#pragma once

#include <ATen/Tensor.h>
#include <torch/csrc/Export.h>
#include <vector>

// A hook that's called on gradients

namespace torch {
namespace autograd {

using Variable = at::Tensor;
using variable_list = std::vector<Variable>;

struct TORCH_API FunctionPreHook {
  virtual ~FunctionPreHook() = default;
  virtual variable_list operator()(const variable_list& grads) = 0;
};

struct TORCH_API FunctionPostHook {
  virtual ~FunctionPostHook() = default;
  virtual variable_list operator()(
      const variable_list& outputs /* grad_inputs */,
      const variable_list& inputs /* grad_outputs */) = 0;
};

} // namespace autograd
} // namespace torch