/* // $Id: //guest/julian_hyde/saffron/src/main/saffron/rel/java/JavaExists.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.java; import openjava.mop.OJClass; import openjava.mop.Toolbox; import openjava.ptree.StatementList; import openjava.ptree.util.SyntheticClass; import saffron.Planner; import saffron.opt.CallingConvention; import saffron.opt.Cluster; import saffron.opt.Cost; import saffron.opt.Implementor; import saffron.rel.Distinct; import saffron.rel.Rel; import saffron.util.Util; /** * <code>JavaExists</code> implements {@link Distinct} inline for the * special case that the input relation has zero columns. **/ public class JavaExists extends Distinct { public JavaExists(Cluster cluster, Rel child) { super(cluster, child); OJClass rowType = child.getRowType(); Toolbox.assert( rowType instanceof SyntheticClass && ((SyntheticClass) rowType).getWidth() == 0); } // implement Rel public Object clone() { return new JavaExists(cluster, child); } public int getConvention() { return CallingConvention.JAVA; } public Cost computeSelfCost(Planner planner) { // cheaper than JavaDistinct double dRows = 1, dCpu = dRows, dIo = 0; return planner.makeCost(dRows, dCpu, dIo); } public Object implement(Implementor implementor, int ordinal) { switch (ordinal) { case -1: { // Generate // <<parent>> return implementor.implementChild(this, 0, child); } case 0: // called from child { // Generate // <<parent-handler>> // break; StatementList stmtList = implementor.getStatementList(); implementor.generateParentBody(this, stmtList); stmtList.add(implementor.getExitStatement()); return null; } default: throw Util.newInternal( "implement: ordinal=" + ordinal); } } }
# | Change | User | Description | Committed | |
---|---|---|---|---|---|
#1 | 1467 | Julian Hyde |
saffron: First saffron check-in; incorporate my changes to openjava. |