}

    @Override
    public final String toString() {
      return description;
    }
  }

  /** Negation of a {@link FastMatcher}. */
  private static class NegatedFastMatcher extends Negated {

    NegatedFastMatcher(CharMatcher original) {
      super(original);
    }

    @Override
    public final CharMatcher precomputed() {
      return this;
    }
  }