Issue 10889: Support slicing and indexing of large ranges (no docs changes, since, as far as I know, we never said anywhere that this *didn't* work)
This commit is contained in:
Nick Coghlan
parent
b436b6cabc
commit
e993b10041
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@ -125,23 +125,102 @@ class RangeTest(unittest.TestCase):
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self.assertIn(a, seq)
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self.assertNotIn(b, seq)
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self.assertEqual(len(seq), 2)
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self.assertEqual(seq[0], a)
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self.assertEqual(seq[-1], a+c)
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seq = list(range(b, a, -c))
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self.assertIn(b, seq)
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self.assertNotIn(a, seq)
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self.assertEqual(len(seq), 2)
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self.assertEqual(seq[0], b)
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self.assertEqual(seq[-1], b-c)
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seq = list(range(-a, -b, -c))
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self.assertIn(-a, seq)
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self.assertNotIn(-b, seq)
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self.assertEqual(len(seq), 2)
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self.assertEqual(seq[0], -a)
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self.assertEqual(seq[-1], -a-c)
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self.assertRaises(OverflowError, len,
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range(-sys.maxsize, sys.maxsize))
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self.assertRaises(OverflowError, len,
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range(0, 2*sys.maxsize))
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self.assertRaises(OverflowError, len,
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range(0, sys.maxsize**10))
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def test_large_range(self):
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# Check long ranges (len > sys.maxsize)
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# len() is expected to fail due to limitations of the __len__ protocol
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def _range_len(x):
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try:
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length = len(x)
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except OverflowError:
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step = x[1] - x[0]
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length = 1 + ((x[-1] - x[0]) // step)
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return length
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a = -sys.maxsize
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b = sys.maxsize
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expected_len = b - a
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x = range(a, b)
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self.assertIn(a, x)
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self.assertNotIn(b, x)
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self.assertRaises(OverflowError, len, x)
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self.assertEqual(_range_len(x), expected_len)
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self.assertEqual(x[0], a)
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idx = sys.maxsize+1
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self.assertEqual(x[idx], a+idx)
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self.assertEqual(x[idx:idx+1][0], a+idx)
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with self.assertRaises(IndexError):
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x[-expected_len-1]
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with self.assertRaises(IndexError):
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x[expected_len]
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a = 0
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b = 2 * sys.maxsize
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expected_len = b - a
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x = range(a, b)
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self.assertIn(a, x)
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self.assertNotIn(b, x)
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self.assertRaises(OverflowError, len, x)
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self.assertEqual(_range_len(x), expected_len)
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self.assertEqual(x[0], a)
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idx = sys.maxsize+1
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self.assertEqual(x[idx], a+idx)
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self.assertEqual(x[idx:idx+1][0], a+idx)
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with self.assertRaises(IndexError):
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x[-expected_len-1]
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with self.assertRaises(IndexError):
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x[expected_len]
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a = 0
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b = sys.maxsize**10
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c = 2*sys.maxsize
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expected_len = 1 + (b - a) // c
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x = range(a, b, c)
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self.assertIn(a, x)
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self.assertNotIn(b, x)
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self.assertRaises(OverflowError, len, x)
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self.assertEqual(_range_len(x), expected_len)
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self.assertEqual(x[0], a)
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idx = sys.maxsize+1
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self.assertEqual(x[idx], a+(idx*c))
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self.assertEqual(x[idx:idx+1][0], a+(idx*c))
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with self.assertRaises(IndexError):
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x[-expected_len-1]
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with self.assertRaises(IndexError):
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x[expected_len]
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a = sys.maxsize**10
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b = 0
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c = -2*sys.maxsize
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expected_len = 1 + (b - a) // c
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x = range(a, b, c)
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self.assertIn(a, x)
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self.assertNotIn(b, x)
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self.assertRaises(OverflowError, len, x)
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self.assertEqual(_range_len(x), expected_len)
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self.assertEqual(x[0], a)
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idx = sys.maxsize+1
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self.assertEqual(x[idx], a+(idx*c))
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self.assertEqual(x[idx:idx+1][0], a+(idx*c))
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with self.assertRaises(IndexError):
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x[-expected_len-1]
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with self.assertRaises(IndexError):
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x[expected_len]
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def test_invalid_invocation(self):
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self.assertRaises(TypeError, range)
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@ -230,18 +230,14 @@ range_length(rangeobject *r)
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return PyLong_AsSsize_t(r->length);
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}
