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  1. #include <iostream>
  2. #include <vector>
  3. #include <algorithm>
  4. #include <numeric>
  5. #include <functional>
  6. #include <iterator>
  7. using namespace std;
  8. using namespace std::placeholders;
  9.  
  10. class sequence {
  11.  
  12.   vector<int> data;
  13.  
  14.   public:
  15.     typedef vector<int>::const_iterator it;
  16.  
  17.     // add
  18.     sequence& operator<<(int rhs) { 
  19.       data.push_back(rhs);
  20.       return *this;
  21.     }
  22.  
  23.     // reduce
  24.     sequence& operator<<(function<int(int,int)> binary_op) {
  25.       if (data.size() > 1) {
  26.         const int result = accumulate (data.begin()+1, data.end(), *data.begin(), binary_op);
  27.         data.clear();
  28.         data.push_back (result);
  29.       }
  30.       return *this;
  31.     }
  32.  
  33.     // map
  34.     sequence& operator<<(function<int(int)> unary_op) {
  35.       transform(data.begin(), data.end(), data.begin(), unary_op);      
  36.       return *this;
  37.     }
  38.  
  39.     // manipulate
  40.     sequence& operator<<(function<void(vector<int>::const_iterator begin, vector<int>::const_iterator end)> manip) {
  41.       manip (data.begin(), data.end());
  42.       return *this;
  43.     }
  44. };
  45.  
  46. // functional objects
  47. auto sum = plus<int>();
  48. auto prod = multiplies<int>();
  49.  
  50. // template functor
  51. struct out {
  52.   ostream& os_;
  53.   out (ostream& os) : os_(os) {}
  54.  
  55.   template <typename Iterator>
  56.   void operator ()(Iterator begin, Iterator end) {
  57.     copy (begin, end, ostream_iterator<typename Iterator::value_type>(os_," "));  
  58.     os_ << endl;
  59.   }
  60. };
  61.  
  62. auto out_cout=out(cout);
  63.  
  64. // lambda
  65. auto change_sign = [](int x)->int { return -x; };
  66.  
  67. // function
  68. int sqr (int x) { return x*x; }
  69.  
  70. int main() {
  71. 	sequence seq;
  72.     seq << 1 << 2 << 3 << out_cout 
  73.         << sum << out_cout
  74.         << 4 << 5 << prod << out_cout
  75.         << 2 << sqr << out_cout
  76.         << -42 << change_sign << out_cout;
  77. }
  78.  
Success #stdin #stdout 0s 3476KB
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stdin
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Standard input is empty
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1 2 3 
6 
120 
14400 4 
-14400 -4 42
https://ideone.com/YnvBqL
language:
C++14 (gcc 8.3)
created:
12 years ago
visibility:
public

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