cpp-study/visitor.cpp at master · straszheim/cpp-study · GitHub

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#include "study.hpp"

struct D1;
struct D2;

struct BVisitor {

  virtual void visit(D1& d) = 0;
  virtual void visit(D2& d) = 0;
};

struct B {
  virtual void foo() = 0;
  virtual void accept(BVisitor& bv) = 0;
};

template <typename Derived, typename Base, typename Visitor>
struct visitable : Base{
  virtul void accept(

};

struct D1 : B {
  void foo() { SHOW(); }
  virtual void accept(BVisitor& bv) { bv.visit(*this); }
};

struct D2 : B {
  void foo() { SHOW(); }
  virtual void accept(BVisitor& bv) { bv.visit(*this); }
};


struct ShowVisitor : BVisitor {

  void visit(D1& d) { SHOW(); }
  void visit(D2& d) { SHOW(); }

};


int main()
{
  ShowVisitor sv;
  BVisitor& bv = sv;

  D1 d1;
  D2 d2;
  B& b1 = d1;
  B& b2 = d2;

  b1.accept(bv);
  b2.accept(bv);

  return 0;
}