lemon/bits/invalid.h
author Alpar Juttner <alpar@cs.elte.hu>
Fri, 04 Jan 2008 23:51:37 +0100
changeset 37 582c594ecd01
parent 7 4d461e9867da
child 39 0a01d811071f
permissions -rw-r--r--
Merge
     1 /* -*- C++ -*-
     2  *
     3  * This file is a part of LEMON, a generic C++ optimization library
     4  *
     5  * Copyright (C) 2003-2007
     6  * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
     7  * (Egervary Research Group on Combinatorial Optimization, EGRES).
     8  *
     9  * Permission to use, modify and distribute this software is granted
    10  * provided that this copyright notice appears in all copies. For
    11  * precise terms see the accompanying LICENSE file.
    12  *
    13  * This software is provided "AS IS" with no warranty of any kind,
    14  * express or implied, and with no claim as to its suitability for any
    15  * purpose.
    16  *
    17  */
    18 
    19 #ifndef LEMON_BITS_INVALID_H
    20 #define LEMON_BITS_INVALID_H
    21 
    22 ///\file
    23 ///\brief Definition of INVALID.
    24 
    25 namespace lemon {
    26 
    27   /// \brief Dummy type to make it easier to create invalid iterators.
    28   ///
    29   /// See \ref INVALID for the usage.
    30   struct Invalid {
    31   public:
    32     bool operator==(Invalid) { return true;  }
    33     bool operator!=(Invalid) { return false; }
    34     bool operator< (Invalid) { return false; }
    35   };
    36   
    37   /// \brief Invalid iterators.
    38   ///
    39   /// \ref Invalid is a global type that converts to each iterator
    40   /// in such a way that the value of the target iterator will be invalid.
    41 
    42   //Some people didn't like this:
    43   //const Invalid &INVALID = *(Invalid *)0;
    44 
    45 #ifdef LEMON_ONLY_TEMPLATES
    46   const Invalid INVALID = Invalid();
    47 #else
    48   extern const Invalid INVALID;
    49 #endif
    50 
    51 } //namespace lemon
    52 
    53 #endif
    54