/*
Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016. All rights reserved.
Contact:
SYSTAP, LLC DBA Blazegraph
2501 Calvert ST NW #106
Washington, DC 20008
licenses@blazegraph.com
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package com.bigdata.rdf.internal.constraints;
import java.util.Map;
import org.apache.log4j.Logger;
import com.bigdata.bop.BOp;
import com.bigdata.bop.IBindingSet;
import com.bigdata.bop.IValueExpression;
import com.bigdata.rdf.error.SparqlTypeErrorException;
import com.bigdata.rdf.internal.IV;
import com.bigdata.rdf.internal.impl.literal.XSDBooleanIV;
import com.bigdata.rdf.sparql.ast.FilterNode;
import com.bigdata.util.InnerCause;
/**
* BOpConstraint that wraps a {@link EBVBOp}, which itself computes the
* effective boolean value of an {@link IValueExpression}.
*/
@SuppressWarnings("rawtypes")
public class SPARQLConstraint<X extends XSDBooleanIV> extends
com.bigdata.bop.constraint.Constraint<X> {
/**
*
*/
private static final long serialVersionUID = -5796492538735372727L;
private static final transient Logger log = Logger
.getLogger(SPARQLConstraint.class);
/**
* The operand of this operator must evaluate to a boolean. If the operand
* is not known to evaluate to a boolean, wrap it with an {@link EBVBOp}.
*/
private static XSDBooleanIVValueExpression wrap(
final IValueExpression<? extends IV> ve) {
return ve instanceof XSDBooleanIVValueExpression ?
(XSDBooleanIVValueExpression) ve : new EBVBOp(ve);
}
/**
* Construct a SPARQL constraint using the specified value expression.
* The value expression will be automatically wrapped inside an
* {@link EBVBOp} if it does not itself evaluate to a boolean.
*/
public SPARQLConstraint(final IValueExpression<? extends IV> x) {
this(new BOp[] { wrap(x) }, null/*annocations*/);
}
/**
* Required shallow copy constructor.
*/
public SPARQLConstraint(final BOp[] args, final Map<String, Object> anns) {
super(args, anns);
if (args.length != 1 || args[0] == null)
throw new IllegalArgumentException();
}
/**
* Constructor required for {@link com.bigdata.bop.BOpUtility#deepCopy(FilterNode)}.
*/
public SPARQLConstraint(final SPARQLConstraint<X> op) {
super(op);
}
@SuppressWarnings("unchecked")
@Override
public IValueExpression<? extends XSDBooleanIV> get(final int i) {
return (IValueExpression<? extends XSDBooleanIV>) super.get(i);
}
// public IValueExpression<X> getValueExpression() {
// return (IValueExpression<X>) get(0);
// }
@Override
public boolean accept(final IBindingSet bs) {
try {
// evaluate the EBV operator
final XSDBooleanIV iv = get(0).get(bs);
return iv.booleanValue();
} catch (Throwable t) {
if (InnerCause.isInnerCause(t, SparqlTypeErrorException.class)) {
// trap the type error and filter out the solution
if (log.isInfoEnabled())
log.info("discarding solution due to type error: " + bs
+ " : " + t);
return false;
}
throw new RuntimeException(t);
}
}
/**
* Overridden to provide a little bit of information about the attached
* constraint.
*/
@Override
public String toShortString() {
return super.toShortString() + "{condition="
+ getValueExpression().toShortString() + "}";
}
}