Quadcap Embeddable Database

com/quadcap/sql/HavingCursor.java

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package com.quadcap.sql;

/* Copyright 1999 - 2003 Quadcap Software.  All rights reserved.
 *
 * This software is distributed under the Quadcap Free Software License.
 * This software may be used or modified for any purpose, personal or
 * commercial.  Open Source redistributions are permitted.  Commercial
 * redistribution of larger works derived from, or works which bundle
 * this software requires a "Commercial Redistribution License"; see
 * http://www.quadcap.com/purchase.
 *
 * Redistributions qualify as "Open Source" under  one of the following terms:
 *   
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 *    Redistributions are accompanied by a copy of the Source Code or by an
 *    irrevocable offer to provide a copy of the Source Code for up to three
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 *    must allow further use, modification, and redistribution of the Source
 *    Code under substantially the same terms as this license.
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 * Redistributions of source code must retain the copyright notices as they
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 */

import java.util.Vector;

import java.sql.SQLException;

import com.quadcap.sql.types.Value;
import com.quadcap.sql.types.ValueBoolean;

import com.quadcap.util.Debug;

/**
 * Cursor to support <b>HAVING</b> clause.
 *
 * <p>XXX Optimize this by use of a 'HavingRow' class which would perform less
 * copying.</p>
 *
 * @author Stan Bailes
 */
public class HavingCursor extends FilterCursor {
    Row         row                             = null;

    public HavingCursor(Session session, Cursor cursor) throws SQLException {
        super(session, cursor);
    }

    public Row getRow() throws SQLException {
        return row;
    }

    public void updateRow(Row row) throws SQLException {
        this.row = row;
        Row t = new Row(row.size()-1);
        for (int i = 1; i <= row.size(); i++) {
            t.set(i, row.item(i));
        }
        cursor.updateRow(t);
    }

    public int getColumnCount() throws SQLException {
        return cursor.getColumnCount() - 1;
    }

    public boolean next() throws SQLException {
        final int size = cursor.getColumnCount();
        boolean have = false;
        while (!have && cursor.next()) {
            Row r = cursor.getRow();
            Value val = r.item(size);
            if (val instanceof ValueBoolean &&
                ((ValueBoolean)val).isTrue()) {
                if (this.row == null) {
                    this.row = new Row(size-1);
                }
                for (int i = 1; i < size; i++) row.set(i, r.item(i));
                have = true;
            }
        }
        return have;
    }

}