CSVFormat.java

/*
 * $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 <a href="mailto:oldman1004@gmail.com">skim</a>
 * @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 <code>char[]</code> value
     * @param offset an <code>int</code> value
     * @param len an <code>int</code> value
     * @return a <code>String</code> 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 = ',';
    
}