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  1. namespace mpl
  2. {
  3.  
  4. namespace detail
  5. {
  6.  
  7. template < typename... >
  8. struct tuple_;
  9.  
  10. } // namespace detail
  11.  
  12. template < unsigned int x >
  13. struct arg
  14. {
  15.     static constexpr unsigned int value = x;
  16. };
  17.  
  18. typedef arg< 1 > _1;
  19.  
  20. template < typename F, typename... T >
  21. struct apply
  22. {
  23.     typedef typename F::template apply<
  24.       typename F::template replace< T... >::type >::type type;
  25. };
  26.  
  27. template < typename T >
  28. struct lambda;
  29.  
  30. template < template < typename... > class F, typename... Args >
  31. struct lambda< F< Args... > >
  32. {
  33.     template < typename >
  34.     struct apply;
  35.  
  36.     template < typename... T >
  37.     struct apply< detail::tuple_< T... > >
  38.     {
  39.         typedef typename F< T... >::type type;
  40.     };
  41.  
  42.     template < typename P, typename... T >
  43.     struct replace_detail
  44.     {
  45.         template < unsigned int, typename U, typename... >
  46.         struct replace_impl
  47.         {
  48.             typedef U type;
  49.         };
  50.  
  51.         template < unsigned int n, unsigned int x,
  52.                    typename Head, typename... Tail >
  53.         struct replace_impl< n, arg< x >, Head, Tail... >
  54.           : public replace_impl< n + 1, arg< x >, Tail... > {};
  55.  
  56.         template < unsigned int x, typename Head, typename... Tail >
  57.         struct replace_impl< x, arg< x >, Head, Tail... >
  58.         {
  59.             typedef Head type;
  60.         };
  61.  
  62.         typedef typename replace_impl< 1, P, T... >::type type;
  63.     };
  64.  
  65.     template < typename... T >
  66.     struct replace
  67.     {
  68.         typedef detail::tuple_< typename replace_detail< Args, T... >::type... > type;
  69.     };
  70. };
  71.  
  72. } // namespace mpl
  73.  
  74. template < typename T >
  75. struct add_pointer
  76. { typedef T * type; };
  77.  
  78. template < typename, typename >
  79. struct is_same
  80. {
  81.     static constexpr bool value = false;
  82. };
  83.  
  84. template < typename T >
  85. struct is_same< T, T >
  86. {
  87.     static constexpr bool value = true;
  88. };
  89.  
  90. static_assert(
  91.   is_same<
  92.     mpl::apply<
  93.       mpl::lambda< add_pointer< mpl::_1 > >,
  94.       int >::type,
  95.     int * >::value, "types are not same" );
  96.  
Compilation error #stdin compilation error #stdout 0s 0KB
comments (?)
stdin 
Standard input is empty
compilation info 
/usr/lib/gcc/i686-pc-linux-gnu/4.5.1/../../../crt1.o: In function `_start':
(.text+0x18): undefined reference to `main'
collect2: ld returned 1 exit status
stdout 
Standard output is empty
https://ideone.com/92NuQ
language:
C++14 (gcc 8.3)
created:
13 years ago
visibility:
secret

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