1 | /* |
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2 | * ORXONOX - the hottest 3D action shooter ever to exist |
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3 | * > www.orxonox.net < |
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4 | * |
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5 | * |
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6 | * License notice: |
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7 | * |
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8 | * This program is free software; you can redistribute it and/or |
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9 | * modify it under the terms of the GNU General Public License |
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10 | * as published by the Free Software Foundation; either version 2 |
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11 | * of the License, or (at your option) any later version. |
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12 | * |
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13 | * This program is distributed in the hope that it will be useful, |
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14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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16 | * GNU General Public License for more details. |
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17 | * |
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18 | * You should have received a copy of the GNU General Public License |
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19 | * along with this program; if not, write to the Free Software |
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20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. |
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21 | * |
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22 | * Author: |
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23 | * Fabian 'x3n' Landau |
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24 | * Co-authors: |
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25 | * ... |
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26 | * |
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27 | */ |
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28 | |
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29 | // Inspired by boost::intrusive_ptr by Peter Dimov |
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30 | |
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31 | /** |
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32 | @file |
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33 | @ingroup Object SmartPtr |
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34 | @brief Definition of WeakPtr<T>, wraps a pointer to an object. |
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35 | |
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36 | @anchor WeakPtrExample |
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37 | |
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38 | A WeakPtr wraps a pointer to an object. If the object gets deleted, the WeakPtr becomes |
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39 | NULL. This can be used to store pointers to objects without knowing when they will be |
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40 | destroyed. |
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41 | |
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42 | WeakPtr works only with objects that are derived from orxonox::OrxonoxClass, because |
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43 | WeakPtr is intrusive and registers itself in the stored object, to get a notification if |
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44 | the object is being deleted. |
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45 | |
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46 | Example: |
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47 | @code |
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48 | MyClass* object = new MyClass(); // create an instance of MyClass |
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49 | |
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50 | WeakPtr<MyClass> pointer = object; // create a WeakPtr and assign the object |
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51 | |
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52 | if (pointer) // checks if pointer is not NULL (which is true) |
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53 | pointer->someFunction(); // calls MyClass::someFunction() |
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54 | |
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55 | object->destroy(); // calls destroy() which deletes the object |
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56 | |
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57 | if (pointer) // checks if pointer is not NULL (which is now false) |
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58 | pointer->someFunction(); // this will not be executed |
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59 | @endcode |
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60 | In this example we assumed that MyClass is derived of OrxonoxClass (otherwise it couldn't |
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61 | be used with a WeakPtr). |
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62 | |
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63 | A callback can be registerd with the WeakPtr that will be called if the object gets deleted. |
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64 | @code |
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65 | void myCallback() // definition of the callback function |
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66 | { |
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67 | COUT(0) << "Object destroyed" << std::endl; |
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68 | } |
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69 | |
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70 | MyClass* object = new MyClass(); // create an instance of MyClass |
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71 | |
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72 | WeakPtr<MyClass> pointer = object; // create a WeakPtr and assign the object |
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73 | |
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74 | pointer.setCallback(createFunctor(&myCallback)); // defines a callback |
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75 | |
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76 | object->destroy(); // calls destroy() which deletes the object. prints "Object destroyed" to the console |
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77 | @endcode |
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78 | */ |
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79 | |
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80 | #ifndef _WeakPtr_H__ |
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81 | #define _WeakPtr_H__ |
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82 | |
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83 | #include "CorePrereqs.h" |
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84 | |
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85 | #include <cassert> |
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86 | #include "Identifier.h" |
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87 | #include "OrxonoxClass.h" |
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88 | #include "command/Functor.h" |
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89 | |
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90 | namespace orxonox |
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91 | { |
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92 | /** |
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93 | @brief WeakPtr wraps a pointer to an object, which becomes NULL if the object is deleted. |
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94 | |
