partials_propagator.hpp

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#ifndef STAN_MATH_REV_META_PARTIALS_PROPOGATOR_HPP
#define STAN_MATH_REV_META_PARTIALS_PROPOGATOR_HPP
 
#include <stan/math/rev/meta.hpp>
#include <stan/math/rev/core/var.hpp>
#include <stan/math/rev/core/typedefs.hpp>
#include <stan/math/rev/functor/operands_and_partials.hpp>
#include <stan/math/rev/functor/broadcast_array.hpp>
#include <stan/math/prim/functor/for_each.hpp>
#include <vector>
#include <tuple>
 
namespace stan {
namespace math {
 
namespace internal {
 
template <typename ReturnType, typename Enable, typename... Ops>
class partials_propagator;
 
template <typename ReturnType, typename... Ops>
class partials_propagator<ReturnType, require_var_t<ReturnType>, Ops...> {
 public:
  std::tuple<
      internal::ops_partials_edge<double, plain_type_t<std::decay_t<Ops>>>...>
      edges_;
 
  template <typename... Types>
  explicit partials_propagator(Types&&... ops)
      : edges_(
          internal::ops_partials_edge<double, plain_type_t<std::decay_t<Ops>>>(
              std::forward<Types>(ops))...) {}
 
  inline var build(double value) {
    var ret(value);
    stan::math::for_each(
        [ret](auto&& edge) mutable {
          reverse_pass_callback(
              [operand = edge.operand(), partial = edge.partial(),
               ret]() mutable { update_adjoints(operand, partial, ret); });
        },
        edges_);
    return ret;
  }
};
}  // namespace internal
}  // namespace math
}  // namespace stan
#endif