Vector of pairs with generic vector and pair type, template of template

问题

I'd like to pass a vector of pairs to a function. The actual vector implementation as well as the types of the pair should be a template parameter.

I thought of something like this:

template<uint8_t t_k,
        typename t_bv,
        typename t_rank,
        template <template <template<typename t_x,
                                     typename t_y> class std::pair>
                  typename t_vector>> typename t_vector>

The first 3 are other template parameters. The last template parameter should allow to pass a vector (std or stxxl:vector) of std::pair with either uint32_t or uint64_t as type of the pair.first and pair.second.

回答1:

You can use this:

template<typename X,
         typename Y,
         template<typename, typename> class Pair,
         template<typename...> class Vector>
void fun(Vector<Pair<X, Y>> vec)
{
     //...
}

回答2:

Not sure to understand your requirements but... what about the following example?

#include <iostream>
#include <utility>
#include <vector>
#include <deque>

template <typename P1, typename P2, template<typename...> class Vect>
std::size_t func (const Vect<std::pair<P1, P2>> & v)
 { return v.size(); }

int main()
 {
   std::vector<std::pair<int, long>> v1{ {1, 1L}, {2, 2L}, {3, 3L} };
   std::deque<std::pair<long, int>> v2{ {3L, 1}, {2L, 2} };

   std::cout << func(v1) << std::endl;
   std::cout << func(v2) << std::endl;

   return 0;
 }

回答3:

If I understand you correctly, you want to have a function that takes std::vector of generic std::pair. Here you go:

template <typename First, typename Second>
void function(std::vector< std::pair<First,Second> > vector_of_pairs)
{
  ...
}

EDIT: If you want to take both std::vector and stxxl::vector, you can use template template parameters with c++11's variadic templates (since std::vector and stxxl::vector have different number of template parameters):

template <typename First,
          typename Second,
          template <typename...> class AnyVector,
          typename... OtherStuff>
          void function(AnyVector<std::pair<First,Second>, OtherStuff...> vector_of_pairs)
          {
              /*...*/
          }

来源：https://stackoverflow.com/questions/38396212/vector-of-pairs-with-generic-vector-and-pair-type-template-of-template

标签

c++

templates

c++11

vector

template-templates