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/******************************************************************
* File: Builtin.java
* Created by: Dave Reynolds
* Created on: 11-Apr-2003
*
* (c) Copyright 2003, 2004, 2005, 2006, 2007, 2008 Hewlett-Packard Development Company, LP
* [See end of file]
* $Id: Builtin.java,v 1.13 2008/01/02 12:07:47 andy_seaborne Exp $
*****************************************************************/
package com.hp.hpl.jena.reasoner.rulesys;
import com.hp.hpl.jena.graph.*;
/**
* Rules employ builtins to do all tests and actions other than simple triple
* matches and triple creation.
*
* Builtins can be invoked in two contexts. In the head of forward rules they perform
* some action based on the variable bindings generated by the body and additional context
* (the graph being reasoned over, the set of triples bound by the body). In the body
* of rules they perform tests, and additional variable bindings.
*
* The mapping from the rule definition (which uses functors to hold the parsed call)
* to the java implementation of the builtin is done via the
* {@link BuiltinRegistry BuiltinRegistry} which can
* be user extended.
*
* @author Dave Reynolds
* @version $Revision: 1.13 $ on $Date: 2008/01/02 12:07:47 $
*/
public interface Builtin {
/**
* Return a convenient name for this builtin, normally this will be the name of the
* functor that will be used to invoke it and will often be the final component of the
* URI.
*/
public String getName();
/**
* Return the full URI which identifies this built in.
*/
public String getURI();
/**
* Return the expected number of arguments for this functor or 0 if the number is flexible.
*/
public int getArgLength();
/**
* This method is invoked when the builtin is called in a rule body.
* @param args the array of argument values for the builtin, this is an array
* of Nodes, some of which may be Node_RuleVariables.
* @param length the length of the argument list, may be less than the length of the args array
* for some rule engines
* @param context an execution context giving access to other relevant data
* @return return true if the buildin predicate is deemed to have succeeded in
* the current environment
*/
public boolean bodyCall(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.
* @param args the array of argument values for the builtin, this is an array
* of Nodes.
* @param length the length of the argument list, may be less than the length of the args array
* for some rule engines
* @param context an execution context giving access to other relevant data
*/
public void headAction(Node[] args, int length, RuleContext context);
/**
* Returns false if this builtin has side effects when run in a body clause,
* other than the binding of environment variables.
*/
public boolean isSafe();
/**
* 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.
*/
public boolean isMonotonic();
}
/*
(c) Copyright 2003, 2004, 2005, 2006, 2007, 2008 Hewlett-Packard Development Company, LP
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
3. The name of the author may not be used to endorse or promote products
derived from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/