Michael W. Hudson | f0d777c | 2002-07-19 15:47:06 +0000 | [diff] [blame] | 1 | # tests for slice objects; in particular the indices method. |
| 2 | |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 3 | import unittest |
Benjamin Peterson | ee8712c | 2008-05-20 21:35:26 +0000 | [diff] [blame] | 4 | from test import support |
Guido van Rossum | 99603b0 | 2007-07-20 00:22:32 +0000 | [diff] [blame] | 5 | from pickle import loads, dumps |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 6 | |
Mark Dickinson | c8a6967 | 2012-11-10 14:52:10 +0000 | [diff] [blame] | 7 | import itertools |
| 8 | import operator |
Michael W. Hudson | 173f11d | 2002-11-05 15:28:51 +0000 | [diff] [blame] | 9 | import sys |
Michael W. Hudson | f0d777c | 2002-07-19 15:47:06 +0000 | [diff] [blame] | 10 | |
Mark Dickinson | c8a6967 | 2012-11-10 14:52:10 +0000 | [diff] [blame] | 11 | |
| 12 | def evaluate_slice_index(arg): |
| 13 | """ |
| 14 | Helper function to convert a slice argument to an integer, and raise |
| 15 | TypeError with a suitable message on failure. |
| 16 | |
| 17 | """ |
| 18 | if hasattr(arg, '__index__'): |
| 19 | return operator.index(arg) |
| 20 | else: |
| 21 | raise TypeError( |
| 22 | "slice indices must be integers or " |
| 23 | "None or have an __index__ method") |
| 24 | |
| 25 | def slice_indices(slice, length): |
| 26 | """ |
| 27 | Reference implementation for the slice.indices method. |
| 28 | |
| 29 | """ |
| 30 | # Compute step and length as integers. |
| 31 | length = operator.index(length) |
| 32 | step = 1 if slice.step is None else evaluate_slice_index(slice.step) |
| 33 | |
| 34 | # Raise ValueError for negative length or zero step. |
| 35 | if length < 0: |
| 36 | raise ValueError("length should not be negative") |
| 37 | if step == 0: |
| 38 | raise ValueError("slice step cannot be zero") |
| 39 | |
| 40 | # Find lower and upper bounds for start and stop. |
| 41 | lower = -1 if step < 0 else 0 |
| 42 | upper = length - 1 if step < 0 else length |
| 43 | |
| 44 | # Compute start. |
| 45 | if slice.start is None: |
| 46 | start = upper if step < 0 else lower |
| 47 | else: |
| 48 | start = evaluate_slice_index(slice.start) |
| 49 | start = max(start + length, lower) if start < 0 else min(start, upper) |
| 50 | |
| 51 | # Compute stop. |
| 52 | if slice.stop is None: |
| 53 | stop = lower if step < 0 else upper |
| 54 | else: |
| 55 | stop = evaluate_slice_index(slice.stop) |
| 56 | stop = max(stop + length, lower) if stop < 0 else min(stop, upper) |
| 57 | |
| 58 | return start, stop, step |
| 59 | |
| 60 | |
| 61 | # Class providing an __index__ method. Used for testing slice.indices. |
| 62 | |
| 63 | class MyIndexable(object): |
| 64 | def __init__(self, value): |
| 65 | self.value = value |
| 66 | |
| 67 | def __index__(self): |
| 68 | return self.value |
| 69 | |
| 70 | |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 71 | class SliceTest(unittest.TestCase): |
Michael W. Hudson | 173f11d | 2002-11-05 15:28:51 +0000 | [diff] [blame] | 72 | |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 73 | def test_constructor(self): |
| 74 | self.assertRaises(TypeError, slice) |
| 75 | self.assertRaises(TypeError, slice, 1, 2, 3, 4) |
| 76 | |
| 77 | def test_repr(self): |
| 78 | self.assertEqual(repr(slice(1, 2, 3)), "slice(1, 2, 3)") |
| 79 | |
Raymond Hettinger | b859c07 | 2003-09-05 14:27:30 +0000 | [diff] [blame] | 80 | def test_hash(self): |
| 81 | # Verify clearing of SF bug #800796 |
| 82 | self.assertRaises(TypeError, hash, slice(5)) |
| 83 | self.assertRaises(TypeError, slice(5).__hash__) |
| 84 | |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 85 | def test_cmp(self): |
| 86 | s1 = slice(1, 2, 3) |
| 87 | s2 = slice(1, 2, 3) |
| 88 | s3 = slice(1, 2, 4) |
| 89 | self.assertEqual(s1, s2) |
| 90 | self.assertNotEqual(s1, s3) |
Thomas Wouters | 3e57b52 | 2007-08-28 23:07:26 +0000 | [diff] [blame] | 91 | self.assertNotEqual(s1, None) |
