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  1. #include <iostream>
  2.  
  3. namespace
  4. {
  5.     enum Block_Edges
  6.     {
  7.         FROM = 0,
  8.         TO = 4,
  9.     };
  10.  
  11.     Block_Edges& operator++(Block_Edges& e)
  12.     {
  13.         return e = static_cast<Block_Edges>(e + 1);
  14.     }
  15.  
  16. }
  17.  
  18. template<typename T, bool enable = std::is_integral<T>::value || std::is_enum<T>::value>
  19. struct range_impl
  20. {
  21.     struct iterator
  22.     {
  23.         T operator * ()const noexcept
  24.         {
  25.             return value;
  26.         }
  27.  
  28.         iterator& operator ++() noexcept
  29.         {
  30.             ++value;
  31.             return *this;
  32.         }
  33.  
  34.         friend bool operator != (const iterator& lhs, const iterator& rhs) noexcept
  35.         {
  36.             return lhs.value != rhs.value;
  37.         }
  38.  
  39.         T value;
  40.     };
  41.  
  42.     std::size_t size() const
  43.     {
  44.         return last - first;
  45.     }
  46.  
  47.     const iterator begin()const noexcept
  48.     {
  49.         return{ first };
  50.     }
  51.  
  52.         const iterator end()const noexcept
  53.     {
  54.         return{ last };
  55.     }
  56.  
  57.     T first;
  58.     T last;
  59. };
  60.  
  61. template<typename T>
  62. struct range_impl<T, false>
  63. {
  64.     range_impl(T first, T last)
  65.         : first(first)
  66.         , last(last)
  67.     {}
  68.  
  69.     std::size_t size() const
  70.     {
  71.         return std::distance(first, last);
  72.     }
  73.  
  74.     const T begin()const noexcept
  75.     {
  76.         return{ first };
  77.     }
  78.  
  79.         const T end()const noexcept
  80.     {
  81.         return{ last };
  82.     }
  83.  
  84.     T first;
  85.     T last;
  86. };
  87.  
  88. template<typename T>
  89. range_impl<T>  range(T first, T last) noexcept
  90. {
  91.     return{ first, last };
  92. }
  93.  
  94. int main()
  95. {
  96.     for (const auto& i : range(Block_Edges::FROM, Block_Edges::TO))
  97.     {
  98.         std::cout << '\n' << i << ':';
  99.         for (const auto& j : range(Block_Edges::FROM, Block_Edges::TO))
  100.         {
  101.             std::cout << j << ' ';
  102.         }
  103.     }
  104. }
  105.  
Success #stdin #stdout 0s 3140KB
comments (?)
stdin 
Standard input is empty
stdout 
0:0 1 2 3 
1:0 1 2 3 
2:0 1 2 3 
3:0 1 2 3
https://ideone.com/5fGiv8
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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