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_ALTERATION_NOTIFIER_H |
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20 | #define LEMON_BITS_ALTERATION_NOTIFIER_H |
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21 | |
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22 | #include <vector> |
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23 | #include <list> |
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24 | |
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25 | #include <lemon/core.h> |
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26 | |
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27 | //\ingroup graphbits |
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28 | //\file |
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29 | //\brief Observer notifier for graph alteration observers. |
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30 | |
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31 | namespace lemon { |
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32 | |
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33 | // \ingroup graphbits |
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34 | // |
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35 | // \brief Notifier class to notify observes about alterations in |
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36 | // a container. |
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37 | // |
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38 | // The simple graphs can be refered as two containers: a node container |
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39 | // and an edge container. But they do not store values directly, they |
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40 | // are just key continars for more value containers, which are the |
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41 | // node and edge maps. |
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42 | // |
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43 | // The node and edge sets of the graphs can be changed as we add or erase |
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44 | // nodes and edges in the graph. LEMON would like to handle easily |
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45 | // that the node and edge maps should contain values for all nodes or |
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46 | // edges. If we want to check on every indicing if the map contains |
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47 | // the current indicing key that cause a drawback in the performance |
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48 | // in the library. We use another solution: we notify all maps about |
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49 | // an alteration in the graph, which cause only drawback on the |
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50 | // alteration of the graph. |
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51 | // |
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52 | // This class provides an interface to a node or edge container. |
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53 | // The first() and next() member functions make possible |
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54 | // to iterate on the keys of the container. |
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55 | // The id() function returns an integer id for each key. |
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56 | // The maxId() function gives back an upper bound of the ids. |
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57 | // |
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58 | // For the proper functonality of this class, we should notify it |
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59 | // about each alteration in the container. The alterations have four type: |
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60 | // add(), erase(), build() and clear(). The add() and |
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61 | // erase() signal that only one or few items added or erased to or |
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62 | // from the graph. If all items are erased from the graph or if a new graph |
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63 | // is built from an empty graph, then it can be signaled with the |
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64 | // clear() and build() members. Important rule that if we erase items |
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65 | // from graphs we should first signal the alteration and after that erase |
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66 | // them from the container, on the other way on item addition we should |
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67 | // first extend the container and just after that signal the alteration. |
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68 | // |
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69 | // The alteration can be observed with a class inherited from the |
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70 | // ObserverBase nested class. The signals can be handled with |
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71 | // overriding the virtual functions defined in the base class. The |
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72 | // observer base can be attached to the notifier with the |
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73 | // attach() member and can be detached with detach() function. The |
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74 | // alteration handlers should not call any function which signals |
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75 | // an other alteration in the same notifier and should not |
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76 | // detach any observer from the notifier. |
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77 | // |
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78 | // Alteration observers try to be exception safe. If an add() or |
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79 | // a clear() function throws an exception then the remaining |
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80 | // observeres will not be notified and the fulfilled additions will |
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81 | // be rolled back by calling the erase() or clear() functions. |
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82 | // Hence erase() and clear() should not throw exception. |
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83 | // Actullay, they can throw only \ref ImmediateDetach exception, |
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84 | // which detach the observer from the notifier. |
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85 | // |
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86 | // There are some cases, when the alteration observing is not completly |
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87 | // reliable. If we want to carry out the node degree in the graph |
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88 | // as in the \ref InDegMap and we use the reverseArc(), then it cause |
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89 | // unreliable functionality. Because the alteration observing signals |
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90 | // only erasing and adding but not the reversing, it will stores bad |
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91 | // degrees. Apart form that the subgraph adaptors cannot even signal |
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92 | // the alterations because just a setting in the filter map can modify |
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93 | // the graph and this cannot be watched in any way. |
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94 | // |
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95 | // \param _Container The container which is observed. |
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96 | // \param _Item The item type which is obserbved. |
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97 | |
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98 | template <typename _Container, typename _Item> |
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99 | class AlterationNotifier { |
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100 | public: |
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101 | |
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102 | typedef True Notifier; |
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103 | |
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104 | typedef _Container Container; |
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105 | typedef _Item Item; |
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106 | |
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107 | // \brief Exception which can be called from clear() and |
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108 | // erase(). |
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109 | // |
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110 | // From the clear() and erase() function only this |
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111 | // exception is allowed to throw. The exception immediatly |
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112 | // detaches the current observer from the notifier. Because the |
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113 | // clear() and erase() should not throw other exceptions |
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114 | // it can be used to invalidate the observer. |
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115 | struct ImmediateDetach {}; |
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116 | |
