Package com.saxonica.ee.stream.adjunct

Class FilterFnStreamer

java.lang.Object
com.saxonica.ee.stream.adjunct.StreamingAdjunct
com.saxonica.ee.stream.adjunct.TransmissionAdjunct
com.saxonica.ee.stream.adjunct.FilteringAdjunct
com.saxonica.ee.stream.adjunct.FilterFnStreamer
All Implemented Interfaces:
FeedMaker
Direct Known Subclasses:
ItemsAfterStreamer, ItemsBeforeStreamer, ItemsFromStreamer, ItemsUntilStreamer
public class FilterFnStreamer extends FilteringAdjunct
Generate streaming code for the fn:filter function. Only streamable if the operand is grounded

  • Constructor Details

    • FilterFnStreamer

      public FilterFnStreamer()

  • Method Details

    • computeStreamability

      public PostureAndSweep computeStreamability(ContextItemStaticInfoEE contextInfo, List<String> reasons)
      Compute the posture and sweep of this expression as defined in the W3C streamability specifications. This must be implemented in all subclasses that don't use the general streamability rules. The implementation should have the side-effect of computing the streamability of all subexpressions, recursively.
      Overrides:
      computeStreamability in class StreamingAdjunct
      Parameters:
      contextInfo - Information about the context item type and posture
      reasons - the caller may supply a list, in which case the implementation may add to this; the contents are human-readable messages explaining why the expression is not streamable.
      Returns:
      the posture and sweep of the expression

    • checkPredicateFunction

      public static boolean checkPredicateFunction(Expression fn, List<String> reasons)

    • makeFilter

      public FilteringFeed.Filter makeFilter(XPathContext context, ItemFeed out) throws XPathException
      Make a filter for the event stream
      Specified by:
      makeFilter in class FilteringAdjunct
      Parameters:
      context - the XPath dynamic context
      out - destination for the filtered output
      Returns:
      a filter that can be added to the event stream
      Throws:
      XPathException - if a dynamic evaluation error occurs