[Boost-users] How to do accumulation on boost::fusion::vector

From: Peng Yu (pengyu.ut_at_[hidden])
Date: 2008-08-24 12:37:57

Hi,

I want to do accumulation on boost::fusion::vector. Please refer to
the comment in the code. Can somebody let me know how to do it?

Thanks,
Peng

#include <boost/fusion/sequence.hpp>
#include <boost/fusion/include/at.hpp>
#include <boost/fusion/container.hpp>
#include <boost/fusion/iterator.hpp>
#include <boost/typeof/typeof.hpp>
#include <iostream>

struct A {
  A(int value) : _value(value) { }
  int _value;
};

struct B {
  B(int value) : _value(value) { }
  int _value;
};

struct C {
  C(int value) : _value(value) { }
  int _value;
};

template <typename T>
int get_it(const T &t) {
  return t._value;
}

int main() {
  BOOST_AUTO(v, boost::fusion::make_vector(A(0), B(1), C(3), B(8), C(7)));
// I want to make the following code more generic, the fusion vector
length could be anything.
// It sum over all the vector elements.
  int sum = get_it(boost::fusion::at_c<0>(v))
    + get_it(boost::fusion::at_c<1>(v))
    + get_it(boost::fusion::at_c<2>(v))
    + get_it(boost::fusion::at_c<3>(v))
    + get_it(boost::fusion::at_c<4>(v));
  std::cout << sum << std::endl;
}