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  1. #include <iostream>
  2. #include <vector>
  3. #include <iterator>
  4. #include <algorithm>
  5. using namespace std;
  6.  
  7. template <class F>
  8. class generator{
  9. public:
  10. //typedefs required for iterator-use
  11. typedef typename F::value_type value_type;
  12. typedef typename F::step_type step_type;
  13. typedef value_type * pointer;
  14. typedef value_type & reference;
  15. typedef typename F::size_type size_type;
  16. typedef typename F::difference_type difference_type;
  17. typedef std::bidirectional_iterator_tag iterator_category;
  18.  
  19. generator(value_type init, step_type step) : t(init), step(step){}
  20.  
  21. generator<F> &operator++() {
  22.     t += step; return *this;
  23. }
  24.  
  25. generator<F> &
  26. operator+=(size_type n)
  27. {
  28.     t += n * step;
  29.     return *this;
  30. }
  31.  
  32. generator<F>
  33. operator+(size_type n)
  34. {
  35.     return generator(*this) += n;
  36. }
  37.  
  38. value_type operator*() const {
  39.     return f(t);
  40. }
  41.  
  42. friend bool operator==(const generator<F> &lhs, const generator<F> &rhs){
  43.         return lhs.t == rhs.t;
  44. }
  45. friend bool operator!=(const generator<F> &lhs, const generator<F> &rhs){
  46.         return !(lhs == rhs);
  47. }
  48. private:
  49.     value_type t;
  50.     value_type step;
  51.     F f;
  52. };
  53.  
  54. template <typename T>
  55.     struct simple_generator_function
  56.     {
  57.         typedef T value_type;
  58.         typedef T step_type;
  59.         typedef T difference_type;
  60.         typedef size_t size_type;
  61.     };
  62.  
  63.     template <typename T>
  64.     struct square_generator : public simple_generator_function<T> {
  65.  
  66.         T operator()(T t) const{
  67.             return t * t;
  68.         }
  69.     };
  70.  
  71.  
  72. int main(void) {
  73.         using int_sqg = generator<square_generator<int>>;
  74.         int_sqg gen(1, 1);
  75.         vector<int> v(gen, gen+10);
  76.         copy(begin(v), end(v), ostream_iterator<int>(cout, ","));
  77.         cout << '\n';
  78.     }
Success #stdin #stdout 0s 3272KB
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stdin
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Standard input is empty
stdout
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1,4,9,16,25,36,49,64,81,100,
https://ideone.com/9Ph5el
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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