Staging
v0.5.1
v0.5.1
https://github.com/python/cpython
Revision b3468f79efa45c8adaf86c0b9b797b9b3d4c12a2 authored by Michael Foord on 19 December 2010, 03:19:47 UTC, committed by Michael Foord on 19 December 2010, 03:19:47 UTC
1 parent addc6f5
Tip revision: b3468f79efa45c8adaf86c0b9b797b9b3d4c12a2 authored by Michael Foord on 19 December 2010, 03:19:47 UTC
Issue 10611. Issue 9857. Improve the way exception handling, including test skipping, is done inside TestCase.run
Issue 10611. Issue 9857. Improve the way exception handling, including test skipping, is done inside TestCase.run
Tip revision: b3468f7
rangeobject.c
/* Range object implementation */
#include "Python.h"
/* Support objects whose length is > PY_SSIZE_T_MAX.
This could be sped up for small PyLongs if they fit in an Py_ssize_t.
This only matters on Win64. Though we could use PY_LONG_LONG which
would presumably help perf.
*/
typedef struct {
PyObject_HEAD
PyObject *start;
PyObject *stop;
PyObject *step;
PyObject *length;
} rangeobject;
/* Helper function for validating step. Always returns a new reference or
NULL on error.
*/
static PyObject *
validate_step(PyObject *step)
{
/* No step specified, use a step of 1. */
if (!step)
return PyLong_FromLong(1);
step = PyNumber_Index(step);
if (step) {
Py_ssize_t istep = PyNumber_AsSsize_t(step, NULL);
if (istep == -1 && PyErr_Occurred()) {
/* Ignore OverflowError, we know the value isn't 0. */
PyErr_Clear();
}
else if (istep == 0) {
PyErr_SetString(PyExc_ValueError,
"range() arg 3 must not be zero");
Py_CLEAR(step);
}
}
return step;
}
static PyObject *
compute_range_length(PyObject *start, PyObject *stop, PyObject *step);
static rangeobject *
make_range_object(PyTypeObject *type, PyObject *start,
PyObject *stop, PyObject *step)
{
rangeobject *obj = NULL;
PyObject *length;
length = compute_range_length(start, stop, step);
if (length == NULL) {
return NULL;
}
obj = PyObject_New(rangeobject, type);
if (obj == NULL) {
Py_DECREF(length);
return NULL;
}
obj->start = start;
obj->stop = stop;
obj->step = step;
obj->length = length;
return obj;
}
/* XXX(nnorwitz): should we error check if the user passes any empty ranges?
range(-10)
range(0, -5)
range(0, 5, -1)
*/
static PyObject *
range_new(PyTypeObject *type, PyObject *args, PyObject *kw)
{
rangeobject *obj;
PyObject *start = NULL, *stop = NULL, *step = NULL;
if (!_PyArg_NoKeywords("range()", kw))
return NULL;
if (PyTuple_Size(args) <= 1) {
if (!PyArg_UnpackTuple(args, "range", 1, 1, &stop))
return NULL;
stop = PyNumber_Index(stop);
if (!stop)
return NULL;
start = PyLong_FromLong(0);
if (!start) {
Py_DECREF(stop);
return NULL;
}
step = PyLong_FromLong(1);
if (!step) {
Py_DECREF(stop);
Py_DECREF(start);
return NULL;
}
}
else {
if (!PyArg_UnpackTuple(args, "range", 2, 3,
&start, &stop, &step))
return NULL;
/* Convert borrowed refs to owned refs */
start = PyNumber_Index(start);
if (!start)
return NULL;
stop = PyNumber_Index(stop);
if (!stop) {
Py_DECREF(start);
return NULL;
}
step = validate_step(step); /* Caution, this can clear exceptions */
if (!step) {
Py_DECREF(start);
Py_DECREF(stop);
return NULL;
}
}
obj = make_range_object(type, start, stop, step);
if (obj != NULL)
return (PyObject *) obj;
/* Failed to create object, release attributes */
Py_XDECREF(start);
Py_XDECREF(stop);
Py_XDECREF(step);
return NULL;
}
PyDoc_STRVAR(range_doc,
"range([start,] stop[, step]) -> range object\n\
\n\
Returns a virtual sequence of numbers from start to stop by step.");
static void
range_dealloc(rangeobject *r)
{
Py_DECREF(r->start);
Py_DECREF(r->stop);
Py_DECREF(r->step);
Py_DECREF(r->length);
PyObject_Del(r);
}
/* Return number of items in range (lo, hi, step) as a PyLong object,
* when arguments are PyLong objects. Arguments MUST return 1 with
* PyLong_Check(). Return NULL when there is an error.
