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  1. //             Copyright Evgeny Panasyuk 2012.
  2. // Distributed under the Boost Software License, Version 1.0.
  3. //    (See accompanying file LICENSE_1_0.txt or copy at
  4. //          http://w...content-available-to-author-only...t.org/LICENSE_1_0.txt)
  5.  
  6. #include <type_traits>
  7. #include <functional>
  8. #include <algorithm>
  9. #include <stdexcept>
  10. #include <iostream>
  11. #include <typeinfo>
  12. #include <utility>
  13. #include <ostream>
  14. #include <vector>
  15. #include <string>
  16.  
  17. using namespace std;
  18.  
  19. // _____________________________Implementation__________________________________________
  20.  
  21. #define USE_VARIADIC_TEMPLATES 0
  22.  
  23. template<typename Callback,typename Function> inline
  24. bool func_compare(const Function &lhs,const Function &rhs)
  25. {
  26.     typedef typename conditional
  27.     <
  28.         is_function<Callback>::value,
  29.         typename add_pointer<Callback>::type,
  30.         Callback
  31.     >::type request_type;
  32.  
  33.     if (const request_type *lhs_internal = lhs.template target<request_type>())
  34.         if (const request_type *rhs_internal = rhs.template target<request_type>())
  35.             return *rhs_internal == *lhs_internal;
  36.     return false;
  37. }
  38.  
  39. #if USE_VARIADIC_TEMPLATES
  40.     #define FUNC_SIG_TYPES typename ...Args
  41.     #define FUNC_SIG_TYPES_PASS Args...
  42. #else
  43.     #define FUNC_SIG_TYPES typename function_signature
  44.     #define FUNC_SIG_TYPES_PASS function_signature
  45. #endif
  46.  
  47. template<FUNC_SIG_TYPES>
  48. struct function_comparable: function<FUNC_SIG_TYPES_PASS>
  49. {
  50.     typedef function<FUNC_SIG_TYPES_PASS> Function;
  51.     bool (*type_holder)(const Function &,const Function &);
  52. public:
  53.     function_comparable() {}
  54.     template<typename Func> function_comparable(Func f)
  55.         : Function(f), type_holder(func_compare<Func,Function>)
  56.     {
  57.     }
  58.     template<typename Func> function_comparable &operator=(Func f)
  59.     {
  60.         Function::operator=(f);
  61.         type_holder=func_compare<Func,Function>;
  62.         return *this;
  63.     }
  64.     friend bool operator==(const Function &lhs,const function_comparable &rhs)
  65.     {
  66.         return rhs.type_holder(lhs,rhs);
  67.     }
  68.     friend bool operator==(const function_comparable &lhs,const Function &rhs)
  69.     {
  70.         return rhs==lhs;
  71.     }
  72.     // ...
  73.     friend void swap(function_comparable &lhs,function_comparable &rhs)// noexcept
  74.     {
  75.         lhs.swap(rhs);
  76.         lhs.type_holder.swap(rhs.type_holder);
  77.     }
  78. };
  79.  
  80. // ________________________________Example______________________________________________
  81.  
  82. typedef void (function_signature)();
  83.  
  84. void func1()
  85. {
  86.     cout << "func1" << endl;
  87. }
  88.  
  89. void func3()
  90. {
  91.     cout << "func3" << endl;
  92. }
  93.  
  94. class func2
  95. {
  96.     int data;
  97. public:
  98.     explicit func2(int n) : data(n) {}
  99.     friend bool operator==(const func2 &lhs,const func2 &rhs)
  100.     {
  101.         return lhs.data==rhs.data;
  102.     }
  103.     void operator()()
  104.     {
  105.         cout << "func2, data=" << data << endl;
  106.     }
  107. };
  108. struct Caller
  109. {
  110.     template<typename Func>
  111.     void operator()(Func f)
  112.     {
  113.         f();
  114.     }
  115. };
  116. class Callbacks
  117. {
  118.     vector<function<function_signature>> v;
  119. public:
  120.     void register_callback_comparator(function_comparable<function_signature> callback)
  121.     {
  122.         v.push_back(callback);
  123.     }
  124.     void register_callback(function<function_signature> callback)
  125.     {
  126.         v.push_back(callback);
  127.     }
  128.     void unregister_callback(function_comparable<function_signature> callback)
  129.     {
  130.         auto it=find(v.begin(),v.end(),callback);
  131.         if(it!=v.end())
  132.             v.erase(it);
  133.         else
  134.             throw runtime_error("not found");
  135.     }
  136.     void call_all()
  137.     {
  138.         for_each(v.begin(),v.end(),Caller());
  139.         cout << string(16,'_') << endl;
  140.     }
  141. };
  142.  
  143. int main()
  144. {
  145.     Callbacks cb;
  146.     function_comparable<function_signature> f;
  147.     f=func1;
  148.     cb.register_callback_comparator(f);
  149.  
  150.     cb.register_callback(func2(1));
  151.     cb.register_callback(func2(2));
  152.     cb.register_callback(func3);
  153.     cb.call_all();
  154.  
  155.     cb.unregister_callback(func2(2));
  156.     cb.call_all();
  157.     cb.unregister_callback(func1);
  158.     cb.call_all();
  159. }
  160.  
Success #stdin #stdout 0s 3024KB
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func1
func2, data=1
func2, data=2
func3
________________
func1
func2, data=1
func3
________________
func2, data=1
func3
________________
https://ideone.com/M1Qnpj
language:
C++14 (gcc 8.3)
created:
12 years ago
visibility:
secret

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