return new NegatedFastMatcher(this);
    }
  }

  /** {@link FastMatcher} which overrides {@code toString()} with a custom name. */
  abstract static class NamedFastMatcher extends FastMatcher {

    private final String description;

    NamedFastMatcher(String description) {
      this.description = checkNotNull(description);
    }

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