throw closer.rethrow(e);
      } finally {
        closer.close();
      }
    }
  }

  private static final class EmptyCharSource extends StringCharSource {

    private static final EmptyCharSource INSTANCE = new EmptyCharSource();

    private EmptyCharSource() {
      super("");
    }

    @Override
    public String toString() {
      return "CharSource.empty()";
    }
  }