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/* range(...)[x] is necessary for: seq[:] = range(...) */
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static PyObject *
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compute_range_item(rangeobject *r, Py_ssize_t i)
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compute_item(rangeobject *r, PyObject *i)
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{
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PyObject *rem, *incr, *result;
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/* XXX(nnorwitz): optimize for short ints. */
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rem = PyLong_FromSsize_t(i);
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if (!rem)
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return NULL;
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incr = PyNumber_Multiply(rem, r->step);
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Py_DECREF(rem);
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PyObject *incr, *result;
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/* PyLong equivalent to:
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* return r->start + (i * r->step)
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*/
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incr = PyNumber_Multiply(i, r->step);
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if (!incr)
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return NULL;
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result = PyNumber_Add(r->start, incr);
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@ -250,22 +246,304 @@ compute_range_item(rangeobject *r, Py_ssize_t i)
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}
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static PyObject *
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range_item(rangeobject *r, Py_ssize_t i)
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compute_range_item(rangeobject *r, PyObject *arg)
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{
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/* XXX(nnorwitz): should we support range[x] where x > PY_SSIZE_T_MAX? */
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Py_ssize_t len = range_length(r);
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int cmp_result;
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PyObject *i, *result;
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if (i < 0)
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i += len;
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PyObject *zero = PyLong_FromLong(0);
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if (zero == NULL)
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return NULL;
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if (i < 0 || i >= len) {
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/* Also handles case where len < 0 due to (e.g) OverflowError */
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if (!PyErr_Occurred())
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PyErr_SetString(PyExc_IndexError,
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"range object index out of range");
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/* PyLong equivalent to:
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* if (arg < 0) {
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* i = r->length + arg
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* } else {
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* i = arg
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* }
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*/
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cmp_result = PyObject_RichCompareBool(arg, zero, Py_LT);
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if (cmp_result == -1) {
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Py_DECREF(zero);
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return NULL;
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}
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return compute_range_item(r, i);
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if (cmp_result == 1) {
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i = PyNumber_Add(r->length, arg);
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if (!i) {
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Py_DECREF(zero);
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return NULL;
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}
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} else {
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i = arg;
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Py_INCREF(i);
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}
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/* PyLong equivalent to:
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* if (i < 0 || i >= r->length) {
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* <report index out of bounds>
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* }
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*/
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cmp_result = PyObject_RichCompareBool(i, zero, Py_LT);
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Py_DECREF(zero);
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if (cmp_result == 0) {
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cmp_result = PyObject_RichCompareBool(i, r->length, Py_GE);
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}
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if (cmp_result == -1) {
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Py_DECREF(i);
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return NULL;
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}
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if (cmp_result == 1) {
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Py_DECREF(i);
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PyErr_SetString(PyExc_IndexError,
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"range object index out of range");
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return NULL;
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}
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result = compute_item(r, i);
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Py_DECREF(i);
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return result;
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}
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static PyObject *
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range_item(rangeobject *r, Py_ssize_t i)
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{
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PyObject *arg = PyLong_FromLong(i);
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if (!arg) {
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return NULL;
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}
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return compute_range_item(r, arg);
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}
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/* Additional helpers, since the standard slice helpers
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* all clip to PY_SSIZE_T_MAX
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*/
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/* Replace _PyEval_SliceIndex */
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static PyObject *
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compute_slice_element(PyObject *obj)
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{
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PyObject *result = NULL;
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if (obj != NULL) {
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if (PyIndex_Check(obj)) {
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result = PyNumber_Index(obj);
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}
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}
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if (result == NULL) {
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PyErr_SetString(PyExc_TypeError,
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"slice indices must be integers or "
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"None or have an __index__ method");
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}
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return result;
