/**
* 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.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import lupos.datastructures.items.Item;
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.singleinput.AddBinding;
import lupos.engine.operators.singleinput.Projection;
import lupos.engine.operators.singleinput.ReplaceVar;
import lupos.engine.operators.singleinput.filter.Filter;
import lupos.engine.operators.singleinput.generate.Generate;
import lupos.engine.operators.tripleoperator.TriplePattern;
import lupos.misc.Tuple;
import lupos.optimizations.logical.rules.Rule;
import lupos.sparql1_1.ASTFilterConstraint;
import lupos.sparql1_1.SPARQL1_1Parser;
public class RuleReplaceGenPat extends Rule {
@Override
protected void init() {
final Generate generate = new Generate();
final TriplePattern pat = new TriplePattern();
generate.setSucceedingOperator(new OperatorIDTuple(pat, -1));
pat.setPrecedingOperator(generate);
subGraphMap = new HashMap<BasicOperator, String>();
subGraphMap.put(generate, "generate");
subGraphMap.put(pat, "pat");
startNode = generate;
}
@Override
protected boolean checkPrecondition(final Map<String, BasicOperator> mso) {
final Generate generate = (Generate) mso.get("generate");
final LinkedList<OperatorIDTuple> succs = (LinkedList<OperatorIDTuple>) generate
.getSucceedingOperators();
// First finish RuleSplitGenerates
return ((succs.size() == 1) && (succs.get(0).getOperator() instanceof TriplePattern));
}
@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 Generate generate = (Generate) mso.get("generate");
final TriplePattern pat = (TriplePattern) mso.get("pat");
final Item[] patItems = pat.getItems();
final Item[] generateItems = generate.getValueOrVariable();
// System.out.println(generate.toString() + "---" + pat.toString());
Filter filter = null;
final ReplaceVar replaceVar = new ReplaceVar();
replaceVar.setIntersectionVariables(new HashSet<Variable>());
replaceVar.setUnionVariables(replaceVar.getIntersectionVariables());
final LinkedList<Variable> addBindingsVar = new LinkedList<Variable>();
final LinkedList<Literal> addBindingsLit = new LinkedList<Literal>();
String filterConstraint = "Filter( ";
for (int i = 0; i < 3; i++) {
final Item patItem = patItems[i];
final Item generateItem = generateItems[i];
if ((!patItem.isVariable()) && generateItem.isVariable()) {
filterConstraint += generateItems[i].toString() + " = "
+ patItems[i].toString() + " && ";
} else if (patItem.isVariable() && generateItem.isVariable()) {
replaceVar.addSubstitution((Variable) patItem,
(Variable) generateItem);
replaceVar.getIntersectionVariables().add((Variable) patItem);
} else if (patItem.isVariable() && (!generateItem.isVariable())) {
addBindingsVar.add((Variable) patItem);
addBindingsLit.add((Literal) generateItem);
} else if (!patItem.isVariable() && !generateItem.isVariable()
&& !generateItem.equals(patItem)) {
// cannot match, remove generate.
