utils_pybind11.h

// Copyright 2025 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
 
#ifndef ACTIONENGINE_PYBIND11_ACTIONENGINE_UTILS_H_
#define ACTIONENGINE_PYBIND11_ACTIONENGINE_UTILS_H_
 
#include <memory>
 
#include <absl/status/statusor.h>
#include <pybind11/attr.h>
#include <pybind11/cast.h>
#include <pybind11/pybind11.h>
#include <pybind11/pytypes.h>
 
namespace act::pybindings {
 
namespace py = ::pybind11;

template <typename T>
auto MakeSameObjectRefConstructor() {
  return py::init([](const std::shared_ptr<T>& other) { return other; });
}

template <typename T>
std::shared_ptr<T> ShareWithNoDeleter(T* ptr) {
  return std::shared_ptr<T>(ptr, [](T*) {});
}

py::object& GetGloballySavedEventLoop();

void SaveEventLoopGlobally(const py::object& loop);
 
void SaveFirstEncounteredEventLoop();

struct keep_event_loop_memo {};

absl::StatusOr<py::object> RunThreadsafeIfCoroutine(
    py::object function_call_result, py::object loop = py::none(),
    bool return_future = false);
 
}  // namespace act::pybindings
 
// implementation of PyBind11's machinery for the keep_event_loop_memo
// annotation.
template <>
struct pybind11::detail::process_attribute<
    act::pybindings::keep_event_loop_memo>
    : process_attribute_default<act::pybindings::keep_event_loop_memo> {
  static void precall(function_call&) {
    act::pybindings::SaveFirstEncounteredEventLoop();
  }
};
 
#endif  // ACTIONENGINE_PYBIND11_ACTIONENGINE_UTILS_H_