Michael W. Hudson | f0d777c | 2002-07-19 15:47:06 +0000 | [diff] [blame] | 1 | # tests for slice objects; in particular the indices method. |
| 2 | |
Mark Dickinson | c8a6967 | 2012-11-10 14:52:10 +0000 | [diff] [blame] | 3 | import itertools |
| 4 | import operator |
Michael W. Hudson | 173f11d | 2002-11-05 15:28:51 +0000 | [diff] [blame] | 5 | import sys |
Benjamin Peterson | 2b601d3 | 2016-04-16 14:47:12 -0700 | [diff] [blame] | 6 | import unittest |
| 7 | import weakref |
| 8 | |
| 9 | from pickle import loads, dumps |
| 10 | from test import support |
Michael W. Hudson | f0d777c | 2002-07-19 15:47:06 +0000 | [diff] [blame] | 11 | |
Mark Dickinson | c8a6967 | 2012-11-10 14:52:10 +0000 | [diff] [blame] | 12 | |
| 13 | def evaluate_slice_index(arg): |
| 14 | """ |
| 15 | Helper function to convert a slice argument to an integer, and raise |
| 16 | TypeError with a suitable message on failure. |
| 17 | |
| 18 | """ |
| 19 | if hasattr(arg, '__index__'): |
| 20 | return operator.index(arg) |
| 21 | else: |
| 22 | raise TypeError( |
| 23 | "slice indices must be integers or " |
| 24 | "None or have an __index__ method") |
| 25 | |
| 26 | def slice_indices(slice, length): |
| 27 | """ |
| 28 | Reference implementation for the slice.indices method. |
| 29 | |
| 30 | """ |
| 31 | # Compute step and length as integers. |
| 32 | length = operator.index(length) |
| 33 | step = 1 if slice.step is None else evaluate_slice_index(slice.step) |
| 34 | |
| 35 | # Raise ValueError for negative length or zero step. |
| 36 | if length < 0: |
| 37 | raise ValueError("length should not be negative") |
| 38 | if step == 0: |
| 39 | raise ValueError("slice step cannot be zero") |
| 40 | |
| 41 | # Find lower and upper bounds for start and stop. |
| 42 | lower = -1 if step < 0 else 0 |
| 43 | upper = length - 1 if step < 0 else length |
| 44 | |
| 45 | # Compute start. |
| 46 | if slice.start is None: |
| 47 | start = upper if step < 0 else lower |
| 48 | else: |
| 49 | start = evaluate_slice_index(slice.start) |
| 50 | start = max(start + length, lower) if start < 0 else min(start, upper) |
| 51 | |
| 52 | # Compute stop. |
| 53 | if slice.stop is None: |
| 54 | stop = lower if step < 0 else upper |
| 55 | else: |
| 56 | stop = evaluate_slice_index(slice.stop) |
| 57 | stop = max(stop + length, lower) if stop < 0 else min(stop, upper) |
| 58 | |
| 59 | return start, stop, step |
| 60 | |
| 61 | |
| 62 | # Class providing an __index__ method. Used for testing slice.indices. |
| 63 | |
| 64 | class MyIndexable(object): |
| 65 | def __init__(self, value): |
| 66 | self.value = value |
| 67 | |
| 68 | def __index__(self): |
| 69 | return self.value |
| 70 | |
| 71 | |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 72 | class SliceTest(unittest.TestCase): |
Michael W. Hudson | 173f11d | 2002-11-05 15:28:51 +0000 | [diff] [blame] | 73 | |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 74 | def test_constructor(self): |
| 75 | self.assertRaises(TypeError, slice) |