*/
static PyObject*
compute_range_length(PyObject *start, PyObject *stop, PyObject *step)
{
/* -------------------------------------------------------------
Algorithm is equal to that of get_len_of_range(), but it operates
on PyObjects (which are assumed to be PyLong objects).
---------------------------------------------------------------*/
int cmp_result;
PyObject *lo, *hi;
PyObject *diff = NULL;
PyObject *one = NULL;
PyObject *tmp1 = NULL, *tmp2 = NULL, *result;
/* holds sub-expression evaluations */
PyObject *zero = PyLong_FromLong(0);
if (zero == NULL)
return NULL;
cmp_result = PyObject_RichCompareBool(step, zero, Py_GT);
Py_DECREF(zero);
if (cmp_result == -1)
return NULL;
if (cmp_result == 1) {
lo = start;
hi = stop;
Py_INCREF(step);
} else {
lo = stop;
hi = start;
step = PyNumber_Negative(step);
if (!step)
return NULL;
}
/* if (lo >= hi), return length of 0. */
if (PyObject_RichCompareBool(lo, hi, Py_GE) == 1) {
Py_XDECREF(step);
return PyLong_FromLong(0);
}
if ((one = PyLong_FromLong(1L)) == NULL)
goto Fail;
if ((tmp1 = PyNumber_Subtract(hi, lo)) == NULL)
goto Fail;
if ((diff = PyNumber_Subtract(tmp1, one)) == NULL)
goto Fail;
if ((tmp2 = PyNumber_FloorDivide(diff, step)) == NULL)
goto Fail;
if ((result = PyNumber_Add(tmp2, one)) == NULL)
goto Fail;
Py_DECREF(tmp2);
Py_DECREF(diff);
Py_DECREF(step);
Py_DECREF(tmp1);
Py_DECREF(one);
return result;
Fail:
Py_XDECREF(tmp2);
Py_XDECREF(diff);
Py_XDECREF(step);
Py_XDECREF(tmp1);
Py_XDECREF(one);
return NULL;
}
static Py_ssize_t
range_length(rangeobject *r)
{
return PyLong_AsSsize_t(r->length);
}
/* range(...)[x] is necessary for: seq[:] = range(...) */
static PyObject *
compute_range_item(rangeobject *r, Py_ssize_t i)
{
PyObject *rem, *incr, *result;
/* XXX(nnorwitz): optimize for short ints. */
rem = PyLong_FromSsize_t(i);
if (!rem)
return NULL;
incr = PyNumber_Multiply(rem, r->step);
Py_DECREF(rem);
if (!incr)
return NULL;
result = PyNumber_Add(r->start, incr);
Py_DECREF(incr);
return result;
}
static PyObject *
range_item(rangeobject *r, Py_ssize_t i)
{
/* XXX(nnorwitz): should we support range[x] where x > PY_SSIZE_T_MAX? */
Py_ssize_t len = range_length(r);
if (i < 0)
i += len;
if (i < 0 || i >= len) {
/* Also handles case where len < 0 due to (e.g) OverflowError */
if (!PyErr_Occurred())
PyErr_SetString(PyExc_IndexError,
"range object index out of range");
return NULL;
}
return compute_range_item(r, i);
}
/* Assumes (PyLong_CheckExact(ob) || PyBool_Check(ob)) */
static int
range_contains_long(rangeobject *r, PyObject *ob)
{
int cmp1, cmp2, cmp3;
PyObject *tmp1 = NULL;
PyObject *tmp2 = NULL;
PyObject *zero = NULL;
int result = -1;
zero = PyLong_FromLong(0);
if (zero == NULL) /* MemoryError in int(0) */
goto end;
/* Check if the value can possibly be in the range. */
cmp1 = PyObject_RichCompareBool(r->step, zero, Py_GT);
if (cmp1 == -1)
goto end;
if (cmp1 == 1) { /* positive steps: start <= ob < stop */
cmp2 = PyObject_RichCompareBool(r->start, ob, Py_LE);
cmp3 = PyObject_RichCompareBool(ob, r->stop, Py_LT);
}
else { /* negative steps: stop < ob <= start */
cmp2 = PyObject_RichCompareBool(ob, r->start, Py_LE);
