//
// This software is now distributed according to
// the Lesser Gnu Public License.  Please see
// http://www.gnu.org/copyleft/lesser.txt for
// the details.
//    -- Happy Computing!
//
package com.stevesoft.pat;

import java.util.*;

/**
 Shareware: package pat
 <a href="copyright.html">Copyright 2001, Steven R. Brandt</a>
 */
/**
 * The RegexTokenizer is similar to the StringTokenizer class provided with
 * java, but allows one to tokenize using regular expressions, rather than a
 * simple list of characters. Tokens are any strings between the supplied
 * regular expression, as well as any backreferences (things in parenthesis)
 * contained within the regular expression.
 */
public class RegexTokenizer implements Enumeration
{
  String toParse;

  Regex r;

  int count = 0;

  Vector v = new Vector();

  Vector vi = new Vector();

  int pos = 0;

  int offset = 1;

  void getMore()
  {
    String s = r.right();
    if (r.searchFrom(toParse, pos))
    {
      v.addElement(r.left().substring(pos));
      vi.addElement(new Integer(r.matchFrom() + r.charsMatched()));
      for (int i = 0; i < r.numSubs(); i++)
      {
        if (r.substring() != null)
        {
          v.addElement(r.substring(i + offset));
          vi.addElement(new Integer(r.matchFrom(i + offset)
                  + r.charsMatched(i + offset)));
        }
      }
      pos = r.matchFrom() + r.charsMatched();
    }
    else if (s != null)
    {
      v.addElement(s);
    }
  }

  /** Initialize the tokenizer with a string of text and a pattern */
  public RegexTokenizer(String txt, String ptrn)
  {
    toParse = txt;
    r = new Regex(ptrn);
    offset = Regex.BackRefOffset;
    getMore();
  }

  /** Initialize the tokenizer with a Regex object. */
  public RegexTokenizer(String txt, Regex r)
  {
    toParse = txt;
    this.r = r;
    offset = Regex.BackRefOffset;
    getMore();
  }

  /**
   * This should always be cast to a String, as in StringTokenizer, and as in
   * StringTokenizer one can do this by calling nextString().
   */
  public Object nextElement()
  {
    if (count >= v.size())
    {
      getMore();
    }
    return v.elementAt(count++);
  }

  /** This is the equivalent (String)nextElement(). */
  public String nextToken()
  {
    return (String) nextElement();
  }

  /**
   * This asks for the next token, and changes the pattern being used at the
   * same time.
   */
  public String nextToken(String newpat)
  {
    try
    {
      r.compile(newpat);
    } catch (RegSyntax r_)
    {
    }
    return nextToken(r);
  }

  /**
   * This asks for the next token, and changes the pattern being used at the
   * same time.
   */
  public String nextToken(Regex nr)
  {
    r = nr;
    if (vi.size() > count)
    {
      pos = ((Integer) vi.elementAt(count)).intValue();
      v.setSize(count);
      vi.setSize(count);
    }
    getMore();
    return nextToken();
  }

  /** Tells whether there are more tokens in the pattern. */
  public boolean hasMoreElements()
  {
    if (count >= v.size())
    {
      getMore();
    }
    return count < v.size();
  }

  /**
   * Tells whether there are more tokens in the pattern, but in the fashion of
   * StringTokenizer.
   */
  public boolean hasMoreTokens()
  {
    return hasMoreElements();
  }

  /** Determines the # of remaining tokens */
  public int countTokens()
  {
    int _count = count;
    while (hasMoreTokens())
    {
      nextToken();
    }
    count = _count;
    return v.size() - count;
  }

  /** Returns all tokens in the String */
  public String[] allTokens()
  {
    countTokens();
    String[] ret = new String[v.size()];
    v.copyInto(ret);
    return ret;
  }
};
