/**
* 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.externalontology;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import lupos.engine.operators.BasicOperator;
import lupos.engine.operators.OperatorIDTuple;
import lupos.engine.operators.multiinput.join.Join;
import lupos.engine.operators.singleinput.AddBinding;
import lupos.engine.operators.singleinput.filter.Filter;
import lupos.misc.Tuple;
import lupos.optimizations.logical.rules.Rule;
import lupos.sparql1_1.ParseException;
public class RuleConstantPropagationOverJoin extends Rule {
@Override
protected void init() {
final AddBinding add = new AddBinding(null, null);
final Join join = new Join();
add.setSucceedingOperator(new OperatorIDTuple(join, -1));
join.setPrecedingOperator(add);
subGraphMap = new HashMap<BasicOperator, String>();
subGraphMap.put(add, "add");
subGraphMap.put(join, "join");
startNode = add;
}
@Override
protected boolean checkPrecondition(final Map<String, BasicOperator> mso) {
// should be fulfilled!
for (final BasicOperator bo : mso.get("join").getPrecedingOperators()) {
if (bo.getSucceedingOperators().size() > 1)
return false;
}
return mso.get("add").getPrecedingOperators().size() == 1;
}
@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 AddBinding add = (AddBinding) mso.get("add");
final Join join = (Join) mso.get("join");
boolean afterJoin = true;
final List<BasicOperator> joinPrec = new LinkedList<BasicOperator>();
joinPrec.addAll(join.getPrecedingOperators());
for (final BasicOperator bo : joinPrec) {
// check if Filter(Add.Var = Add.Constant) must be put to a join
// operand in order to fulfill the join condition
if (!bo.equals(add)
&& bo.getUnionVariables().contains(add.getVar())) {
try {
final Filter filter = new Filter("FILTER( "
+ add.getVar().toString() + " = "
+ add.getLiteral().toString() + " )");
filter.setIntersectionVariables(bo.getUnionVariables());
filter.setUnionVariables(bo.getUnionVariables());
// we assume that
filter.setSucceedingOperators(bo.getSucceedingOperators());
bo.setSucceedingOperator(new OperatorIDTuple(filter, 0));
join.removePrecedingOperator(bo);
join.addPrecedingOperator(filter);
filter.setPrecedingOperator(bo);
afterJoin = false;
added.add(filter);
} catch (final ParseException e) {
System.err.println(e);
e.printStackTrace();
}
}
}
// remove add
for (final BasicOperator bo : add.getPrecedingOperators()) {
bo.removeSucceedingOperator(add);
bo.addSucceedingOperators(add.getSucceedingOperators());
join.addPrecedingOperator(bo);
}
join.removePrecedingOperator(add);
join.getIntersectionVariables().remove(add.getVar());
// must add be put after the join?
if (afterJoin) {
add.setSucceedingOperators(join.getSucceedingOperators());
add.setPrecedingOperator(join);
join.setSucceedingOperator(new OperatorIDTuple(add, 0));
for (final OperatorIDTuple oid : add.getSucceedingOperators()) {
oid.getOperator().removePrecedingOperator(join);
oid.getOperator().addPrecedingOperator(add);
}
} else
deleted.add(add);
alreadyAppliedTo = new HashSet<BasicOperator>();
if (deleted.size() > 0 || added.size() > 0)
return new Tuple<Collection<BasicOperator>, Collection<BasicOperator>>(
added, deleted);
else
return null;
}
}