Package org.apache.jena.reasoner.rulesys.builtins

Class Drop

  • All Implemented Interfaces:
    Builtin
    public class Drop
extends BaseBuiltin
    A variant of the "remove" builtin that will delete matched triples from the graph but will not trigger further rule processing for the removed triples. This makes it seriously non-monotonic but useful for rewrite rules.

    • Field Summary

    • Constructor Summary

      Constructors 
      Constructor Description
      Drop()  

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      java.lang.String getName()
      Return a name for this builtin, normally this will be the name of the functor that will be used to invoke it.
      void headAction​(Node[] args, int length, RuleContext context)
      This method is invoked when the builtin is called in a rule head.
      boolean isMonotonic()
      Returns false if this builtin is non-monotonic.

      • Methods inherited from class java.lang.Object

        equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Constructor Detail

      • Drop

        public Drop()

    • Method Detail

      • getName

        public java.lang.String getName()
        Return a name for this builtin, normally this will be the name of the functor that will be used to invoke it.

      • headAction

        public void headAction​(Node[] args,
                       int length,
                       RuleContext context)
        This method is invoked when the builtin is called in a rule head. Such a use is only valid in a forward rule.
        Specified by:
        headAction in interface Builtin
        Overrides:
        headAction in class BaseBuiltin
        Parameters:
        args - the array of argument values for the builtin, this is an array of Nodes.
        length - the length of the argument list, may be less than the length of the args array for some rule engines
        context - an execution context giving access to other relevant data

      • isMonotonic

        public boolean isMonotonic()
        Returns false if this builtin is non-monotonic. This includes non-monotonic checks like noValue and non-monotonic actions like remove/drop. A non-monotonic call in a head is assumed to be an action and makes the overall rule and ruleset non-monotonic. Most JenaRules are monotonic deductive closure rules in which this should be false.
        Specified by:
        isMonotonic in interface Builtin
        Overrides:
        isMonotonic in class BaseBuiltin