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  1. #include <iterator>
  2. #include <type_traits>
  3. #include <utility>
  4.  
  5.     template<typename T, typename=void>
  6.     struct is_iterable : std::false_type {};
  7.  
  8.     namespace aux {
  9.       using std::begin;
  10.       // note: no implementation
  11.       template<typename C>
  12.       auto adl_begin( C&& c )->decltype( begin( std::forward<C>(c) ) );
  13.       using std::end;
  14.       // note: no implementation
  15.       template<typename C>
  16.       auto adl_end( C&& c )->decltype( end( std::forward<C>(c) ) );
  17.     }
  18.     template<typename T>
  19.     struct is_iterable<T,
  20.       typename std::enable_if<
  21.         std::is_same<
  22.           typename std::iterator_traits< typename std::decay<decltype( aux::adl_begin( std::declval<T>() ) )>::type >::iterator_category,
  23.           typename std::iterator_traits< typename std::decay<decltype( aux::adl_end( std::declval<T>() ) )>::type >::iterator_category
  24.         >::value
  25.       >::type
  26.     > : std::true_type {};
  27. #include <vector>
  28. #include <iostream>
  29. int main() {
  30.     std::cout << is_iterable< std::vector<int> >::value << "\n";
  31.     std::cout << is_iterable< int >::value << "\n";
  32. }
Success #stdin #stdout 0s 2852KB
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https://ideone.com/Fw6R84
language:
C++14 (gcc 8.3)
created:
12 years ago
visibility:
secret

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