Package net.sf.saxon.expr.sort

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

      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

    • getBaseIterator

      protected SequenceIterator getBaseIterator()

    • setHostLanguage

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

    • supportsHasNext

      public boolean supportsHasNext()
      Description copied from interface: LookaheadIterator
      Ask whether the hasNext() method can be called. This method must be called before calling hasNext(), because some iterators implement this interface, but only support look-ahead under particular circumstances (this is usually because they delegate to another iterator)
      Specified by:
      supportsHasNext in interface LookaheadIterator
      Returns:
      true if the LookaheadIterator.hasNext() method is available

    • 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 method supportsHasNext() returns true.

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

    • next

      public Item next()
      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.

    • supportsGetLength

      public boolean supportsGetLength()
      Ask whether this iterator supports use of the getLength() method. This method should always be called before calling getLength(), because an iterator that implements this interface may support use of getLength() in some situations and not in others
      Specified by:
      supportsGetLength in interface LastPositionFinder
      Returns:
      true if the getLength() method can be called to determine the length of the underlying sequence.

    • 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 LastPositionFinder.supportsGetLength() has been called and has returned true.
      Specified by:
      getLength in interface LastPositionFinder
      Returns:
      the number of items in the sequence

    • 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