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117 | // \brief ObserverBase is the base class for the observers. |
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118 | // |
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119 | // ObserverBase is the abstract base class for the observers. |
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120 | // It will be notified about an item was inserted into or |
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121 | // erased from the graph. |
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122 | // |
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123 | // The observer interface contains some pure virtual functions |
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124 | // to override. The add() and erase() functions are |
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125 | // to notify the oberver when one item is added or erased. |
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126 | // |
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127 | // The build() and clear() members are to notify the observer |
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128 | // about the container is built from an empty container or |
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129 | // is cleared to an empty container. |
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130 | class ObserverBase { |
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131 | protected: |
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132 | typedef AlterationNotifier Notifier; |
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133 | |
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134 | friend class AlterationNotifier; |
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135 | |
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136 | // \brief Default constructor. |
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137 | // |
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138 | // Default constructor for ObserverBase. |
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139 | ObserverBase() : _notifier(0) {} |
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140 | |
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141 | // \brief Constructor which attach the observer into notifier. |
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142 | // |
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143 | // Constructor which attach the observer into notifier. |
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144 | ObserverBase(AlterationNotifier& nf) { |
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145 | attach(nf); |
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146 | } |
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147 | |
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148 | // \brief Constructor which attach the obserever to the same notifier. |
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149 | // |
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150 | // Constructor which attach the obserever to the same notifier as |
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151 | // the other observer is attached to. |
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152 | ObserverBase(const ObserverBase& copy) { |
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153 | if (copy.attached()) { |
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154 | attach(*copy.notifier()); |
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155 | } |
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156 | } |
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157 | |
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158 | // \brief Destructor |
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159 | virtual ~ObserverBase() { |
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160 | if (attached()) { |
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161 | detach(); |
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162 | } |
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163 | } |
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164 | |
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165 | // \brief Attaches the observer into an AlterationNotifier. |
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166 | // |
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167 | // This member attaches the observer into an AlterationNotifier. |
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168 | void attach(AlterationNotifier& nf) { |
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169 | nf.attach(*this); |
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170 | } |
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171 | |
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172 | // \brief Detaches the observer into an AlterationNotifier. |
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173 | // |
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174 | // This member detaches the observer from an AlterationNotifier. |
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175 | void detach() { |
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176 | _notifier->detach(*this); |
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177 | } |
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178 | |
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179 | // \brief Gives back a pointer to the notifier which the map |
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180 | // attached into. |
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181 | // |
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182 | // This function gives back a pointer to the notifier which the map |
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183 | // attached into. |
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184 | Notifier* notifier() const { return const_cast<Notifier*>(_notifier); } |
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185 | |
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186 | // Gives back true when the observer is attached into a notifier. |
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187 | bool attached() const { return _notifier != 0; } |
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188 | |
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189 | private: |
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190 | |
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191 | ObserverBase& operator=(const ObserverBase& copy); |
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192 | |
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193 | protected: |
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194 | |
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195 | Notifier* _notifier; |
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196 | typename std::list<ObserverBase*>::iterator _index; |
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197 | |
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198 | // \brief The member function to notificate the observer about an |
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199 | // item is added to the container. |
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200 | // |
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201 | // The add() member function notificates the observer about an item |
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202 | // is added to the container. It have to be overrided in the |
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203 | // subclasses. |
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204 | virtual void add(const Item&) = 0; |
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205 | |
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206 | // \brief The member function to notificate the observer about |
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207 | // more item is added to the container. |
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208 | // |
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209 | // The add() member function notificates the observer about more item |
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210 | // is added to the container. It have to be overrided in the |
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211 | // subclasses. |
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212 | virtual void add(const std::vector<Item>& items) = 0; |
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213 | |
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214 | // \brief The member function to notificate the observer about an |
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215 | // item is erased from the container. |
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216 | // |
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217 | // The erase() member function notificates the observer about an |
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218 | // item is erased from the container. It have to be overrided in |
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219 | // the subclasses. |
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220 | virtual void erase(const Item&) = 0; |
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221 | |
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222 | // \brief The member function to notificate the observer about |
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223 | // more item is erased from the container. |
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224 | // |
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225 | // The erase() member function notificates the observer about more item |
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226 | // is erased from the container. It have to be overrided in the |
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227 | // subclasses. |
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228 | virtual void erase(const std::vector<Item>& items) = 0; |
