/*
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.NotMaterializedException;
import com.bigdata.rdf.sparql.ast.GlobalAnnotations;
/**
* Coalesce BOp The COALESCE function form returns the RDF term value of the first expression that evaluates without error. In
* SPARQL, evaluating an unbound variable raises an error.
*/
public class CoalesceBOp extends IVValueExpression<IV> implements IPassesMaterialization {
private static final long serialVersionUID = 7391999162162545704L;
private static final transient Logger log = Logger.getLogger(CoalesceBOp.class);
public CoalesceBOp(final GlobalAnnotations globals, final IValueExpression<? extends IV>... expressions) {
this(expressions, anns(globals));
}
/**
* Required shallow copy constructor.
*/
public CoalesceBOp(final BOp[] args, final Map<String, Object> anns) {
super(args, anns);
if (args.length <= 0)
throw new IllegalArgumentException();
for (BOp b : args) {
if (b == null) {
throw new IllegalArgumentException();
}
}
}
/**
* Constructor required for {@link com.bigdata.bop.BOpUtility#deepCopy(FilterNode)}.
*/
public CoalesceBOp(final CoalesceBOp op) {
super(op);
}
public IV get(final IBindingSet bs) {
for (int i = 0; i < arity(); i++) {
try {
IV result = get(i).get(bs);
if(result!=null){
return result;
}
} catch (NotMaterializedException nme) {
throw nme;
} catch (Throwable t) {
}
}
throw new SparqlTypeErrorException();
}
}