/*
// $Id: //open/dev/farrago/src/org/eigenbase/relopt/CommonRelSubExprRule.java#1 $
// Package org.eigenbase is a class library of data management components.
// Copyright (C) 2005-2009 The Eigenbase Project
// Copyright (C) 2005-2009 SQLstream, Inc.
// Copyright (C) 2005-2009 LucidEra, Inc.
// Portions Copyright (C) 2003-2009 John V. Sichi
//
// This program is free software; you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by the Free
// Software Foundation; either version 2 of the License, or (at your option)
// any later version approved by The Eigenbase Project.
//
// This program 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/
package org.eigenbase.relopt;


/**
 * A <code>CommonRelSubExprRule</code> is an abstract base class for rules
 * that are fired only on relational expressions that appear more than once
 * in a query tree.
 */
public abstract class CommonRelSubExprRule
    extends RelOptRule
{
    //~ Constructors -----------------------------------------------------------

    /**
     * Creates a <code>CommonRelSubExprRule</code>.
     *
     * @param operand root operand, must not be null
     *
     * @pre operand != null
     */
    public CommonRelSubExprRule(RelOptRuleOperand operand)
    {
        super(operand);
    }

    //~ Methods ----------------------------------------------------------------

}

// End CommonRelSubExprRule.java
