/**
* 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.optimizations.logical.rules.rdfs;
import java.util.Collection;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.Map;
import lupos.datastructures.items.Variable;
import lupos.engine.operators.BasicOperator;
import lupos.engine.operators.OperatorIDTuple;
import lupos.engine.operators.messages.BoundVariablesMessage;
import lupos.engine.operators.singleinput.Projection;
import lupos.misc.Tuple;
import lupos.optimizations.logical.rules.Rule;
public class RuleMergeTwoProjection extends Rule {
@Override
protected void init() {
final Projection proj1 = new Projection();
final Projection proj2 = new Projection();
proj1.setSucceedingOperator(new OperatorIDTuple(proj2, -1));
proj2.setPrecedingOperator(proj1);
subGraphMap = new HashMap<BasicOperator, String>();
subGraphMap.put(proj1, "proj1");
subGraphMap.put(proj2, "proj2");
startNode = proj1;
}
@Override
protected boolean checkPrecondition(final Map<String, BasicOperator> mso) {
return true;
}
@Override
public Tuple<Collection<BasicOperator>, Collection<BasicOperator>> transformOperatorGraph(
final Map<String, BasicOperator> mso,
final BasicOperator rootOperator) {
final Collection<BasicOperator> deleted = new LinkedList<BasicOperator>();
final Collection<BasicOperator> added = new LinkedList<BasicOperator>();
final Projection proj1 = (Projection) mso.get("proj1");
final Projection proj2 = (Projection) mso.get("proj2");
final Object[] proj1Vars = proj1.getProjectedVariables().toArray();
final Object[] proj2Vars = proj2.getProjectedVariables().toArray();
final Projection proj_new = new Projection();
for (int i = 0; i < proj2Vars.length; i++) {
// Only intersection variables go into the new projection
if (arrayContains(proj1Vars, (Variable) proj2Vars[i])) {
proj_new.addProjectionElement((Variable) proj2Vars[i]);
}
}
final LinkedList<BasicOperator> pres = (LinkedList<BasicOperator>) proj1
.getPrecedingOperators();
BasicOperator pre;
for (int i = 0; i < pres.size(); i++) {
pre = pres.get(i);
pre.addSucceedingOperator(new OperatorIDTuple(proj_new, pre
.getOperatorIDTuple(proj1).getId()));
pre.removeSucceedingOperator(proj1);
}
proj_new.setPrecedingOperators(proj1.getPrecedingOperators());
proj_new.setSucceedingOperators(proj2.getSucceedingOperators());
final LinkedList<OperatorIDTuple> succs = (LinkedList<OperatorIDTuple>) proj2
.getSucceedingOperators();
for (int i = 0; i < succs.size(); i++) {
succs.get(i).getOperator().addPrecedingOperator(proj_new);
}
proj2.removePrecedingOperator(proj1);
rootOperator.deleteParents();
rootOperator.setParents();
rootOperator.detectCycles();
rootOperator.sendMessage(new BoundVariablesMessage());
added.add(proj_new);
deleted.add(proj1);
deleted.add(proj2);
if (deleted.size() > 0 || added.size() > 0)
return new Tuple<Collection<BasicOperator>, Collection<BasicOperator>>(
added, deleted);
else
return null;
}
private boolean arrayContains(final Object[] vars, final Variable var) {
for (int i = 0; i < vars.length; i++) {
if (vars[i].equals(var))
return true;
}
return false;
}
}