Class Inspect

java.lang.Object
org.projog.core.predicate.builtin.kb.Inspect
All Implemented Interfaces:
PredicateFactory
public final class Inspect extends Object implements PredicateFactory
clause(X,Y) / retract(X) - matches terms to existing clauses.

clause(X,Y) causes X and Y to be matched to the head and body of an existing clause. If no clauses are found for the predicate represented by X then the goal fails. If there are more than one that matches, the clauses will be matched one at a time as the goal is re-satisfied. X must be suitably instantiated that the predicate of the clause can be determined.

retract(X) - remove clauses from the knowledge base. The first clause that X matches is removed from the knowledge base. When an attempt is made to re-satisfy the goal, the next clause that X matches is removed. X must be suitably instantiated that the predicate of the clause can be determined.

  • Method Details

    • inspectClause

      public static Inspect inspectClause(KnowledgeBase kb)

    • retract

      public static Inspect retract(KnowledgeBase kb)

    • getPredicate

      public Predicate getPredicate(Term term)
      Description copied from interface: PredicateFactory
      Returns a Predicate to be used in the evaluation of a goal.
      Specified by:
      getPredicate in interface PredicateFactory
      Parameters:
      term - the term containing the arguments to use in the evaluation of the goal
      Returns:
      Predicate to be used in the evaluation of the goal
      See Also:

    • isRetryable

      public boolean isRetryable()
      Description copied from interface: PredicateFactory
      Should instances of this implementation be re-evaluated when backtracking?

      Some goals (e.g. X is 1) are only meant to be evaluated once (the statement is either true or false) while others (e.g. repeat(3)) are meant to be evaluated multiple times. For instances of Predicate that are designed to possibly have Predicate.evaluate() called on them multiple times for the same individual query this method should return true. For instances of Predicate that are designed to only be evaluated once per individual query this method should return false.

      Specified by:
      isRetryable in interface PredicateFactory
      Returns:
      true if an attempt should be made to re-evaluate instances of implementing classes when backtracking, false otherwise