Package com.saxonica.ee.stream.adjunct

Class ForkAdjunct

java.lang.Object
com.saxonica.ee.stream.adjunct.StreamingAdjunct
com.saxonica.ee.stream.adjunct.ForkAdjunct
public class ForkAdjunct extends StreamingAdjunct
Streaming code to implement an xsl:fork expression

The general strategy is to create an inversion of the expression in each prong of the fork, and to create a separate watch for each one. These watches create output which is buffered, and on completion the outputs of each watch are assembled in the right order.

The implementation is NOT multithreaded: although the prongs of the fork execute conceptually in parallel, in that they all act as listeners responding to the same sequence of events, they actually all run in the same thread.

  • Constructor Details

    • ForkAdjunct

      public ForkAdjunct()

  • 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.
      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
      Returns:
      the posture and sweep of the expression

    • getWatchMaker

      public WatchMaker getWatchMaker(boolean forGrouping) throws XPathException
      Description copied from class: StreamingAdjunct
      Get a WatchMaker, a factory class that creates a Watch to evaluate this expression in streaming mode. This method will only be called if the getImplementationMethod() method of the expression includes the value Expression.WATCH_METHOD
      Overrides:
      getWatchMaker in class StreamingAdjunct
      Parameters:
      forGrouping - true if the selected items are being grouped
      Returns:
      a Watchmaker to evaluate the expression, or null if it is not streamable with respect to the specificed argument.
      Throws:
      XPathException - in the event of a failure