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  1. #include <iostream>
  2. #include <type_traits>
  3. #include <string>
  4. #include <limits>
  5.  
  6. template<typename T>
  7. using StringReplaceIsInPlace = std::conditional_t<std::is_lvalue_reference<T>::value && !std::is_const<std::remove_reference_t<T>>::value, std::true_type, std::false_type>;
  8.  
  9. template<typename Str, typename = std::enable_if_t<StringReplaceIsInPlace<Str>::value>>
  10. Str StringReplace(
  11.     Str&& str,
  12.     const std::remove_reference_t<Str>& from,
  13.     const std::remove_reference_t<Str>& to
  14. ) {
  15.     std::cout << "in place: " << __PRETTY_FUNCTION__ << std::endl;
  16.     return std::forward<Str>(str);
  17. }
  18.  
  19. template<typename Str, typename = std::enable_if_t<!StringReplaceIsInPlace<Str>::value>>
  20. std::decay_t<Str> StringReplace(
  21.     Str&& str, // const lvalues and rvalues
  22.     const std::remove_reference_t<Str>& from,
  23.     const std::remove_reference_t<Str>& to
  24. ) {
  25.     std::cout << "in a copy: " << __PRETTY_FUNCTION__ << std::endl;
  26.     std::decay_t<Str> mutableStr{std::forward<Str>(str)};
  27.     StringReplace(mutableStr, from, to);
  28.     return mutableStr;
  29. }
  30.  
  31. int main()
  32. {
  33.     {
  34.         std::cout << "lvalue" << std::endl;
  35.         std::string v;
  36.         StringReplace(v, "", "");
  37.     }
  38.  
  39.     {
  40.         std::cout << std::endl << "const lvalue" << std::endl;
  41.         const std::string v;
  42.         StringReplace(v, "", "");
  43.     }
  44.  
  45.     {
  46.         std::cout << std::endl << "lvalue reference" << std::endl;
  47.         std::string v;
  48.         std::string& vref = v;
  49.         StringReplace(vref, "", "");
  50.     }
  51.  
  52.     {
  53.         std::cout << std::endl << "const lvalue reference" << std::endl;
  54.         std::string v;
  55.         const std::string& vref = v;
  56.         StringReplace(vref, "", "");
  57.     }
  58.  
  59.     {
  60.         std::cout << std::endl << "rvalue" << std::endl;
  61.         std::string v;
  62.         StringReplace(std::move(v), "", "");
  63.     }
  64.  
  65.     {
  66.         std::cout << std::endl << "const rvalue" << std::endl;
  67.         const std::string v;
  68.         StringReplace(std::move(v), "", "");
  69.     }
  70.  
  71.     {
  72.         std::cout << std::endl << "rvalue reference" << std::endl;
  73.         std::string&& v = std::string();
  74.         StringReplace(v, "", "");
  75.     }
  76.  
  77.     {
  78.         std::cout << std::endl << "const rvalue reference" << std::endl;
  79.         const std::string&& v = std::string();
  80.         StringReplace(v, "", "");
  81.     }
  82.  
  83.     {
  84.         std::cout << std::endl << "string literal" << std::endl;
  85.         StringReplace<std::string>("", "", "");
  86.     }
  87.  
  88. 	return 0;
  89. }
Success #stdin #stdout 0s 4500KB
comments (?)
stdin 
Standard input is empty
stdout 
lvalue
in place: Str StringReplace(Str&&, std::remove_reference_t<T>&, std::remove_reference_t<T>&) [with Str = std::__cxx11::basic_string<char>&; <template-parameter-1-2> = void; std::remove_reference_t<T> = std::__cxx11::basic_string<char>]

const lvalue
in a copy: std::decay_t<Str> StringReplace(Str&&, std::remove_reference_t<T>&, std::remove_reference_t<T>&) [with Str = const std::__cxx11::basic_string<char>&; <template-parameter-1-2> = void; std::decay_t<Str> = std::__cxx11::basic_string<char>; std::remove_reference_t<T> = const std::__cxx11::basic_string<char>]
in place: Str StringReplace(Str&&, std::remove_reference_t<T>&, std::remove_reference_t<T>&) [with Str = std::__cxx11::basic_string<char>&; <template-parameter-1-2> = void; std::remove_reference_t<T> = std::__cxx11::basic_string<char>]

