/*
 * Copyright (C) 2003-2004 Red Hat Inc. All Rights Reserved.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2.1 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser 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
 *
 */
package com.redhat.persistence.oql;


/**
 * Filter
 *
 * @author Rafael H. Schloming &lt;rhs@mit.edu&gt;
 * @version $Revision: #6 $ $Date: 2004/08/16 $
 **/

public class Filter extends Expression {

    public final static String versionId = "$Id: Filter.java 737 2005-09-01 12:27:29Z sskracic $ by $Author: sskracic $, $DateTime: 2004/08/16 18:10:38 $";

    private Expression m_expr;
    private Expression m_condition;

    public Filter(Expression expr, Expression condition) {
        m_expr = expr;
        m_condition = condition;
    }

    void frame(Generator gen) {
        m_expr.frame(gen);
        QFrame expr = gen.getFrame(m_expr);
        QFrame frame = gen.frame(this, expr.getType());
        frame.addChild(expr);
        frame.setValues(expr.getValues());
        frame.setMappings(expr.getMappings());
        gen.addUses(this, gen.getUses(m_expr));
        gen.addBoolean(m_condition);
        gen.push(frame);
        try {
            m_condition.frame(gen);
            frame.setCondition(m_condition);
            gen.addUses(this, gen.getUses(m_condition));
        } finally {
            gen.pop();
        }
    }

    Code emit(Generator gen) {
        return gen.getFrame(this).emit();
    }

    void hash(Generator gen) {
        m_expr.hash(gen);
        m_condition.hash(gen);
        gen.hash(getClass());
    }

    public String toString() {
        return "filter(" + m_expr + ", " + m_condition + ")";
    }

    String summary() { return "filter"; }

}
