/* // $Id: //guest/julian_hyde/saffron/src/main/saffron/opt/Rule.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.opt; import openjava.mop.Environment; import saffron.rel.Rel; /** * A <code>Rule</code> transforms an expression into another. **/ abstract class Rule { /** * Current planner; set by {@link VolcanoPlanner#VolcanoPlanner}. **/ protected VolcanoPlanner planner; /** Root of operand tree. */ Operand operand; /** Flattened list of operands. */ Operand[] operands; Rule(Operand operand) { this.operand = operand; } /** * Return the current {@link VolcanoPlanner}. */ VolcanoPlanner getPlanner() { return planner; } /** * Return the calling convention which the generated expression will * support. */ public abstract int getConvention(); /** * Apply this rule to an expression, to produce an expression whose * output matches <code>convention</code>. If the rule is not * applicable, return null. * * @param rels the parameters to the operands of this rule; all * <code>rels[i]</code> are expressions which match * <code>operands[i]</code>; <code>rels[0]</code> is the root * expression. */ public abstract Rel apply(Environment env, Rel[] rels); /** * Return a description of this rule. */ String getDescription() { return getClass().toString(); } }
# | 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. |