mirror of https://github.com/acidanthera/audk.git
348 lines
12 KiB
C
348 lines
12 KiB
C
/* Range object implementation */
|
|
|
|
#include "Python.h"
|
|
|
|
typedef struct {
|
|
PyObject_HEAD
|
|
long start;
|
|
long step;
|
|
long len;
|
|
} rangeobject;
|
|
|
|
/* 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;
|
|
}
|
|
|
|
/* Return a stop value suitable for reconstructing the xrange from
|
|
* a (start, stop, step) triple. Used in range_repr and range_reduce.
|
|
* Computes start + len * step, clipped to the range [LONG_MIN, LONG_MAX].
|
|
*/
|
|
static long
|
|
get_stop_for_range(rangeobject *r)
|
|
{
|
|
long last;
|
|
|
|
if (r->len == 0)
|
|
return r->start;
|
|
|
|
/* The tricky bit is avoiding overflow. We first compute the last entry in
|
|
the xrange, start + (len - 1) * step, which is guaranteed to lie within
|
|
the range of a long, and then add step to it. See the range_reverse
|
|
comments for an explanation of the casts below.
|
|
*/
|
|
last = (long)(r->start + (unsigned long)(r->len - 1) * r->step);
|
|
if (r->step > 0)
|
|
return last > LONG_MAX - r->step ? LONG_MAX : last + r->step;
|
|
else
|
|
return last < LONG_MIN - r->step ? LONG_MIN : last + r->step;
|
|
}
|
|
|
|
static PyObject *
|
|
range_new(PyTypeObject *type, PyObject *args, PyObject *kw)
|
|
{
|
|
rangeobject *obj;
|
|
long ilow = 0, ihigh = 0, istep = 1;
|
|
unsigned long n;
|
|
|
|
if (!_PyArg_NoKeywords("xrange()", kw))
|
|
return NULL;
|
|
|
|
if (PyTuple_Size(args) <= 1) {
|
|
if (!PyArg_ParseTuple(args,
|
|
"l;xrange() requires 1-3 int arguments",
|
|
&ihigh))
|
|
return NULL;
|
|
}
|
|
else {
|
|
if (!PyArg_ParseTuple(args,
|
|
"ll|l;xrange() requires 1-3 int arguments",
|
|
&ilow, &ihigh, &istep))
|
|
return NULL;
|
|
}
|
|
if (istep == 0) {
|
|
PyErr_SetString(PyExc_ValueError, "xrange() arg 3 must not be zero");
|
|
return NULL;
|
|
}
|
|
n = get_len_of_range(ilow, ihigh, istep);
|
|
if (n > (unsigned long)LONG_MAX || (long)n > PY_SSIZE_T_MAX) {
|
|
PyErr_SetString(PyExc_OverflowError,
|
|
"xrange() result has too many items");
|
|
return NULL;
|
|
}
|
|
|
|
obj = PyObject_New(rangeobject, &PyRange_Type);
|
|
if (obj == NULL)
|
|
return NULL;
|
|
obj->start = ilow;
|
|
obj->len = (long)n;
|
|
obj->step = istep;
|
|
return (PyObject *) obj;
|
|
}
|
|
|
|
PyDoc_STRVAR(range_doc,
|
|
"xrange(stop) -> xrange object\n\
|
|
xrange(start, stop[, step]) -> xrange object\n\
|
|
\n\
|
|
Like range(), but instead of returning a list, returns an object that\n\
|
|
generates the numbers in the range on demand. For looping, this is \n\
|
|
slightly faster than range() and more memory efficient.");
|
|
|
|
static PyObject *
|
|
range_item(rangeobject *r, Py_ssize_t i)
|
|
{
|
|
if (i < 0 || i >= r->len) {
|
|
PyErr_SetString(PyExc_IndexError,
|
|
"xrange object index out of range");
|
|
return NULL;
|
|
}
|
|
/* do calculation entirely using unsigned longs, to avoid
|
|
undefined behaviour due to signed overflow. */
|
|
return PyInt_FromLong((long)(r->start + (unsigned long)i * r->step));
|
|
}
|
|
|
|
static Py_ssize_t
|
|
range_length(rangeobject *r)
|
|
{
|
|
return (Py_ssize_t)(r->len);
|
|
}
|
|
|
|
static PyObject *
|
|
range_repr(rangeobject *r)
|
|
{
|
|
PyObject *rtn;
|
|
|
|
if (r->start == 0 && r->step == 1)
|
|
rtn = PyString_FromFormat("xrange(%ld)",
|
|
get_stop_for_range(r));
|
|
|
|
else if (r->step == 1)
|
|
rtn = PyString_FromFormat("xrange(%ld, %ld)",
|
|
r->start,
|
|
get_stop_for_range(r));
|
|
|
|
else
|
|
rtn = PyString_FromFormat("xrange(%ld, %ld, %ld)",
|
|
r->start,
|
|
get_stop_for_range(r),
|
|
r->step);
|
|
return rtn;
|
|
}
|
|
|
|
/* Pickling support */
|
|
static PyObject *
|
|
range_reduce(rangeobject *r, PyObject *args)
|
|
{
|
|