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}
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/* Replace PySlice_GetIndicesEx
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* Result indicates whether or not the slice is empty
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* (-1 = error, 0 = empty slice, 1 = slice contains elements)
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*/
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int
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compute_slice_indices(rangeobject *r, PySliceObject *slice,
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PyObject **start, PyObject **stop, PyObject **step)
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{
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int cmp_result, has_elements;
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Py_ssize_t clamped_step = 0;
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PyObject *zero = NULL, *one = NULL, *neg_one = NULL, *candidate = NULL;
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PyObject *tmp_start = NULL, *tmp_stop = NULL, *tmp_step = NULL;
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zero = PyLong_FromLong(0);
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if (zero == NULL) goto Fail;
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one = PyLong_FromLong(1);
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if (one == NULL) goto Fail;
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neg_one = PyLong_FromLong(-1);
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if (neg_one == NULL) goto Fail;
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/* Calculate step value */
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if (slice->step == Py_None) {
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clamped_step = 1;
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tmp_step = one;
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Py_INCREF(tmp_step);
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} else {
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if (!_PyEval_SliceIndex(slice->step, &clamped_step)) goto Fail;
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if (clamped_step == 0) {
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PyErr_SetString(PyExc_ValueError,
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"slice step cannot be zero");
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goto Fail;
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}
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tmp_step = compute_slice_element(slice->step);
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if (tmp_step == NULL) goto Fail;
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}
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/* Calculate start value */
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if (slice->start == Py_None) {
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if (clamped_step < 0) {
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tmp_start = PyNumber_Subtract(r->length, one);
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if (tmp_start == NULL) goto Fail;
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} else {
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tmp_start = zero;
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Py_INCREF(tmp_start);
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}
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} else {
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candidate = compute_slice_element(slice->start);
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if (candidate == NULL) goto Fail;
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cmp_result = PyObject_RichCompareBool(candidate, zero, Py_LT);
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if (cmp_result == -1) goto Fail;
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if (cmp_result) {
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/* candidate < 0 */
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tmp_start = PyNumber_Add(r->length, candidate);
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if (tmp_start == NULL) goto Fail;
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Py_CLEAR(candidate);
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} else {
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/* candidate >= 0 */
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tmp_start = candidate;
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candidate = NULL;
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}
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cmp_result = PyObject_RichCompareBool(tmp_start, zero, Py_LT);
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if (cmp_result == -1) goto Fail;
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if (cmp_result) {
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/* tmp_start < 0 */
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Py_CLEAR(tmp_start);
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if (clamped_step < 0) {
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tmp_start = neg_one;
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} else {
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tmp_start = zero;
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}
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Py_INCREF(tmp_start);
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} else {
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/* tmp_start >= 0 */
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cmp_result = PyObject_RichCompareBool(tmp_start, r->length, Py_GE);
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if (cmp_result == -1) goto Fail;
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if (cmp_result) {
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/* tmp_start >= r->length */
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Py_CLEAR(tmp_start);
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if (clamped_step < 0) {
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tmp_start = PyNumber_Subtract(r->length, one);
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if (tmp_start == NULL) goto Fail;
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} else {
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tmp_start = r->length;
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Py_INCREF(tmp_start);
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}
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}
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}
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}
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/* Calculate stop value */
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if (slice->stop == Py_None) {
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if (clamped_step < 0) {
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tmp_stop = neg_one;
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} else {
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tmp_stop = r->length;
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}
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Py_INCREF(tmp_stop);
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} else {
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candidate = compute_slice_element(slice->stop);
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if (candidate == NULL) goto Fail;
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cmp_result = PyObject_RichCompareBool(candidate, zero, Py_LT);
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if (cmp_result == -1) goto Fail;
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if (cmp_result) {
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/* candidate < 0 */
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tmp_stop = PyNumber_Add(r->length, candidate);
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if (tmp_stop == NULL) goto Fail;
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Py_CLEAR(candidate);
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} else {
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/* candidate >= 0 */
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tmp_stop = candidate;
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candidate = NULL;
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}
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cmp_result = PyObject_RichCompareBool(tmp_stop, zero, Py_LT);
