DateToCharFunction.java :  » Database-DBMS » axion » org » axiondb » functions » Java Open Source

/*
 * $Id: DateToCharFunction.java,v 1.8 2005/05/02 22:28:41 ahimanikya Exp $
 * =======================================================================
 * Copyright (c) 2002-2005 Axion Development Team.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above
 *    copyright notice, this list of conditions and the following
 *    disclaimer.
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 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
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 *    distribution.
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 * 3. The names "Tigris", "Axion", nor the names of its contributors may
 *    not be used to endorse or promote products derived from this
 *    software without specific prior written permission.
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 * 4. Products derived from this software may not be called "Axion", nor
 *    may "Tigris" or "Axion" appear in their names without specific prior
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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package org.axiondb.functions;

import java.sql.Timestamp;

import org.axiondb.AxionException;
import org.axiondb.DataType;
import org.axiondb.FunctionFactory;
import org.axiondb.RowDecorator;
import org.axiondb.types.StringType;
import org.axiondb.types.TimestampType;
import org.axiondb.util.DateTimeUtils;

/**
 * Syntax: DateToChar( date-expr, 'format-string' )
 * 
 * @version $Revision: 1.8 $ $Date: 2005/05/02 22:28:41 $
 * @author Jonathan Giron
 */
public class DateToCharFunction extends BaseFunction implements ScalarFunction, FunctionFactory {

    /** Creates a new instance of Class */
    public DateToCharFunction() {
        super("DATETOCHAR");
    }

    public ConcreteFunction makeNewInstance() {
        return new DateToCharFunction();
    }

    /** {@link DataType} */
    public DataType getDataType() {
        return RETURN_TYPE;
    }

    /**
     * Returns String value representing the timestamp/date value in the given format.
     * 
     * @param row
     * @return String representation of the timestamp/date value
     */
    public Object evaluate(RowDecorator row) throws AxionException {
        Timestamp timestamp = null;
        String formatStr = null;

        // Get 'format-literal'
        Object arg2 = getArgument(1).evaluate(row);
        if (null == arg2) {
            throw new AxionException("DateToChar cannot accept a null format string.");
        } else {
            formatStr = (String) ARG2_TYPE.convert(arg2);
        } 

        // Get 'date-expr'
        Object arg1 = getArgument(0).evaluate(row);
        if (null == arg1) {
            return null;
        } else  {
            timestamp = (Timestamp) ARG1_TYPE.convert(arg1);
        }

        return DateTimeUtils.convertToChar(timestamp, formatStr);
    }

    public boolean isValid() {
        return (getArgumentCount() >= 2);
    }

    private static final DataType RETURN_TYPE = new StringType();
    private static final DataType ARG1_TYPE = new TimestampType();
    private static final DataType ARG2_TYPE = new StringType();
}