1 /* -*- mode: C++; indent-tabs-mode: nil; -*- |
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2 * |
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3 * This file is a part of LEMON, a generic C++ optimization library. |
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4 * |
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5 * Copyright (C) 2003-2008 |
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6 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport |
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7 * (Egervary Research Group on Combinatorial Optimization, EGRES). |
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8 * |
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9 * Permission to use, modify and distribute this software is granted |
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10 * provided that this copyright notice appears in all copies. For |
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11 * precise terms see the accompanying LICENSE file. |
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12 * |
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13 * This software is provided "AS IS" with no warranty of any kind, |
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14 * express or implied, and with no claim as to its suitability for any |
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15 * purpose. |
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16 * |
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17 */ |
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18 |
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19 #ifndef LEMON_BITS_INVALID_H |
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20 #define LEMON_BITS_INVALID_H |
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21 |
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22 ///\file |
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23 ///\brief Definition of INVALID. |
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24 |
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25 namespace lemon { |
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26 |
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27 /// \brief Dummy type to make it easier to create invalid iterators. |
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28 /// |
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29 /// Dummy type to make it easier to create invalid iterators. |
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30 /// See \ref INVALID for the usage. |
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31 struct Invalid { |
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32 public: |
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33 bool operator==(Invalid) { return true; } |
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34 bool operator!=(Invalid) { return false; } |
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35 bool operator< (Invalid) { return false; } |
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36 }; |
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37 |
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38 /// \brief Invalid iterators. |
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39 /// |
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40 /// \ref Invalid is a global type that converts to each iterator |
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41 /// in such a way that the value of the target iterator will be invalid. |
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42 |
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43 //Some people didn't like this: |
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44 //const Invalid &INVALID = *(Invalid *)0; |
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45 |
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46 #ifdef LEMON_ONLY_TEMPLATES |
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47 const Invalid INVALID = Invalid(); |
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48 #else |
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49 extern const Invalid INVALID; |
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50 #endif |
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51 |
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52 } //namespace lemon |
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53 |
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54 #endif |
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55 |
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