/**
* Copyright (c) 2013, Institute of Information Systems (Sven Groppe and contributors of LUPOSDATE), University of Luebeck
*
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
* following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice, this list of conditions and the following
* disclaimer.
* - 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.
* - Neither the name of the University of Luebeck nor the names of its contributors may be used to endorse or promote
* products derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS 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 COPYRIGHT HOLDER OR 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.
*/
package lupos.engine.operators.singleinput;
import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.Set;
import lupos.datastructures.bindings.Bindings;
import lupos.datastructures.items.Variable;
import lupos.datastructures.items.literal.Literal;
import lupos.datastructures.queryresult.QueryResult;
import lupos.engine.operators.messages.BoundVariablesMessage;
import lupos.engine.operators.messages.Message;
import lupos.misc.util.ImmutableIterator;
public class AddBindingFromOtherVar extends SingleInputOperator {
private Variable var;
private Variable valueFromVar;
public AddBindingFromOtherVar(final Variable var,
final Variable valueFromVar) {
this.var = var;
this.valueFromVar = valueFromVar;
}
public AddBindingFromOtherVar() {
}
public void setVar(final Variable var) {
this.var = var;
}
public void setOtherVar(final Variable valueFromVar) {
this.valueFromVar = valueFromVar;
}
public Variable getVar() {
return this.var;
}
public Variable getOtherVar() {
return this.valueFromVar;
}
// bindings should contain exactly one element!
@Override
public QueryResult process(final QueryResult oldBindings,
final int operandID) {
return QueryResult.createInstance(new ImmutableIterator<Bindings>() {
Iterator<Bindings> itb = oldBindings.oneTimeIterator();
@Override
public boolean hasNext() {
return this.itb.hasNext();
}
@Override
public Bindings next() {
if (!this.itb.hasNext()) {
return null;
}
final Bindings oldBinding = this.itb.next();
final Literal literal = oldBinding.get(AddBindingFromOtherVar.this.var);
if (literal == null) {
oldBinding.add(AddBindingFromOtherVar.this.var, oldBinding.get(AddBindingFromOtherVar.this.valueFromVar));
}
// if the item is a variable which is already bound
// and the value differs from the value of the triple
// which would be used as binding, a conflict was
// detected
else if (!literal.valueEquals(oldBinding.get(AddBindingFromOtherVar.this.valueFromVar))) {
System.out
.println("AddBindingFromOtherVar: Error: Variable "
+ AddBindingFromOtherVar.this.var + " was already bound!");
return null;
}
return oldBinding;
}
});
}
@Override
public Message preProcessMessage(final BoundVariablesMessage msg) {
msg.getVariables().add(this.var);
this.intersectionVariables = new LinkedList<Variable>();
this.intersectionVariables.addAll(msg.getVariables());
this.unionVariables = this.intersectionVariables;
return msg;
}
@Override
public String toString() {
return "Add (" + this.var.toString() + "=" + this.valueFromVar.toString() + ")";
}
@Override
public boolean remainsSortedData(final Collection<Variable> sortCriterium){
return true;
}
@Override
public Collection<Variable> transformSortCriterium(final Collection<Variable> sortCriterium){
if (sortCriterium
.contains(this.getVar())) {
final Set<Variable> sortCriterium2 = new HashSet<Variable>();
sortCriterium2.addAll(sortCriterium);
sortCriterium2.remove(this.getVar());
sortCriterium2.add(this.getOtherVar());
return sortCriterium2;
} else {
return sortCriterium;
}
}
}