cmp3 = PyObject_RichCompareBool(r->stop, ob, Py_LT);
}
if (cmp2 == -1 || cmp3 == -1) /* TypeError */
goto end;
if (cmp2 == 0 || cmp3 == 0) { /* ob outside of range */
result = 0;
goto end;
}
/* Check that the stride does not invalidate ob's membership. */
tmp1 = PyNumber_Subtract(ob, r->start);
if (tmp1 == NULL)
goto end;
tmp2 = PyNumber_Remainder(tmp1, r->step);
if (tmp2 == NULL)
goto end;
/* result = (int(ob) - start % step) == 0 */
result = PyObject_RichCompareBool(tmp2, zero, Py_EQ);
end:
Py_XDECREF(tmp1);
Py_XDECREF(tmp2);
Py_XDECREF(zero);
return result;
}
static int
range_contains(rangeobject *r, PyObject *ob)
{
if (PyLong_CheckExact(ob) || PyBool_Check(ob))
return range_contains_long(r, ob);
return (int)_PySequence_IterSearch((PyObject*)r, ob,
PY_ITERSEARCH_CONTAINS);
}
static PyObject *
range_count(rangeobject *r, PyObject *ob)
{
if (PyLong_CheckExact(ob) || PyBool_Check(ob)) {
int result = range_contains_long(r, ob);
if (result == -1)
return NULL;
else if (result)
return PyLong_FromLong(1);
else
return PyLong_FromLong(0);
} else {
Py_ssize_t count;
count = _PySequence_IterSearch((PyObject*)r, ob, PY_ITERSEARCH_COUNT);
if (count == -1)
return NULL;
return PyLong_FromSsize_t(count);
}
}
static PyObject *
range_index(rangeobject *r, PyObject *ob)
{
int contains;
if (!PyLong_CheckExact(ob) && !PyBool_Check(ob)) {
Py_ssize_t index;
index = _PySequence_IterSearch((PyObject*)r, ob, PY_ITERSEARCH_INDEX);
if (index == -1)
return NULL;
return PyLong_FromSsize_t(index);
}
contains = range_contains_long(r, ob);
if (contains == -1)
return NULL;
if (contains) {
PyObject *idx, *tmp = PyNumber_Subtract(ob, r->start);
if (tmp == NULL)
return NULL;
/* idx = (ob - r.start) // r.step */
idx = PyNumber_FloorDivide(tmp, r->step);
Py_DECREF(tmp);
return idx;
}
/* object is not in the range */
PyErr_Format(PyExc_ValueError, "%R is not in range", ob);
return NULL;
}
static PySequenceMethods range_as_sequence = {
(lenfunc)range_length, /* sq_length */
0, /* sq_concat */
0, /* sq_repeat */
(ssizeargfunc)range_item, /* sq_item */
0, /* sq_slice */
0, /* sq_ass_item */
0, /* sq_ass_slice */
(objobjproc)range_contains, /* sq_contains */
};
static PyObject *
range_repr(rangeobject *r)
{
Py_ssize_t istep;
/* Check for special case values for printing. We don't always
need the step value. We don't care about errors
(it means overflow), so clear the errors. */
istep = PyNumber_AsSsize_t(r->step, NULL);
if (istep != 1 || (istep == -1 && PyErr_Occurred())) {
PyErr_Clear();
}
if (istep == 1)
return PyUnicode_FromFormat("range(%R, %R)", r->start, r->stop);
else
return PyUnicode_FromFormat("range(%R, %R, %R)",
r->start, r->stop, r->step);
}
/* Pickling support */
static PyObject *
range_reduce(rangeobject *r, PyObject *args)
{
return Py_BuildValue("(O(OOO))", Py_TYPE(r),
r->start, r->stop, r->step);
}
static PyObject *
range_subscript(rangeobject* self, PyObject* item)
{
if (PyIndex_Check(item)) {
Py_ssize_t i;
i = PyNumber_AsSsize_t(item, PyExc_IndexError);
if (i == -1 && PyErr_Occurred())
return NULL;
return range_item(self, i);
}
if (PySlice_Check(item)) {
Py_ssize_t start, stop, step, len, rlen;
rangeobject *result;
