/* // $Id: //guest/julian_hyde/saffron/src/main/saffron/rel/Distinct.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.mop.OJClass; import saffron.Planner; import saffron.opt.CallingConvention; import saffron.opt.Cluster; import saffron.opt.Cost; import saffron.rel.java.JavaDistinct; import saffron.util.Util; /** * <code>Distinct</code> is a {@link saffron.rel.Rel} which eliminates duplicates from its * input. * * @author jhyde * @since 30 September, 2001 * @version $Id: //guest/julian_hyde/saffron/src/main/saffron/rel/Distinct.java#1 $ **/ public class Distinct extends SingleRel { public Distinct(Cluster cluster, Rel child) { super(cluster, child); } public Object clone() { return new Distinct(cluster, Util.clone(child)); } // implement Rel protected OJClass deriveRowType() { return child.getRowType(); } // implement Plan public Cost computeSelfCost(Planner planner) { return planner.makeZeroCost(); } // override Rel public Rel changeConvention(Planner planner, int convention) { switch (convention) { case CallingConvention.JAVA: Rel convertedChild = planner.convert(child, convention); if (convertedChild == null) { return null; } return new JavaDistinct(cluster, convertedChild); default: return null; } } } // End Distinct.java
# | Change | User | Description | Committed | |
---|---|---|---|---|---|
#1 | 1467 | Julian Hyde |
saffron: First saffron check-in; incorporate my changes to openjava. |