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95 | @see See @ref WeakPtrExample "this description" for more information and an example. |
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96 | */ |
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97 | template <class T> |
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98 | class WeakPtr : public DestructionListener |
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99 | { |
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100 | public: |
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101 | /// Constructor: Initializes the weak pointer with a null pointer. |
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102 | inline WeakPtr() : pointer_(0), base_(0), callback_(0) |
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103 | { |
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104 | } |
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105 | |
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106 | /// Constructor: Used to explicitly initialize the weak pointer with a null pointer |
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107 | inline WeakPtr(int) : pointer_(0), base_(0), callback_(0) |
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108 | { |
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109 | } |
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110 | |
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111 | /// Constructor: Initializes the weak pointer with a pointer to an object. |
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112 | inline WeakPtr(T* pointer) : pointer_(pointer), base_(pointer), callback_(0) |
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113 | { |
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114 | this->registerAsDestructionListener(this->base_); |
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115 | } |
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116 | |
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117 | /// Copy-constructor |
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118 | inline WeakPtr(const WeakPtr& other) : pointer_(other.pointer_), base_(other.base_), callback_(0) |
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119 | { |
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120 | this->registerAsDestructionListener(this->base_); |
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121 | } |
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122 | |
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123 | /// Copy-constructor for weak pointers to objects of another class. |
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124 | template <class O> |
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125 | inline WeakPtr(const WeakPtr<O>& other) : pointer_(other.get()), base_(other.base_), callback_(0) |
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126 | { |
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127 | this->registerAsDestructionListener(this->base_); |
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128 | } |
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129 | |
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130 | /// Destructor |
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131 | inline ~WeakPtr() |
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132 | { |
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133 | this->unregisterAsDestructionListener(this->base_); |
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134 | } |
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135 | |
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136 | /// Used to assign a null pointer. |
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137 | inline WeakPtr& operator=(int) |
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138 | { |
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139 | WeakPtr(0).swap(*this); |
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140 | return *this; |
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141 | } |
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142 | |
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143 | /// Assigns a new pointer. |
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144 | inline WeakPtr& operator=(T* pointer) |
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145 | { |
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146 | WeakPtr(pointer).swap(*this); |
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147 | return *this; |
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148 | } |
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149 | |
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150 | /// Assigns the wrapped pointer of another WeakPtr. |
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151 | inline WeakPtr& operator=(const WeakPtr& other) |
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152 | { |
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153 | WeakPtr(other).swap(*this); |
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154 | return *this; |
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155 | } |
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156 | |
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157 | /// Assigns the wrapped pointer of a WeakPtr of another class |
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158 | template <class O> |
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159 | inline WeakPtr& operator=(const WeakPtr<O>& other) |
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160 | { |
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161 | WeakPtr(other).swap(*this); |
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162 | return *this; |
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163 | } |
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164 | |
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165 | /// Returns the wrapped pointer as @c T* |
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166 | inline T* get() const |
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167 | { |
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168 | return this->pointer_; |
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169 | } |
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170 | |
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171 | /// Returns the wrapped pointer as @c OrxonoxClass* |
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172 | inline OrxonoxClass* getBase() const |
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173 | { |
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174 | return this->base_; |
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175 | } |
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176 | |
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177 | /// Implicitly converts the WeakPtr to a pointer of type @c T* |
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178 | inline operator T*() const |
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179 | { |
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180 | return this->pointer_; |
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181 | } |
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182 | |
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183 | /// Overloaded operator, returns a pointer to the stored object. |
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184 | inline T* operator->() const |
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185 | { |
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186 | assert(this->pointer_ != 0); |
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187 | return this->pointer_; |
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188 | } |
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189 | |
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190 | /// Overloaded operator, returns a reference to the stored object. |
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191 | inline T& operator*() const |
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192 | { |
