lemon/bits/invalid.h
author Peter Kovacs <kpeter@inf.elte.hu>
Fri, 04 Jan 2008 23:20:08 +0100
changeset 34 b88dd07e6349
child 13 83c84df7a956
permissions -rw-r--r--
Bug fix in maps.h.
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/* -*- C++ -*-
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 *
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 * This file is a part of LEMON, a generic C++ optimization library
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 *
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 * Copyright (C) 2003-2007
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 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
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 * (Egervary Research Group on Combinatorial Optimization, EGRES).
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 *
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 * Permission to use, modify and distribute this software is granted
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 * provided that this copyright notice appears in all copies. For
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 * precise terms see the accompanying LICENSE file.
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 *
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 * This software is provided "AS IS" with no warranty of any kind,
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 * express or implied, and with no claim as to its suitability for any
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 * purpose.
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 *
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 */
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#ifndef LEMON_BITS_INVALID_H
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#define LEMON_BITS_INVALID_H
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///\file
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///\brief Definition of INVALID.
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namespace lemon {
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  /// \brief Dummy type to make it easier to make invalid iterators.
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  ///
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  /// See \ref INVALID for the usage.
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  struct Invalid {
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  public:
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    bool operator==(Invalid) { return true;  }
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    bool operator!=(Invalid) { return false; }
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    bool operator< (Invalid) { return false; }
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  };
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  /// Invalid iterators.
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  /// \ref Invalid is a global type that converts to each iterator
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  /// in such a way that the value of the target iterator will be invalid.
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  //Some people didn't like this:
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  //const Invalid &INVALID = *(Invalid *)0;
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#ifdef LEMON_ONLY_TEMPLATES
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  const Invalid INVALID = Invalid();
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#else
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  extern const Invalid INVALID;
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#endif
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} //namespace lemon
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#endif
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