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  1. #include <iostream>
  2. #include <stdexcept>
  3. #include <type_traits>
  4.  
  5. #define noexcept
  6.  
  7. namespace
  8. {
  9. 	enum class Block_Edges : int
  10. 	{
  11. 		from = 0,
  12. 		to = 4,
  13. 	};
  14. 	template<typename T, bool enable = std::is_enum<T>::value>
  15. 	int operator+(const T& e, int i)
  16. 	{
  17. 		//const T rei = i + static_cast<int>(e);
  18. 		const int rei = i + static_cast<int>(e);
  19. 		if (rei < static_cast<int>(T::from) || rei > static_cast<int>(T::to))
  20. 		{
  21. 			throw std::out_of_range("Addition to Row_Edges would create out of bounds index");
  22. 		}
  23. 		return  rei;
  24. 	}
  25. 	template<typename T, bool enable = std::is_enum<T>::value>
  26. 	int operator-(const T& e, int i)
  27. 	{
  28. 		const int rei = i - static_cast<int>(e);
  29. 		if (rei < static_cast<int>(T::from) || rei > static_cast<int>(T::to))
  30. 		{
  31. 			throw std::out_of_range("Addition to Row_Edges would create out of bounds index");
  32. 		}
  33. 		return  rei;
  34. 	}
  35.  
  36. 	template<typename T, bool enable = std::is_enum<T>::value>
  37. 	int& operator++(T& e)
  38. 	{
  39. 		return e = static_cast<int>(e + 1);
  40. 	}
  41.  
  42. #if 0 //this does not do the right thing
  43. 	template<typename T, bool enable = std::is_enum<T>::value>
  44. 	const int& operator*(T& e)
  45. 	{
  46. 		return static_cast<int>(e);
  47. 	}
  48. #endif
  49. };
  50.  
  51. template<typename T, bool enable = std::is_integral<T>::value || std::is_enum<T>::value>
  52. struct range_impl
  53. {
  54. 	struct iterator
  55. 	{
  56. 		const T operator * ()const noexcept
  57. 		{
  58. 			return value;
  59. 		}
  60.  
  61. 			iterator& operator ++() noexcept
  62. 		{
  63. 			++value;
  64. 			return *this;
  65. 		}
  66.  
  67. 			friend	const bool operator != (const iterator& lhs, const iterator& rhs) noexcept
  68. 		{
  69. 			return lhs.value != rhs.value;
  70. 		}
  71.  
  72. 		T value;
  73. 	};
  74.  
  75. 	std::size_t size() const
  76. 	{
  77. 		return last - first;
  78. 	}
  79.  
  80. 	const iterator begin()const noexcept
  81. 	{
  82. 		return{ first };
  83. 	}
  84.  
  85. 		const iterator end()const noexcept
  86. 	{
  87. 		return{ last };
  88. 	}
  89.  
  90. 	T first;
  91. 	T last;
  92. };
  93.  
  94. template<typename T>
  95. struct range_impl<T, false>
  96. {
  97. 	range_impl(T first, T last)
  98. 		: first(first)
  99. 		, last(last)
  100. 	{}
  101.  
  102. 	std::size_t size() const
  103. 	{
  104. 		return std::distance(first, last);
  105. 	}
  106.  
  107. 	const T begin()const noexcept
  108. 	{
  109. 		return{ first };
  110. 	}
  111.  
  112. 		const T end()const noexcept
  113. 	{
  114. 		return{ last };
  115. 	}
  116.  
  117. 	T first;
  118. 	T last;
  119. };
  120.  
  121. //template<typename T>
  122. //range_impl<T>  range(T first, T last) noexcept
  123. //{
  124. //	return{ first, last };
  125. //}
  126. template<typename T1, typename T2>
  127. range_impl<typename std::common_type<T1, T2>::type>
  128. range(T1 first, T2 last) noexcept
  129. {
  130. 	return{ first, last };
  131. }
  132.  
  133. int main()
  134. {
  135. 	for (const auto& i : range(Block_Edges::from - 1, Block_Edges::to + 1)) //succeeds
  136. 	{
  137. 		std::cout << '\n' << i << ':';
  138. 		for (const auto& j : range(Block_Edges::from - 2, Block_Edges::to + 0))
  139. 		{
  140. 			std::cout << j << ' ';
  141. 		}
  142. 	}
  143. }
Runtime error #stdin #stdout #stderr 0s 3268KB
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Standard input is empty
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Standard output is empty
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terminate called after throwing an instance of 'std::out_of_range'
  what():  Addition to Row_Edges would create out of bounds index
https://ideone.com/gabRH4
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
secret

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