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  1. /// //////////////////////////////////////////////////////////////////////// ///
  2. /// //////////////////////////////////////////////////////////////////////// ///
  3. /// //////////////////////////////////////////////////////////////////////// ///
  4. #include <cxxabi.h>
  5. #include <string>
  6. #include <typeinfo>
  7. #include <cassert>
  8. #include <cstdlib>
  9. #include <iostream>
  10.  
  11. const std::string demangle(const char* const mangledTypeName) {
  12.    int resultStatus = -4;
  13.    const char* const result = abi::__cxa_demangle( mangledTypeName, 0, 0, &resultStatus );
  14.    std::string demangledTypeName;
  15.    const bool noError = (0 == resultStatus);
  16.    const bool demangledSuccess = (noError && result != 0);
  17.    assert(demangledSuccess);
  18.    demangledTypeName = (demangledSuccess ? result : "Unknown type.");
  19.    free(const_cast<char*>(result));
  20.    return demangledTypeName;
  21. }
  22.  
  23. const std::string demangle(const std::string& mangledTypeName) {
  24.    return demangle(mangledTypeName.c_str());
  25. }
  26.  
  27. const std::string demangledNameOfType(const std::type_info& type_id) {
  28.    return demangle(type_id.name());
  29. }
  30.  
  31. #define DEMANGLED_NAME_OF_TYPE(TypeOrValue) (demangledNameOfType(typeid(TypeOrValue)))
  32. #define PRINT_NAME_OF_TYPE(TypeOrValue) {std::cout<<DEMANGLED_NAME_OF_TYPE(TypeOrValue)<<std::endl;}
  33. /// //////////////////////////////////////////////////////////////////////// ///
  34. /// //////////////////////////////////////////////////////////////////////// ///
  35. /// //////////////////////////////////////////////////////////////////////// ///
  36.  
  37. #include <string>
  38. #include <vector>
  39. #include <iostream>
  40.  
  41. // Store parameter pack
  42. template<typename... T>
  43. struct pack
  44. {
  45.     static const unsigned int size = sizeof...(T);
  46. };
  47.  
  48. // Get i-th element of parameter pack
  49. template<int n, typename F, typename... T>
  50. struct element_at : public element_at<n-1, T...>
  51. {
  52. };
  53.  
  54. template<typename F, typename... T>
  55. struct element_at<0, F, T...>
  56. {
  57.     typedef F type;
  58. };
  59.  
  60. // Get i-th element of pack
  61. template<int n, typename P>
  62. struct element
  63. {
  64. };
  65.  
  66. template<int n, typename... T>
  67. struct element<n, pack<T...>>
  68. {
  69.     typedef typename element_at<n, T...>::type type;
  70. };
  71.  
  72. // Concat at left
  73. template<typename a, typename b>
  74. struct tuple_concat_left
  75. {
  76. };
  77.  
  78. template<typename a, typename... b>
  79. struct tuple_concat_left<a, pack<b...>>
  80. {
  81.     typedef pack<a, b...> type;
  82. };
  83.  
  84. // Concat 2 tuples
  85. template<typename a, typename b, int n = 0, bool ok = (n < a::size)>
  86. struct tuple_concat : public tuple_concat<a, b, n+1>
  87. {
  88.     typedef typename tuple_concat_left<
  89.         typename element<n, a>::type,
  90.         typename tuple_concat<a, b, n+1>::type
  91.     >::type type;
  92. };
  93.  
  94. template<typename a, typename b, int n>
  95. struct tuple_concat<a, b, n, false>
  96. {
  97.     typedef b type;
  98. };
  99.  
  100. // Test
  101. typedef pack<bool, int, char, float, std::string> MyPack;
  102. typedef pack<double, std::vector<std::string>> PackToAppend;
  103.  
  104. int main()
  105. {
  106.     typedef tuple_concat_left<void, MyPack>::type concat1;
  107.     typedef element<2, concat1>::type elem_at_2;
  108.     typedef tuple_concat<MyPack, PackToAppend>::type concat2;
  109.     typedef tuple_concat<PackToAppend, MyPack>::type concat3;
  110.  
  111.  
  112.     std::cout << "MyPack: "; PRINT_NAME_OF_TYPE(MyPack);
  113.     std::cout << "concat1: "; PRINT_NAME_OF_TYPE(concat1);
  114.     std::cout << "elem_at_2: "; PRINT_NAME_OF_TYPE(elem_at_2);
  115.     std::cout << "concat2: "; PRINT_NAME_OF_TYPE(concat2);
  116.     std::cout << "concat3: "; PRINT_NAME_OF_TYPE(concat3);
  117. }
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Success #stdin #stdout 0s 3032KB
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stdin
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Standard input is empty
stdout
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MyPack: pack<bool, int, char, float, std::string>
concat1: pack<void, bool, int, char, float, std::string>
elem_at_2: int
concat2: pack<bool, int, char, float, std::string, double, std::vector<std::string, std::allocator<std::string> > >
concat3: pack<double, std::vector<std::string, std::allocator<std::string> >, bool, int, char, float, std::string>
https://ideone.com/ALUSYa
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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