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229 | |
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230 | // \brief The member function to notificate the observer about the |
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231 | // container is built. |
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232 | // |
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233 | // The build() member function notificates the observer about the |
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234 | // container is built from an empty container. It have to be |
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235 | // overrided in the subclasses. |
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236 | virtual void build() = 0; |
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237 | |
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238 | // \brief The member function to notificate the observer about all |
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239 | // items are erased from the container. |
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240 | // |
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241 | // The clear() member function notificates the observer about all |
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242 | // items are erased from the container. It have to be overrided in |
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243 | // the subclasses. |
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244 | virtual void clear() = 0; |
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245 | |
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246 | }; |
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247 | |
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248 | protected: |
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249 | |
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250 | const Container* container; |
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251 | |
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252 | typedef std::list<ObserverBase*> Observers; |
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253 | Observers _observers; |
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254 | |
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255 | |
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256 | public: |
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257 | |
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258 | // \brief Default constructor. |
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259 | // |
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260 | // The default constructor of the AlterationNotifier. |
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261 | // It creates an empty notifier. |
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262 | AlterationNotifier() |
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263 | : container(0) {} |
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264 | |
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265 | // \brief Constructor. |
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266 | // |
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267 | // Constructor with the observed container parameter. |
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268 | AlterationNotifier(const Container& _container) |
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269 | : container(&_container) {} |
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270 | |
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271 | // \brief Copy Constructor of the AlterationNotifier. |
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272 | // |
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273 | // Copy constructor of the AlterationNotifier. |
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274 | // It creates only an empty notifier because the copiable |
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275 | // notifier's observers have to be registered still into that notifier. |
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276 | AlterationNotifier(const AlterationNotifier& _notifier) |
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277 | : container(_notifier.container) {} |
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278 | |
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279 | // \brief Destructor. |
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280 | // |
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281 | // Destructor of the AlterationNotifier. |
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282 | ~AlterationNotifier() { |
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283 | typename Observers::iterator it; |
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284 | for (it = _observers.begin(); it != _observers.end(); ++it) { |
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285 | (*it)->_notifier = 0; |
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286 | } |
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287 | } |
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288 | |
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289 | // \brief Sets the container. |
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290 | // |
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291 | // Sets the container. |
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292 | void setContainer(const Container& _container) { |
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293 | container = &_container; |
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294 | } |
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295 | |
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296 | protected: |
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297 | |
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298 | AlterationNotifier& operator=(const AlterationNotifier&); |
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299 | |
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300 | public: |
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301 | |
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302 | // \brief First item in the container. |
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303 | // |
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304 | // Returns the first item in the container. It is |
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305 | // for start the iteration on the container. |
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306 | void first(Item& item) const { |
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307 | container->first(item); |
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308 | } |
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309 | |
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310 | // \brief Next item in the container. |
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311 | // |
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312 | // Returns the next item in the container. It is |
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313 | // for iterate on the container. |
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314 | void next(Item& item) const { |
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315 | container->next(item); |
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316 | } |
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317 | |
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318 | // \brief Returns the id of the item. |
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319 | // |
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320 | // Returns the id of the item provided by the container. |
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321 | int id(const Item& item) const { |
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322 | return container->id(item); |
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323 | } |
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324 | |
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325 | // \brief Returns the maximum id of the container. |
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326 | // |
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327 | // Returns the maximum id of the container. |
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328 | int maxId() const { |
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329 | return container->maxId(Item()); |
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330 | } |
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331 | |
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332 | protected: |
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333 | |
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334 | void attach(ObserverBase& observer) { |
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335 | observer._index = _observers.insert(_observers.begin(), &observer); |
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336 | observer._notifier = this; |
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337 | } |
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338 | |
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339 | void detach(ObserverBase& observer) { |
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340 | _observers.erase(observer._index); |
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341 | observer._index = _observers.end(); |
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342 | observer._notifier = 0; |
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343 | } |
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344 | |
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345 | public: |
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346 | |
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347 | // \brief Notifies all the registed observers about an item added to |
