/**
* 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.HashSet;
import java.util.LinkedList;
import java.util.Map;
import lupos.datastructures.items.Variable;
import lupos.datastructures.items.literal.Literal;
import lupos.engine.operators.BasicOperator;
import lupos.engine.operators.OperatorIDTuple;
import lupos.engine.operators.multiinput.join.Join;
import lupos.engine.operators.singleinput.ReplaceLit;
import lupos.misc.Tuple;
import lupos.optimizations.logical.rules.Rule;
public class RuleReplaceLitOverJoin extends Rule {
@Override
protected void init() {
final ReplaceLit replaceLit = new ReplaceLit();
final Join join = new Join();
replaceLit.setSucceedingOperator(new OperatorIDTuple(join, -1));
join.setPrecedingOperator(replaceLit);
subGraphMap = new HashMap<BasicOperator, String>();
subGraphMap.put(replaceLit, "replaceLit");
subGraphMap.put(join, "join");
startNode = replaceLit;
}
@Override
protected boolean checkPrecondition(final Map<String, BasicOperator> mso) {
final Join join = (Join) mso.get("join");
final ReplaceLit replaceLit = (ReplaceLit) mso.get("replaceLit");
// final Object[] joinVars = join.getIntersectionVariables().toArray();
final Object[] joinVars = join.getUnionVariables().toArray();
final LinkedList<Variable> v = replaceLit.getSubstitutionsLiteralLeft();
// If there is minimum one substitution which can be pulled down
for (int i = 0; i < v.size(); i++) {
// Otherwise join could trigger after transformation
if (!arrayContains(joinVars, v.get(i))) {
return true;
}
}
return false;
}
@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 ReplaceLit replaceLit = (ReplaceLit) mso.get("replaceLit");
final Join join = (Join) mso.get("join");
final ReplaceLit replaceLitUnder = new ReplaceLit();
final Collection<Variable> vars = new HashSet<Variable>();
vars.addAll(join.getIntersectionVariables());
replaceLitUnder.setIntersectionVariables(vars);
replaceLitUnder.setUnionVariables(vars);
final Object[] joinVars = join.getIntersectionVariables().toArray();
final LinkedList<Variable> replaceLitLeft = replaceLit
.getSubstitutionsLiteralLeft();
final LinkedList<Literal> replaceLitRight = replaceLit
.getSubstitutionsLiteralRight();
Variable var;
Literal lit;
for (int i = replaceLitLeft.size() - 1; i >= 0; i--) {
var = replaceLitLeft.get(i);
// Split ReplaceLit and pull only not intersection variables
// downwards
if (!arrayContains(joinVars, var)) {
lit = replaceLitRight.get(i);
replaceLitUnder.addSubstitution(var, lit);
replaceLit.removeSubstitutionVars(i);
replaceLitUnder.getIntersectionVariables().add(var); // var is
// also
// added
// to
// unionVariables
// as
// they
// are
// the
// same
// objects
// !
}
}
final LinkedList<BasicOperator> pres = (LinkedList<BasicOperator>) replaceLit
.getPrecedingOperators();
final LinkedList<OperatorIDTuple> succs = (LinkedList<OperatorIDTuple>) join
.getSucceedingOperators();
final int index = replaceLit.getOperatorIDTuple(join).getId();
// If everything could be pushed downwards, the old ReplaceLit can be
// deleted
if (replaceLit.getSubstitutionsLiteralLeft().size() == 0) {
BasicOperator pre;
for (int i = 0; i < pres.size(); i++) {
pre = pres.get(i);
pre.addSucceedingOperator(new OperatorIDTuple(join, index));
pre.removeSucceedingOperator(replaceLit);
join.addPrecedingOperator(pre);
}
join.removePrecedingOperator(replaceLit);
deleted.add(replaceLit);
}
// Insert the new ReplaceLit under the Join
// (only if there is not already an equivalent ReplaceLit!)
if (!((join.getSucceedingOperators().size() == 1)
&& (join.getSucceedingOperators().get(0).getOperator() instanceof ReplaceLit) && (replaceLitUnder
.equals(join.getSucceedingOperators().get(0).getOperator())))) {
join.setSucceedingOperator(new OperatorIDTuple(replaceLitUnder, 0));
replaceLitUnder.setPrecedingOperator(join);
replaceLitUnder.setSucceedingOperators(succs);
added.add(replaceLitUnder);
}
BasicOperator succ;
for (int i = 0; i < succs.size(); i++) {
succ = succs.get(i).getOperator();
succ.addPrecedingOperator(replaceLitUnder);
succ.removePrecedingOperator(join);
}
rootOperator.deleteParents();
rootOperator.setParents();
rootOperator.detectCycles();
// should have already been done manually: rootOperator.sendMessage(new
// BoundVariablesMessage());
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++) {
System.out.println(vars[i].toString() + "," + var.toString());
if (vars[i].equals(var))
return true;
}
return false;
}
}