using apply_visitor to filter from vector of variant

Question

Yesterday I asked this question and "juanchopanza" answered my question, but unfortunately I cant caught one of bounded types. Since using a "visitor" is more robust, I'm also wondering of anyone could give me a solution using "visitor"?

I am looking for the best way to filter a vector of the boost variant which has been defined like this:

 boost::variant<T1*, T2, T3> Var;
 std::vector<Var> Vec;

when I call this vector, what is the best way to filter only T2 bounded type and insert into new vector? or in other way, I want something like this

std::vector<T2> T2Vec = ...(how to filter it from Vec using apply_visitor)...

thanks again!

EDIT: the sulotion by @ ForEveR:

template<typename T>
struct T_visitor : public boost::static_visitor<>
{
   T_visitor(std::vector<T>& v) : vec(v) {}
   template<typename U>
   void operator () (const U&) {}
   void operator () (const T& value)
   {
      vec.push_back(value);
   }
private:
   std::vector<T>& vec;
};

and:

  std::vector<T1> t1vec;
  T_visitor<T1> vis(t1vec);
  std::for_each(vec.begin(), vec.end(), boost::apply_visitor(vis));

would you please tell me what's wrong here?

Answer 1

struct T2_visitor : public boost::static_visitor<>
{
   T2_visitor(std::vector<T2>& v) : vec(v) {}
   template<typename T>
   void operator () (const T&) {}
   void operator () (const T2& value)
   {
      vec.push_back(value);
   }
private:
   std::vector<T2>& vec;
};

std::vector<T2> T2Vec;
T2_visitor vis(T2Vec);
std::for_each(Vec.begin(), Vec.end(), boost::apply_visitor(vis));