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/*

 * Geotools 2 - OpenSource mapping toolkit

 * (C) 2005, Geotools Project Managment Committee (PMC)

 *

 *    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 org.geotools.referencing.factory.epsg;

// J2SE dependencies

import java.sql.Statement;

import java.sql.Connection;

import java.sql.SQLException;

import java.util.regex.Pattern;

import java.util.regex.Matcher;

// Geotools dependencies

import org.geotools.factory.Hints;

import org.geotools.referencing.factory.FactoryGroup;

/**

 * Adapts SQL statements for HSQL. The HSQL database engine doesn't understand

 * the parenthesis in (INNER JOIN ... ON) statements for the "BursaWolfParameters"

 * query. Unfortunatly, those parenthesis are required by MS-Access. We need to

 * removes them programmatically here.

 *

 * @version $Id: FactoryUsingHSQL.java 14624 2005-06-29 02:19:08Z desruisseaux $

 * @author Martin Desruisseaux

 *

 * @since 2.2

 */

final class FactoryUsingHSQL extends FactoryUsingAnsiSQL {

    /**

     * The regular expression pattern for searching the "FROM (" clause.

     * This is the pattern for the opening parenthesis.

     */

    private static final Pattern OPENING_PATTERN =

            Pattern.compile("\\s+FROM\\s*\\(",

            Pattern.CASE_INSENSITIVE);

    /**

     * Constructs the factory for the given connection to the HSQL database.

     */

    public FactoryUsingHSQL(final FactoryGroup factories, final Connection connection) {

        super(factories, connection);

    }

    /**

     * If the query contains a "FROM (" expression, remove the parenthesis.

     */

    public String adaptSQL(String query) {

        query = super.adaptSQL(query);

        final Matcher matcher = OPENING_PATTERN.matcher(query);

        if (matcher.find()) {

            final int opening = matcher.end()-1;

            final int length  = query.length();

            int closing = opening;

            for (int count=0; ; closing++) {

                if (closing >= length) {

                    // Should never happen with well formed SQL statement.

                    // If it happen anyway, don't change anything and let

                    // the HSQL driver produces a "syntax error" message.

                    return query;

                }

                switch (query.charAt(closing)) {

                    case '(': count++; break;

                    case ')': count--; break;

                    default : continue;

                }

                if (count == 0) {

                    break;

                }

            }

            query = query.substring(0,         opening) +

                    query.substring(opening+1, closing) +

                    query.substring(closing+1);

        }

        return query;

    }

    /**

     * Shutdown the HSQL database engine.

     */

    void shutdown(final boolean active) throws SQLException {

        if (active) {

            final Statement statement = connection.createStatement();

            statement.execute("SHUTDOWN");

            statement.close();

        }

        super.shutdown(active);

    }

}