return Py_BuildValue("(O(lll))", Py_TYPE(r),
|
|
r->start,
|
|
get_stop_for_range(r),
|
|
r->step);
|
|
}
|
|
|
|
static PySequenceMethods range_as_sequence = {
|
|
(lenfunc)range_length, /* sq_length */
|
|
0, /* sq_concat */
|
|
0, /* sq_repeat */
|
|
(ssizeargfunc)range_item, /* sq_item */
|
|
0, /* sq_slice */
|
|
};
|
|
|
|
static PyObject * range_iter(PyObject *seq);
|
|
static PyObject * range_reverse(PyObject *seq);
|
|
|
|
PyDoc_STRVAR(reverse_doc,
|
|
"Returns a reverse iterator.");
|
|
|
|
static PyMethodDef range_methods[] = {
|
|
{"__reversed__", (PyCFunction)range_reverse, METH_NOARGS, reverse_doc},
|
|
{"__reduce__", (PyCFunction)range_reduce, METH_VARARGS},
|
|
{NULL, NULL} /* sentinel */
|
|
};
|
|
|
|
PyTypeObject PyRange_Type = {
|
|
PyObject_HEAD_INIT(&PyType_Type)
|
|
0, /* Number of items for varobject */
|
|
"xrange", /* Name of this type */
|
|
sizeof(rangeobject), /* Basic object size */
|
|
0, /* Item size for varobject */
|
|
(destructor)PyObject_Del, /* tp_dealloc */
|
|
0, /* tp_print */
|
|
0, /* tp_getattr */
|
|
0, /* tp_setattr */
|
|
0, /* tp_compare */
|
|
(reprfunc)range_repr, /* tp_repr */
|
|
0, /* tp_as_number */
|
|
&range_as_sequence, /* 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 */
|
|
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 */
|
|
};
|
|
|
|
/*********************** Xrange Iterator **************************/
|
|
|
|
typedef struct {
|
|
PyObject_HEAD
|
|
long index;
|
|
long start;
|
|
long step;
|
|
long len;
|
|
} rangeiterobject;
|
|
|
|
static PyObject *
|
|
rangeiter_next(rangeiterobject *r)
|
|
{
|
|
if (r->index < r->len)
|
|
return PyInt_FromLong(r->start + (r->index++) * r->step);
|
|
return NULL;
|
|
}
|
|
|
|
static PyObject *
|
|
rangeiter_len(rangeiterobject *r)
|
|
{
|
|
return PyInt_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 PyTypeObject Pyrangeiter_Type = {
|
|
PyObject_HEAD_INIT(&PyType_Type)
|
|
0, /* ob_size */
|
|
"rangeiterator", /* 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_compare */
|
|
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,
|
|
};
|
|
|
|
static PyObject *
|
|
range_iter(PyObject *seq)
|
|
{
|
|
rangeiterobject *it;
|
|
|
|
if (!PyRange_Check(seq)) {
|
|
PyErr_BadInternalCall();
|
|
return NULL;
|
|
}
|
|
it = PyObject_New(rangeiterobject, &Pyrangeiter_Type);
|
|
if (it == NULL)
|
|
return NULL;
|
|
it->index = 0;
|
|
it->start = ((rangeobject *)seq)->start;
|
|
it->step = ((rangeobject *)seq)->step;
|
|
it->len = ((rangeobject *)seq)->len;
|
|
return (PyObject *)it;
|
|
}
|
|
|
|
static PyObject *
|
|
range_reverse(PyObject *seq)
|
|
{
|
|
rangeiterobject *it;
|
|
long start, step, len;
|
|
|
|
if (!PyRange_Check(seq)) {
|
|
PyErr_BadInternalCall();
|
|
return NULL;
|
|
}
|
|
it = PyObject_New(rangeiterobject, &Pyrangeiter_Type);
|
|
if (it == NULL)
|
|
return NULL;
|
|
|
|
start = ((rangeobject *)seq)->start;
|
|
step = ((rangeobject *)seq)->step;
|
|
len = ((rangeobject *)seq)->len;
|
|
|
|
it->index = 0;
|
|
it->len = len;
|
|
/* the casts below guard against signed overflow by turning it
|
|
into unsigned overflow instead. The correctness of this
|
|
code still depends on conversion from unsigned long to long
|
|
wrapping modulo ULONG_MAX+1, which isn't guaranteed (see
|
|
C99 6.3.1.3p3) but seems to hold in practice for all
|
|
platforms we're likely to meet.
|
|
|
|
If step == LONG_MIN then we still end up with LONG_MIN
|
|
after negation; but this works out, since we've still got
|
|
the correct value modulo ULONG_MAX+1, and the range_item
|
|
calculation is also done modulo ULONG_MAX+1.
|
|
*/
|
|
it->start = (long)(start + (unsigned long)(len-1) * step);
|
|
it->step = (long)(0UL-step);
|
|
|
|
return (PyObject *)it;
|
|
}
|