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  1. #include <type_traits>
  2. #include <unordered_map>
  3. #include <vector>
  4. #include <queue>
  5. #include <iostream>
  6. #include <map>
  7. #include <memory>
  8. #include <functional>
  9. #include <cmath>
  10. #include <list>
  11.  
  12. #include <boost/iterator/transform_iterator.hpp>
  13. #include <boost/core/demangle.hpp>
  14.  
  15. namespace xstd
  16. {
  17.    template <typename Container>
  18.     struct container_traits
  19.     {
  20.  
  21.     };
  22.  
  23.     template <template <typename, typename> typename ValueContainer, 
  24.         typename Value, 
  25.         typename Allocator>
  26.     struct container_traits<ValueContainer<Value, Allocator>> {
  27.         using container_type = ValueContainer<Value, Allocator>;
  28.         using allocator_type = typename container_type::allocator_type;
  29.         using allocator_traits = std::allocator_traits<allocator_type>;
  30.  
  31.         using value_type = Value;
  32.  
  33.         template <typename U>
  34.         using rebound_allocator_type = typename allocator_traits::template rebind_alloc<U>;
  35.  
  36.         template <typename U>
  37.         using rebound_container_type = ValueContainer<U, rebound_allocator_type<U>>;
  38.     };
  39.  
  40.     template <template <typename, typename, typename, typename> typename KeyValueContainer, 
  41.         typename Key, 
  42.         typename Value, 
  43.         template <typename> typename Less, 
  44.         typename Allocator>
  45.     struct container_traits<KeyValueContainer<Key, Value, Less<Key>, Allocator>> {
  46.         using container_type = KeyValueContainer<Key, Value, Less<Key>, Allocator>;
  47.         using allocator_type = typename container_type::allocator_type;
  48.         using less_type = Less<Key>;
  49.         using allocator_traits = std::allocator_traits<allocator_type>;
  50.  
  51.         using key_type = Key;
  52.         using value_type = Value;
  53.  
  54.         template <typename U>
  55.         using rebound_allocator_type = typename allocator_traits::template rebind_alloc<U>;
  56.  
  57.         template <typename U>
  58.         using rebound_compare_type = Less<U>;
  59.  
  60.         template <typename T, typename U>
  61.         using rebound_kv_container_type = KeyValueContainer<T, U, rebound_compare_type<T>, rebound_allocator_type<std::pair<T, U>>>;
  62.  
  63.         template <typename T, 
  64.             typename U = rebound_allocator_type<T>, 
  65.             template <typename, typename> typename Container = std::vector>
  66.         using rebound_container_type = Container<T, U>;
  67.     };
  68.  
  69.  
  70.     template <template <typename, size_t> typename Container, typename T, size_t N>
  71.     struct container_traits<Container<T, N>>
  72.     {
  73.         using container_type = Container<T, N>;
  74.         using value_type = T;
  75.         constexpr static const size_t arity = N;
  76.  
  77.         template <typename U>
  78.         using rebound_container_type = Container<U, arity>;
  79.     };
  80.  
  81.     template <typename T, 
  82.         typename Container, 
  83.         typename U>
  84.     auto transform(Container const& source, std::function<U(T*)> fn) 
  85.         -> std::enable_if<
  86.             std::is_same<
  87.                 typename container_traits<Container>::value_type, 
  88.                 typename std::add_pointer<T>::type
  89.             >::value, 
  90.             typename container_traits<Container>::template rebound_container_type<U>
  91.         > {
  92.         auto begin = boost::make_transform_iterator(source.begin(), fn);
  93.         auto end = boost::make_transform_iterator(source.end(), fn);
  94.  
  95.         using target_t = typename container_traits<Container>::template rebound_container_type<U>;
  96.         target_t transformed(begin, end);
  97.         return transformed;
  98.     }
  99.  
  100.     template <typename T, 
  101.         typename Container, 
  102.         typename U>
  103.     auto transform(Container const& source, std::function<U(T const&)> fn) 
  104.         -> typename container_traits<Container>::template rebound_container_type<U> {
  105.         auto begin = boost::make_transform_iterator(source.begin(), fn);
  106.         auto end = boost::make_transform_iterator(source.end(), fn);
  107.  
  108.         using target_t = typename container_traits<Container>::template rebound_container_type<U>;
  109.         target_t transformed(begin, end);
  110.         return transformed;
  111.     }
  112.  
