CSV Parser Class

package com.darwinsys;
 
/*
 * Copyright (c) Ian F. Darwin, http://www.darwinsys.com/, 1996-2002. All rights reserved. Software
 * written by Ian F. Darwin and others. $Id: LICENSE,v 1.8 2004/02/09 03:33:38 ian Exp $
 * 
 * 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. 2. Redistributions
 * in binary form must reproduce the above copyright notice, this list of conditions and the
 * following disclaimer in the documentation and/or other materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 * Java, the Duke mascot, and all variants of Sun's Java "steaming coffee cup" logo are trademarks
 * of Sun Microsystems. Sun's, and James Gosling's, pioneering role in inventing and promulgating
 * (and standardizing) the Java language and environment is gratefully acknowledged.
 * 
 * The pioneering role of Dennis Ritchie and Bjarne Stroustrup, of AT&T, for inventing predecessor
 * languages C and C++ is also gratefully acknowledged.
 */
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
 
/*
 * Simple demo of CSV parser class.
 */
public class CSVSimple {
    public static void main(String[] args) {
	CSV parser = new CSV();
	List list = parser.parse("\"LU\",86.25,\"11/4/1998\",\"2:19PM\",+4.0625");
	Iterator it = list.iterator();
	while (it.hasNext()) {
	    System.out.println(it.next());
	}
 
	// Now test with a non-default separator
	parser = new CSV('|');
	list = parser.parse("\"LU\"|86.25|\"11/4/1998\"|\"2:19PM\"|+4.0625");
	it = list.iterator();
	while (it.hasNext()) {
	    System.out.println(it.next());
	}
    }
}
 
/**
 * Parse comma-separated values (CSV), a common Windows file format. Sample input:
 * "LU",86.25,"11/4/1998","2:19PM",+4.0625
 * <p>
 * Inner logic adapted from a C++ original that was Copyright (C) 1999 Lucent Technologies Excerpted
 * from 'The Practice of Programming' by Brian W. Kernighan and Rob Pike.
 * <p>
 * Included by permission of the http://tpop.awl.com/ web site, which says: "You may use this code
 * for any purpose, as long as you leave the copyright notice and book citation attached." I have
 * done so.
 * 
 * @author Brian W. Kernighan and Rob Pike (C++ original)
 * @author Ian F. Darwin (translation into Java and removal of I/O)
 * @author Ben Ballard (rewrote advQuoted to handle '""' and for readability)
 */
class CSV {
 
    public static final char DEFAULT_SEP = ',';
 
    /** Construct a CSV parser, with the default separator (`,'). */
    public CSV() {
	this(DEFAULT_SEP);
    }
 
    /**
     * Construct a CSV parser with a given separator.
     * 
     * @param sep
     *            The single char for the separator (not a list of separator characters)
     */
    public CSV(char sep) {
	fieldSep = sep;
    }
 
    /** The fields in the current String */
    protected List list = new ArrayList();
 
    /** the separator char for this parser */
    protected char fieldSep;
 
    /**
     * parse: break the input String into fields
     * 
     * @return java.util.Iterator containing each field from the original as a String, in order.
     */
    public List parse(String line) {
	StringBuffer sb = new StringBuffer();
	list.clear(); // recycle to initial state
	int i = 0;
 
	if (line.length() == 0) {
	    list.add(line);
	    return list;
	}
 
	do {
	    sb.setLength(0);
	    if (i < line.length() && line.charAt(i) == '"')
		i = advQuoted(line, sb, ++i); // skip quote
	    else
		i = advPlain(line, sb, i);
	    list.add(sb.toString());
	    i++;
	} while (i < line.length());
 
	return list;
    }
 
    /** advQuoted: quoted field; return index of next separator */
    protected int advQuoted(String s, StringBuffer sb, int i) {
	int j;
	int len = s.length();
	for (j = i; j < len; j++) {
	    if (s.charAt(j) == '"' && j + 1 < len) {
		if (s.charAt(j + 1) == '"') {
		    j++; // skip escape char
		} else if (s.charAt(j + 1) == fieldSep) { // next delimeter
		    j++; // skip end quotes
		    break;
		}
	    } else if (s.charAt(j) == '"' && j + 1 == len) { // end quotes at end of line
		break; // done
	    }
	    sb.append(s.charAt(j)); // regular character.
	}
	return j;
    }
 
    /** advPlain: unquoted field; return index of next separator */
    protected int advPlain(String s, StringBuffer sb, int i) {
	int j;
 
	j = s.indexOf(fieldSep, i); // look for separator
	if (j == -1) { // none found
	    sb.append(s.substring(i));
	    return s.length();
	} else {
	    sb.append(s.substring(i, j));
	    return j;
	}
    }
}