| 76 | self.assertRaises(TypeError, slice, 1, 2, 3, 4) |
| 77 | |
| 78 | def test_repr(self): |
| 79 | self.assertEqual(repr(slice(1, 2, 3)), "slice(1, 2, 3)") |
| 80 | |
Raymond Hettinger | b859c07 | 2003-09-05 14:27:30 +0000 | [diff] [blame] | 81 | def test_hash(self): |
| 82 | # Verify clearing of SF bug #800796 |
| 83 | self.assertRaises(TypeError, hash, slice(5)) |
Serhiy Storchaka | c0e0022 | 2015-05-20 18:37:37 +0300 | [diff] [blame] | 84 | with self.assertRaises(TypeError): |
| 85 | slice(5).__hash__() |
Raymond Hettinger | b859c07 | 2003-09-05 14:27:30 +0000 | [diff] [blame] | 86 | |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 87 | def test_cmp(self): |
| 88 | s1 = slice(1, 2, 3) |
| 89 | s2 = slice(1, 2, 3) |
| 90 | s3 = slice(1, 2, 4) |
| 91 | self.assertEqual(s1, s2) |
| 92 | self.assertNotEqual(s1, s3) |
Thomas Wouters | 3e57b52 | 2007-08-28 23:07:26 +0000 | [diff] [blame] | 93 | self.assertNotEqual(s1, None) |
| 94 | self.assertNotEqual(s1, (1, 2, 3)) |
| 95 | self.assertNotEqual(s1, "") |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 96 | |
| 97 | class Exc(Exception): |
| 98 | pass |
| 99 | |
| 100 | class BadCmp(object): |
| 101 | def __eq__(self, other): |
| 102 | raise Exc |
| 103 | |
| 104 | s1 = slice(BadCmp()) |
| 105 | s2 = slice(BadCmp()) |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 106 | self.assertEqual(s1, s1) |
Guido van Rossum | 47b9ff6 | 2006-08-24 00:41:19 +0000 | [diff] [blame] | 107 | self.assertRaises(Exc, lambda: s1 == s2) |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 108 | |
| 109 | s1 = slice(1, BadCmp()) |
| 110 | s2 = slice(1, BadCmp()) |
| 111 | self.assertEqual(s1, s1) |
Guido van Rossum | 47b9ff6 | 2006-08-24 00:41:19 +0000 | [diff] [blame] | 112 | self.assertRaises(Exc, lambda: s1 == s2) |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 113 | |
| 114 | s1 = slice(1, 2, BadCmp()) |
| 115 | s2 = slice(1, 2, BadCmp()) |
| 116 | self.assertEqual(s1, s1) |
Guido van Rossum | 47b9ff6 | 2006-08-24 00:41:19 +0000 | [diff] [blame] | 117 | self.assertRaises(Exc, lambda: s1 == s2) |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 118 | |
| 119 | def test_members(self): |
| 120 | s = slice(1) |
| 121 | self.assertEqual(s.start, None) |
| 122 | self.assertEqual(s.stop, 1) |
| 123 | self.assertEqual(s.step, None) |
| 124 | |
| 125 | s = slice(1, 2) |
| 126 | self.assertEqual(s.start, 1) |
| 127 | self.assertEqual(s.stop, 2) |
| 128 | self.assertEqual(s.step, None) |
| 129 | |
| 130 | s = slice(1, 2, 3) |
| 131 | self.assertEqual(s.start, 1) |
| 132 | self.assertEqual(s.stop, 2) |
| 133 | self.assertEqual(s.step, 3) |
| 134 | |
| 135 | class AnyClass: |
| 136 | pass |
| 137 | |
| 138 | obj = AnyClass() |
| 139 | s = slice(obj) |
Benjamin Peterson | c9c0f20 | 2009-06-30 23:06:06 +0000 | [diff] [blame] | 140 | self.assertTrue(s.stop is obj) |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 141 | |
Mark Dickinson | c8a6967 | 2012-11-10 14:52:10 +0000 | [diff] [blame] | 142 | def check_indices(self, slice, length): |