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193 | assert(this->pointer_ != 0); |
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194 | return *this->pointer_; |
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195 | } |
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196 | |
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197 | /// Returns true if the wrapped pointer is NULL. |
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198 | inline bool operator!() const |
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199 | { |
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200 | return (this->pointer_ == 0); |
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201 | } |
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202 | |
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203 | /// Swaps the contents of two weak pointers. |
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204 | inline void swap(WeakPtr& other) |
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205 | { |
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206 | this->unregisterAsDestructionListener(this->base_); |
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207 | other.unregisterAsDestructionListener(other.base_); |
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208 | |
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209 | { |
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210 | T* temp = this->pointer_; |
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211 | this->pointer_ = other.pointer_; |
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212 | other.pointer_ = temp; |
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213 | } |
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214 | { |
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215 | OrxonoxClass* temp = this->base_; |
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216 | this->base_ = other.base_; |
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217 | other.base_ = temp; |
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218 | } |
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219 | |
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220 | this->registerAsDestructionListener(this->base_); |
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221 | other.registerAsDestructionListener(other.base_); |
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222 | } |
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223 | |
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224 | /// Resets the weak pointer (equivalent to assigning a NULL pointer). |
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225 | inline void reset() |
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226 | { |
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227 | WeakPtr().swap(*this); |
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228 | } |
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229 | |
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230 | /// Registers a callback that will be executed if the stored object is destroyed. |
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231 | inline void setCallback(const FunctorPtr& callback) |
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232 | { |
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233 | this->callback_ = callback; |
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234 | } |
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235 | |
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236 | /// Returns the registered callback. |
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237 | inline const FunctorPtr& getCallback() const |
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238 | { |
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239 | return this->callback_; |
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240 | } |
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241 | |
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242 | private: |
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243 | /// Will be called by OrxonoxClass::~OrxonoxClass() if the stored object is deleted. Resets the wrapped pointer and executes the callback. |
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244 | inline void objectDeleted() |
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245 | { |
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246 | this->base_ = 0; |
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247 | this->pointer_ = 0; |
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248 | if (this->callback_) |
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249 | (*this->callback_)(); |
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250 | } |
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251 | |
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252 | T* pointer_; ///< The wrapped pointer to an object of type @a T |
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253 | OrxonoxClass* base_; ///< The wrapped pointer, casted up to OrxonoxClass (this is needed because with just a T* pointer, WeakPtr couln't be used with forward declarations) |
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254 | FunctorPtr callback_; ///< This callback will be executed if the stored object is deleted |
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255 | }; |
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256 | |
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257 | /// Swaps the contents of two weak pointers. |
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258 | template <class T> |
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259 | void swap(WeakPtr<T>& a, WeakPtr<T>& b) |
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260 | { |
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261 | a.swap(b); |
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262 | } |
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263 | |
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264 | /// Uses a static_cast to cast a pointer of type U* to a pointer of type T* and returns it in a new WeakPtr<T>. |
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265 | template <class T, class U> |
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266 | WeakPtr<T> static_pointer_cast(const WeakPtr<U>& p) |
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267 | { |
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268 | return static_cast<T*>(p.get()); |
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269 | } |
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270 | |
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271 | /// Uses a const_cast to cast a pointer of type U* to a pointer of type T* and returns it in a new WeakPtr<T>. |
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272 | template <class T, class U> |
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273 | WeakPtr<T> const_pointer_cast(const WeakPtr<U>& p) |
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274 | { |
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275 | return const_cast<T*>(p.get()); |
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276 | } |
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277 | |
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278 | /// Uses a dynamic_cast to cast a pointer of type U* to a pointer of type T* and returns it in a new WeakPtr<T>. |
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279 | template <class T, class U> |
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280 | WeakPtr<T> dynamic_pointer_cast(const WeakPtr<U>& p) |
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281 | { |
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282 | return orxonox_cast<T*>(p.get()); |
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283 | } |
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284 | } |
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285 | |
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286 | #endif /* _WeakPtr_H__ */ |
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