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// BSD 3-Clause License; see https://github.com/scikit-hep/awkward/blob/main/LICENSE
#ifndef AWKWARDPY_UTIL_H_
#define AWKWARDPY_UTIL_H_
#include <pybind11/pybind11.h>
#include <pybind11/numpy.h>
/// @class pyobject_deleter
///
/// @brief Used as a `std::shared_ptr` deleter (second argument) to
/// overload `delete ptr` with `Py_DECREF(ptr)`.
///
/// This allows data to be shared between C++ and Python that will be
/// deleted when _both_ reference counts reach zero.
///
/// The effective reference count is a lexicographical tuple of
/// (Python reference count, C++ reference count), where the Python
/// reference count is the most significant digit. A single Python
/// reference count is held for all C++ references to the object.
///
/// See also
/// - array_deleter, which frees array buffers, rather
/// than objects.
template<typename T>
class pyobject_deleter {
public:
/// @brief Creates a pyobject_deleter and calls `Py_INCREF(ptr)`.
pyobject_deleter(PyObject *pyobj): pyobj_(pyobj) {
Py_INCREF(pyobj_);
}
/// @brief Called by `std::shared_ptr` when its reference count reaches
/// zero.
void operator()(T const * /* p */) {
Py_DECREF(pyobj_);
}
private:
/// @brief The Python object that we hold a reference to.
PyObject* pyobj_;
};
#endif // AWKWARDPY_UTIL_H_
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