1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
|
# tests for slice objects; in particular the indices method.
import itertools
import operator
import sys
import unittest
import weakref
import copy
from pickle import loads, dumps
from test import support
def evaluate_slice_index(arg):
"""
Helper function to convert a slice argument to an integer, and raise
TypeError with a suitable message on failure.
"""
if hasattr(arg, '__index__'):
return operator.index(arg)
else:
raise TypeError(
"slice indices must be integers or "
"None or have an __index__ method")
def slice_indices(slice, length):
"""
Reference implementation for the slice.indices method.
"""
# Compute step and length as integers.
length = operator.index(length)
step = 1 if slice.step is None else evaluate_slice_index(slice.step)
# Raise ValueError for negative length or zero step.
if length < 0:
raise ValueError("length should not be negative")
if step == 0:
raise ValueError("slice step cannot be zero")
# Find lower and upper bounds for start and stop.
lower = -1 if step < 0 else 0
upper = length - 1 if step < 0 else length
# Compute start.
if slice.start is None:
start = upper if step < 0 else lower
else:
start = evaluate_slice_index(slice.start)
start = max(start + length, lower) if start < 0 else min(start, upper)
# Compute stop.
if slice.stop is None:
stop = lower if step < 0 else upper
else:
stop = evaluate_slice_index(slice.stop)
stop = max(stop + length, lower) if stop < 0 else min(stop, upper)
return start, stop, step
# Class providing an __index__ method. Used for testing slice.indices.
class MyIndexable(object):
def __init__(self, value):
self.value = value
def __index__(self):
return self.value
class SliceTest(unittest.TestCase):
def test_constructor(self):
self.assertRaises(TypeError, slice)
self.assertRaises(TypeError, slice, 1, 2, 3, 4)
def test_repr(self):
self.assertEqual(repr(slice(1, 2, 3)), "slice(1, 2, 3)")
def test_hash(self):
self.assertEqual(hash(slice(5)), slice(5).__hash__())
self.assertEqual(hash(slice(1, 2)), slice(1, 2).__hash__())
self.assertEqual(hash(slice(1, 2, 3)), slice(1, 2, 3).__hash__())
self.assertNotEqual(slice(5), slice(6))
with self.assertRaises(TypeError):
hash(slice(1, 2, []))
with self.assertRaises(TypeError):
hash(slice(4, {}))
def test_cmp(self):
s1 = slice(1, 2, 3)
s2 = slice(1, 2, 3)
s3 = slice(1, 2, 4)
self.assertEqual(s1, s2)
self.assertNotEqual(s1, s3)
self.assertNotEqual(s1, None)
self.assertNotEqual(s1, (1, 2, 3))
self.assertNotEqual(s1, "")
class Exc(Exception):
pass
class BadCmp(object):
def __eq__(self, other):
raise Exc
s1 = slice(BadCmp())
s2 = slice(BadCmp())
self.assertEqual(s1, s1)
self.assertRaises(Exc, lambda: s1 == s2)
s1 = slice(1, BadCmp())
s2 = slice(1, BadCmp())
self.assertEqual(s1, s1)
self.assertRaises(Exc, lambda: s1 == s2)
s1 = slice(1, 2, BadCmp())
s2 = slice(1, 2, BadCmp())
self.assertEqual(s1, s1)
self.assertRaises(Exc, lambda: s1 == s2)
def test_members(self):
s = slice(1)
self.assertEqual(s.start, None)
self.assertEqual(s.stop, 1)
self.assertEqual(s.step, None)
s = slice(1, 2)
self.assertEqual(s.start, 1)
self.assertEqual(s.stop, 2)
self.assertEqual(s.step, None)
s = slice(1, 2, 3)
self.assertEqual(s.start, 1)
self.assertEqual(s.stop, 2)
self.assertEqual(s.step, 3)
class AnyClass:
pass
obj = AnyClass()
s = slice(obj)
self.assertTrue(s.stop is obj)
def check_indices(self, slice, length):
try:
actual = slice.indices(length)
except ValueError:
actual = "valueerror"
try:
expected = slice_indices(slice, length)
except ValueError:
expected = "valueerror"
self.assertEqual(actual, expected)
if length >= 0 and slice.step != 0:
actual = range(*slice.indices(length))
expected = range(length)[slice]
self.assertEqual(actual, expected)
def test_indices(self):
self.assertEqual(slice(None ).indices(10), (0, 10, 1))
self.assertEqual(slice(None, None, 2).indices(10), (0, 10, 2))
self.assertEqual(slice(1, None, 2).indices(10), (1, 10, 2))
self.assertEqual(slice(None, None, -1).indices(10), (9, -1, -1))
self.assertEqual(slice(None, None, -2).indices(10), (9, -1, -2))
self.assertEqual(slice(3, None, -2).indices(10), (3, -1, -2))
# issue 3004 tests
self.assertEqual(slice(None, -9).indices(10), (0, 1, 1))
self.assertEqual(slice(None, -10).indices(10), (0, 0, 1))
self.assertEqual(slice(None, -11).indices(10), (0, 0, 1))
self.assertEqual(slice(None, -10, -1).indices(10), (9, 0, -1))
self.assertEqual(slice(None, -11, -1).indices(10), (9, -1, -1))
self.assertEqual(slice(None, -12, -1).indices(10), (9, -1, -1))
self.assertEqual(slice(None, 9).indices(10), (0, 9, 1))
self.assertEqual(slice(None, 10).indices(10), (0, 10, 1))
self.assertEqual(slice(None, 11).indices(10), (0, 10, 1))
self.assertEqual(slice(None, 8, -1).indices(10), (9, 8, -1))
self.assertEqual(slice(None, 9, -1).indices(10), (9, 9, -1))
self.assertEqual(slice(None, 10, -1).indices(10), (9, 9, -1))
self.assertEqual(
slice(-100, 100 ).indices(10),
slice(None).indices(10)
)
self.assertEqual(
slice(100, -100, -1).indices(10),
slice(None, None, -1).indices(10)
)
self.assertEqual(slice(-100, 100, 2).indices(10), (0, 10, 2))
self.assertEqual(list(range(10))[::sys.maxsize - 1], [0])
