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  1. #include <iostream>
  2. #include <string>
  3. #include <stdexcept>
  4. #include <functional>
  5. #include <utility>
  6.  
  7. template <typename... Args, typename F, size_t... ints>
  8. void match_impl(size_t n, const std::tuple<Args...>& t, const F& f, std::integer_sequence<size_t, ints...> int_seq)
  9. {
  10.   std::function<void()> fs[sizeof...(Args)] = {
  11.     [&]() { f(std::get<ints>(t)); }...
  12.   };
  13.  
  14.   fs[n]();
  15. }
  16.  
  17. template <typename... Args, typename F>
  18. void match(size_t n, const std::tuple<Args...>& t, const F& f )
  19. {
  20.   match_impl(n, t, f, std::index_sequence_for<Args...>{});
  21. }
  22.  
  23. int main() {
  24.   auto tuple = std::make_tuple(1, '2', 3.33, std::string("abcdef"));
  25.  
  26.   int tuple_index = 3;
  27.  
  28.   auto visitor = [](const auto& tuple_value) {
  29.     std::cout << tuple_value << std::endl;
  30.   };
  31.  
  32.   match(tuple_index, tuple, visitor);
  33.  
  34.   return 0;
  35. }
Success #stdin #stdout 0s 4528KB
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stdin
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Standard input is empty
stdout
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abcdef
https://ideone.com/bwvuuC
language:
C++14 (gcc 8.3)
created:
3 years ago
visibility:
public

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