| 143 | try: |
| 144 | actual = slice.indices(length) |
| 145 | except ValueError: |
| 146 | actual = "valueerror" |
| 147 | try: |
| 148 | expected = slice_indices(slice, length) |
| 149 | except ValueError: |
| 150 | expected = "valueerror" |
| 151 | self.assertEqual(actual, expected) |
| 152 | |
| 153 | if length >= 0 and slice.step != 0: |
| 154 | actual = range(*slice.indices(length)) |
| 155 | expected = range(length)[slice] |
| 156 | self.assertEqual(actual, expected) |
| 157 | |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 158 | def test_indices(self): |
| 159 | self.assertEqual(slice(None ).indices(10), (0, 10, 1)) |
| 160 | self.assertEqual(slice(None, None, 2).indices(10), (0, 10, 2)) |
| 161 | self.assertEqual(slice(1, None, 2).indices(10), (1, 10, 2)) |
| 162 | self.assertEqual(slice(None, None, -1).indices(10), (9, -1, -1)) |
| 163 | self.assertEqual(slice(None, None, -2).indices(10), (9, -1, -2)) |
| 164 | self.assertEqual(slice(3, None, -2).indices(10), (3, -1, -2)) |
Benjamin Peterson | fea6a94 | 2008-07-02 16:11:42 +0000 | [diff] [blame] | 165 | # issue 3004 tests |
| 166 | self.assertEqual(slice(None, -9).indices(10), (0, 1, 1)) |
| 167 | self.assertEqual(slice(None, -10).indices(10), (0, 0, 1)) |
| 168 | self.assertEqual(slice(None, -11).indices(10), (0, 0, 1)) |
| 169 | self.assertEqual(slice(None, -10, -1).indices(10), (9, 0, -1)) |
| 170 | self.assertEqual(slice(None, -11, -1).indices(10), (9, -1, -1)) |
| 171 | self.assertEqual(slice(None, -12, -1).indices(10), (9, -1, -1)) |
| 172 | self.assertEqual(slice(None, 9).indices(10), (0, 9, 1)) |
| 173 | self.assertEqual(slice(None, 10).indices(10), (0, 10, 1)) |
| 174 | self.assertEqual(slice(None, 11).indices(10), (0, 10, 1)) |
| 175 | self.assertEqual(slice(None, 8, -1).indices(10), (9, 8, -1)) |
| 176 | self.assertEqual(slice(None, 9, -1).indices(10), (9, 9, -1)) |
| 177 | self.assertEqual(slice(None, 10, -1).indices(10), (9, 9, -1)) |
| 178 | |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 179 | self.assertEqual( |
| 180 | slice(-100, 100 ).indices(10), |
| 181 | slice(None).indices(10) |
| 182 | ) |
| 183 | self.assertEqual( |
| 184 | slice(100, -100, -1).indices(10), |
| 185 | slice(None, None, -1).indices(10) |
| 186 | ) |
Guido van Rossum | e2a383d | 2007-01-15 16:59:06 +0000 | [diff] [blame] | 187 | self.assertEqual(slice(-100, 100, 2).indices(10), (0, 10, 2)) |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 188 | |
Christian Heimes | a37d4c6 | 2007-12-04 23:02:19 +0000 | [diff] [blame] | 189 | self.assertEqual(list(range(10))[::sys.maxsize - 1], [0]) |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 190 | |
Mark Dickinson | c8a6967 | 2012-11-10 14:52:10 +0000 | [diff] [blame] | 191 | # Check a variety of start, stop, step and length values, including |
| 192 | # values exceeding sys.maxsize (see issue #14794). |
| 193 | vals = [None, -2**100, -2**30, -53, -7, -1, 0, 1, 7, 53, 2**30, 2**100] |
| 194 | lengths = [0, 1, 7, 53, 2**30, 2**100] |
