109 /* start, stop, and step are python objects with None indicating no
114 PySlice_New(PyObject *start, PyObject *stop, PyObject *step)  in PySlice_New()  argument
116     if (step == NULL) {  in PySlice_New()
117         step = Py_None;  in PySlice_New()
140     Py_INCREF(step);  in PySlice_New()
141     obj->step = step;  in PySlice_New()
172                    Py_ssize_t *start, Py_ssize_t *stop, Py_ssize_t *step)  in PySlice_GetIndices()  argument
176     if (r->step == Py_None) {  in PySlice_GetIndices()
177         *step = 1;  in PySlice_GetIndices()
179         if (!PyLong_Check(r->step)) return -1;  in PySlice_GetIndices()
180         *step = PyLong_AsSsize_t(r->step);  in PySlice_GetIndices()
183         *start = *step < 0 ? length-1 : 0;  in PySlice_GetIndices()
190         *stop = *step < 0 ? -1 : length;  in PySlice_GetIndices()
198     if (*step == 0) return -1;  in PySlice_GetIndices()
204                Py_ssize_t *start, Py_ssize_t *stop, Py_ssize_t *step)  in PySlice_Unpack()  argument
212     if (r->step == Py_None) {  in PySlice_Unpack()
213         *step = 1;  in PySlice_Unpack()
216         if (!_PyEval_SliceIndex(r->step, step)) return -1;  in PySlice_Unpack()
217         if (*step == 0) {  in PySlice_Unpack()
219                             "slice step cannot be zero");  in PySlice_Unpack()
222         /* Here *step might be -PY_SSIZE_T_MAX-1; in this case we replace it  in PySlice_Unpack()
225          * does "step = -step" as part of a slice reversal.  in PySlice_Unpack()
227         if (*step < -PY_SSIZE_T_MAX)  in PySlice_Unpack()
228             *step = -PY_SSIZE_T_MAX;  in PySlice_Unpack()
232         *start = *step < 0 ? PY_SSIZE_T_MAX : 0;  in PySlice_Unpack()
239         *stop = *step < 0 ? PY_SSIZE_T_MIN : PY_SSIZE_T_MAX;  in PySlice_Unpack()
250                       Py_ssize_t *start, Py_ssize_t *stop, Py_ssize_t step)  in PySlice_AdjustIndices()  argument
254     assert(step != 0);  in PySlice_AdjustIndices()
255     assert(step >= -PY_SSIZE_T_MAX);  in PySlice_AdjustIndices()
260             *start = (step < 0) ? -1 : 0;  in PySlice_AdjustIndices()
264         *start = (step < 0) ? length - 1 : length;  in PySlice_AdjustIndices()
270             *stop = (step < 0) ? -1 : 0;  in PySlice_AdjustIndices()
274         *stop = (step < 0) ? length - 1 : length;  in PySlice_AdjustIndices()
277     if (step < 0) {  in PySlice_AdjustIndices()
279             return (*start - *stop - 1) / (-step) + 1;  in PySlice_AdjustIndices()
284             return (*stop - *start - 1) / step + 1;  in PySlice_AdjustIndices()
294                      Py_ssize_t *start, Py_ssize_t *stop, Py_ssize_t *step,  in PySlice_GetIndicesEx()  argument
297     if (PySlice_Unpack(_r, start, stop, step) < 0)  in PySlice_GetIndicesEx()
299     *slicelength = PySlice_AdjustIndices(length, start, stop, *step);  in PySlice_GetIndicesEx()
306     PyObject *start, *stop, *step;  in slice_new()  local
308     start = stop = step = NULL;  in slice_new()
313     if (!PyArg_UnpackTuple(args, "slice", 1, 3, &start, &stop, &step))  in slice_new()
322     return PySlice_New(start, stop, step);  in slice_new()
327 slice(start, stop[, step])\n\
336     Py_DECREF(r->step);  in slice_dealloc()
350     return PyUnicode_FromFormat("slice(%R, %R, %R)", r->start, r->stop, r->step);  in slice_repr()
356     {"step", T_OBJECT, offsetof(PySliceObject, step), READONLY},
386     PyObject *start=NULL, *stop=NULL, *step=NULL;  in _PySlice_GetLongIndices()  local
390     /* Convert step to an integer; raise for zero step. */  in _PySlice_GetLongIndices()
391     if (self->step == Py_None) {  in _PySlice_GetLongIndices()
392         step = _PyLong_GetOne();  in _PySlice_GetLongIndices()
393         Py_INCREF(step);  in _PySlice_GetLongIndices()
398         step = evaluate_slice_index(self->step);  in _PySlice_GetLongIndices()
399         if (step == NULL)  in _PySlice_GetLongIndices()
401         step_sign = _PyLong_Sign(step);  in _PySlice_GetLongIndices()
404                             "slice step cannot be zero");  in _PySlice_GetLongIndices()
507     *step_ptr = step;  in _PySlice_GetLongIndices()
516     Py_XDECREF(step);  in _PySlice_GetLongIndices()
527     PyObject *start, *stop, *step;  in slice_indices()  local
543     error = _PySlice_GetLongIndices(self, length, &start, &stop, &step);  in slice_indices()
548         return Py_BuildValue("(NNN)", start, stop, step);  in slice_indices()
562     return Py_BuildValue("O(OOO)", Py_TYPE(self), self->start, self->stop, self->step);  in slice_reduce()
603                                 ((PySliceObject *)v)->step);  in slice_richcompare()
611                                 ((PySliceObject *)w)->step);  in slice_richcompare()
628     Py_VISIT(v->step);  in slice_traverse()