1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/lemon/invalid.h	Mon May 23 04:48:14 2005 +0000
     1.3 @@ -0,0 +1,52 @@
     1.4 +/* -*- C++ -*-
     1.5 + * lemon/invalid.h - Part of LEMON, a generic C++ optimization library
     1.6 + *
     1.7 + * Copyright (C) 2005 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
     1.8 + * (Egervary Research Group on Combinatorial Optimization, EGRES).
     1.9 + *
    1.10 + * Permission to use, modify and distribute this software is granted
    1.11 + * provided that this copyright notice appears in all copies. For
    1.12 + * precise terms see the accompanying LICENSE file.
    1.13 + *
    1.14 + * This software is provided "AS IS" with no warranty of any kind,
    1.15 + * express or implied, and with no claim as to its suitability for any
    1.16 + * purpose.
    1.17 + *
    1.18 + */
    1.19 +
    1.20 +#ifndef LEMON_INVALID_H
    1.21 +#define LEMON_INVALID_H
    1.22 +
    1.23 +///\file
    1.24 +///\brief Definition of INVALID.
    1.25 +
    1.26 +namespace lemon {
    1.27 +
    1.28 +  /// Dummy type to make it easier to make invalid iterators.
    1.29 +  
    1.30 +  /// See \ref INVALID, how to use it.
    1.31 +  
    1.32 +  struct Invalid {
    1.33 +  public:
    1.34 +    bool operator==(Invalid) { return true;  }
    1.35 +    bool operator!=(Invalid) { return false; }
    1.36 +    bool operator< (Invalid) { return false; }
    1.37 +  };
    1.38 +  
    1.39 +  /// Invalid iterators.
    1.40 +  
    1.41 +  /// \ref Invalid is a global type that converts to each iterator
    1.42 +  /// in such a way that the value of the target iterator will be invalid.
    1.43 +
    1.44 +  // It is also used to convert the \c INVALID constant to the
    1.45 +  // node iterator that makes is possible to write 
    1.46 +
    1.47 +  //extern Invalid INVALID;
    1.48 +
    1.49 +  //const Invalid &INVALID = *(Invalid *)0;
    1.50 +  const Invalid INVALID = Invalid();
    1.51 +
    1.52 +} //namespace lemon
    1.53 +
    1.54 +#endif
    1.55 +