lvalue reference
in place: Str StringReplace(Str&&, std::remove_reference_t<T>&, std::remove_reference_t<T>&) [with Str = std::__cxx11::basic_string<char>&; <template-parameter-1-2> = void; std::remove_reference_t<T> = std::__cxx11::basic_string<char>]

const lvalue reference
in a copy: std::decay_t<Str> StringReplace(Str&&, std::remove_reference_t<T>&, std::remove_reference_t<T>&) [with Str = const std::__cxx11::basic_string<char>&; <template-parameter-1-2> = void; std::decay_t<Str> = std::__cxx11::basic_string<char>; std::remove_reference_t<T> = const std::__cxx11::basic_string<char>]
in place: Str StringReplace(Str&&, std::remove_reference_t<T>&, std::remove_reference_t<T>&) [with Str = std::__cxx11::basic_string<char>&; <template-parameter-1-2> = void; std::remove_reference_t<T> = std::__cxx11::basic_string<char>]

rvalue
in a copy: std::decay_t<Str> StringReplace(Str&&, std::remove_reference_t<T>&, std::remove_reference_t<T>&) [with Str = std::__cxx11::basic_string<char>; <template-parameter-1-2> = void; std::decay_t<Str> = std::__cxx11::basic_string<char>; std::remove_reference_t<T> = std::__cxx11::basic_string<char>]
in place: Str StringReplace(Str&&, std::remove_reference_t<T>&, std::remove_reference_t<T>&) [with Str = std::__cxx11::basic_string<char>&; <template-parameter-1-2> = void; std::remove_reference_t<T> = std::__cxx11::basic_string<char>]

const rvalue
in a copy: std::decay_t<Str> StringReplace(Str&&, std::remove_reference_t<T>&, std::remove_reference_t<T>&) [with Str = const std::__cxx11::basic_string<char>; <template-parameter-1-2> = void; std::decay_t<Str> = std::__cxx11::basic_string<char>; std::remove_reference_t<T> = const std::__cxx11::basic_string<char>]
in place: Str StringReplace(Str&&, std::remove_reference_t<T>&, std::remove_reference_t<T>&) [with Str = std::__cxx11::basic_string<char>&; <template-parameter-1-2> = void; std::remove_reference_t<T> = std::__cxx11::basic_string<char>]

rvalue reference
in place: Str StringReplace(Str&&, std::remove_reference_t<T>&, std::remove_reference_t<T>&) [with Str = std::__cxx11::basic_string<char>&; <template-parameter-1-2> = void; std::remove_reference_t<T> = std::__cxx11::basic_string<char>]

const rvalue reference
in a copy: std::decay_t<Str> StringReplace(Str&&, std::remove_reference_t<T>&, std::remove_reference_t<T>&) [with Str = const std::__cxx11::basic_string<char>&; <template-parameter-1-2> = void; std::decay_t<Str> = std::__cxx11::basic_string<char>; std::remove_reference_t<T> = const std::__cxx11::basic_string<char>]
in place: Str StringReplace(Str&&, std::remove_reference_t<T>&, std::remove_reference_t<T>&) [with Str = std::__cxx11::basic_string<char>&; <template-parameter-1-2> = void; std::remove_reference_t<T> = std::__cxx11::basic_string<char>]

string literal
in a copy: std::decay_t<Str> StringReplace(Str&&, std::remove_reference_t<T>&, std::remove_reference_t<T>&) [with Str = std::__cxx11::basic_string<char>; <template-parameter-1-2> = void; std::decay_t<Str> = std::__cxx11::basic_string<char>; std::remove_reference_t<T> = std::__cxx11::basic_string<char>]
in place: Str StringReplace(Str&&, std::remove_reference_t<T>&, std::remove_reference_t<T>&) [with Str = std::__cxx11::basic_string<char>&; <template-parameter-1-2> = void; std::remove_reference_t<T> = std::__cxx11::basic_string<char>]
https://ideone.com/TulRXJ
language:
C++14 (gcc 8.3)
created:
6 years ago
visibility:
public

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