#ifndef STAN_MATH_PRIM_MAT_FUN_TO_ARRAY_1D_HPP
#define STAN_MATH_PRIM_MAT_FUN_TO_ARRAY_1D_HPP

#include <stan/math/prim/meta.hpp>
#include <stan/math/prim/mat/fun/Eigen.hpp>
#include <vector>

namespace stan {
namespace math {

// real[] to_array_1d(matrix)
// real[] to_array_1d(row_vector)
// real[] to_array_1d(vector)
template <typename T, int R, int C>
inline std::vector<T> to_array_1d(const Eigen::Matrix<T, R, C>& matrix) {
  const T* datap = matrix.data();
  int size = matrix.size();
  std::vector<T> result(size);
  for (int i = 0; i < size; i++) {
    result[i] = datap[i];
  }
  return result;
}

// real[] to_array_1d(...)
template <typename T>
inline std::vector<T> to_array_1d(const std::vector<T>& x) {
  return x;
}

// real[] to_array_1d(...)
template <typename T>
inline std::vector<typename scalar_type<T>::type> to_array_1d(
    const std::vector<std::vector<T> >& x) {
  size_t size1 = x.size();
  size_t size2 = 0;
  if (size1 != 0) {
    size2 = x[0].size();
  }
  std::vector<T> y(size1 * size2);
  for (size_t i = 0, ij = 0; i < size1; i++) {
    for (size_t j = 0; j < size2; j++, ij++) {
      y[ij] = x[i][j];
    }
  }
  return to_array_1d(y);
}

}  // namespace math
}  // namespace stan
#endif
