Function _validate_object_field_overlap

numpy/core/src/multiarray/descriptor.c:919–984

* Validates that any field of the structured array 'dtype' which has * the NPY_ITEM_HASOBJECT flag set does not overlap with another field. * * This algorithm is worst case O(n^2). It could be done with a sort * and sweep algorithm, but the structured dtype representation is * rather ugly right now, so writing something better can wait until * that representation is made sane. * * Returns

 * Returns 0 on success, -1 if an exception is raised.
 */
static int
_validate_object_field_overlap(PyArray_Descr *dtype)
{
    PyObject *names, *fields, *key, *tup, *title;
    Py_ssize_t i, j, names_size;
    PyArray_Descr *fld_dtype, *fld2_dtype;
    int fld_offset, fld2_offset;

    /* Get some properties from the dtype */
    names = dtype->names;
    names_size = PyTuple_GET_SIZE(names);
    fields = dtype->fields;

    for (i = 0; i < names_size; ++i) {
        key = PyTuple_GET_ITEM(names, i);
        if (key == NULL) {
            return -1;
        }
        tup = PyDict_GetItemWithError(fields, key);
        if (tup == NULL) {
            if (!PyErr_Occurred()) {
                /* fields was missing the name it claimed to contain */
                PyErr_BadInternalCall();
            }
            return -1;
        }
        if (!PyArg_ParseTuple(tup, "Oi|O", &fld_dtype, &fld_offset, &title)) {
            return -1;
        }

        /* If this field has objects, check for overlaps */
        if (PyDataType_REFCHK(fld_dtype)) {
            for (j = 0; j < names_size; ++j) {
                if (i != j) {
                    key = PyTuple_GET_ITEM(names, j);
                    if (key == NULL) {
                        return -1;
                    }
                    tup = PyDict_GetItemWithError(fields, key);
                    if (tup == NULL) {
                        if (!PyErr_Occurred()) {
                            /* fields was missing the name it claimed to contain */
                            PyErr_BadInternalCall();
                        }
                        return -1;
                    }
                    if (!PyArg_ParseTuple(tup, "Oi|O", &fld2_dtype,
                                                &fld2_offset, &title)) {
                        return -1;
                    }
                    /* Raise an exception if it overlaps */
                    if (fld_offset < fld2_offset + fld2_dtype->elsize &&
                                fld2_offset < fld_offset + fld_dtype->elsize) {
                        PyErr_SetString(PyExc_TypeError,
                                "Cannot create a NumPy dtype with overlapping "
                                "object fields");
                        return -1;
                    }