| 92 | self.assertNotEqual(s1, (1, 2, 3)) |
| 93 | self.assertNotEqual(s1, "") |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 94 | |
| 95 | class Exc(Exception): |
| 96 | pass |
| 97 | |
| 98 | class BadCmp(object): |
| 99 | def __eq__(self, other): |
| 100 | raise Exc |
| 101 | |
| 102 | s1 = slice(BadCmp()) |
| 103 | s2 = slice(BadCmp()) |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 104 | self.assertEqual(s1, s1) |
Guido van Rossum | 47b9ff6 | 2006-08-24 00:41:19 +0000 | [diff] [blame] | 105 | self.assertRaises(Exc, lambda: s1 == s2) |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 106 | |
| 107 | s1 = slice(1, BadCmp()) |
| 108 | s2 = slice(1, BadCmp()) |
| 109 | self.assertEqual(s1, s1) |
Guido van Rossum | 47b9ff6 | 2006-08-24 00:41:19 +0000 | [diff] [blame] | 110 | self.assertRaises(Exc, lambda: s1 == s2) |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 111 | |
| 112 | s1 = slice(1, 2, BadCmp()) |
| 113 | s2 = slice(1, 2, BadCmp()) |
| 114 | self.assertEqual(s1, s1) |
Guido van Rossum | 47b9ff6 | 2006-08-24 00:41:19 +0000 | [diff] [blame] | 115 | self.assertRaises(Exc, lambda: s1 == s2) |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 116 | |
| 117 | def test_members(self): |
| 118 | s = slice(1) |
| 119 | self.assertEqual(s.start, None) |
| 120 | self.assertEqual(s.stop, 1) |
| 121 | self.assertEqual(s.step, None) |
| 122 | |
| 123 | s = slice(1, 2) |
| 124 | self.assertEqual(s.start, 1) |
| 125 | self.assertEqual(s.stop, 2) |
| 126 | self.assertEqual(s.step, None) |
| 127 | |
| 128 | s = slice(1, 2, 3) |
| 129 | self.assertEqual(s.start, 1) |
| 130 | self.assertEqual(s.stop, 2) |
| 131 | self.assertEqual(s.step, 3) |
| 132 | |
| 133 | class AnyClass: |
| 134 | pass |
| 135 | |
| 136 | obj = AnyClass() |
| 137 | s = slice(obj) |
Benjamin Peterson | c9c0f20 | 2009-06-30 23:06:06 +0000 | [diff] [blame] | 138 | self.assertTrue(s.stop is obj) |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 139 | |
Mark Dickinson | c8a6967 | 2012-11-10 14:52:10 +0000 | [diff] [blame] | 140 | def check_indices(self, slice, length): |
| 141 | try: |
| 142 | actual = slice.indices(length) |
| 143 | except ValueError: |
| 144 | actual = "valueerror" |
| 145 | try: |
| 146 | expected = slice_indices(slice, length) |
| 147 | except ValueError: |
| 148 | expected = "valueerror" |
| 149 | self.assertEqual(actual, expected) |
| 150 | |
| 151 | if length >= 0 and slice.step != 0: |
| 152 | actual = range(*slice.indices(length)) |
| 153 | expected = range(length)[slice] |
| 154 | self.assertEqual(actual, expected) |
| 155 | |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 156 | def test_indices(self): |
| 157 | self.assertEqual(slice(None ).indices(10), (0, 10, 1)) |
| 158 | self.assertEqual(slice(None, None, 2).indices(10), (0, 10, 2)) |
| 159 | self.assertEqual(slice(1, None, 2).indices(10), (1, 10, 2)) |
| 160 | self.assertEqual(slice(None, None, -1).indices(10), (9, -1, -1)) |
| 161 | self.assertEqual(slice(None, None, -2).indices(10), (9, -1, -2)) |
| 162 | self.assertEqual(slice(3, None, -2).indices(10), (3, -1, -2)) |
Benjamin Peterson | fea6a94 | 2008-07-02 16:11:42 +0000 | [diff] [blame] | 163 | # issue 3004 tests |
| 164 | self.assertEqual(slice(None, -9).indices(10), (0, 1, 1)) |
| 165 | self.assertEqual(slice(None, -10).indices(10), (0, 0, 1)) |
| 166 | self.assertEqual(slice(None, -11).indices(10), (0, 0, 1)) |
| 167 | self.assertEqual(slice(None, -10, -1).indices(10), (9, 0, -1)) |
| 168 | self.assertEqual(slice(None, -11, -1).indices(10), (9, -1, -1)) |
| 169 | self.assertEqual(slice(None, -12, -1).indices(10), (9, -1, -1)) |
| 170 | self.assertEqual(slice(None, 9).indices(10), (0, 9, 1)) |
| 171 | self.assertEqual(slice(None, 10).indices(10), (0, 10, 1)) |
| 172 | self.assertEqual(slice(None, 11).indices(10), (0, 10, 1)) |
| 173 | self.assertEqual(slice(None, 8, -1).indices(10), (9, 8, -1)) |
