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Issue #9213: Add index and count methods to range objects, needed to 

meet the API of the collections.Sequence ABC.
This commit is contained in:
Daniel Stutzbach 2010-09-13 21:16:29 +00:00
parent e4d6317c87
commit 9f0cbf1c72
4 changed files with 207 additions and 52 deletions
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18
Doc/library/stdtypes.rst
View File

@ -1554,9 +1554,23 @@ looping. The advantage of the :class:`range` type is that an :class:`range`
object will always take the same amount of memory, no matter the size of the
range it represents. There are no consistent performance advantages.
Range objects have very little behavior: they only support indexing, iteration,
and the :func:`len` function.
Range objects have relatively little behavior: they support indexing,
iteration, the :func:`len` function, and the following methods.
.. method:: range.count(x)
Return the number of *i*'s for which ``s[i] == x``. Normally the
result will be 0 or 1, but it could be greater if *x* defines an
unusual equality function.
.. versionadded:: 3.2
.. method:: range.index(x)
Return the smallest *i* such that ``s[i] == x``. Raises
:exc:`ValueError` when *x* is not in the range.
.. versionadded:: 3.2
.. _typesseq-mutable:

54
Lib/test/test_builtin.py
View File

@ -1028,6 +1028,60 @@ class BuiltinTest(unittest.TestCase):
self.assertRaises(TypeError, range, 0.0, 0.0, 1)
self.assertRaises(TypeError, range, 0.0, 0.0, 1.0)
self.assertEqual(range(3).count(-1), 0)
self.assertEqual(range(3).count(0), 1)
self.assertEqual(range(3).count(1), 1)
self.assertEqual(range(3).count(2), 1)
self.assertEqual(range(3).count(3), 0)
self.assertEqual(range(10**20).count(1), 1)
self.assertEqual(range(10**20).count(10**20), 0)
self.assertEqual(range(3).index(1), 1)
self.assertEqual(range(1, 2**100, 2).count(2**87), 0)
self.assertEqual(range(1, 2**100, 2).count(2**87+1), 1)
self.assertEqual(range(1, 10, 3).index(4), 1)
self.assertEqual(range(1, -10, -3).index(-5), 2)
self.assertEqual(range(10**20).index(1), 1)
self.assertEqual(range(10**20).index(10**20 - 1), 10**20 - 1)
self.assertRaises(ValueError, range(1, 2**100, 2).index, 2**87)
self.assertEqual(range(1, 2**100, 2).index(2**87+1), 2**86)
class AlwaysEqual(object):
def __eq__(self, other):
return True
always_equal = AlwaysEqual()
self.assertEqual(range(10).count(always_equal), 10)
self.assertEqual(range(10).index(always_equal), 0)
def test_range_index(self):
u = range(2)
self.assertEqual(u.index(0), 0)
self.assertEqual(u.index(1), 1)
self.assertRaises(ValueError, u.index, 2)
u = range(-2, 3)
self.assertEqual(u.count(0), 1)
self.assertEqual(u.index(0), 2)
self.assertRaises(TypeError, u.index)
class BadExc(Exception):
pass
class BadCmp:
def __eq__(self, other):
if other == 2:
raise BadExc()
return False
a = range(4)
self.assertRaises(BadExc, a.index, BadCmp())
a = range(-2, 3)
self.assertEqual(a.index(0), 2)
def test_input(self):
self.write_testfile()
fp = open(TESTFN, 'r')

4
Misc/NEWS
View File

@ -10,6 +10,10 @@ What's New in Python 3.2 Alpha 3?
Core and Builtins
-----------------
- Issue #9212: The range type_items now provides index() and count()
methods, to conform to the Sequence ABC. Patch by Daniel Urban and
Daniel Stutzbach.
- Issue #7994: Issue a PendingDeprecationWarning if object.__format__
is called with a non-empty format string. This is an effort to
future-proof user code. If a derived class does not currently

183
Objects/rangeobject.c
View File

@ -273,60 +273,135 @@ range_reduce(rangeobject *r, PyObject *args)
r->start, r->stop, r->step);
}
/* 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)) {
int cmp1, cmp2, cmp3;
PyObject *tmp1 = NULL;
PyObject *tmp2 = NULL;
PyObject *zero = NULL;
int result = -1;
if (PyLong_CheckExact(ob) || PyBool_Check(ob))
return range_contains_long(r, ob);
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;
}
/* Fall back to iterative search. */
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)) {
if (range_contains_long(r, ob))
Py_RETURN_TRUE;
else
Py_RETURN_FALSE;
} 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)
{
PyObject *idx, *tmp;
int contains;
PyObject *format_tuple, *err_string;
static PyObject *err_format = NULL;
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)
goto value_error;
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;
value_error:
/* object is not in the range */
if (err_format == NULL) {
err_format = PyUnicode_FromString("%r is not in range");
if (err_format == NULL)
return NULL;
}
format_tuple = PyTuple_Pack(1, ob);
if (format_tuple == NULL)
return NULL;
err_string = PyUnicode_Format(err_format, format_tuple);
Py_DECREF(format_tuple);
if (err_string == NULL)
return NULL;
PyErr_SetObject(PyExc_ValueError, err_string);
Py_DECREF(err_string);
return NULL;
}
static PySequenceMethods range_as_sequence = {
(lenfunc)range_length, /* sq_length */
0, /* sq_concat */
@ -344,10 +419,18 @@ 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},
{"__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 */
};