/**
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 Mar 27, 2012
*/
package com.bigdata.rdf.sparql.ast;
import java.util.Set;
import com.bigdata.bop.IVariable;
/**
* Interface and annotations for AST nodes which have a {@link ProjectionNode}.
*
* @author <a href="mailto:thompsonbry@users.sourceforge.net">Bryan Thompson</a>
* @version $Id$
*/
public interface IProjectionDecl {
public interface Annotations {
/**
* The {@link ProjectionNode} (optional). This is also used for DESCRIBE
* queries to capture the list of variables and IRIs which are then used
* to rewrite the DESCRIBE query into what amounts to a CONSTRUCT query.
* The resulting CONSTRUCT query will have a different
* {@link ProjectionNode} suitable for use with the generated
* {@link ConstructNode}.
*/
String PROJECTION = "projection";
}
/**
* Set or clear the projection.
*
* @param projection
* The projection (may be <code>null</code>).
*/
void setProjection(final ProjectionNode projection);
/**
* Return the projection -or- <code>null</code> if there is no projection.
*/
ProjectionNode getProjection();
/**
* Return the set of variables projected out of this query (this is a NOP if
* there is no {@link ProjectionNode} for the query, which can happen for an
* ASK query). This DOES NOT report the variables which are used by the
* SELECT expressions, just the variables which are PROJECTED out by the
* BINDs.
*
* @param vars
* The projected variables are added to this set.
*
* @return The caller's set.
*/
Set<IVariable<?>> getProjectedVars(final Set<IVariable<?>> vars);
}