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  1. #include <iostream>
  2.  
  3. namespace live_without_statements
  4. {
  5.  
  6.     template <typename Action> void exec(Action action)
  7.     {
  8.         action();
  9.     }
  10.  
  11.     template <typename Action> void skip(Action action) {
  12.         (void)action;
  13.     }
  14.  
  15.     template <typename Then>
  16.     void if_op(bool cond, Then thenAction)
  17.     {
  18.         void (*fns[])(Then) = {&skip, &exec};
  19.         fns[cond](thenAction);
  20.     }
  21.  
  22.     template <typename Then, typename Else>
  23.     void if_op(bool cond, Then t, Else e)
  24.     {
  25.         if_op(cond, t);
  26.         if_op(!cond, e);
  27.     }
  28.  
  29.     template <typename Cond, typename Body, size_t level>
  30.     struct looper
  31.     {
  32.         static bool loop(Cond cond, Body body)
  33.         {
  34.             bool c = looper<Cond, Body, level-1>::loop(cond, body);
  35.             if_op(c, [&c, &cond, &body](){c = looper<Cond, Body, level-1>::loop(cond, body);});
  36.             return c;
  37.         }
  38.     };
  39.  
  40.     template <typename Cond, typename Body>
  41.     struct looper<Cond, Body, 0>
  42.     {
  43.         static bool loop(Cond cond, Body body)
  44.         {
  45.             bool c = cond();
  46.             if_op(c, body);
  47.             return c;
  48.         }
  49.     };
  50.  
  51.     // don't worry, thermal death of the universe will happen earlier...
  52.     const int level_limit = 128; 
  53.  
  54.     template <typename Cond, typename Body>
  55.     void while_op(Cond cond, Body body)
  56.     {
  57.         looper<Cond, Body, level_limit>::loop(cond, body);
  58.     }
  59. }
  60.  
  61. int main()
  62. {
  63.     using namespace live_without_statements;
  64.  
  65.     int a[] {1, 7, 3, 2, 8, 4, 2, 5, 9, 0};
  66.  
  67.     size_t len = sizeof(a) / sizeof(a[0]);
  68.  
  69.     size_t i = 0;
  70.     while_op([&](){return i < len - 1;}, [&](){
  71.         size_t j = 0;
  72.         while_op([&](){return j < len - i - 1;}, [&](){
  73.             if_op(a[j] > a[j+1], [&](){std::swap(a[j], a[j+1]);});
  74.             ++j;
  75.         });
  76.         ++i;
  77.     });
  78.  
  79.     i = 0;
  80.     while_op([&](){return i < 10;}, [&](){
  81.         std::cout << "a[" << i << "] = " << a[i] << std::endl;
  82.         ++i;
  83.     });
  84.  
  85.     return 0;
  86. }
Success #stdin #stdout 0s 3608KB
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stdin
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Standard input is empty
stdout
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a[0] = 0
a[1] = 1
a[2] = 2
a[3] = 2
a[4] = 3
a[5] = 4
a[6] = 5
a[7] = 7
a[8] = 8
a[9] = 9
https://ideone.com/vSRw1c
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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