| 195 | for slice_args in itertools.product(vals, repeat=3): |
| 196 | s = slice(*slice_args) |
| 197 | for length in lengths: |
| 198 | self.check_indices(s, length) |
| 199 | self.check_indices(slice(0, 10, 1), -3) |
| 200 | |
| 201 | # Negative length should raise ValueError |
| 202 | with self.assertRaises(ValueError): |
| 203 | slice(None).indices(-1) |
| 204 | |
| 205 | # Zero step should raise ValueError |
| 206 | with self.assertRaises(ValueError): |
| 207 | slice(0, 10, 0).indices(5) |
| 208 | |
| 209 | # Using a start, stop or step or length that can't be interpreted as an |
| 210 | # integer should give a TypeError ... |
| 211 | with self.assertRaises(TypeError): |
| 212 | slice(0.0, 10, 1).indices(5) |
| 213 | with self.assertRaises(TypeError): |
| 214 | slice(0, 10.0, 1).indices(5) |
| 215 | with self.assertRaises(TypeError): |
| 216 | slice(0, 10, 1.0).indices(5) |
| 217 | with self.assertRaises(TypeError): |
| 218 | slice(0, 10, 1).indices(5.0) |
| 219 | |
| 220 | # ... but it should be fine to use a custom class that provides index. |
| 221 | self.assertEqual(slice(0, 10, 1).indices(5), (0, 5, 1)) |
| 222 | self.assertEqual(slice(MyIndexable(0), 10, 1).indices(5), (0, 5, 1)) |
| 223 | self.assertEqual(slice(0, MyIndexable(10), 1).indices(5), (0, 5, 1)) |
| 224 | self.assertEqual(slice(0, 10, MyIndexable(1)).indices(5), (0, 5, 1)) |
| 225 | self.assertEqual(slice(0, 10, 1).indices(MyIndexable(5)), (0, 5, 1)) |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 226 | |
Guido van Rossum | d8faa36 | 2007-04-27 19:54:29 +0000 | [diff] [blame] | 227 | def test_setslice_without_getslice(self): |
| 228 | tmp = [] |
| 229 | class X(object): |
Thomas Wouters | d2cf20e | 2007-08-30 22:57:53 +0000 | [diff] [blame] | 230 | def __setitem__(self, i, k): |
| 231 | tmp.append((i, k)) |
Guido van Rossum | d8faa36 | 2007-04-27 19:54:29 +0000 | [diff] [blame] | 232 | |
| 233 | x = X() |
| 234 | x[1:2] = 42 |
Ezio Melotti | b3aedd4 | 2010-11-20 19:04:17 +0000 | [diff] [blame] | 235 | self.assertEqual(tmp, [(slice(1, 2), 42)]) |
Guido van Rossum | d8faa36 | 2007-04-27 19:54:29 +0000 | [diff] [blame] | 236 | |
| 237 | def test_pickle(self): |
| 238 | s = slice(10, 20, 3) |
| 239 | for protocol in (0,1,2): |
| 240 | t = loads(dumps(s, protocol)) |
| 241 | self.assertEqual(s, t) |
| 242 | self.assertEqual(s.indices(15), t.indices(15)) |
| 243 | self.assertNotEqual(id(s), id(t)) |
| 244 | |
Benjamin Peterson | 2b601d3 | 2016-04-16 14:47:12 -0700 | [diff] [blame] | 245 | def test_cycle(self): |
| 246 | class myobj(): pass |
| 247 | o = myobj() |
| 248 | o.s = slice(o) |
| 249 | w = weakref.ref(o) |
| 250 | o = None |
Benjamin Peterson | 8917226 | 2016-04-16 15:02:23 -0700 | [diff] [blame] | 251 | support.gc_collect() |
Benjamin Peterson | 2b601d3 | 2016-04-16 14:47:12 -0700 | [diff] [blame] | 252 | self.assertIsNone(w()) |
| 253 | |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 254 | if __name__ == "__main__": |
Zachary Ware | 38c707e | 2015-04-13 15:00:43 -0500 | [diff] [blame] | 255 | unittest.main() |