/**
Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016. All rights reserved.
Contact:
SYSTAP, LLC DBA Blazegraph
2501 Calvert ST NW #106
Washington, DC 20008
licenses@blazegraph.com
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
* Created on June 18, 2015
*/
package com.bigdata.rdf.sparql.ast;
import java.util.HashSet;
import java.util.Set;
import com.bigdata.bop.IVariable;
import com.bigdata.rdf.sparql.ast.optimizers.ASTJoinGroupFilterExistsInfo;
/**
* Class summarizing the variable binding requirements for a given node
* (used for children in the join group), thus providing easy access to its
* variable binding information {@link IGroupMemberNode}s.
*
* @author <a href="mailto:ms@metaphacts.com">Michael Schmidt</a>
* @version $Id$
*/
public class GroupNodeVarBindingInfo {
/**
* The node for which the information is valid.
*/
final private IGroupMemberNode node;
/**
* Variables that must be bound upon evaluation of this node,
* see {@link IVariableBindingRequirements} for detailed documentation.
*/
final private Set<IVariable<?>> requiredBound;
/**
* Variables that are desired to be bound upon evaluation of this node,
* see {@link IVariableBindingRequirements} for detailed documentation.
*/
final private Set<IVariable<?>> desiredBound;
/**
* Variables that are possibly bound by this node.
*/
final private Set<IVariable<?>> maybeProduced;
/**
* Variables that are definitely bound by this node.
*/
final private Set<IVariable<?>> definitelyProduced;
/**
* Constructor
* @param node
* @param sa
*/
public GroupNodeVarBindingInfo(
final IGroupMemberNode node,
final StaticAnalysis sa,
final ASTJoinGroupFilterExistsInfo fExInfo) {
this.node = node;
this.requiredBound = node.getRequiredBound(sa);
this.desiredBound = node.getDesiredBound(sa);
this.maybeProduced = new HashSet<IVariable<?>>();
if (node instanceof IBindingProducerNode) {
sa.getMaybeProducedBindings(
(IBindingProducerNode)node, maybeProduced, true);
}
this.definitelyProduced = new HashSet<IVariable<?>>();
if (node instanceof IBindingProducerNode) {
if (!StaticAnalysis.isMinusOrOptional(node)) {
sa.getDefinitelyProducedBindings(
(IBindingProducerNode)node, definitelyProduced, true);
}
}
/**
* Special handing for ASK subqueries. See also ticket #BLZG-1284
* and the associated test in TestTickets for why this is necessary.
*/
if (fExInfo!=null && node instanceof SubqueryRoot &&
fExInfo.containsSubqueryRoot((SubqueryRoot)node)) {
final SubqueryRoot sqr = (SubqueryRoot)node;
// there are no variables that are desired bound (all are required)
this.desiredBound.clear();
// in addition to what's reported by getDefinitelyProducedBindings,
// the askVar of the subquery must be considered
this.definitelyProduced.add(sqr.getAskVar());
// required are all projection vars minus the ask var, i.e. these
// must be bound when evaluating the FILTER (NOT) EXISTS node
sqr.getProjectedVars(this.requiredBound);
this.requiredBound.remove(sqr.getAskVar());
}
}
public IGroupMemberNode getNode() {
return node;
}
public Set<IVariable<?>> getRequiredBound() {
return requiredBound;
}
public Set<IVariable<?>> getDesiredBound() {
return desiredBound;
}
public Set<IVariable<?>> getMaybeProduced() {
return maybeProduced;
}
public Set<IVariable<?>> getDefinitelyProduced() {
return definitelyProduced;
}
/**
* Get variables that remain to be bound, assuming that the definitely
* incoming variables plus the variables passed as parameter are bound
* already.
*/
public Set<IVariable<?>> leftToBeBound(Set<IVariable<?>> knownBound) {
HashSet<IVariable<?>> toBeBound = new HashSet<IVariable<?>>();
toBeBound.addAll(requiredBound);
toBeBound.removeAll(knownBound);
return toBeBound;
}
}