for (final BasicOperator parent : generate
.getPrecedingOperators())
parent.removeSucceedingOperator(generate);
generate.getPrecedingOperators().clear();
generate.removeFromOperatorGraph();
return null;
}
}
// If (?x = ?a) and (?x = ?b) then (valueOf(?a) = value(?b)) must be
// fulfilled
for (int i = 0; i < 2; i++) {
for (int x = i + 1; x < 3; x++) {
if (patItems[i].equals(patItems[x])) {
filterConstraint += generateItems[i].toString() + " = "
+ generateItems[x].toString() + " && ";
}
}
}
if (!filterConstraint.equals("Filter( ")) {
filterConstraint = filterConstraint.substring(0,
filterConstraint.length() - 3)
+ ") ";
try {
final ASTFilterConstraint ASTfilter = (ASTFilterConstraint) SPARQL1_1Parser
.parseFilter(filterConstraint);
filter = new Filter(ASTfilter);
} catch (final Exception e) {
System.err
.println("This should never happen in RuleReplaceGenPat!");
System.err.println(e);
e.printStackTrace();
}
}
// Only Operators with a not empty definition are put into the
// operatorgraph
final LinkedList<BasicOperator> order = new LinkedList<BasicOperator>();
if (filter != null) {
order.add(filter);
added.add(filter);
}
final int substVar = replaceVar.getSubstitutionsVariableLeft().size();
if (substVar > 0) {
order.add(replaceVar);
added.add(replaceVar);
} else {
final Projection p = new Projection();
p.setIntersectionVariables(new HashSet<Variable>());
p.setUnionVariables(p.getUnionVariables());
order.add(p);
added.add(p);
}
if (addBindingsVar.size() > 0) {
final Iterator<Literal> lit_it = addBindingsLit.iterator();
final HashSet<Variable> hsv = new HashSet<Variable>();
hsv.addAll(replaceVar.getUnionVariables());
for (final Variable v : addBindingsVar) {
final AddBinding ab = new AddBinding(v, lit_it.next());
hsv.add(v);
ab.setIntersectionVariables((HashSet<Variable>) hsv.clone());
ab.setUnionVariables(ab.getIntersectionVariables());
order.add(ab);
added.add(ab);
}
}
// In case that Generate or TriplePattern has minimum one variable, than
// minimum one operator has to be inserted
if (order.size() > 0) {
final List<BasicOperator> pres = (List<BasicOperator>) generate
.getPrecedingOperators();
BasicOperator pre;
for (int i = 0; i < pres.size(); i++) {
pre = pres.get(i);
pre.addSucceedingOperator(new OperatorIDTuple(order.getFirst(),
0));
if (filter != null) {
Collection<Variable> vars = filter
.getIntersectionVariables();
if (vars == null)
vars = new HashSet<Variable>();
vars.addAll(pre.getIntersectionVariables());
filter.setIntersectionVariables(vars);
filter.setUnionVariables(vars);
}
pre.removeSucceedingOperator(generate);
order.getFirst().addPrecedingOperator(pre);
}
for (int i = 0; i < order.size() - 1; i++) {
order.get(i + 1).setPrecedingOperator(order.get(i));
order.get(i).setSucceedingOperator(
new OperatorIDTuple(order.get(i + 1), 0));
}
final LinkedList<OperatorIDTuple> succs = (LinkedList<OperatorIDTuple>) pat
.getSucceedingOperators();
for (int i = 0; i < succs.size(); i++) {
succs.get(i).getOperator()
.addPrecedingOperator(order.getLast());
}
final LinkedList<OperatorIDTuple> sops = new LinkedList<OperatorIDTuple>();
sops.addAll(pat.getSucceedingOperators());
order.getLast().setSucceedingOperators(sops);
} else {
final LinkedList<BasicOperator> pres = (LinkedList<BasicOperator>) generate
.getPrecedingOperators();
final LinkedList<OperatorIDTuple> succs = (LinkedList<OperatorIDTuple>) pat
.getSucceedingOperators();
BasicOperator pre;
BasicOperator succ;
for (int i = 0; i < pres.size(); i++) {
pre = pres.get(i);
pre.removeSucceedingOperator(generate);
for (int x = 0; x < succs.size(); x++) {
pre.addSucceedingOperator(succs.get(x));
succ = succs.get(x).getOperator();
succ.removePrecedingOperator(pat);
succ.addPrecedingOperator(pre);
}
}
}
// TriplePattern can have more predecessors then Generate..
pat.removePrecedingOperator(generate);
if (pat.getPrecedingOperators().size() == 0)
deleted.add(pat);
// System.out.println(pat.getPrecedingOperators());
deleted.add(generate);
rootOperator.deleteParents();
rootOperator.setParents();
rootOperator.detectCycles();
// has 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;
}
}