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Maven Package for datafile.sourceforge.net Java data file read/write utility that provides a convenient set of interfaces for reading and writing data to and from files in widely accepted format such as comma separated values (CSV), fixed width, tab separated, as well as others.
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/*
 * $Id: CSVFormat.java,v 1.5 2005/12/19 12:31:29 oldman1004 Exp $
 *
 * Copyright(c) 2002 Infomata
 * 
 * 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.infomata.data;

import java.util.Iterator;

/**
 * Implementation DataFormat interface for CSV formated files.
 *
 * @author skim
 * @version $Revision: 1.5 $
 */
public class CSVFormat implements DataFormat {

     /** 
      * Converts a set of data into a line in data file.
      * @see com.infomata.data.DataFormat#format(DataRow)
      * @param row row of data to be converted in to String
      * @return properly CSV formatted line of data.
      */
    public String format(DataRow row) {
        
        StringBuffer o = new StringBuffer();
        boolean first = true;
        Iterator items = row.iterator();
        while (items.hasNext()) {
            if (first) {
                first = false;
            }
            else
            {
                o.append(",");
            }
            String cell = (String)items.next();
            o.append(encode(cell));
        }

        return o.toString();

    } // format(DataRow)

  
    /** 
     * Parses a line of data properly formatted in CSV format
     * into set of data.
     * @see com.infomata.data.DataFormat#parseLine(String)
     * @param line CSV formated line of data
     * @return row of data
     */
    public DataRow parseLine(String line) {

        DataRow res = null;

        if (row == null) {
            row = new DataRow();
        }
        else {
            line = remainder + NEW_LINE + line;
        }

        int offset = 0;
        boolean paired = true;

        if (line != null) {
            char[] cs = line.toCharArray();
            for (int i = 0; i < cs.length; i++) {
                if (cs[i] == QUOTE) {
                    paired = !paired;
                }
                else if (cs[i] == COMMA && paired) {
                    row.add(decode(cs, offset, i - offset));
                    offset = i + 1;
                }
            }
            if (paired) {
                if (offset < cs.length) {
                    row.add(decode(cs, offset, cs.length - offset));
                }
                else if (cs[offset - 1] == COMMA)
                {
                    row.addEmpty();
                }
                res = row;
                row = null;
            }
            else {
                remainder = new String(cs, offset, cs.length - offset);
            }
        }

        return res;

    } // parseLine(String)


    /**
     * Helper method to convert one data item into
     * CSV compliant format.
     *
     * @param datum data item
     * @return CSV encoded string
     */
    private String encode(String datum) {

        String res = null;
        if (datum == null) {
            res = "null";
        }
        else if (datum.length() == 0) {
            res = "";
        }
        else if (datum.indexOf(QUOTE) >= 0 
                 || datum.indexOf(COMMA) >= 0
                 || datum.indexOf(NEW_LINE) >= 0
                 || Character.isWhitespace(datum.charAt(0))) {
            
            StringBuffer o = new StringBuffer();
            o.append(QUOTE);
            
            char[] cs = datum.toCharArray();
            for (int i = 0; i < cs.length; i++) {
                if (cs[i] == QUOTE) {
                    o.append(QUOTE); // add 1 more.
                }
                o.append(cs[i]);
            }
            
            o.append(QUOTE);
            res = o.toString();
            
        }
        else {
            res = datum;
        }

        return res;

    } // encode(String)


    /**
     * Helper method to remove CSV encoding from CSV formated
     * data cell.
     *
     * @param cs a char[] value
     * @param offset an int value
     * @param len an int value
     * @return a String value
     */
    private static String decode(char[] cs, int offset, int len) {
        
        while (Character.isWhitespace(cs[offset]) && offset < cs.length) {
            offset += 1;
            len -= 1;
        }

        int end = offset + len - 1;
        
        StringBuffer o = new StringBuffer();

        // decode escaped content.
        if (cs[offset] == QUOTE && cs[end] == QUOTE) {

            for (int i = offset + 1; i < end; i++) {
                // remove doubled '"'
                if (cs[i] == QUOTE) {
                    i++;
                }
                if (i < end) {
                    o.append(cs[i]);
                }
            }

        }
        else {
            o.append(cs, offset, len);
        }

        return o.toString();

    } // decode(char[], int, int)

    private DataRow row = null;
    private String remainder = null;

    /**
     * Double quote
     */
    private static final char QUOTE = '"';

    /**
     * new line character.
     */
    private static final char NEW_LINE = '\n';

    /**
     * Delimiter (comma)
     */
    private static final char COMMA = ',';
    
}