/* // $Id: //guest/julian_hyde/saffron/src/main/saffron/rel/RemoveTrivialProjectRule.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.Environment; import openjava.ptree.Variable; import saffron.opt.*; import saffron.util.RelEnvironment; /** * <code>RemoveTrivialProjectRule</code> removes {@link Project} nodes * which merely return their input. For example, * <code>Project(ArrayReader(a), {$input0})</code> becomes * <code>ArrayReader(a)</code>. **/ public class RemoveTrivialProjectRule extends SingleConventionRule { public RemoveTrivialProjectRule() { super( new Operand(Project.class, null), CallingConvention.NONE); } public Rel apply(Environment env, Rel[] rels) { Project project = (Project) rels[0]; if (project.exps.length == 1 && project.exps[0] instanceof Variable && RelEnvironment.getInputOrdinal( project.exps[0].toString()) == 0) { Rel rel = project.child; RelSubset subset = planner.register( rel, planner.getSet(project), VolcanoPlanner.MAY_BE_REGISTERED); return planner.convert(subset, CallingConvention.NONE); } return null; } }
# | Change | User | Description | Committed | |
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#2 | 1801 | Julian Hyde |
saffron: add ObjectSchema; rules can now be matched more than once; started to implement correlations in queries in from list. |
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#1 | 1467 | Julian Hyde |
saffron: First saffron check-in; incorporate my changes to openjava. |