/**
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 Nov 27, 2011
*/
package com.bigdata.rdf.sparql.ast.hints;
import com.bigdata.rdf.sparql.ast.ASTBase;
import com.bigdata.rdf.sparql.ast.IJoinNode;
import com.bigdata.rdf.sparql.ast.QueryHints;
import com.bigdata.rdf.sparql.ast.QueryRoot;
import com.bigdata.rdf.sparql.ast.eval.AST2BOpContext;
import com.bigdata.rdf.sparql.ast.optimizers.ASTRunFirstRunLastOptimizer;
import com.bigdata.rdf.sparql.ast.optimizers.ASTStaticJoinOptimizer;
/**
* Query hint to run a join last in a join group. This hint must be used with
* {@link QueryHintScope#Prior}.
* <p>
* Note: This sets an AST annotation which is interpreted by the
* {@link ASTRunFirstRunLastOptimizer} and {@link ASTStaticJoinOptimizer}.
*/
final class RunLastHint extends AbstractBooleanQueryHint {
protected RunLastHint() {
super(QueryHints.RUN_LAST, null/* default */);
}
@Override
public void handle(final AST2BOpContext context,
final QueryRoot queryRoot,
final QueryHintScope scope, final ASTBase op, final Boolean value) {
if (scope == QueryHintScope.Prior && op instanceof IJoinNode) {
_setAnnotation(context, scope, op, getName(), value);
return;
}
throw new QueryHintException(scope, op, getName(), value);
}
}