PyObject *substart = NULL, *substep = NULL, *substop = NULL;
rlen = range_length(self);
if (rlen < 0) {
return NULL;
}
if (PySlice_GetIndicesEx(item, rlen,
&start, &stop, &step, &len) < 0) {
return NULL;
}
if (step == 1) {
substep = self->step;
Py_INCREF(substep);
} else {
/* NB: slice step != Py_None here */
substep = PyNumber_Multiply(self->step, ((PySliceObject*)item)->step);
if (substep == NULL)
goto fail;
}
substart = compute_range_item(self, start);
if (substart == NULL)
goto fail;
if (len <= 0) {
substop = substart;
Py_INCREF(substop);
}
else {
substop = compute_range_item(self, stop);
if (substop == NULL)
goto fail;
}
result = make_range_object(Py_TYPE(self), substart, substop, substep);
if (result != NULL)
return (PyObject *) result;
fail:
Py_XDECREF(substart);
Py_XDECREF(substep);
Py_XDECREF(substop);
return NULL;
}
PyErr_Format(PyExc_TypeError,
"range indices must be integers or slices, not %.200s",
item->ob_type->tp_name);
return NULL;
}
static PyMappingMethods range_as_mapping = {
(lenfunc)range_length, /* mp_length */
(binaryfunc)range_subscript, /* mp_subscript */
(objobjargproc)0, /* mp_ass_subscript */
};
static PyObject * range_iter(PyObject *seq);
static PyObject * range_reverse(PyObject *seq);
PyDoc_STRVAR(reverse_doc,
"Returns a reverse iterator.");
PyDoc_STRVAR(count_doc,
"rangeobject.count(value) -> integer -- return number of occurrences of value");
PyDoc_STRVAR(index_doc,
"rangeobject.index(value, [start, [stop]]) -> integer -- return index of value.\n"
"Raises ValueError if the value is not present.");
static PyMethodDef range_methods[] = {
{"__reversed__", (PyCFunction)range_reverse, METH_NOARGS, reverse_doc},
{"__reduce__", (PyCFunction)range_reduce, METH_VARARGS},
{"count", (PyCFunction)range_count, METH_O, count_doc},
{"index", (PyCFunction)range_index, METH_O, index_doc},
{NULL, NULL} /* sentinel */
};
PyTypeObject PyRange_Type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
"range", /* Name of this type */
sizeof(rangeobject), /* Basic object size */
0, /* Item size for varobject */
(destructor)range_dealloc, /* tp_dealloc */
0, /* tp_print */
0, /* tp_getattr */
0, /* tp_setattr */
0, /* tp_reserved */
(reprfunc)range_repr, /* tp_repr */
0, /* tp_as_number */
&range_as_sequence, /* tp_as_sequence */
&range_as_mapping, /* tp_as_mapping */
0, /* tp_hash */
0, /* tp_call */
0, /* tp_str */
PyObject_GenericGetAttr, /* tp_getattro */
0, /* tp_setattro */
0, /* tp_as_buffer */
Py_TPFLAGS_DEFAULT, /* tp_flags */
range_doc, /* tp_doc */
0, /* tp_traverse */
0, /* tp_clear */
0, /* tp_richcompare */
0, /* tp_weaklistoffset */
range_iter, /* tp_iter */
0, /* tp_iternext */
range_methods, /* tp_methods */
0, /* tp_members */
0, /* tp_getset */
0, /* tp_base */
0, /* tp_dict */
0, /* tp_descr_get */
0, /* tp_descr_set */
0, /* tp_dictoffset */
0, /* tp_init */
0, /* tp_alloc */
range_new, /* tp_new */
};
/*********************** range Iterator **************************/
/* There are 2 types of iterators, one for C longs, the other for
Python longs (ie, PyObjects). This should make iteration fast
in the normal case, but possible for any numeric value.
