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  1. #include <array>
  2. #include <iostream>
  3. #include <queue>
  4.  
  5. template <typename T, size_t N = 2>
  6. class CyclicArray {
  7.  public:
  8.   typedef typename std::array<T, N>::value_type value_type;
  9.   typedef typename std::array<T, N>::reference reference;
  10.   typedef typename std::array<T, N>::const_reference const_reference;
  11.   typedef typename std::array<T, N>::size_type size_type;
  12.  
  13.   ~CyclicArray() {
  14.   	while (size())
  15.   	  pop_front();
  16.   }
  17.  
  18.   void push_back(const T& v) {
  19.     if (size_ + 1 > N)
  20.       throw;
  21.     new (&array_[(front_ + size_) % N]) T(v);
  22.     ++size_;
  23.   }
  24.  
  25.   void pop_front() {
  26.   	if (size_ < 1)
  27.   	  throw;
  28.   	front().~T();
  29.   	++front_;
  30.   	--size_;
  31.   	if (front_ >= N)
  32.   	  front_ = 0;
  33.   }
  34.  
  35.   const_reference front() const {
  36.   	return *static_cast<const T*>(&array_[front_]);
  37.   }
  38.  
  39.   reference front() {
  40.   	return *reinterpret_cast<T*>(&array_[front_]);
  41.   }
  42.  
  43.   size_type size() const {
  44.     return size_;
  45.   }
  46.  
  47.  private:
  48.   size_type front_ = 0;
  49.   size_type size_ = 0;
  50.   std::array<char[sizeof(T)], N> array_;
  51. };
  52.  
  53. int main() {
  54. 	std::queue<int, CyclicArray<int, 2>> queue;
  55. 	queue.push(1);
  56. 	queue.push(2);
  57. 	queue.pop();
  58. 	queue.push(3);
  59. 	int f = queue.front();
  60. 	queue.pop();
  61. 	std::cout << f << std::endl;
  62. 	f = queue.front();
  63. 	queue.pop();
  64. 	std::cout << f << std::endl;
  65. 	return 0;
  66. }
Success #stdin #stdout 0s 4552KB
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Standard input is empty
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https://ideone.com/0nEBZa
language:
C++14 (gcc 8.3)
created:
4 years ago
visibility:
public

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