    • SortedIterator

      public SortedIterator(XPathContext context, SequenceIterator base, SortKeyEvaluator sortKeyEvaluator, AtomicComparer[] comparators, boolean createNewContext)
      Create a sorted iterator
      Parameters:
      context - the dynamic XPath evaluation context
      base - an iterator over the sequence to be sorted
      sortKeyEvaluator - an object that allows the n'th sort key for a given item to be evaluated
      comparators - an array of AtomicComparers, one for each sort key, for comparing sort key values
      createNewContext - true if sort keys are computed relative to the item being sorted (as in XSLT but not XQuery)
  • Method Details

    • setHostLanguage

      public void setHostLanguage(HostLanguage language)
      Set the host language
      Parameters:
      language - the host language (for example HostLanguage.XQUERY)
    • hasNext

      public boolean hasNext()
      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.Property.LOOKAHEAD

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

      public Item next() throws XPathException
      Get the next item, in sorted order
      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
    • getLength

      public int getLength() 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.Property.LAST_POSITION_FINDER
      Specified by:
      getLength in interface LastPositionFinder
      Returns:
      the number of items in the sequence
      Throws:
      XPathException - if an error occurs evaluating the sequence in order to determine the number of items
    • 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.
    • buildArray

      protected void buildArray() throws XPathException
      Create an array holding the items to be sorted and the values of their sort keys
      Throws:
      XPathException - if an error occurs for example in evaluating a sort key