*/
typedef struct {
PyObject_HEAD
long index;
long start;
long step;
long len;
} rangeiterobject;
static PyObject *
rangeiter_next(rangeiterobject *r)
{
if (r->index < r->len)
/* cast to unsigned to avoid possible signed overflow
in intermediate calculations. */
return PyLong_FromLong((long)(r->start +
(unsigned long)(r->index++) * r->step));
return NULL;
}
static PyObject *
rangeiter_len(rangeiterobject *r)
{
return PyLong_FromLong(r->len - r->index);
}
PyDoc_STRVAR(length_hint_doc,
"Private method returning an estimate of len(list(it)).");
static PyMethodDef rangeiter_methods[] = {
{"__length_hint__", (PyCFunction)rangeiter_len, METH_NOARGS,
length_hint_doc},
{NULL, NULL} /* sentinel */
};
static PyObject *rangeiter_new(PyTypeObject *, PyObject *args, PyObject *kw);
PyTypeObject PyRangeIter_Type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
"range_iterator", /* tp_name */
sizeof(rangeiterobject), /* tp_basicsize */
0, /* tp_itemsize */
/* methods */
(destructor)PyObject_Del, /* tp_dealloc */
0, /* tp_print */
0, /* tp_getattr */
0, /* tp_setattr */
0, /* tp_reserved */
0, /* tp_repr */
0, /* tp_as_number */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
0, /* tp_hash */
0, /* tp_call */
0, /* tp_str */
PyObject_GenericGetAttr, /* tp_getattro */
0, /* tp_setattro */
0, /* tp_as_buffer */
Py_TPFLAGS_DEFAULT, /* tp_flags */
0, /* tp_doc */
0, /* tp_traverse */
0, /* tp_clear */
0, /* tp_richcompare */
0, /* tp_weaklistoffset */
PyObject_SelfIter, /* tp_iter */
(iternextfunc)rangeiter_next, /* tp_iternext */
rangeiter_methods, /* tp_methods */
0, /* tp_members */
0, /* tp_getset */
0, /* tp_base */
0, /* tp_dict */
0, /* tp_descr_get */
0, /* tp_descr_set */
0, /* tp_dictoffset */
0, /* tp_init */
0, /* tp_alloc */
rangeiter_new, /* tp_new */
};
/* Return number of items in range (lo, hi, step). step != 0
* required. The result always fits in an unsigned long.
*/
static unsigned long
get_len_of_range(long lo, long hi, long step)
{
/* -------------------------------------------------------------
If step > 0 and lo >= hi, or step < 0 and lo <= hi, the range is empty.
Else for step > 0, if n values are in the range, the last one is
lo + (n-1)*step, which must be <= hi-1. Rearranging,
n <= (hi - lo - 1)/step + 1, so taking the floor of the RHS gives
the proper value. Since lo < hi in this case, hi-lo-1 >= 0, so
the RHS is non-negative and so truncation is the same as the
floor. Letting M be the largest positive long, the worst case
for the RHS numerator is hi=M, lo=-M-1, and then
hi-lo-1 = M-(-M-1)-1 = 2*M. Therefore unsigned long has enough
precision to compute the RHS exactly. The analysis for step < 0
is similar.
