Package org.apache.jena.reasoner.rulesys

Class Functor

  • All Implemented Interfaces:
    ClauseEntry
    public class Functor
extends java.lang.Object
implements ClauseEntry
    A functor comprises a functor name and a list of arguments. The arguments are Nodes of any type except functor nodes (there is no functor nesting). Functors play three roles in rules - in heads they represent actions (procedural attachment); in bodies they represent builtin predicates; in TriplePatterns they represent embedded structured literals that are used to cache matched subgraphs such as restriction specifications.

    • Field Summary

      Fields 
      Modifier and Type Field Description
      static java.util.function.Predicate<Triple> acceptFilter
      A static Predicate instance that detects triples with Functor objects

    • Field Detail

      • acceptFilter

        public static final java.util.function.Predicate<Triple> acceptFilter
        A static Predicate instance that detects triples with Functor objects

    • Constructor Detail

      • Functor

        public Functor​(java.lang.String name,
               Node[] args)
        Constructor.
        Parameters:
        name - the name of the functor
        args - an array of nodes defining the arguments, this will not be copied so beware of accidental structure sharing

      • Functor

        public Functor​(java.lang.String name,
               java.util.List<Node> args,
               BuiltinRegistry registry)
        Constructor
        Parameters:
        name - the name of the functor
        args - a list of nodes defining the arguments
        registry - a table of builtins to consult to check for implementations of this functor when used as a rule clause

      • Functor

        public Functor​(java.lang.String name,
               Node[] args,
               BuiltinRegistry registry)
        Constructor
        Parameters:
        name - the name of the functor
        args - an array of nodes defining the arguments
        registry - a table of builtins to consult to check for implementations of this functor when used as a rule clause

      • Functor

        public Functor​(java.lang.String name,
               java.util.List<Node> args,
               Builtin impl)
        Constructor
        Parameters:
        name - the name of the functor
        args - a list of nodes defining the arguments
        impl - a specific builtin implementation of this functor

      • Functor

        public Functor​(java.lang.String name,
               Node[] args,
               Builtin impl)
        Constructor
        Parameters:
        name - the name of the functor
        args - a list of nodes defining the arguments
        impl - a specific builtin implementation of this functor

    • Method Detail

      • getName

        public java.lang.String getName()
        Return the functor name

      • getArgs

        public Node[] getArgs()
        Return the functor arguments as an array of nodes

      • getArgLength

        public int getArgLength()
        Return the length of the functor argument array.

      • isGround

        public boolean isGround()
        Returns true if the functor is fully ground, no variables

      • isGround

        public boolean isGround​(BindingEnvironment env)
        Returns true if the functor is fully ground in the given environment

      • evalAsBodyClause

        public boolean evalAsBodyClause​(RuleContext context)
        Execute the given built in as a body clause.
        Parameters:
        context - an execution context giving access to other relevant data
        Returns:
        true if the functor has an implementation and that implementation returns true when evaluated

      • safeEvalAsBodyClause

        public boolean safeEvalAsBodyClause​(RuleContext context)
        Execute the given built in as a body clause, only if it is side-effect-free.
        Parameters:
        context - an execution context giving access to other relevant data
        Returns:
        true if the functor has an implementation and that implementation returns true when evaluated

      • getBoundArgs

        public Node[] getBoundArgs​(BindingEnvironment env)
        Return a new Node array containing the bound versions of this Functor's arguments

      • getImplementor

        public Builtin getImplementor()
        Return the Builtin that implements this functor
        Returns:
        the Builtin or null if there isn't one

      • setImplementor

        public void setImplementor​(Builtin implementor)
        Set the Builtin that implements this functor.

      • toString

        public java.lang.String toString()
        Printable string describing the functor
        Overrides:
        toString in class java.lang.Object

      • isFunctor

        public static boolean isFunctor​(Node n)
        tests that a given Node represents a functor

      • equals

        public boolean equals​(java.lang.Object obj)
        Equality is based on structural comparison
        Overrides:
        equals in class java.lang.Object

      • hashCode

        public int hashCode()
        hash function override
        Overrides:
        hashCode in class java.lang.Object

      • sameAs

        public boolean sameAs​(java.lang.Object o)
        Compare Functors, taking into account variable indices. The equality function ignores differences between variables.
        Specified by:
        sameAs in interface ClauseEntry

      • makeFunctorNode

        public static Node makeFunctorNode​(java.lang.String name,
                                   Node[] args)
        Create a functor and wrap it up as a Literal node
        Parameters:
        name - the name of the functor
        args - an array of nodes defining the arguments, this will not be copied so beware of accidental structure sharing

      • makeFunctorNode

        public static Node makeFunctorNode​(Functor f)
        Wrap a functor as a Literal node
        Parameters:
        f - the functor data structure to be wrapped in a node.