com.hp.hpl.jena.reasoner.rulesys
Class Functor

java.lang.Object
  com.hp.hpl.jena.reasoner.rulesys.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 attachement); in bodies they represent builtin predicates; in TriplePatterns they represent embedded structured literals that are used to cache matched subgraphs such as restriction specifications.

Version:

$Revision: 1.1 $ on $Date: 2009/06/29 08:55:38 $

Author:

Dave Reynolds

Nested Class Summary

static class

Functor.FunctorDatatype Inner class.

Field Summary

static com.hp.hpl.jena.util.iterator.Filter<Triple>

acceptFilter A static Filter instance that detects triples with Functor objects

Constructor Summary

Functor(java.lang.String name, java.util.List<Node> args)
Constructor.

Functor(java.lang.String name, java.util.List<Node> args, BuiltinRegistry registry)
Constructor

Functor(java.lang.String name, Node[] args)
Constructor.

Method Summary

boolean	equals(java.lang.Object obj) Equality is based on structural comparison
boolean	evalAsBodyClause(RuleContext context) Execute the given built in as a body clause.
int	getArgLength() Return the length of the functor argument array.
Node[]	getArgs() Return the functor aguments as an array of nodes
Node[]	getBoundArgs(BindingEnvironment env) Return a new Node array containing the bound versions of this Functor's arguments
Builtin	getImplementor() Return the Builtin that implements this functor
java.lang.String	getName() Return the functor name
int	hashCode() hash function override
static boolean	isFunctor(Node n) tests that a given Node represents a functor
boolean	isGround() Returns true if the functor is fully ground, no variables
boolean	isGround(BindingEnvironment env) Returns true if the functor is fully ground in the given environment
static Node	makeFunctorNode(Functor f) Wrap a functor as a Literal node
static Node	makeFunctorNode(java.lang.String name, Node[] args) Create a functor and wrap it up as a Literal node
boolean	safeEvalAsBodyClause(RuleContext context) Execute the given built in as a body clause, only if it is side-effect-free.
boolean	sameAs(java.lang.Object o) Compare Functors, taking into account variable indices.
void	setImplementor(Builtin implementor) Set the Builtin that implements this functor.
java.lang.String	toString() Printable string describing the functor

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Field Detail

acceptFilter

public static final com.hp.hpl.jena.util.iterator.Filter<Triple> acceptFilter

A static Filter instance that detects triples with Functor objects

Constructor Detail

Functor

public Functor(java.lang.String name,
               java.util.List<Node> args)

Constructor.

Parameters:

name - the name of the functor

args - a list of nodes defining the arguments

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

Method Detail

getName

public java.lang.String getName()

Return the functor name

getArgs

public Node[] getArgs()

Return the functor aguments 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.