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  1. #ifndef CUSTOM_ALLCATOR_HPP
  2. #define CUSTOM_ALLCATOR_HPP
  3.  
  4. #include <cstdlib>  // for malloc and free
  5. #include <memory>   // for std::allocator
  6. #include <iostream> // for std::cout
  7.  
  8. namespace katahiromz {
  9.  
  10. template <typename T>
  11. class custom_allocator : public std::allocator<T> {
  12. public:
  13.     typedef typename std::allocator<T>::size_type       size_type;
  14.     typedef typename std::allocator<T>::pointer         pointer;
  15.     typedef typename std::allocator<T>::const_pointer   const_pointer;
  16.     typedef typename std::allocator<T>::reference       reference;
  17.     typedef typename std::allocator<T>::const_reference const_reference;
  18.     typedef typename std::allocator<T>::difference_type difference_type;
  19.  
  20.     custom_allocator() {}
  21.     custom_allocator(const custom_allocator<T>& x) {}
  22.     template <typename U>
  23.     custom_allocator(const custom_allocator<U>& x) {}
  24.     pointer allocate(size_type count, const_pointer hinst = NULL) {
  25.         size_type size = count * sizeof(T);
  26.         std::cout << "custom_allocator: allocate " << size << std::endl;
  27.         return reinterpret_cast<pointer>(std::malloc(size));
  28.     }
  29.     void deallocate(pointer ptr, size_type count) {
  30.         std::cout << "custom_allocator: free " << ptr << std::endl;
  31.         std::free(ptr);
  32.     }
  33.     template <typename U>
  34.     struct rebind { typedef custom_allocator<U> other; };
  35. };
  36.  
  37. } // namespace katahiromz
  38.  
  39. #endif  // ndef CUSTOM_ALLCATOR_HPP
  40.  
  41. #include <string>
  42. #include <vector>
  43. #include <map>
  44.  
  45. namespace katahiromz {
  46.  
  47. typedef std::basic_string<char, std::char_traits<char>,
  48.                           custom_allocator<char> >      custom_string;
  49. typedef std::basic_string<wchar_t, std::char_traits<wchar_t>,
  50.                           custom_allocator<wchar_t> >   custom_wstring;
  51.  
  52. template <typename T>
  53. using custom_vector = std::vector<T, custom_allocator<T> >;
  54.  
  55. template <typename KEY, typename VALUE, typename COMPARE = std::less<KEY> >
  56. using custom_map = std::map<KEY, VALUE, COMPARE,
  57.                             custom_allocator<std::pair<const KEY, VALUE> > >;
  58.  
  59. } // namespace katahiromz
  60.  
  61. int main(void) {
  62.     katahiromz::custom_string str;
  63.     str = "OK\n";
  64.     str += "OK\n";
  65.     std::cout << str << std::endl;
  66.     katahiromz::custom_vector<int> vec;
  67.     vec.push_back(2);
  68.     vec.push_back(3);
  69.     std::cout << vec[0] << std::endl;
  70.     std::cout << vec[1] << std::endl;
  71.     return 0;
  72. }
Success #stdin #stdout 0s 3464KB
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stdin
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Standard input is empty
stdout
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custom_allocator: allocate 16
custom_allocator: allocate 19
custom_allocator: free 
OK
OK

custom_allocator: allocate 4
custom_allocator: allocate 8
custom_allocator: free 0x934ea40
2
3
custom_allocator: free 0x934ea50
custom_allocator: free 
https://ideone.com/ZmTMFB
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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