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348 | // the container. |
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349 | // |
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350 | // It notifies all the registed observers about an item added to |
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351 | // the container. |
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352 | void add(const Item& item) { |
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353 | typename Observers::reverse_iterator it; |
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354 | try { |
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355 | for (it = _observers.rbegin(); it != _observers.rend(); ++it) { |
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356 | (*it)->add(item); |
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357 | } |
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358 | } catch (...) { |
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359 | typename Observers::iterator jt; |
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360 | for (jt = it.base(); jt != _observers.end(); ++jt) { |
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361 | (*jt)->erase(item); |
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362 | } |
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363 | throw; |
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364 | } |
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365 | } |
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366 | |
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367 | // \brief Notifies all the registed observers about more item added to |
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368 | // the container. |
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369 | // |
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370 | // It notifies all the registed observers about more item added to |
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371 | // the container. |
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372 | void add(const std::vector<Item>& items) { |
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373 | typename Observers::reverse_iterator it; |
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374 | try { |
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375 | for (it = _observers.rbegin(); it != _observers.rend(); ++it) { |
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376 | (*it)->add(items); |
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377 | } |
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378 | } catch (...) { |
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379 | typename Observers::iterator jt; |
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380 | for (jt = it.base(); jt != _observers.end(); ++jt) { |
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381 | (*jt)->erase(items); |
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382 | } |
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383 | throw; |
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384 | } |
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385 | } |
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386 | |
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387 | // \brief Notifies all the registed observers about an item erased from |
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388 | // the container. |
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389 | // |
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390 | // It notifies all the registed observers about an item erased from |
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391 | // the container. |
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392 | void erase(const Item& item) throw() { |
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393 | typename Observers::iterator it = _observers.begin(); |
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394 | while (it != _observers.end()) { |
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395 | try { |
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396 | (*it)->erase(item); |
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397 | ++it; |
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398 | } catch (const ImmediateDetach&) { |
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399 | (*it)->_index = _observers.end(); |
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400 | (*it)->_notifier = 0; |
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401 | it = _observers.erase(it); |
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402 | } |
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403 | } |
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404 | } |
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405 | |
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406 | // \brief Notifies all the registed observers about more item erased |
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407 | // from the container. |
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408 | // |
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409 | // It notifies all the registed observers about more item erased from |
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410 | // the container. |
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411 | void erase(const std::vector<Item>& items) { |
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412 | typename Observers::iterator it = _observers.begin(); |
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413 | while (it != _observers.end()) { |
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414 | try { |
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415 | (*it)->erase(items); |
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416 | ++it; |
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417 | } catch (const ImmediateDetach&) { |
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418 | (*it)->_index = _observers.end(); |
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419 | (*it)->_notifier = 0; |
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420 | it = _observers.erase(it); |
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421 | } |
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422 | } |
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423 | } |
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424 | |
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425 | // \brief Notifies all the registed observers about the container is |
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426 | // built. |
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427 | // |
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428 | // Notifies all the registed observers about the container is built |
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429 | // from an empty container. |
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430 | void build() { |
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431 | typename Observers::reverse_iterator it; |
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432 | try { |
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433 | for (it = _observers.rbegin(); it != _observers.rend(); ++it) { |
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434 | (*it)->build(); |
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435 | } |
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436 | } catch (...) { |
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437 | typename Observers::iterator jt; |
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438 | for (jt = it.base(); jt != _observers.end(); ++jt) { |
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439 | (*jt)->clear(); |
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440 | } |
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441 | throw; |
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442 | } |
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443 | } |
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444 | |
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445 | // \brief Notifies all the registed observers about all items are |
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446 | // erased. |
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447 | // |
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448 | // Notifies all the registed observers about all items are erased |
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449 | // from the container. |
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450 | void clear() { |
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451 | typename Observers::iterator it = _observers.begin(); |
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452 | while (it != _observers.end()) { |
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453 | try { |
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454 | (*it)->clear(); |
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455 | ++it; |
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456 | } catch (const ImmediateDetach&) { |
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457 | (*it)->_index = _observers.end(); |
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458 | (*it)->_notifier = 0; |
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459 | it = _observers.erase(it); |
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460 | } |
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461 | } |
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462 | } |
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463 | }; |
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464 | |
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465 | } |
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466 | |
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467 | #endif |
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