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  1. #include <type_traits>
  2. #include <memory>
  3. #include <iterator>
  4. #include <algorithm>
  5. #include <iostream>
  6. #include <iomanip>
  7. #include <vector>
  8. #include <list>
  9.  
  10. template < typename ALLOCATOR, typename T >
  11. using rebind_to_type = typename std::allocator_traits<ALLOCATOR>::template rebind_alloc<T> ;
  12.  
  13. template < typename ALLOCATOR, typename FN, typename T >
  14. using rebind_to_result_type = rebind_to_type< ALLOCATOR, typename std::result_of< FN(T) >::type > ;
  15.  
  16. template < typename U, typename T, typename A, template<typename,typename> class CONTAINER >
  17. CONTAINER< U, rebind_to_type<A,U> > adapt( const CONTAINER<T,A>& c )
  18. {   return CONTAINER< U, rebind_to_type<A,U> >( c.begin(), c.end() ) ; }
  19.  
  20. template < typename T, typename A, template<typename,typename> class CONTAINER, typename FN >
  21. CONTAINER< typename std::result_of< FN(T) >::type, rebind_to_result_type<A,FN,T> >
  22. adapt( const CONTAINER<T,A>& c, FN fn )
  23. {
  24.     CONTAINER< typename std::result_of< FN(T) >::type, rebind_to_result_type<A,FN,T> > result ;
  25.     std::transform( c.begin(), c.end(), std::back_inserter(result), fn ) ;
  26.     return result ;
  27. }
  28.  
  29. int main()
  30. {
  31.     std::cout << std::fixed << std::showpoint << std::setprecision(2) ;
  32.  
  33.     std::vector<int> vec { 64, 74, 77, 87, 58, 58, 75, 87 } ;
  34.     for( auto i : vec ) std::cout << i << ' ' ;
  35.     std::cout << '\n' ;
  36.  
  37.     // implicit conversion int to double => std::vector<int> => std::vector<double>
  38.     auto vec2 = adapt<double>(vec) ;
  39.     for( auto d : vec2 ) std::cout << d << ' ' ;
  40.     std::cout << '\n' ;
  41.  
  42.     std::list<short> lst( vec.rbegin(), vec.rend() ) ;
  43.     for( auto s : lst ) std::cout << s << ' ' ;
  44.     std::cout << '\n' ;
  45.  
  46.     // explicit transformation short to double => std::list<short> => std::list<double>
  47.     auto lst2 = adapt( lst, [] ( int v ) { return v*v / 100.0 ; } ) ;
  48.     for( auto d : lst2 ) std::cout << d << ' ' ;
  49.     std::cout << '\n' ;
  50.  
  51.     struct base { int i ; }; struct offset { int i ; }; struct derived : offset, base {} ;
  52.     std::vector<derived*> vec3 { new derived, new derived, new derived } ;
  53.     for( auto p : vec3 ) std::cout << p << ' ' ;
  54.     std::cout << '\n' ;
  55.  
  56.     // implicit conversion derived* to base* => std::vector<base*> => std::vector<derived*>
  57.     std::vector<base*> vec4 = adapt<base*>(vec3) ;
  58.     for( auto p : vec4 ) std::cout << p << ' ' ;
  59.     std::cout << '\n' ;
  60. }
  61.  
Success #stdin #stdout 0s 2988KB
comments (?)
stdin
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Standard input is empty
stdout
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64 74 77 87 58 58 75 87 
64.00 74.00 77.00 87.00 58.00 58.00 75.00 87.00 
87 75 58 58 87 77 74 64 
75.69 56.25 33.64 33.64 75.69 59.29 54.76 40.96 
0x8c8d1b8 0x8c8d1c8 0x8c8d1d8 
0x8c8d1bc 0x8c8d1cc 0x8c8d1dc
https://ideone.com/4Lz8M2
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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