/* // $Id: //guest/julian_hyde/saffron/src/main/saffron/rel/Correlator.java#1 $ // Saffron preprocessor and data engine // Copyright (C) 2002 Julian Hyde <julian.hyde@mail.com> // // This library is free software; you can redistribute it and/or // modify it under the terms of the GNU Library General Public // License as published by the Free Software Foundation; either // version 2 of the License, or (at your option) any later version. // // This library 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 // Library General Public License for more details. // // You should have received a copy of the GNU Library General Public // License along with this library; if not, write to the // Free Software Foundation, Inc., 59 Temple Place - Suite 330, // Boston, MA 02111-1307, USA. // // See the COPYING file located in the top-level-directory of // the archive of this library for complete text of license. */ package saffron.rel; import openjava.ptree.Expression; import openjava.ptree.Literal; import saffron.Planner; import saffron.opt.Cluster; import saffron.util.Util; /** * A <code>Correlator</code> behaves like a kind of {@link Join}, but works by * setting variables in its environment and restarting its right-hand input. * It is used to represent a correlated query; one implementation option is to * de-correlate the expression. * * @author jhyde * @since 23 September, 2001 * @version $Id: //guest/julian_hyde/saffron/src/main/saffron/rel/Correlator.java#1 $ **/ public class Correlator extends Join { Expression[] correlations; /** * Creates a Correlator. * * @param cluster {@link Cluster} this relational expression belongs to * @param left left input relational expression * @param right right input relational expression * @param joinType join type (see {@link Join#joinType}) * @param correlations set of expressions to set as variables each time a * row arrives from the left input **/ Correlator( Cluster cluster, Rel left, Rel right, int joinType, Expression[] correlations) { super(cluster, left, right, Literal.constantTrue(), joinType); this.correlations = correlations; } public Object clone() { return new Correlator( cluster, (Rel) left.clone(), (Rel) right.clone(), joinType, Util.clone(correlations)); } // override Rel public Rel changeConvention(Planner planner, int convention) { switch (convention) { // case CallingConvention.INLINE: // return new saffron.rel.java.JavaFilter( // cluster, planner.convert(child, convention), condition); // case CallingConvention.PLAN: // return new PlanRel.PlanFilter( // cluster, planner.convert(child, convention), condition); default: return null; } } } // End Correlator.java
# | Change | User | Description | Committed | |
---|---|---|---|---|---|
#1 | 1467 | Julian Hyde |
saffron: First saffron check-in; incorporate my changes to openjava. |