# Check a variety of start, stop, step and length values, including
# values exceeding sys.maxsize (see issue #14794).
vals = [None, -2**100, -2**30, -53, -7, -1, 0, 1, 7, 53, 2**30, 2**100]
lengths = [0, 1, 7, 53, 2**30, 2**100]
for slice_args in itertools.product(vals, repeat=3):
s = slice(*slice_args)
for length in lengths:
self.check_indices(s, length)
self.check_indices(slice(0, 10, 1), -3)
# Negative length should raise ValueError
with self.assertRaises(ValueError):
slice(None).indices(-1)
# Zero step should raise ValueError
with self.assertRaises(ValueError):
slice(0, 10, 0).indices(5)
# Using a start, stop or step or length that can't be interpreted as an
# integer should give a TypeError ...
with self.assertRaises(TypeError):
slice(0.0, 10, 1).indices(5)
with self.assertRaises(TypeError):
slice(0, 10.0, 1).indices(5)
with self.assertRaises(TypeError):
slice(0, 10, 1.0).indices(5)
with self.assertRaises(TypeError):
slice(0, 10, 1).indices(5.0)
# ... but it should be fine to use a custom class that provides index.
self.assertEqual(slice(0, 10, 1).indices(5), (0, 5, 1))
self.assertEqual(slice(MyIndexable(0), 10, 1).indices(5), (0, 5, 1))
self.assertEqual(slice(0, MyIndexable(10), 1).indices(5), (0, 5, 1))
self.assertEqual(slice(0, 10, MyIndexable(1)).indices(5), (0, 5, 1))
self.assertEqual(slice(0, 10, 1).indices(MyIndexable(5)), (0, 5, 1))
def test_setslice_without_getslice(self):
tmp = []
class X(object):
def __setitem__(self, i, k):
tmp.append((i, k))
x = X()
x[1:2] = 42
self.assertEqual(tmp, [(slice(1, 2), 42)])
def test_pickle(self):
import pickle
s = slice(10, 20, 3)
for protocol in range(pickle.HIGHEST_PROTOCOL + 1):
t = loads(dumps(s, protocol))
self.assertEqual(s, t)
self.assertEqual(s.indices(15), t.indices(15))
self.assertNotEqual(id(s), id(t))
def test_copy(self):
s = slice(1, 10)
c = copy.copy(s)
self.assertIs(s, c)
s = slice(1, 10, 2)
c = copy.copy(s)
self.assertIs(s, c)
# Corner case for mutable indices:
s = slice([1, 2], [3, 4], [5, 6])
c = copy.copy(s)
self.assertIs(s, c)
self.assertIs(s.start, c.start)
self.assertIs(s.stop, c.stop)
self.assertIs(s.step, c.step)
def test_deepcopy(self):
s = slice(1, 10)
c = copy.deepcopy(s)
self.assertEqual(s, c)
s = slice(1, 10, 2)
c = copy.deepcopy(s)
self.assertEqual(s, c)
# Corner case for mutable indices:
s = slice([1, 2], [3, 4], [5, 6])
c = copy.deepcopy(s)
self.assertIsNot(s, c)
self.assertEqual(s, c)
self.assertIsNot(s.start, c.start)
self.assertIsNot(s.stop, c.stop)
self.assertIsNot(s.step, c.step)
def test_cycle(self):
class myobj(): pass
o = myobj()
o.s = slice(o)
w = weakref.ref(o)
o = None
support.gc_collect()
self.assertIsNone(w())
if __name__ == "__main__":
unittest.main()
|