| 174 | self.assertEqual(slice(None, 9, -1).indices(10), (9, 9, -1)) |
| 175 | self.assertEqual(slice(None, 10, -1).indices(10), (9, 9, -1)) |
| 176 | |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 177 | self.assertEqual( |
| 178 | slice(-100, 100 ).indices(10), |
| 179 | slice(None).indices(10) |
| 180 | ) |
| 181 | self.assertEqual( |
| 182 | slice(100, -100, -1).indices(10), |
| 183 | slice(None, None, -1).indices(10) |
| 184 | ) |
Guido van Rossum | e2a383d | 2007-01-15 16:59:06 +0000 | [diff] [blame] | 185 | self.assertEqual(slice(-100, 100, 2).indices(10), (0, 10, 2)) |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 186 | |
Christian Heimes | a37d4c6 | 2007-12-04 23:02:19 +0000 | [diff] [blame] | 187 | self.assertEqual(list(range(10))[::sys.maxsize - 1], [0]) |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 188 | |
Mark Dickinson | c8a6967 | 2012-11-10 14:52:10 +0000 | [diff] [blame] | 189 | # Check a variety of start, stop, step and length values, including |
| 190 | # values exceeding sys.maxsize (see issue #14794). |
| 191 | vals = [None, -2**100, -2**30, -53, -7, -1, 0, 1, 7, 53, 2**30, 2**100] |
| 192 | lengths = [0, 1, 7, 53, 2**30, 2**100] |
| 193 | for slice_args in itertools.product(vals, repeat=3): |
| 194 | s = slice(*slice_args) |
| 195 | for length in lengths: |
| 196 | self.check_indices(s, length) |
| 197 | self.check_indices(slice(0, 10, 1), -3) |
| 198 | |
| 199 | # Negative length should raise ValueError |
| 200 | with self.assertRaises(ValueError): |
| 201 | slice(None).indices(-1) |
| 202 | |
| 203 | # Zero step should raise ValueError |
| 204 | with self.assertRaises(ValueError): |
| 205 | slice(0, 10, 0).indices(5) |
| 206 | |
| 207 | # Using a start, stop or step or length that can't be interpreted as an |
| 208 | # integer should give a TypeError ... |
| 209 | with self.assertRaises(TypeError): |
| 210 | slice(0.0, 10, 1).indices(5) |
| 211 | with self.assertRaises(TypeError): |
| 212 | slice(0, 10.0, 1).indices(5) |
| 213 | with self.assertRaises(TypeError): |
| 214 | slice(0, 10, 1.0).indices(5) |
| 215 | with self.assertRaises(TypeError): |
| 216 | slice(0, 10, 1).indices(5.0) |
| 217 | |
| 218 | # ... but it should be fine to use a custom class that provides index. |
| 219 | self.assertEqual(slice(0, 10, 1).indices(5), (0, 5, 1)) |
| 220 | self.assertEqual(slice(MyIndexable(0), 10, 1).indices(5), (0, 5, 1)) |
| 221 | self.assertEqual(slice(0, MyIndexable(10), 1).indices(5), (0, 5, 1)) |
| 222 | self.assertEqual(slice(0, 10, MyIndexable(1)).indices(5), (0, 5, 1)) |
| 223 | self.assertEqual(slice(0, 10, 1).indices(MyIndexable(5)), (0, 5, 1)) |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 224 | |
Guido van Rossum | d8faa36 | 2007-04-27 19:54:29 +0000 | [diff] [blame] | 225 | def test_setslice_without_getslice(self): |
| 226 | tmp = [] |
| 227 | class X(object): |
Thomas Wouters | d2cf20e | 2007-08-30 22:57:53 +0000 | [diff] [blame] | 228 | def __setitem__(self, i, k): |
| 229 | tmp.append((i, k)) |
Guido van Rossum | d8faa36 | 2007-04-27 19:54:29 +0000 | [diff] [blame] | 230 | |
| 231 | x = X() |
| 232 | x[1:2] = 42 |
Ezio Melotti | b3aedd4 | 2010-11-20 19:04:17 +0000 | [diff] [blame] | 233 | self.assertEqual(tmp, [(slice(1, 2), 42)]) |
Guido van Rossum | d8faa36 | 2007-04-27 19:54:29 +0000 | [diff] [blame] | 234 | |
| 235 | def test_pickle(self): |
| 236 | s = slice(10, 20, 3) |
| 237 | for protocol in (0,1,2): |
| 238 | t = loads(dumps(s, protocol)) |
| 239 | self.assertEqual(s, t) |
| 240 | self.assertEqual(s.indices(15), t.indices(15)) |
| 241 | self.assertNotEqual(id(s), id(t)) |
| 242 | |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 243 | def test_main(): |
Benjamin Peterson | ee8712c | 2008-05-20 21:35:26 +0000 | [diff] [blame] | 244 | support.run_unittest(SliceTest) |
Raymond Hettinger | 5d2e777 | 2003-09-02 01:53:01 +0000 | [diff] [blame] | 245 | |
| 246 | if __name__ == "__main__": |
| 247 | test_main() |