Package com.saxonica.ee.stream.watch

Class Trigger

java.lang.Object
com.saxonica.ee.stream.watch.AbstractWatch
com.saxonica.ee.stream.watch.PatternWatch
com.saxonica.ee.stream.watch.Trigger
All Implemented Interfaces:
Watch
public class Trigger extends PatternWatch
A Trigger is a Watch that contains a pattern used for matching streamed nodes, and a WatchAction which is invoked when a matching node is found.

  • Constructor Details

  • Method Details

    • matchesNode

      public boolean matchesNode(FleetingNode node, XPathContext context) throws XPathException
      Description copied from class: PatternWatch
      Determine whether the watch matches a given node
      Specified by:
      matchesNode in interface Watch
      Overrides:
      matchesNode in class PatternWatch
      Parameters:
      node - the node to be tested
      context - the XPath dynamic context
      Returns:
      true if the node is one of those the Watch is looking out for
      Throws:
      XPathException - if a dynamic error occurs

    • getAction

      public ItemFeed getAction()
      Get the Feed representing the pipeline of operations performed by this Trigger
      Returns:
      the Feed through which matched items are processed

    • open

      public void open(Terminator terminator) throws XPathException
      Open the watch. This is done at the point where it first starts watching for nodes that match the selection.
      Specified by:
      open in interface Watch
      Overrides:
      open in class PatternWatch
      Parameters:
      terminator - the callback to be used to signal early exit
      Throws:
      XPathException - May be raised if a dynamic error occurs

    • startSelectedParentNode

      public Receiver startSelectedParentNode(FleetingParentNode node, Location locationId) throws XPathException
      Signal that an element or document node has been found that matches the selection that this Watch is looking for. This method is called by the WatchManager while processing the startElement or startDocument event that matches the selection.
      Parameters:
      node - the element or document node whose start event has been matched
      locationId - the location associated with the element or document node (may be the location of the instruction that created it)
      Returns:
      a Receiver to be notified of all events starting with the startElement/startDocument event for the matched element, and ending with the endElement event for that element; or null if this feature is not required.
      Throws:
      XPathException - May be raised if a dynamic error occurs

    • endSelectedParentNode

      public void endSelectedParentNode(Location locationId) throws XPathException
      Signal that the endElement event has occurred for the element whose startElement event caused the Watch to be activated.
      Parameters:
      locationId - the location of the element
      Throws:
      XPathException - May be raised if a constraint implemented by this Watch is violated

    • processItem

      public void processItem(Item item) throws XPathException
      Signal that a node (other than an element) that matches the selection has been found.
      Specified by:
      processItem in interface Watch
      Overrides:
      processItem in class PatternWatch
      Parameters:
      item - the node that was matched.
      Throws:
      XPathException - May be raised if a dynamic error occurs

    • close

      public void close() throws XPathException
      The close() method is called immediately before the Watch is destroyed, that is, when the element whose declaration scopes the constraint implemented by this Watch goes out of scope. The default implementation does nothing.
      Specified by:
      close in interface Watch
      Overrides:
      close in class PatternWatch
      Throws:
      XPathException - May be raised if a dynamic error occurs

    • isMatchCurrentGroup

      public boolean isMatchCurrentGroup()
      Ask whether or not the pattern should use all nodes in the current group as anchor nodes (by default only the first is matched)
      Returns:
      true if every node in the current group is to act as an anchor node

    • setSelection

      public void setSelection(Pattern selection)
      Set the selection (that is, the streamable XPath expression) that defines the nodes that this Watch is looking for
      Overrides:
      setSelection in class PatternWatch
      Parameters:
      selection - the streamable XPath expression

    • setMatchCurrentGroup

      public void setMatchCurrentGroup(boolean matchCurrentGroup)
      Set whether or not the pattern should use all nodes in the current group as anchor nodes (by default only the first is matched)
      Parameters:
      matchCurrentGroup - true if every node in the current group is to act as an anchor node