---------------------------------------------------------------*/
assert(step != 0);
if (step > 0 && lo < hi)
return 1UL + (hi - 1UL - lo) / step;
else if (step < 0 && lo > hi)
return 1UL + (lo - 1UL - hi) / (0UL - step);
else
return 0UL;
}
/* Initialize a rangeiter object. If the length of the rangeiter object
is not representable as a C long, OverflowError is raised. */
static PyObject *
fast_range_iter(long start, long stop, long step)
{
rangeiterobject *it = PyObject_New(rangeiterobject, &PyRangeIter_Type);
unsigned long ulen;
if (it == NULL)
return NULL;
it->start = start;
it->step = step;
ulen = get_len_of_range(start, stop, step);
if (ulen > (unsigned long)LONG_MAX) {
Py_DECREF(it);
PyErr_SetString(PyExc_OverflowError,
"range too large to represent as a range_iterator");
return NULL;
}
it->len = (long)ulen;
it->index = 0;
return (PyObject *)it;
}
static PyObject *
rangeiter_new(PyTypeObject *type, PyObject *args, PyObject *kw)
{
long start, stop, step;
if (!_PyArg_NoKeywords("rangeiter()", kw))
return NULL;
if (!PyArg_ParseTuple(args, "lll;rangeiter() requires 3 int arguments",
&start, &stop, &step))
return NULL;
return fast_range_iter(start, stop, step);
}
typedef struct {
PyObject_HEAD
PyObject *index;
PyObject *start;
PyObject *step;
PyObject *len;
} longrangeiterobject;
static PyObject *
longrangeiter_len(longrangeiterobject *r, PyObject *no_args)
{
return PyNumber_Subtract(r->len, r->index);
}
static PyMethodDef longrangeiter_methods[] = {
{"__length_hint__", (PyCFunction)longrangeiter_len, METH_NOARGS,
length_hint_doc},
{NULL, NULL} /* sentinel */
};
static void
longrangeiter_dealloc(longrangeiterobject *r)
{
Py_XDECREF(r->index);
Py_XDECREF(r->start);
Py_XDECREF(r->step);
Py_XDECREF(r->len);
PyObject_Del(r);
}
static PyObject *
longrangeiter_next(longrangeiterobject *r)
{
PyObject *one, *product, *new_index, *result;
if (PyObject_RichCompareBool(r->index, r->len, Py_LT) != 1)
return NULL;
one = PyLong_FromLong(1);
if (!one)
return NULL;
new_index = PyNumber_Add(r->index, one);
Py_DECREF(one);
if (!new_index)
return NULL;
product = PyNumber_Multiply(r->index, r->step);
if (!product) {
Py_DECREF(new_index);
return NULL;
}
result = PyNumber_Add(r->start, product);
Py_DECREF(product);
if (result) {
Py_DECREF(r->index);
r->index = new_index;
}
else {
Py_DECREF(new_index);
}
return result;
}
PyTypeObject PyLongRangeIter_Type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
"longrange_iterator", /* tp_name */
sizeof(longrangeiterobject), /* tp_basicsize */
0, /* tp_itemsize */
/* methods */
(destructor)longrangeiter_dealloc, /* tp_dealloc */
0, /* tp_print */
0, /* tp_getattr */
0, /* tp_setattr */
0, /* tp_reserved */
0, /* tp_repr */
0, /* tp_as_number */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
0, /* tp_hash */
0, /* tp_call */
0, /* tp_str */
PyObject_GenericGetAttr, /* tp_getattro */
0, /* tp_setattro */
0, /* tp_as_buffer */
Py_TPFLAGS_DEFAULT, /* tp_flags */
0, /* tp_doc */
0, /* tp_traverse */
0, /* tp_clear */
0, /* tp_richcompare */
0, /* tp_weaklistoffset */
PyObject_SelfIter, /* tp_iter */
(iternextfunc)longrangeiter_next, /* tp_iternext */
longrangeiter_methods, /* tp_methods */
0,
};
static PyObject *
range_iter(PyObject *seq)
{
rangeobject *r = (rangeobject *)seq;
longrangeiterobject *it;
long lstart, lstop, lstep;
PyObject *int_it;
assert(PyRange_Check(seq));
/* If all three fields and the length convert to long, use the int
* version */
lstart = PyLong_AsLong(r->start);
if (lstart == -1 && PyErr_Occurred()) {
PyErr_Clear();
goto long_range;
