/*
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.bop.constraint;
import java.util.Map;
import com.bigdata.bop.BOp;
import com.bigdata.bop.BOpBase;
import com.bigdata.bop.IBindingSet;
import com.bigdata.bop.IConstant;
import com.bigdata.bop.IVariable;
/**
* Imposes the constraint <code>var == constant</code>.
*/
public class EQConstant extends BOpBase implements BooleanValueExpression {
/**
*
*/
private static final long serialVersionUID = 4619002304068158318L;
public EQConstant(final IVariable<?> x, final IConstant<?> y) {
this(new BOp[] { x, y }, null/* annotations */);
}
/**
* Required shallow copy constructor.
*/
public EQConstant(final BOp[] args, final Map<String, Object> annotations) {
super(args, annotations);
if (args.length != 2 || args[0] == null || args[1] == null)
throw new IllegalArgumentException();
}
/**
* Constructor required for {@link com.bigdata.bop.BOpUtility#deepCopy(FilterNode)}.
*/
public EQConstant(final EQConstant op) {
super(op);
}
public Boolean get(final IBindingSet bset) {
final IVariable<?> var = (IVariable<?>) get(0)/* var */;
// get binding for the variable.
final IConstant<?> asBound = bset.get(var);
if (asBound == null)
return true; // not yet bound.
final IConstant<?> cnst = (IConstant<?>) get(1);
final boolean ret = asBound.equals(cnst);
return ret;
}
}