1 | #ifndef _theplu_yat_utility_smart_ptr_ |
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2 | #define _theplu_yat_utility_smart_ptr_ |
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3 | |
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4 | // $Id: SmartPtr.h 1486 2008-09-09 21:17:19Z jari $ |
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5 | |
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6 | /* |
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7 | Copyright (C) 2008 Jari Häkkinen, Peter Johansson |
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8 | |
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9 | This file is part of the yat library, http://dev.thep.lu.se/yat |
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10 | |
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11 | The yat library is free software; you can redistribute it and/or |
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12 | modify it under the terms of the GNU General Public License as |
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13 | published by the Free Software Foundation; either version 3 of the |
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14 | License, or (at your option) any later version. |
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15 | |
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16 | The yat library is distributed in the hope that it will be useful, |
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17 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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18 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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19 | General Public License for more details. |
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20 | |
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21 | You should have received a copy of the GNU General Public License |
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22 | along with this program; if not, write to the Free Software |
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23 | Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA |
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24 | 02111-1307, USA. |
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25 | */ |
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26 | |
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27 | #include "yat_assert.h" |
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28 | |
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29 | namespace theplu { |
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30 | namespace yat { |
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31 | namespace utility { |
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32 | |
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33 | /** |
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34 | SmartPtr is a wrapper around a pointer. Default SmartPtr is set |
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35 | to be owner of pointer, which implies pointer will be deleted in |
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36 | destructor. Pointer can be shared between many SmartPtr, in which |
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37 | case a counter is kept updated in copying and assignment telling |
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38 | how many owners there are. When the counter reaches zero, the |
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39 | pointer is deleted. |
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40 | */ |
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41 | template<typename T> |
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42 | class SmartPtr |
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43 | { |
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44 | public: |
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45 | /** |
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46 | \brief Constructor |
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47 | |
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48 | \param p underlying pointer |
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49 | \param owner if true SmartPtr will be owner of pointer and if |
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50 | there is no more owner delete it in destructor. |
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51 | |
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52 | Never use this constructor to create two SmartPtr to the same |
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53 | pointer such as |
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54 | \code |
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55 | MyClass* my_pointer = new MyClass; |
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56 | SmartPtr<MyClass> sp(my_pointer); |
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57 | SmartPtr<MyClass> sp2(my_pointer); // this is evil |
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58 | \endcode |
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59 | since this will cause multiple deletion. Instead use copy constructor |
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60 | \code |
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61 | MyClass* my_pointer = new MyClass; |
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62 | SmartPtr<MyClass> sp(my_pointer); |
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63 | SmartPtr<MyClass> sp2(sp); |
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64 | \endcode |
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65 | so the internal reference counter is updated. |
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66 | */ |
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67 | explicit SmartPtr(T* p=NULL, bool owner=true) |
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68 | : pointee_(p) |
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69 | { |
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70 | if (owner) |
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71 | ref_count_ = new unsigned int(1); |
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72 | else |
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73 | ref_count_ = NULL; |
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74 | } |
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75 | |
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76 | /** |
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77 | \brief Copy constructor |
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78 | */ |
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79 | SmartPtr(const SmartPtr& other) |
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80 | : pointee_(other.pointee_), ref_count_(other.ref_count_) |
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81 | { |
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82 | if (ref_count_) |
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83 | ++(*ref_count_); |
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84 | } |
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85 | |
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86 | /** |
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87 | \brief Destructor |
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88 | |
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89 | If SmartPtr is owner and the only owner, underlying pointer is deleted. |
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90 | */ |
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91 | virtual ~SmartPtr() |
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92 | { |
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93 | detach(); |
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94 | } |
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95 | |
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96 | /** |
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97 | If SmartPtr is owner and the only owner, underlying pointer is deleted. |
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98 | |
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99 | If rhs is owner, lhs become also owner. |
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100 | */ |
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101 | SmartPtr& operator=(const SmartPtr& rhs) |
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102 | { |
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103 | if (pointee_!=rhs.pointee_){ |
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104 | detach(); |
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105 | pointee_ = rhs.pointee_; |
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106 | ref_count_= rhs.ref_count_; |
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107 | if (ref_count_) |
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108 | ++(*ref_count_); |
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109 | } |
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110 | return *this; |
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111 | } |
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112 | |
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113 | /** |
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114 | \return underlying pointer |
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115 | */ |
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116 | T* operator->(void) const |
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117 | { |
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118 | return pointee_; |
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119 | } |
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120 | |
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121 | /** |
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122 | \return reference to underlying object |
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123 | */ |
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124 | T& operator*(void) const |
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125 | { |
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126 | return *pointee_; |
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127 | } |
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128 | |
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129 | private: |
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130 | T* pointee_; |
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131 | unsigned int* ref_count_; |
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132 | |
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133 | void detach(void) |
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134 | { |
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135 | if (ref_count_) |
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136 | if (!--(*ref_count_)) |
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137 | delete pointee_; |
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138 | } |
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139 | }; |
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140 | |
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141 | |
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142 | |
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143 | |
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144 | |
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145 | |
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146 | }}} // of namespace utility, yat, and theplu |
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147 | |
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148 | #endif |
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