/*
* The contents of this file are subject to the Mozilla Public License
* Version 1.1 (the "License"); you may not use this file except in
* compliance with the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS"
* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
* the License for the specific language governing rights and limitations
* under the License.
*
* The Original Code is the Kowari Metadata Store.
*
* The Initial Developer of the Original Code is Plugged In Software Pty
* Ltd (http://www.pisoftware.com, mailto:info@pisoftware.com). Portions
* created by Plugged In Software Pty Ltd are Copyright (C) 2001,2002
* Plugged In Software Pty Ltd. All Rights Reserved.
*
* Contributor(s):
* getModel() contributed by Netymon Pty Ltd on behalf of
* The Australian Commonwealth Government under contract 4500507038.
*
* [NOTE: The text of this Exhibit A may differ slightly from the text
* of the notices in the Source Code files of the Original Code. You
* should use the text of this Exhibit A rather than the text found in the
* Original Code Source Code for Your Modifications.]
*
*/
package org.mulgara.query;
// Java 2 standard packages
import java.util.*;
// Third party packages
// import org.apache.log4j.Logger;
/**
* A transitive constraint. The elements within the constraint must be variable
* for the subject and object, and a value for the predicate. An optional anchor
* is also provided, which must describe the same predicate and have exactly one
* variable and one object.
*
* @created 2004-05-12
*
* @author Paula Gearon
*
* @version $Revision: 1.9 $
*
* @modified $Date: 2005/05/29 08:32:40 $
*
* @maintenanceAuthor $Author: raboczi $
*
* @company <A href="mailto:info@PIsoftware.com">Plugged In Software</A>
*
* @copyright © 2004 <A href="http://www.PIsoftware.com/">Plugged In
* Software Pty Ltd</A>
*
* @licence <a href="{@docRoot}/../../LICENCE">Mozilla Public License v1.1</a>
*/
public class SingleTransitiveConstraint implements Constraint {
/**
* Allow newer compiled version of the stub to operate when changes
* have not occurred with the class.
* NOTE : update this serialVersionUID when a method or a public member is
* deleted.
*/
static final long serialVersionUID = -3828723182891026790L;
// /** Logger. */
// private final static Logger logger = Logger.getLogger(Constraint.class);
/**
* The constraint containing the transitive predicate.
*/
private final Constraint transConstraint;
/**
* The anchor to be applied if this anchor is to be used for a chain.
*/
private final boolean anchored;
/** Indicates that a zero step must be included */
private final boolean zeroStep;
/**
* Constructor.
*
* @param trans The constraint defining the transitive predicate. Expected form
* is: {$var <uri> $var}
* @throws IllegalArgumentException If trans is null.
*/
public SingleTransitiveConstraint(Constraint trans, boolean zeroStep) throws IllegalArgumentException {
// Validate parameters
if (trans == null) {
throw new IllegalArgumentException("null trans parameter");
}
// Check if this constraint is anchored i.e. starting from a fixed subject
// or object.
if (!trans.getElement(0).getClass().equals(trans.getElement(2).getClass()) &&
((trans.getElement(0) instanceof Value) ||
(trans.getElement(2) instanceof Value))) {
anchored = true;
}
else {
anchored = false;
}
// Initialize fields
this.transConstraint = trans;
this.zeroStep = zeroStep;
}
public SingleTransitiveConstraint(Constraint trans) throws IllegalArgumentException {
this(trans, false);
}
public boolean isRepeating() {
return false;
}
/**
* Get the transitive constraint that describes the predicate.
*
* @return The constraint element referred to by index.
*/
public Constraint getTransConstraint() {
return transConstraint;
}
/**
* Check if this Transitive Rule is anchored.
*
* @return <code>true</code> if this constraint is anchored, <code>false</code> otherwise.
*/
public boolean isAnchored() {
return anchored;
}
/**
* Get all constraints which are variables. For back-compatibility, this
* method currently ignores the fourth element of the triple.
*
* @return A set containing all variable constraints.
*/
public Set<Variable> getVariables() {
return transConstraint.getVariables();
}
/**
* Equality is by value.
*
* @param object PARAMETER TO DO
* @return RETURNED VALUE TO DO
*/
public boolean equals(Object object) {
if (object == null) {
return false;
}
if (object == this) {
return true;
}
boolean returnValue = false;
// Check that the given object is the correct class if so check each
// element.
if (object.getClass() == SingleTransitiveConstraint.class) {
returnValue = transConstraint.equals(((SingleTransitiveConstraint)object).transConstraint);
}
return returnValue;
}
/**
* Creates a relatively unique value representing this constraint.
*
* @return A numerical combination of the elements and the anchor
*/
public int hashCode() {
return transConstraint.hashCode();
}
/**
* Get a constraint element by index.
*
* @param index The constraint element to retrieve, from 0 to 3.
* @return The constraint element referred to by index.
*/
public ConstraintElement getElement(int index) {
return transConstraint.getElement(index);
}
public ConstraintElement getModel() {
return transConstraint.getModel();
}
/**
* Creates a string representation of these constraints. A typical result
* might be <code>[$x <urn:foo> 'bar' $0 ] :
* {<start> <urn:foo> <end>}</code>.
*
* @return String containing all data pertinent to the constraint.
*/
public String toString() {
StringBuffer buffer = new StringBuffer("trans[");
buffer.append(transConstraint);
buffer.append("]");
if (anchored) {
buffer.append(":{anchored}");
}
return buffer.toString();
}
/**
* If true then this constraint requires a zero step to be included in the results.
* @return <code>true</code> when results need to include a zero step.
*/
public boolean isZeroStep() {
return zeroStep;
}
/**
* Not sure what associativity would mean here, but it shouldn't be possible.
* @return <code>false</code> to indicate that this operation is not associative.
*/
public boolean isAssociative() {
return false;
}
}