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1 /* |
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2 * signals.h -- synchronous observer mechanism |
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3 * |
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4 * Copyright (c) 2013-2016 David Demelier <markand@malikania.fr> |
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5 * |
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6 * Permission to use, copy, modify, and/or distribute this software for any |
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7 * purpose with or without fee is hereby granted, provided that the above |
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8 * copyright notice and this permission notice appear in all copies. |
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9 * |
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10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES |
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11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF |
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12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR |
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13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES |
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14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN |
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15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF |
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16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. |
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17 */ |
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18 |
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19 #ifndef _IRCCD_SIGNALS_H_ |
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20 #define _IRCCD_SIGNALS_H_ |
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21 |
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22 #include <functional> |
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23 #include <stack> |
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24 #include <unordered_map> |
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25 #include <vector> |
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26 |
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27 /** |
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28 * @file Signals.h |
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29 * @brief Similar Qt signal subsystem for irccd |
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30 */ |
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31 |
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32 namespace irccd { |
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33 |
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34 /** |
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35 * @class SignalConnection |
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36 * @brief Stores the reference to the callable |
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37 * |
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38 * This class can be stored to remove a registered function from a Signal, be |
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39 * careful to not mix connections between different signals as they are just |
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40 * referenced by ids. |
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41 */ |
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42 class SignalConnection { |
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43 private: |
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44 unsigned m_id; |
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45 |
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46 public: |
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47 /** |
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48 * Create a signal connection. |
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49 * |
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50 * @param id the id |
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51 */ |
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52 inline SignalConnection(unsigned id) noexcept |
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53 : m_id{id} |
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54 { |
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55 } |
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56 |
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57 /** |
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58 * Get the reference object. |
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59 * |
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60 * @return the id |
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61 */ |
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62 inline unsigned id() const noexcept |
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63 { |
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64 return m_id; |
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65 } |
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66 }; |
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67 |
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68 /** |
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69 * @class Signal |
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70 * @brief Stores and call registered functions |
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71 * |
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72 * This class is intended to be use as a public field in the desired object. |
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73 * |
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74 * The user just have to call one of connect(), disconnect() or the call |
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75 * operator to use this class. |
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76 * |
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77 * It stores the callable as std::function so type-erasure is complete. |
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78 * |
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79 * The user is responsible of taking care that the object is still alive |
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80 * in case that the function takes a reference to the object. |
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81 */ |
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82 template <typename... Args> |
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83 class Signal { |
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84 private: |
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85 using Function = std::function<void (Args...)>; |
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86 using FunctionMap = std::unordered_map<unsigned, Function>; |
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87 using Stack = std::stack<unsigned>; |
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88 |
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89 FunctionMap m_functions; |
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90 Stack m_stack; |
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91 unsigned m_max{0}; |
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92 |
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93 public: |
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94 /** |
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95 * Register a new function to the signal. |
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96 * |
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97 * @param function the function |
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98 * @return the connection in case you want to remove it |
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99 */ |
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100 inline SignalConnection connect(Function function) noexcept |
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101 { |
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102 unsigned id; |
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103 |
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104 if (!m_stack.empty()) { |
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105 id = m_stack.top(); |
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106 m_stack.pop(); |
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107 } else { |
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108 id = m_max ++; |
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109 } |
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110 |
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111 m_functions.emplace(id, std::move(function)); |
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112 |
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113 return SignalConnection{id}; |
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114 } |
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115 |
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116 /** |
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117 * Disconnect a connection. |
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118 * |
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119 * @param connection the connection |
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120 * @warning Be sure that the connection belongs to that signal |
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121 */ |
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122 inline void disconnect(const SignalConnection &connection) noexcept |
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123 { |
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124 auto value = m_functions.find(connection.id()); |
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125 |
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126 if (value != m_functions.end()) { |
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127 m_functions.erase(connection.id()); |
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128 m_stack.push(connection.id()); |
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129 } |
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130 } |
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131 |
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132 /** |
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133 * Remove all registered functions. |
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134 */ |
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135 inline void clear() |
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136 { |
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137 m_functions.clear(); |
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138 m_max = 0; |
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139 |
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140 while (!m_stack.empty()) |
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141 m_stack.pop(); |
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142 } |
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143 |
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144 /** |
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145 * Call every functions. |
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146 * |
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147 * @param args the arguments to pass to the signal |
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148 */ |
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149 void operator()(Args... args) const |
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150 { |
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151 /* |
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152 * Make a copy of the ids before iterating because the callbacks may eventually remove or modify |
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153 * the list. |
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154 */ |
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155 std::vector<unsigned> ids; |
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156 |
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157 for (auto &pair : m_functions) |
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158 ids.push_back(pair.first); |
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159 |
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160 /* |
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161 * Now iterate while checking if the next id is still available, however if any new signals were |
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162 * added while iterating, they will not be called immediately. |
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163 */ |
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164 for (unsigned i : ids) { |
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165 auto it = m_functions.find(i); |
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166 |
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167 if (it != m_functions.end()) { |
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168 it->second(args...); |
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169 } |
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170 } |
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171 } |
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172 }; |
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173 |
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174 } // !irccd |
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175 |
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176 #endif // !_IRCCD_SIGNALS_H_ |
