/**
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 Sep 5, 2011
*/
package com.bigdata.rdf.sparql.ast;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import com.bigdata.bop.BOp;
import com.bigdata.bop.IVariable;
import com.bigdata.rdf.sparql.ast.optimizers.ASTSubGroupJoinVarOptimizer;
/**
* Join group or union.
*
* @author <a href="mailto:thompsonbry@users.sourceforge.net">Bryan Thompson</a>
* @version $Id$
*
* TODO It would make the internal APIs significantly easier if we modeled this
* as a type of {@link GraphPatternGroup}, similar to {@link JoinGroupNode} and
* {@link UnionNode}.
*/
abstract public class GraphPatternGroup<E extends IGroupMemberNode> extends
GroupNodeBase<E> implements IJoinNode {
/**
*
*/
private static final long serialVersionUID = 1L;
public interface Annotations extends GroupNodeBase.Annotations {
/**
* An {@link IVariable}[] of the join variables will be definitely bound
* when we begin to evaluate a sub-group. This information is used to
* build a hash index on the join variables and to hash join the
* sub-group's solutions back into the parent group's solutions.
*
* @see ASTSubGroupJoinVarOptimizer
*/
String JOIN_VARS = "joinVars";
/**
* An {@link IVariable}[] of the variables that are used by the
* group and that have already appeared in the query up to this point
* (and thus may be bound and should be projected into the group).
*
* @see ASTSubGroupJoinVarOptimizer
*/
String PROJECT_IN_VARS = "projectInVars";
}
/**
* Constructor required for {@link com.bigdata.bop.BOpUtility#deepCopy(FilterNode)}.
*/
public GraphPatternGroup(final GraphPatternGroup<E> op) {
super(op);
}
/**
* Required shallow copy constructor.
*/
public GraphPatternGroup(final BOp[] args, final Map<String, Object> anns) {
super(args, anns);
}
/**
*
*/
public GraphPatternGroup() {
}
/**
* The join variables for the group.
*
* @see Annotations#JOIN_VARS
*/
public IVariable<?>[] getJoinVars() {
return (IVariable[]) getProperty(Annotations.JOIN_VARS);
}
public void setJoinVars(final IVariable<?>[] joinVars) {
setProperty(Annotations.JOIN_VARS, joinVars);
}
/**
* The variables that should be projected into the group.
*
* @see Annotations#PROJECT_IN_VARS
*/
public IVariable<?>[] getProjectInVars() {
return (IVariable[]) getProperty(Annotations.PROJECT_IN_VARS);
}
public void setProjectInVars(final IVariable<?>[] projectInVars) {
setProperty(Annotations.PROJECT_IN_VARS, projectInVars);
}
/**
* Return the nodes of the supplied type. Uses isAssignableFrom to
* determine whether the node is an instance of the supplied type.
*/
@SuppressWarnings("unchecked")
public <T> List<T> getChildren(final Class<T> type) {
final List<T> children = new LinkedList<T>();
for (IQueryNode node : this) {
if (type.isAssignableFrom(node.getClass())) {
children.add((T) node);
}
}
return children;
}
}