/**
* 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;
import java.util.Collection;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.Map;
import lupos.datastructures.items.Variable;
import lupos.datastructures.items.VariableInInferenceRule;
import lupos.datastructures.items.literal.LanguageTaggedLiteralOriginalLanguage;
import lupos.datastructures.items.literal.LazyLiteral;
import lupos.datastructures.items.literal.Literal;
import lupos.datastructures.items.literal.TypedLiteral;
import lupos.datastructures.items.literal.TypedLiteralOriginalContent;
import lupos.engine.operators.BasicOperator;
import lupos.engine.operators.OperatorIDTuple;
import lupos.engine.operators.messages.BoundVariablesMessage;
import lupos.engine.operators.singleinput.AddBinding;
import lupos.engine.operators.singleinput.filter.Filter;
import lupos.engine.operators.singleinput.filter.expressionevaluation.Helper;
import lupos.engine.operators.tripleoperator.TriplePattern;
import lupos.misc.Tuple;
/**
* This class implements following rule to replace constant values in Index
* operations:
*
* index(...?X...) index(...constant...)
* | |
* filter(?X=constant) => addBinding(?X=constant)
* | |
*
* Preconditions: - the filter should contain an expression like ?X=constant
*
**/
public class RuleReplaceConstantOfFilterInTriplePattern extends Rule {
private Variable var;
private Variable varInference;
private Literal constant;
private TriplePattern triplePattern;
public RuleReplaceConstantOfFilterInTriplePattern() {
super();
}
@Override
protected void init() {
// Define left side of rule
final Filter a = new Filter();
subGraphMap = new HashMap<BasicOperator, String>();
subGraphMap.put(a, "filter");
startNode = a;
}
@Override
protected boolean checkPrecondition(final Map<String, BasicOperator> mso) {
final Filter filter = (Filter) mso.get("filter");
BasicOperator searchTriplePattern = filter;
while (searchTriplePattern != null
&& !(searchTriplePattern instanceof TriplePattern)) {
if (searchTriplePattern.getPrecedingOperators().size() > 1)
return false;
searchTriplePattern = searchTriplePattern.getPrecedingOperators()
.get(0);
}
if (searchTriplePattern == null
|| !(searchTriplePattern instanceof TriplePattern))
return false;
if (searchTriplePattern.getSucceedingOperators().size() > 1)
return false;
triplePattern = (TriplePattern) searchTriplePattern;
lupos.sparql1_1.Node n = filter.getNodePointer();
if (n.jjtGetNumChildren() > 0) {
n = n.jjtGetChild(0);
if (n instanceof lupos.sparql1_1.ASTEqualsNode) {
lupos.sparql1_1.Node left = n.jjtGetChild(0);
lupos.sparql1_1.Node right = n.jjtGetChild(1);
if (right instanceof lupos.sparql1_1.ASTVar) {
final lupos.sparql1_1.Node tmp = left;
left = right;
right = tmp;
}
if (left instanceof lupos.sparql1_1.ASTVar) {
final String varname = ((lupos.sparql1_1.ASTVar) left)
.getName();
var = new Variable(varname);
varInference = new VariableInInferenceRule(varname);
if (!triplePattern.getVariables().contains(var)
&& !triplePattern.getVariables().contains(
varInference)) {
// TODO
// delete triple pattern as it will never have a result!
System.err
.println("Can be optimized by extending RuleReplaceConstantOfFilterInTriplePattern: delete triple pattern with succeeding unsatisfiable filter expression!");
return false;
}
if (right instanceof lupos.sparql1_1.ASTQName
|| right instanceof lupos.sparql1_1.ASTQuotedURIRef
|| right instanceof lupos.sparql1_1.ASTFloatingPoint
|| right instanceof lupos.sparql1_1.ASTInteger
|| right instanceof lupos.sparql1_1.ASTStringLiteral
|| right instanceof lupos.sparql1_1.ASTDoubleCircumflex) {
constant = LazyLiteral.getLiteral(right);
// Is it possible to loose the information of the
// original string representation?
if (constant instanceof TypedLiteralOriginalContent
|| constant instanceof LanguageTaggedLiteralOriginalLanguage)
return false;
else if (constant instanceof TypedLiteral) {
if (Helper.isNumeric(((TypedLiteral) constant)
.getType())) {
return false;
} else
return true;
} else
return true;
}
}
}
}
return false;
}
@Override
protected 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 Filter filter = (Filter) mso.get("filter");
final BasicOperator aboveFilter = filter.getPrecedingOperators().get(0);
aboveFilter.setSucceedingOperators(filter.getSucceedingOperators());
triplePattern.replace(var, constant);
triplePattern.replace(varInference, constant);
final AddBinding addBinding = new AddBinding(var, constant);
added.add(addBinding);
addBinding.setSucceedingOperators(triplePattern
.getSucceedingOperators());
triplePattern.setSucceedingOperator(new OperatorIDTuple(addBinding, 0));
rootOperator.deleteParents();
rootOperator.setParents();
rootOperator.detectCycles();
rootOperator.sendMessage(new BoundVariablesMessage());
deleted.add(filter);
if (deleted.size() > 0 || added.size() > 0)
return new Tuple<Collection<BasicOperator>, Collection<BasicOperator>>(
added, deleted);
else
return null;
}
@Override
public String getName() {
return "Constant Propagation";
}
}