package java.util;

public class StringTokenizer implements Enumeration {
  private final String in;
  private String delimiters;
  private final boolean includeDelimiters;
  private int position;

  public StringTokenizer(String in, String delimiters,
                         boolean includeDelimiters)
  {
    this.in = in;
    this.delimiters = delimiters;
    this.includeDelimiters = includeDelimiters;
  }

  public StringTokenizer(String in, String delimiters) {
    this(in, delimiters, false);
  }

  public StringTokenizer(String in) {
    this(in, " \t\r\n\f");
  }

  private boolean isDelimiter(char c) {
    return delimiters.indexOf(c) >= 0;
  }

  public int countTokens() {
    int count = 0;
    boolean sawNonDelimiter = false;
    for (int i = position; i < in.length(); ++i) {
      if (isDelimiter(in.charAt(i))) {
        if (sawNonDelimiter) {
          sawNonDelimiter = false;
          ++ count;
        }

        if (includeDelimiters) {
          ++ count;
        }
      } else {
        sawNonDelimiter = true;
      }
    }

    if (sawNonDelimiter) {
      ++ count;
    }

    return count;
  }

  public boolean hasMoreTokens() {
    for (int i = position; i < in.length(); ++i) {
      if (isDelimiter(in.charAt(i))) {
        if (includeDelimiters) {
          return true;
        }
      } else {
        position = i;
        return true;
      }
    }
    return false;
  }

  public String nextToken() {
    for (int i = position; i < in.length(); ++i) {
      if (isDelimiter(in.charAt(i))) {
        if (includeDelimiters) {
          return in.substring(i, i + 1);
        }
      } else {
        position = i;
        while (position < in.length() && ! isDelimiter(in.charAt(position))) {
          ++ position;
        }
        return in.substring(i, position);
      }
    }
    throw new NoSuchElementException();
  }

  public String nextToken(String delimiters) {
    this.delimiters = delimiters;
    return nextToken();
  }

  public boolean hasMoreElements() {
    return hasMoreTokens();
  }

  public Object nextElement() {
    return nextToken();
  }

}