diff options
Diffstat (limited to 'Objects/sliceobject.c')
| -rw-r--r-- | Objects/sliceobject.c | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/Objects/sliceobject.c b/Objects/sliceobject.c index 7562d34..7499d31 100644 --- a/Objects/sliceobject.c +++ b/Objects/sliceobject.c @@ -109,6 +109,59 @@ PySlice_GetIndices(PySliceObject *r, int length, return 0; } +int +PySlice_GetIndicesEx(PySliceObject *r, int length, + int *start, int *stop, int *step, int *slicelength) +{ + /* this is harder to get right than you might think */ + int defstart, defstop; + + if (r->step == Py_None) { + *step = 1; + } else { + *step = PyInt_AsLong(r->step); + if (*step == -1 && PyErr_Occurred()) { + return -1; + } + else if (*step == 0) { + PyErr_SetString(PyExc_ValueError, + "slice step cannot be zero"); + return -1; + } + } + + defstart = *step < 0 ? length-1 : 0; + defstop = *step < 0 ? -1 : length; + + if (r->start == Py_None) { + *start = defstart; + } else { + if (!_PyEval_SliceIndex(r->start, start)) return -1; + if (*start < 0) *start += length; + if (*start < 0) *start = (*step < 0) ? -1 : 0; + if (*start >= length) + *start = (*step < 0) ? length - 1 : length; + } + + if (r->stop == Py_None) { + *stop = defstop; + } else { + if (!_PyEval_SliceIndex(r->stop, stop)) return -1; + if (*stop < 0) *stop += length; + if (*stop < 0) *stop = -1; + if (*stop > length) *stop = length; + } + + if (*step < 0) { + *slicelength = (*stop-*start+1)/(*step)+1; + } else { + *slicelength = (*stop-*start-1)/(*step)+1; + } + if (*slicelength < 0) *slicelength = 0; + + return 0; +} + static void slice_dealloc(PySliceObject *r) { |