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a Java JDBC driver for reading comma-separated-value files
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/*
 *  CsvJdbc - a JDBC driver for CSV files
 *  Copyright (C) 2008  Mario Frasca
 *
 *  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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */
package org.relique.jdbc.csv;

import java.sql.SQLException;
import java.util.Calendar;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;

class SQLCalendarFunction extends Expression
{
	String functionName;
	int calendarField;
	Expression expression;
	public SQLCalendarFunction(String functionName, int calendarField,
		Expression expression)
	{
		this.functionName = functionName;
		this.calendarField = calendarField;
		this.expression = expression;
	}
	@Override
	public Object eval(Map env) throws SQLException
	{
		Object retval = null;
		Object o = expression.eval(env);
		if (o != null)
		{
			/*
			 * Accept either java.sql.Date, java.sql.Time or java.sql.Timestamp.
			 */
			java.util.Date date = null;
			if (o instanceof java.util.Date)
			{
				date = (java.util.Date)o;
			}
			else
			{
				/*
				 * Try and convert from String to a Timestamp or Date/Time.
				 */
				Expression stringConverter = new ColumnName(StringConverter.COLUMN_NAME);
				StringConverter sc = (StringConverter) stringConverter.eval(env);
				date = sc.parseTimestamp(o.toString());
				if (date == null)
				{
					if (calendarField == Calendar.DAY_OF_MONTH ||
						calendarField == Calendar.MONTH ||
						calendarField == Calendar.YEAR)
					{
						date = sc.parseDate(o.toString());
					}
					else
					{
						date = sc.parseTime(o.toString());
					}
				}
			}
			if (date != null)
			{
				Calendar cal = Calendar.getInstance();
				cal.setTime(date);
				int fieldValue = cal.get(calendarField);
				if (calendarField == Calendar.MONTH)
					fieldValue++;
				retval = Integer.valueOf(fieldValue);
			}
		}
		return retval;
	}
	@Override
	public String toString()
	{
		return functionName+"("+expression+")";
	}
	@Override
	public List usedColumns(Set availableColumns)
	{
		List result = new LinkedList<>();
		result.addAll(expression.usedColumns(availableColumns));
		return result;
	}
	@Override
	public List aggregateFunctions()
	{
		List result = new LinkedList<>();
		result.addAll(expression.aggregateFunctions());
		return result;
	}
}