/**
* 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.ReplaceVar;
import lupos.misc.Tuple;
import lupos.optimizations.logical.rules.Rule;
public class RuleMergeTwoReplaceVar extends Rule {
public RuleMergeTwoReplaceVar() {
super();
}
@Override
protected void init() {
final ReplaceVar rep1 = new ReplaceVar();
final ReplaceVar rep2 = new ReplaceVar();
rep1.setSucceedingOperator(new OperatorIDTuple(rep2, 0));
rep2.setPrecedingOperator(rep1);
subGraphMap = new HashMap<BasicOperator, String>();
subGraphMap.put(rep1, "rep1");
subGraphMap.put(rep2, "rep2");
startNode = rep1;
}
@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 ReplaceVar rep1 = (ReplaceVar) mso.get("rep1");
final ReplaceVar rep2 = (ReplaceVar) mso.get("rep2");
final ReplaceVar rep_new = new ReplaceVar();
rep_new.setSubstitutionsVariableLeft(rep1
.getSubstitutionsVariableLeft());
rep_new.setSubstitutionsVariableRight(rep1
.getSubstitutionsVariableRight());
final LinkedList<Variable> rep1VarsLeft = rep1
.getSubstitutionsVariableLeft();
final LinkedList<Variable> rep1VarsRight = rep1
.getSubstitutionsVariableRight();
final LinkedList<Variable> rep2VarsRight = rep2
.getSubstitutionsVariableRight();
final LinkedList<Variable> rep2VarsLeft = rep2
.getSubstitutionsVariableLeft();
Variable var;
int index = -1;
for (int i = 0; i < rep2VarsRight.size(); i++) {
var = rep2VarsRight.get(i);
index = rep1VarsLeft.indexOf(var);
// No transitivity
if (index == -1) {
rep_new.addSubstitution(rep2VarsLeft.get(i), rep2VarsRight
.get(i)); // Duplicate prevention by addSubstitution
}
// (y,a),(x,y) => (y,a),(x,a)
else {
rep_new.addSubstitution(rep2VarsLeft.get(i), rep1VarsRight
.get(index));
}
}
final LinkedList<BasicOperator> pres = (LinkedList<BasicOperator>) rep1
.getPrecedingOperators();
final LinkedList<OperatorIDTuple> succs = (LinkedList<OperatorIDTuple>) rep2
.getSucceedingOperators();
// Set precessors
BasicOperator pre;
for (int i = 0; i < pres.size(); i++) {
pre = pres.get(i);
pre.addSucceedingOperator(new OperatorIDTuple(rep_new, pre
.getOperatorIDTuple(rep1).getId()));
pre.removeSucceedingOperator(rep1);
}
rep_new.setPrecedingOperators(pres);
rep_new.setSucceedingOperators(succs);
// Set successors
BasicOperator succ;
for (int i = 0; i < succs.size(); i++) {
succ = succs.get(i).getOperator();
succ.addPrecedingOperator(rep_new);
succ.removePrecedingOperator(rep2);
}
rootOperator.deleteParents();
rootOperator.setParents();
rootOperator.detectCycles();
rootOperator.sendMessage(new BoundVariablesMessage());
deleted.add(rep1);
deleted.add(rep2);
added.add(rep_new);
if (deleted.size() > 0 || added.size() > 0)
return new Tuple<Collection<BasicOperator>, Collection<BasicOperator>>(
added, deleted);
else
return null;
}
}