Function MappingKeys

tensorflow/python/util/util.cc:860–873

Work around a writable-strings warning with Python 2's PyMapping_Keys macro, and while we're at it give them consistent behavior by making sure the returned value is a list. As with PyMapping_Keys, returns a new reference. On failure, returns nullptr.

//
// On failure, returns nullptr.
PyObject* MappingKeys(PyObject* o) {
#if PY_MAJOR_VERSION >= 3
  return PyMapping_Keys(o);
#else
  static char key_method_name[] = "keys";
  Safe_PyObjectPtr raw_result(PyObject_CallMethod(o, key_method_name, nullptr));
  if (PyErr_Occurred() || raw_result.get() == nullptr) {
    return nullptr;
  }
  return PySequence_Fast(
      raw_result.get(),
      "The '.keys()' method of a custom mapping returned a non-sequence.");
#endif
}

PyObject* Flatten(PyObject* nested, bool expand_composites) {
  PyObject* list = PyList_New(0);