1 /* -*- C++ -*- |
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2 * src/lemon/invalid.h - Part of LEMON, a generic C++ optimization library |
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3 * |
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4 * Copyright (C) 2005 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport |
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5 * (Egervary Research Group on Combinatorial Optimization, EGRES). |
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6 * |
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7 * Permission to use, modify and distribute this software is granted |
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8 * provided that this copyright notice appears in all copies. For |
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9 * precise terms see the accompanying LICENSE file. |
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10 * |
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11 * This software is provided "AS IS" with no warranty of any kind, |
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12 * express or implied, and with no claim as to its suitability for any |
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13 * purpose. |
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14 * |
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15 */ |
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16 |
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17 #ifndef LEMON_INVALID_H |
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18 #define LEMON_INVALID_H |
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19 |
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20 ///\file |
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21 ///\brief Definition of INVALID. |
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22 |
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23 namespace lemon { |
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24 |
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25 /// Dummy type to make it easier to make invalid iterators. |
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26 |
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27 /// See \ref INVALID, how to use it. |
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28 |
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29 struct Invalid { |
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30 public: |
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31 bool operator==(Invalid) { return true; } |
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32 bool operator!=(Invalid) { return false; } |
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33 bool operator< (Invalid) { return false; } |
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34 }; |
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35 |
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36 /// Invalid iterators. |
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37 |
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38 /// \ref Invalid is a global type that converts to each iterator |
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39 /// in such a way that the value of the target iterator will be invalid. |
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40 |
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41 // It is also used to convert the \c INVALID constant to the |
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42 // node iterator that makes is possible to write |
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43 |
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44 //extern Invalid INVALID; |
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45 |
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46 //const Invalid &INVALID = *(Invalid *)0; |
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47 const Invalid INVALID = Invalid(); |
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48 |
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49 } //namespace lemon |
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50 |
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51 #endif |
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52 |
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