  113.     // Resolves for free-standing function pointer arguments
  114.     template <typename U, typename Container, typename T>
  115.     auto transform(Container const& source, U (*fn)(T)) 
  116.         -> typename container_traits<Container>::template rebound_container_type<U> {
  117.         auto begin = boost::make_transform_iterator(source.begin(), fn);
  118.         auto end = boost::make_transform_iterator(source.end(), fn);
  119.  
  120.         using target_t = typename container_traits<Container>::template rebound_container_type<U>;
  121.         target_t transformed(begin, end);
  122.         return transformed;
  123.     }
  124.  
  125.     template <typename Container, typename Transform>
  126.     auto transform(Container const& source, Transform fn) 
  127.         -> typename container_traits<Container>::template rebound_container_type<
  128.             typename std::result_of<Transform(typename container_traits<Container>::value_type)>::type
  129.         > {
  130.         auto begin = boost::make_transform_iterator(source.begin(), fn);
  131.         auto end = boost::make_transform_iterator(source.end(), fn);
  132.  
  133.         using U = typename std::result_of<Transform(typename container_traits<Container>::value_type)>::type;
  134.  
  135.         using target_t = typename container_traits<Container>::template rebound_container_type<U>;
  136.         target_t transformed(begin, end);
  137.         return transformed;
  138.     }
  139.  
  140.     template <template <typename, size_t> typename Container, typename T, size_t N, typename Transform>
  141.     auto transform(Container<T, N> const& source, Transform fn) 
  142.         -> typename container_traits<Container<T, N>>::template rebound_container_type<
  143.             typename std::result_of<Transform(typename container_traits<Container<T, N>>::value_type)>::type
  144.         > {
  145.  
  146.         using U = typename std::result_of<Transform(typename container_traits<Container<T, N>>::value_type)>::type;
  147.  
  148.         using target_t = typename container_traits<Container<T, N>>::template rebound_container_type<U>;
  149.         target_t transformed;
  150.  
  151.         for (size_t i = 0; i < N; ++i) {
  152.             transformed[i] = fn(source[i]);
  153.         }
  154.  
  155.         return transformed;
  156.     }
  157. }
  158.  
  159. int round(float f) { return std::round(f); }
  160.  
  161. int main()
  162. {
  163.     using vint_trait = xstd::container_traits<std::vector<int>>;
  164.     using ftype = typename vint_trait::template rebound_container_type<float>;
  165.  
  166.     using mintfloat_trait = xstd::container_traits<std::map<int, float>>;
  167.     using miftype = typename mintfloat_trait::template rebound_kv_container_type<float, int>;
  168.  
  169.     using mitype = typename mintfloat_trait::template rebound_container_type<float>;
  170.  
  171.     std::cout << boost::core::demangle(typeid(ftype).name()) << std::endl;
  172.     std::cout << boost::core::demangle(typeid(miftype).name()) << std::endl;
  173.     std::cout << boost::core::demangle(typeid(mitype).name()) << std::endl;
  174.  
  175.     {
  176.         std::vector<int> is { 1, 2, 3, 4, 5 };
  177.         std::vector<float> fs = xstd::transform(is, [](int i) -> float { return float(0.5f + i); });
  178.         for (auto&& itr : fs) {
  179.             std::cout << itr << " ";
  180.         }std::cout << std::endl;
  181.     }
  182.  
  183.     {
  184.         std::array<int, 5> ia { 1, 2, 3, 4, 5 };
  185.         std::array<float, 5> fa = xstd::transform(ia, [](int i) -> float { return float(0.75f + i); });
  186.         for (auto&& itr : fa) {
  187.             std::cout << itr << " ";
  188.         }
  189.         std::cout << std::endl; 
  190.     }
  191.     return 0;
  192. }
  193.  
Success #stdin #stdout 0s 15240KB
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Standard input is empty
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std::vector<float, std::allocator<float> >
std::map<float, int, std::less<float>, std::allocator<std::pair<float, int> > >
std::vector<float, std::allocator<float> >
1.5 2.5 3.5 4.5 5.5 
1.75 2.75 3.75 4.75 5.75
https://ideone.com/Lov2CD
language:
C++ (gcc 8.3)
created:
7 years ago
visibility:
public

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