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  1. #include <vector>
  2. #include <iostream>
  3. #include <typeinfo>
  4. #include <memory.h>
  5.  
  6. using namespace std;
  7. struct variant
  8. {
  9.     size_t size;
  10.     void* p;
  11.     variant(const variant& v) {
  12.         p = new char[v.size];//этого не надо, и вообще этот оператор
  13.         size = v.size, memcpy(p, v.p, size);
  14.         cout << "copy\n";
  15.     }
  16.     template<typename T>
  17.     variant(T v) {
  18.         p = new T(v);
  19.         size = sizeof(T);
  20.         cout << "new\n";
  21.     }
  22.     template<typename T>
  23.     operator T&() {
  24.         return *(T*)p;
  25.     }
  26.     template<typename T>
  27.     T operator->() const { return *(T*)p; }
  28.     ~variant() {
  29.         //delete p;
  30.         std::cout << "delete\n";
  31.     }
  32. };
  33.  
  34. typedef enum { GUMBO_TAG_HTML, GUMBO_TAG_HEAD } GumboTag;
  35. class tlist
  36. {
  37. public:
  38.     int axis;
  39.     variant node;
  40. };
  41.  
  42. GumboTag f()
  43. {
  44.     return GUMBO_TAG_HEAD;
  45. }
  46.  
  47. int main(int argc, const char * argv[])
  48. {
  49.     std::vector<tlist> tl;
  50.     tl.reserve(2);
  51.     int axis = 0;
  52.     std::cout << "push:\n";
  53.     tl.push_back({ axis, f() });//работает без tlist()
  54.     cout << static_cast<GumboTag>(tl[0].node) << "\n";
  55.     std::cout << "emplace:\n";
  56.     //tl.emplace_back({ axis, f() });
  57.     tl.emplace_back(tlist({ axis, f() }));
  58.     cout << static_cast<GumboTag>(tl[1].node) << "\n";
  59. }
Success #stdin #stdout 0s 3472KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
push:
new
copy
delete
1
emplace:
new
copy
delete
1
delete
delete
https://ideone.com/DLEshF
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
public

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