private Part parsePart(AsciiBuffer value) {
   if (value.equals(any_child_wildcard)) {
     return ANY_CHILD;
   } else if (value.equals(any_descendant_wildcard)) {
     return ANY_DESCENDANT;
   } else {
     if (part_pattern == null || part_pattern.matcher(value.toString()).matches()) {
       return new LiteralPart(value);
     } else {
       throw new PathException(
           String.format(
               "Invalid destination path part: '%s', it does not match regex: %s",
               value, part_pattern));
     }
   }
 }
/**
 * Holds the delimiters used to parse paths.
 *
 * @author <a href="http://hiramchirino.com">Hiram Chirino</a>
 */
public class PathParser {

  public static class PathException extends RuntimeException {
    public PathException(String message) {
      super(message);
    }
  }

  public static final PathParser DEFAULT = new PathParser();

  public AsciiBuffer any_descendant_wildcard = new AsciiBuffer("**");
  public AsciiBuffer any_child_wildcard = new AsciiBuffer("*");
  public AsciiBuffer path_seperator = new AsciiBuffer(".");
  public Pattern part_pattern = Pattern.compile("[a-zA-Z0-9\\_\\-\\%\\~]+");

  public Path parsePath(AsciiBuffer subject) {
    ArrayList<Part> list = new ArrayList<Part>(10);
    int previous = 0;
    int lastIndex = subject.getLength() - 1;
    while (true) {
      int idx = subject.indexOf(path_seperator, previous);
      if (idx < 0) {
        AsciiBuffer buffer = subject.slice(previous, lastIndex + 1).ascii();
        list.add(parsePart(buffer));
        break;
      }
      AsciiBuffer buffer = subject.slice(previous, idx).ascii();
      list.add(parsePart(buffer));
      previous = idx + 1;
    }
    return new Path(new ArrayList(list));
  }

  private Part parsePart(AsciiBuffer value) {
    if (value.equals(any_child_wildcard)) {
      return ANY_CHILD;
    } else if (value.equals(any_descendant_wildcard)) {
      return ANY_DESCENDANT;
    } else {
      if (part_pattern == null || part_pattern.matcher(value.toString()).matches()) {
        return new LiteralPart(value);
      } else {
        throw new PathException(
            String.format(
                "Invalid destination path part: '%s', it does not match regex: %s",
                value, part_pattern));
      }
    }
  }

  /**
   * Converts the path back to the string representation.
   *
   * @return
   */
  public String toString(Path path) {
    StringBuffer buffer = new StringBuffer();
    boolean first = true;
    for (Part p : path.parts) {
      if (!first) {
        buffer.append(path_seperator);
      }
      buffer.append(p.toString(this));
      first = false;
    }
    return buffer.toString();
  }

  public void write(Path path, ByteArrayOutputStream os) throws IOException {
    boolean first = true;
    for (Part p : path.parts) {
      if (!first) {
        path_seperator.writeTo(os);
      }
      new AsciiBuffer(p.toString(this)).writeTo(os);
      first = false;
    }
  }

  static interface PartFilter {
    public boolean matches(LinkedList<Part> remaining);
  }

  class LitteralPathFilter implements PartFilter {

    private final PartFilter next;
    private final LiteralPart path;

    public LitteralPathFilter(PartFilter next, LiteralPart path) {
      this.next = next;

      this.path = path;
    }

    public boolean matches(LinkedList<Part> remaining) {
      if (!remaining.isEmpty()) {
        Part p = remaining.removeFirst();
        if (!path.matches(p)) {
          return false;
        }
        if (next != null) {
          return next.matches(remaining);
        } else {
          return remaining.isEmpty();
        }
      } else {
        return false;
      }
    }
  }

  static class AnyChildPathFilter implements PartFilter {
    private final PartFilter next;

    public AnyChildPathFilter(PartFilter next) {
      this.next = next;
    }

    public boolean matches(LinkedList<Part> remaining) {
      if (!remaining.isEmpty()) {
        Part p = remaining.removeFirst();
        if (next != null) {
          return next.matches(remaining);
        } else {
          return remaining.isEmpty();
        }
      } else {
        return false;
      }
    }
  }

  static class AnyDecendentPathFilter implements PartFilter {
    private final PartFilter next;

    public AnyDecendentPathFilter(PartFilter next) {
      this.next = next;
    }

    public boolean matches(LinkedList<Part> remaining) {
      if (!remaining.isEmpty()) {
        remaining.clear();
        return true;
      } else {
        return false;
      }
    }
  }

  public PathFilter parseFilter(AsciiBuffer path) {
    ArrayList<Part> parts = new ArrayList<Part>(parsePath(path).parts);
    Collections.reverse(parts);
    PartFilter last = null;
    for (Part p : parts) {
      if (p.isLiteral()) {
        last = new LitteralPathFilter(last, (LiteralPart) p);
      } else if (p == ANY_CHILD) {
        last = new AnyChildPathFilter(last);
      } else if (p == ANY_DESCENDANT) {
        last = new AnyDecendentPathFilter(last);
      }
    }
    final PartFilter filter = last;
    return new PathFilter() {
      public boolean matches(Path path) {
        return filter.matches(new LinkedList(path.parts));
      }
    };
  }

  public static boolean containsWildCards(Path path) {
    for (Part p : path.parts) {
      if (p == ANY_DESCENDANT || p == ANY_CHILD) {
        return true;
      }
    }
    return false;
  }
}