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if (cmp_result == -1) goto Fail;
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if (cmp_result) {
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/* tmp_stop < 0 */
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Py_CLEAR(tmp_stop);
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if (clamped_step < 0) {
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tmp_stop = neg_one;
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} else {
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tmp_stop = zero;
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}
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Py_INCREF(tmp_stop);
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} else {
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/* tmp_stop >= 0 */
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cmp_result = PyObject_RichCompareBool(tmp_stop, r->length, Py_GE);
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if (cmp_result == -1) goto Fail;
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if (cmp_result) {
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/* tmp_stop >= r->length */
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Py_CLEAR(tmp_stop);
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if (clamped_step < 0) {
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tmp_stop = PyNumber_Subtract(r->length, one);
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if (tmp_stop == NULL) goto Fail;
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} else {
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tmp_stop = r->length;
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Py_INCREF(tmp_start);
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}
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}
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}
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}
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/* Check if the slice is empty or not */
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if (clamped_step < 0) {
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has_elements = PyObject_RichCompareBool(tmp_start, tmp_stop, Py_GT);
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} else {
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has_elements = PyObject_RichCompareBool(tmp_start, tmp_stop, Py_LT);
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}
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if (has_elements == -1) goto Fail;
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*start = tmp_start;
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*stop = tmp_stop;
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*step = tmp_step;
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Py_DECREF(neg_one);
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Py_DECREF(one);
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Py_DECREF(zero);
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return has_elements;
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Fail:
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Py_XDECREF(tmp_start);
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Py_XDECREF(tmp_stop);
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Py_XDECREF(tmp_step);
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Py_XDECREF(candidate);
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Py_XDECREF(neg_one);
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Py_XDECREF(one);
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Py_XDECREF(zero);
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return -1;
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}
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static PyObject *
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compute_slice(rangeobject *r, PyObject *_slice)
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{
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PySliceObject *slice = (PySliceObject *) _slice;
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rangeobject *result;
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PyObject *start = NULL, *stop = NULL, *step = NULL;
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PyObject *substart = NULL, *substop = NULL, *substep = NULL;
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int has_elements;
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has_elements = compute_slice_indices(r, slice, &start, &stop, &step);
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if (has_elements == -1) return NULL;
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substep = PyNumber_Multiply(r->step, step);
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if (substep == NULL) goto fail;
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Py_CLEAR(step);
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substart = compute_item(r, start);
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if (substart == NULL) goto fail;
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Py_CLEAR(start);
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if (has_elements) {
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substop = compute_item(r, stop);
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if (substop == NULL) goto fail;
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} else {
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substop = substart;
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Py_INCREF(substop);
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}
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Py_CLEAR(stop);
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result = make_range_object(Py_TYPE(r), substart, substop, substep);
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if (result != NULL) {
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return (PyObject *) result;
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}
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fail:
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Py_XDECREF(start);
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Py_XDECREF(stop);
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Py_XDECREF(step);
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Py_XDECREF(substart);
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Py_XDECREF(substop);
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Py_XDECREF(substep);
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return NULL;
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}
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/* Assumes (PyLong_CheckExact(ob) || PyBool_Check(ob)) */
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@ -424,55 +702,16 @@ static PyObject *
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range_subscript(rangeobject* self, PyObject* item)
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{
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if (PyIndex_Check(item)) {
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Py_ssize_t i;
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i = PyNumber_AsSsize_t(item, PyExc_IndexError);
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if (i == -1 && PyErr_Occurred())
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PyObject *i, *result;
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i = PyNumber_Index(item);
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if (!i)
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return NULL;
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return range_item(self, i);
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result = compute_range_item(self, i);
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Py_DECREF(i);
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return result;
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}
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if (PySlice_Check(item)) {
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Py_ssize_t start, stop, step, len, rlen;
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rangeobject *result;
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PyObject *substart = NULL, *substep = NULL, *substop = NULL;
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||||
|
||||
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;
|
||||
return compute_slice(self, item);
|
||||
}
|
||||
PyErr_Format(PyExc_TypeError,
|
||||
"range indices must be integers or slices, not %.200s",
|
||||
|
|
|
|||
Loading…
Reference in New Issue