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  1. #include <iostream>
  2. #include <string>
  3.  
  4. template <class In, class Out>
  5. struct Pipe
  6. {
  7. 	typedef In in_type ;
  8. 	typedef Out out_type ;
  9.  
  10. 	In in_val ;
  11.  
  12. 	Pipe (const in_type &in_val = in_type()) : in_val (in_val)
  13. 	{
  14. 	}
  15.  
  16. 	//virtual auto operator () () const -> out_type = 0 ;
  17.  
  18. 	virtual auto operator () () const -> out_type
  19. 	{
  20. 		return out_type () ;
  21. 	}
  22. };
  23.  
  24. template <class In, class Out, class Out2>
  25. auto operator>> (const Pipe <In, Out> &lhs, Pipe <Out, Out2> &rhs) -> Pipe <Out, Out2>&
  26. {
  27. 	rhs = lhs () ;
  28. 	return rhs ;
  29. }
  30.  
  31. template <class In, class Out, class Out2>
  32. auto operator>> (const Pipe <In, Out> &lhs, Pipe <Out, Out2> &&rhs) -> Pipe <Out, Out2>&
  33. {
  34. 	rhs = lhs () ;
  35. 	return rhs ;
  36. }
  37.  
  38. template <class In, class Out>
  39. auto operator>> (const Pipe <In, Out> &lhs, Out &rhs) -> Out&
  40. {
  41. 	rhs = lhs () ;
  42. 	return rhs ;
  43. }
  44.  
  45. template <class In, class Out>
  46. auto operator>> (const Pipe <In, Out> &lhs, Out &&rhs) -> Out&
  47. {
  48. 	rhs = lhs () ;
  49. 	return rhs ;
  50. }
  51.  
  52. struct StringToInt : public Pipe <std::string, int>
  53. {
  54. 	StringToInt (const std::string &s = "") : Pipe <in_type, out_type> (s)
  55. 	{
  56. 	}
  57.  
  58. 	auto operator () () const -> out_type
  59. 	{
  60. 		return std::stoi (in_val) ;
  61. 	}
  62. };
  63.  
  64. struct IntSquare : public Pipe <int, int>
  65. {
  66. 	IntSquare (int n = 0) : Pipe <in_type, out_type> (n)
  67. 	{
  68. 	}
  69.  
  70. 	auto operator () () const -> out_type
  71. 	{
  72. 		return in_val * in_val ;
  73. 	}
  74. };
  75.  
  76. struct DivideBy42F : public Pipe <int, float>
  77. {
  78. 	DivideBy42F (int n = 0) : Pipe <in_type, out_type> (n)
  79. 	{
  80. 	}
  81.  
  82. 	auto operator () () const -> out_type
  83. 	{
  84. 		return static_cast <float> (in_val) / 42.0f ;
  85. 	}
  86. };
  87.  
  88. int main ()
  89. {
  90. 	float out = 0 ;
  91. 	StringToInt ("42") >> IntSquare () >> DivideBy42F () >> out ;
  92. 	std::cout << out << "\n" ;
  93.  
  94. 	return 0 ;
  95. }
  96.  
Success #stdin #stdout 0s 3472KB
comments (?)
stdin
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Standard input is empty
stdout
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42
https://ideone.com/qSj3l2
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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