accumulator.hpp

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#ifndef STAN__MATH__MATRIX__ACCUMULATOR_HPP
#define STAN__MATH__MATRIX__ACCUMULATOR_HPP

#include <vector>
#include <boost/utility/enable_if.hpp>
#include <boost/type_traits/is_arithmetic.hpp>
#include <boost/type_traits/is_same.hpp>
#include <stan/math/matrix/Eigen.hpp>
#include <stan/math/matrix/sum.hpp>

namespace stan {
  namespace math {

    template <typename T>
    class accumulator {
    private:
      std::vector<T> buf_;

    public:
      accumulator()
        : buf_() {
      }

      ~accumulator() { }
      
      template <typename S>
      typename boost::enable_if<boost::is_arithmetic<S>, void>::type
      add(S x) {
        buf_.push_back(static_cast<T>(x));
      }

      template <typename S>
      typename boost::disable_if<boost::is_arithmetic<S>, 
                                 typename boost::enable_if<boost::is_same<S,T>,
                                                           void>::type >::type
      add(const S& x) {
        buf_.push_back(x);
      }

      template <typename S, int R, int C>
      void add(const Eigen::Matrix<S,R,C>& m) {
        for (int i = 0; i < m.size(); ++i)
          add(m(i));
      }
      
      template <typename S>
      void add(const std::vector<S>& xs) {
        for (size_t i = 0; i < xs.size(); ++i)
          add(xs[i]);
      }
      
      T sum() const {
        using math::sum;
        return sum(buf_);
      }

    };




  }
}

#endif