/*
* $Header$
* $Revision: 982 $
* $Date: 2006-12-08 18:42:51 +1000 (Fri, 08 Dec 2006) $
*
* ====================================================================
*
* The Apache Software License, Version 1.1
*
* Copyright (c) 2003-2009 The JRDF Project. 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 end-user documentation included with the redistribution, if
* any, must include the following acknowlegement:
* "This product includes software developed by the
* the JRDF Project (http://jrdf.sf.net/)."
* Alternately, this acknowlegement may appear in the software itself,
* if and wherever such third-party acknowlegements normally appear.
*
* 4. The names "The JRDF Project" and "JRDF" must not be used to endorse
* or promote products derived from this software without prior written
* permission. For written permission, please contact
* newmana@users.sourceforge.net.
*
* 5. Products derived from this software may not be called "JRDF"
* nor may "JRDF" appear in their names without prior written
* permission of the JRDF Project.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED 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 APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS 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.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the JRDF Project. For more
* information on JRDF, please see <http://jrdf.sourceforge.net/>.
*
*/
package org.jrdf.query.relation.operation.mem.logic;
import static org.jrdf.graph.AnyNode.ANY_NODE;
import org.jrdf.graph.Literal;
import org.jrdf.graph.Node;
import org.jrdf.graph.global.LiteralImpl;
import org.jrdf.query.expression.BoundOperator;
import org.jrdf.query.expression.Expression;
import org.jrdf.query.expression.ExpressionVisitorAdapter;
import org.jrdf.query.expression.LangOperator;
import org.jrdf.query.expression.Operator;
import org.jrdf.query.expression.SingleValue;
import org.jrdf.query.expression.StrOperator;
import org.jrdf.query.relation.Attribute;
import org.jrdf.query.relation.Tuple;
import org.jrdf.query.relation.operation.ValueEvaluator;
import org.jrdf.vocabulary.XSD;
import java.util.Map;
/**
* @author Yuan-Fang Li
* @version $Id:$
*/
public class ValueEvaluatorImpl extends ExpressionVisitorAdapter<Node> implements ValueEvaluator<Node> {
private Tuple tuple;
public void setTuple(Tuple newTuple) {
this.tuple = newTuple;
}
@Override
public Node visitSingleValue(SingleValue singleValue) {
Map<Attribute, Node> avo = singleValue.getValue();
Attribute attribute = avo.keySet().iterator().next();
Node node = avo.get(attribute);
final Node newValue = tuple.getValue(attribute);
if (ANY_NODE.equals(node)) {
if (newValue != null) {
return newValue;
} else {
return null;
}
} else {
return node;
}
}
@Override
public Node visitStr(StrOperator str) {
final Node value = getValue(str);
if (value != null) {
Node node = value;
if (Literal.class.isAssignableFrom(node.getClass())) {
Literal literal = (Literal) value;
return new LiteralImpl(literal.getLexicalForm());
}
}
return null;
}
@Override
public Node visitLang(LangOperator lang) {
final Node value = getValue(lang);
if (value != null) {
Node node = value;
if (Literal.class.isAssignableFrom(node.getClass())) {
Literal literal = (Literal) node;
return new LiteralImpl(literal.getLanguage());
}
}
return null;
}
@Override
public Node visitBound(BoundOperator bound) {
final Node value = getValue(bound);
boolean contradiction = (value == null);
return new LiteralImpl(Boolean.toString(contradiction), XSD.BOOLEAN);
}
private Node getValue(Operator operator) {
final Map<Attribute, Node> avp = operator.getValue();
Attribute attribute = avp.keySet().iterator().next();
return tuple.getValue(attribute);
}
public Node getValue(Tuple newTuple, Expression expression) {
ValueEvaluator<Node> evaluator = new ValueEvaluatorImpl();
evaluator.setTuple(newTuple);
return expression.accept(evaluator);
}
}