/* // $Id: //guest/julian_hyde/saffron/src/main/saffron/rel/DistinctToExistsRule.java#2 $ // 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 openjava.ptree.util.SyntheticClass; import saffron.opt.CallingConvention; import saffron.opt.Operand; import saffron.opt.RuleCall; import saffron.opt.SingleConventionRule; import saffron.rel.java.JavaDistinct; import saffron.rel.java.JavaExists; /** * Rule to translate a {@link saffron.rel.java.JavaDistinct} into a {@link * saffron.rel.java.JavaExists}, provided that the select list contains zero * columns. **/ public class DistinctToExistsRule extends SingleConventionRule { public DistinctToExistsRule() { super( new Operand(JavaDistinct.class, null), CallingConvention.JAVA); } public void onMatch(RuleCall call) { JavaDistinct distinct = (JavaDistinct) call.rels[0]; OJClass rowType = distinct.child.getRowType(); if (rowType instanceof SyntheticClass && ((SyntheticClass) rowType).getWidth() == 0) { call.transformTo(new JavaExists( distinct.cluster, distinct.child)); } } } // End DistinctToExistsRule.java
# | Change | User | Description | Committed | |
---|---|---|---|---|---|
#2 | 1801 | Julian Hyde |
saffron: add ObjectSchema; rules can now be matched more than once; started to implement correlations in queries in from list. |
||
#1 | 1467 | Julian Hyde |
saffron: First saffron check-in; incorporate my changes to openjava. |