// -*- mode:C++ -*-

 #ifndef HUGO_INVALID_H

 #define HUGO_INVALID_H

 namespace hugo {

   /// Dummy type to make it easier to make invalid iterators.

   /// See \ref INVALID, how to use it.

   struct Invalid {};

   /// Invalid iterators.

   /// \ref Invalid is a global type that converts to each iterator

   /// in such a way that the value of the target iterator will be invalid.

   ///extern Invalid INVALID;

   const Invalid &INVALID = *(Invalid *)0;

 };

 #endif