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  1. #include <iostream>
  2. #include <string>
  3. #include <vector>
  4. #include <iterator>
  5.  
  6. namespace internal
  7. {
  8.     class PREORDER {};
  9.     class POSTORDER {};
  10.  
  11.     // ----------------------------------------------------------------------------------
  12.     template<typename P, typename IT>
  13.     class my_iterator;
  14.  
  15.  
  16.     template<typename P>
  17.     class my_iterator<P, PREORDER>
  18.     : public std::iterator<std::forward_iterator_tag, P>
  19.     {
  20.     private:
  21.         int index;
  22.     protected:
  23.     public:
  24.         my_iterator () { index = 0; }
  25.  
  26.         my_iterator& operator++ () {
  27.             std::cout << "Preorder visit of GenericTree of nodes containing int values." << std::endl;
  28.             return (*this);
  29.         }
  30.     };
  31.     // ----------------------------------------------------------------------------------
  32.     template<typename P>
  33.     class my_iterator<P, POSTORDER>
  34.     : public std::iterator<std::forward_iterator_tag, P>
  35.     {
  36.     private:
  37.         int index;
  38.     protected:
  39.     public:
  40.         my_iterator () { index = 0; }
  41.  
  42.         my_iterator& operator++ () {
  43.             std::cout << "Postorder visit of GenericTree of nodes containing int values." << std::endl;
  44.             return (*this);
  45.         }
  46.     };
  47.  
  48. }
  49.  
  50. template<typename P> class GenericTree
  51. {
  52. public:
  53.     template <typename IT>
  54.     using my_iterator = internal::my_iterator<P, IT>;
  55.     using PREORDER = internal::PREORDER;
  56.     using POSTORDER = internal::POSTORDER;
  57.  
  58.     std::vector<P> data;
  59.     GenericTree () {}
  60.     ~GenericTree () {}
  61. };
  62.  
  63.  
  64.  
  65. int main ()
  66. {
  67.     GenericTree<int> c_int;
  68.     GenericTree<int>::my_iterator<GenericTree<int>::PREORDER> iterator_int;
  69.  
  70.     ++iterator_int;
  71.  
  72.     GenericTree<std::string> c_string;
  73.     GenericTree<std::string>::my_iterator<GenericTree<std::string>::POSTORDER> iterator_str;
  74.  
  75.     ++iterator_str;
  76.     return 0;
  77. }
  78.  
Success #stdin #stdout 0s 3340KB
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Preorder visit of GenericTree of nodes containing int values.
Postorder visit of GenericTree of nodes containing int values.
https://ideone.com/m34mga
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
secret

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