Function PyArray_Item_XDECREF

numpy/core/src/multiarray/refcount.c:183–235

NUMPY_API * * XDECREF all objects in a single array item. This is complicated for * structured datatypes where the position of objects needs to be extracted. * The function is execute recursively for each nested field or subarrays dtype * such as as `np.dtype([("field1", "O"), ("field2", "f,O", (3,2))])` */

 * such as as `np.dtype([("field1", "O"), ("field2", "f,O", (3,2))])`
 */
NPY_NO_EXPORT void
PyArray_Item_XDECREF(char *data, PyArray_Descr *descr)
{
    PyObject *temp;

    if (!PyDataType_REFCHK(descr)) {
        return;
    }

    if (descr->type_num == NPY_OBJECT) {
        memcpy(&temp, data, sizeof(temp));
        Py_XDECREF(temp);
    }
    else if (PyDataType_HASFIELDS(descr)) {
            PyObject *key, *value, *title = NULL;
            PyArray_Descr *new;
            int offset;
            Py_ssize_t pos = 0;

            while (PyDict_Next(descr->fields, &pos, &key, &value)) {
                if (NPY_TITLE_KEY(key, value)) {
                    continue;
                }
                if (!PyArg_ParseTuple(value, "Oi|O", &new, &offset,
                                      &title)) {
                    return;
                }
                PyArray_Item_XDECREF(data + offset, new);
            }
        }
    else if (PyDataType_HASSUBARRAY(descr)) {
        int size, i, inner_elsize;

        inner_elsize = descr->subarray->base->elsize;
        if (inner_elsize == 0) {
            /* There cannot be any elements, so return */
            return;
        }
        /* Subarrays are always contiguous in memory */
        size = descr->elsize / inner_elsize;

        for (i = 0; i < size; i++){
            /* Recursively decrement the reference count of subarray elements */
            PyArray_Item_XDECREF(data + i * inner_elsize,
                                 descr->subarray->base);
        }
    }
    else {
        /* This path should not be reachable. */
        assert(0);
    }
    return;
}

/* Used for arrays of python objects to increment the reference count of */
/* every python object in the array. */