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  1. #include <tuple>
  2. #include <string>
  3. #include <sstream>
  4. #include <type_traits>
  5.  
  6. template<bool I>
  7. using Bool = std::integral_constant<bool, I>;
  8.  
  9. template<typename T>
  10. using EnableIf = typename std::enable_if<T::value>::type;
  11.  
  12. namespace detail {
  13. template<size_t N = 0, class Elem, class Traits, typename... Args, EnableIf<Bool<(N >= sizeof...(Args))>>...>
  14. inline void helper(std::basic_ostream<Elem,Traits>& out, const size_t i, const std::tuple<Args...>& tup) {}
  15. template<size_t N = 0, class Elem, class Traits, typename... Args, EnableIf<Bool<(N < sizeof...(Args))>>...>
  16. inline void helper(std::basic_ostream<Elem,Traits>& out, const size_t i, const std::tuple<Args...>& tup) {
  17.     if(i == N) {
  18.         out << std::get<N>(tup);
  19.     }
  20.     else {
  21.         helper<N+1, Elem, Traits, Args...>(out, i, tup);
  22.     }
  23. }
  24. } // detail
  25.  
  26.  
  27. // {{{{{0},1 prints {{1
  28.  
  29. template<size_t N = 0, typename... Args>
  30. std::string format(const std::string& str, Args&&... args) {
  31.     if(sizeof...(args) < 1)
  32.         return str;
  33.     auto tup = std::make_tuple(std::forward<Args>(args)...);
  34.     auto first = std::begin(str);
  35.     auto last = std::end(str);
  36.     size_t index = 0;
  37.     std::ostringstream out;
  38.     while(first != last) {
  39.         if(*first != '{') {
  40.             out << *first++;
  41.             continue;
  42.         }
  43.         else { // If it's a { character
  44.             auto check = first;
  45.             if(++check == last || *check == '}') {
  46.                 // Special cases.
  47.                 out << *first++;
  48.                 continue;
  49.             }
  50.             index = 0;
  51.             // Keep incrementing the index.
  52.             while(check != last && (*check >= '0' && *check <= '9')) {
  53.                 index *= 10;
  54.                 index += ((*check) - '0');
  55.                 ++check;
  56.             }
  57.             if(*check == '}') {
  58.                 detail::helper(out, index, tup);
  59.                 ++check;
  60.             }
  61.             else {
  62.                 out << *check;
  63.             }
  64.             first = check;
  65.         }
  66.     }
  67.     std::string result = out.str();
  68.     return result;
  69. }
  70.  
  71. #include <iostream>
  72.  
  73. int main() {
  74.     std::cout << format("{{{{{0}",1) << '\n' << format("{{{{{0}{{",1) << '\n' << format("{{{{{0}{{}{}",1) << '\n';
  75.     auto a = format("{0},{1},{2},{3},{4},{5},{6},{7},{8},{9},{10},{11}", 1,2,3,4,5,6,7,8,9,10,11,12);
  76.     auto b = format("{0} + {0} = {1}", 2, 4);
  77.     std::cout << format(4 > 5 ? "({0})" : "[{0}]", 10) << '\n' << a << '\n' << b;
  78. }
  79.  
Success #stdin #stdout 0s 2992KB
comments (?)
stdin 
Standard input is empty
stdout 
{{{{1
{{{{1{{
{{{{1{{}{}
[10]
1,2,3,4,5,6,7,8,9,10,11,12
2 + 2 = 4
https://ideone.com/WrTaUG
language:
C++14 (gcc 8.3)
created:
12 years ago
visibility:
public

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