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  1. #include <iostream>
  2. #include <memory>
  3.  
  4. #define CONCAT2(x, y) x ## y
  5. #define CONCAT(x, y) CONCAT2(x, y)
  6.  
  7. #ifdef _WIN32
  8.  
  9. #define GET_LABEL_PTR(p, label)\
  10.   {\
  11.     void* _theLabelPointer;\
  12.     __asm { mov [_theLabelPointer], offset label }\
  13.     p = _theLabelPointer;\
  14.   }
  15.  
  16. #define JUMP_TO_LABEL(p)\
  17.   {\
  18.     void* _theLabelPointer = p;\
  19.     __asm { jmp _theLabelPointer }\
  20.   }
  21.  
  22. #else // _WIN32
  23.  
  24. #define GET_LABEL_PTR(p, label) p = &&label;
  25.  
  26. #define JUMP_TO_LABEL(p) goto *p;
  27.  
  28. #endif // _WIN32
  29.  
  30. #define YIELD2(val,counter)\
  31.   {\
  32.     GET_LABEL_PTR(_p, CONCAT(YIELD,counter));\
  33.     i = (val);\
  34.     return i;\
  35.     CONCAT(YIELD,counter): ;\
  36.   }
  37.  
  38. #define YIELD(val) YIELD2(val,__COUNTER__)
  39.  
  40. #define RETURN { _ended = true; return i; }
  41.  
  42. #define DEF_ITER(ret_type, name, state_vars, code) \
  43.   struct name \
  44.   {\
  45.     state_vars;\
  46.     ret_type i;\
  47.     bool _ended; void* _p;\
  48.     name() : _ended(false), _p(0) {}\
  49.     bool ended() const { return _ended; }\
  50.     operator bool() { next(); return !_ended; }\
  51.     ret_type next()\
  52.     {\
  53.       if (_ended) { throw(0); return i; }\
  54.       if (_p)\
  55.         JUMP_TO_LABEL(_p);\
  56.       code;\
  57.       \
  58.        _ended = true;\
  59.        return i;\
  60.     }\
  61.   };
  62.  
  63. // Test iterators
  64.  
  65. DEF_ITER(int, get57, ,
  66.   YIELD(5);
  67.   YIELD(7);
  68.   RETURN;
  69.   YIELD(42); // Should not happen
  70. )
  71.  
  72. DEF_ITER(int, fibos,  int a;int b,
  73.   a = 1;
  74.   b = 1;
  75.   for (;;)
  76.   {
  77.     YIELD(a);
  78.     std::swap(a, b);
  79.     b += a;
  80.   }
  81. )
  82.  
  83. DEF_ITER(int, range, int start;int end,
  84.   while (start < end)
  85.   {
  86.     YIELD(start);
  87.     ++start;
  88.   }
  89. )
  90.  
  91. DEF_ITER(int, range_recurse, int start; int end; std::unique_ptr<range_recurse> r,
  92.   r = NULL;
  93.  
  94.   if (start >= end)
  95.     RETURN;
  96.  
  97.   YIELD(start);
  98.   r.reset(new range_recurse);
  99.   r->start = start + 1;
  100.   r->end = end;
  101.   while (*r)
  102.     YIELD(r->i);
  103. )
  104.  
  105. DEF_ITER(int, n_fibos, int count; fibos f; range r,
  106.   r.start = 0;
  107.   r.end = count;
  108.   while (r)
  109.     YIELD(f.next());
  110. )
  111.  
  112. int main(int argc, char* argv[])
  113. {
  114.   {
  115.     std::cout << "*** 5 fibos" << std::endl;
  116.     n_fibos s;
  117.     s.count = 5;
  118.     while (s)
  119.       std::cout << s.i << std::endl;
  120.   }
  121.  
  122.   {
  123.     std::cout << "\n*** fibos < 20" << std::endl;
  124.     fibos s;
  125.     while (s && s.i < 20)
  126.       std::cout << s.i << std::endl;
  127.   }
  128.  
  129.   {
  130.     std::cout << "\n*** 5 and 7" << std::endl;
  131.     get57 s;
  132.     while (s)
  133.       std::cout << s.i << std::endl;
  134.   }
  135.  
  136.   {
  137.     std::cout << "\n*** 4..7" << std::endl;
  138.     range s; s.start = 4; s.end = 8;
  139.     while (s)
  140.       std::cout << s.i << std::endl;
  141.   }
  142.  
  143.   {
  144.     std::cout << "\n*** 10..14" << std::endl;
  145.     range_recurse s; s.start = 10; s.end = 15;
  146.     while (s)
  147.       std::cout << s.i << std::endl;
  148.   }
  149.   return 0;
  150. }
Success #stdin #stdout 0s 3432KB
comments (?)
stdin
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Standard input is empty
stdout
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*** 5 fibos
1
1
2
3
5

*** fibos < 20
1
1
2
3
5
8
13

*** 5 and 7
5
7

*** 4..7
4
5
6
7

*** 10..14
10
11
12
13
14
https://ideone.com/pdDqig
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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