}
lstop = PyLong_AsLong(r->stop);
if (lstop == -1 && PyErr_Occurred()) {
PyErr_Clear();
goto long_range;
}
lstep = PyLong_AsLong(r->step);
if (lstep == -1 && PyErr_Occurred()) {
PyErr_Clear();
goto long_range;
}
int_it = fast_range_iter(lstart, lstop, lstep);
if (int_it == NULL && PyErr_ExceptionMatches(PyExc_OverflowError)) {
PyErr_Clear();
goto long_range;
}
return (PyObject *)int_it;
long_range:
it = PyObject_New(longrangeiterobject, &PyLongRangeIter_Type);
if (it == NULL)
return NULL;
/* Do all initialization here, so we can DECREF on failure. */
it->start = r->start;
it->step = r->step;
it->len = r->length;
Py_INCREF(it->start);
Py_INCREF(it->step);
Py_INCREF(it->len);
it->index = PyLong_FromLong(0);
if (!it->index)
goto create_failure;
return (PyObject *)it;
create_failure:
Py_DECREF(it);
return NULL;
}
static PyObject *
range_reverse(PyObject *seq)
{
rangeobject *range = (rangeobject*) seq;
longrangeiterobject *it;
PyObject *one, *sum, *diff, *product;
long lstart, lstop, lstep, new_start, new_stop;
unsigned long ulen;
assert(PyRange_Check(seq));
/* reversed(range(start, stop, step)) can be expressed as
range(start+(n-1)*step, start-step, -step), where n is the number of
integers in the range.
If each of start, stop, step, -step, start-step, and the length
of the iterator is representable as a C long, use the int
version. This excludes some cases where the reversed range is
representable as a range_iterator, but it's good enough for
common cases and it makes the checks simple. */
lstart = PyLong_AsLong(range->start);
if (lstart == -1 && PyErr_Occurred()) {
PyErr_Clear();
goto long_range;
}
lstop = PyLong_AsLong(range->stop);
if (lstop == -1 && PyErr_Occurred()) {
PyErr_Clear();
goto long_range;
}
lstep = PyLong_AsLong(range->step);
if (lstep == -1 && PyErr_Occurred()) {
PyErr_Clear();
goto long_range;
}
/* check for possible overflow of -lstep */
if (lstep == LONG_MIN)
goto long_range;
/* check for overflow of lstart - lstep:
for lstep > 0, need only check whether lstart - lstep < LONG_MIN.
for lstep < 0, need only check whether lstart - lstep > LONG_MAX
Rearrange these inequalities as:
lstart - LONG_MIN < lstep (lstep > 0)
LONG_MAX - lstart < -lstep (lstep < 0)
and compute both sides as unsigned longs, to avoid the
possibility of undefined behaviour due to signed overflow. */
if (lstep > 0) {
if ((unsigned long)lstart - LONG_MIN < (unsigned long)lstep)
goto long_range;
}
else {
if (LONG_MAX - (unsigned long)lstart < 0UL - lstep)
goto long_range;
}
ulen = get_len_of_range(lstart, lstop, lstep);
if (ulen > (unsigned long)LONG_MAX)
goto long_range;
new_stop = lstart - lstep;
new_start = (long)(new_stop + ulen * lstep);
return fast_range_iter(new_start, new_stop, -lstep);
long_range:
it = PyObject_New(longrangeiterobject, &PyLongRangeIter_Type);
if (it == NULL)
return NULL;
/* start + (len - 1) * step */
it->len = range->length;
Py_INCREF(it->len);
one = PyLong_FromLong(1);
if (!one)
goto create_failure;
diff = PyNumber_Subtract(it->len, one);
Py_DECREF(one);
if (!diff)
goto create_failure;
product = PyNumber_Multiply(diff, range->step);
Py_DECREF(diff);
if (!product)
goto create_failure;
sum = PyNumber_Add(range->start, product);
Py_DECREF(product);
it->start = sum;
if (!it->start)
goto create_failure;
it->step = PyNumber_Negative(range->step);
if (!it->step)
goto create_failure;
it->index = PyLong_FromLong(0);
if (!it->index)
goto create_failure;
return (PyObject *)it;
create_failure:
Py_DECREF(it);
return NULL;
}
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