-
-
Notifications
You must be signed in to change notification settings - Fork 385
/
loops.py
269 lines (222 loc) · 8.58 KB
/
loops.py
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
# -*- coding: utf-8 -*-
import ast
from collections import defaultdict
from typing import ClassVar, DefaultDict, List, Optional, Union
from typing_extensions import final
from wemake_python_styleguide.compat.aliases import ForNodes
from wemake_python_styleguide.logic.nodes import get_parent
from wemake_python_styleguide.logic.operators import unwrap_unary_node
from wemake_python_styleguide.logic.variables import (
is_valid_block_variable_definition,
)
from wemake_python_styleguide.logic.walk import is_contained
from wemake_python_styleguide.types import AnyFor, AnyNodes
from wemake_python_styleguide.violations.best_practices import (
LambdaInsideLoopViolation,
LoopVariableDefinitionViolation,
YieldInComprehensionViolation,
)
from wemake_python_styleguide.violations.complexity import (
TooManyForsInComprehensionViolation,
)
from wemake_python_styleguide.violations.consistency import (
MultilineLoopViolation,
MultipleIfsInComprehensionViolation,
UselessContinueViolation,
WrongLoopIterTypeViolation,
)
from wemake_python_styleguide.violations.refactoring import (
ImplicitSumViolation,
UselessLoopElseViolation,
)
from wemake_python_styleguide.visitors import base, decorators
_AnyLoop = Union[AnyFor, ast.While]
_AnyComprehension = Union[
ast.ListComp,
ast.DictComp,
ast.SetComp,
ast.GeneratorExp,
]
@final
@decorators.alias('visit_any_comprehension', (
'visit_ListComp',
'visit_DictComp',
'visit_SetComp',
'visit_GeneratorExp',
))
class WrongComprehensionVisitor(base.BaseNodeVisitor):
"""Checks comprehensions for correctness."""
_max_ifs: ClassVar[int] = 1
_max_fors: ClassVar[int] = 2
def __init__(self, *args, **kwargs) -> None:
"""Creates a counter for tracked metrics."""
super().__init__(*args, **kwargs)
self._fors: DefaultDict[ast.AST, int] = defaultdict(int)
def visit_comprehension(self, node: ast.comprehension) -> None:
"""
Finds multiple ``if`` and ``for`` nodes inside the comprehension.
Raises:
MultipleIfsInComprehensionViolation
TooManyForsInComprehensionViolation
"""
self._check_ifs(node)
self._check_fors(node)
self.generic_visit(node)
def visit_any_comprehension(self, node: _AnyComprehension) -> None:
"""
Finds incorrect patterns inside comprehensions.
Raises:
YieldInComprehensionViolation
"""
self._check_contains_yield(node)
self.generic_visit(node)
def _check_ifs(self, node: ast.comprehension) -> None:
if len(node.ifs) > self._max_ifs:
# We are trying to fix line number in the report,
# since `comprehension` does not have this property.
parent = get_parent(node) or node
self.add_violation(MultipleIfsInComprehensionViolation(parent))
def _check_fors(self, node: ast.comprehension) -> None:
parent = get_parent(node)
self._fors[parent] = len(parent.generators) # type: ignore
def _check_contains_yield(self, node: _AnyComprehension) -> None:
for sub_node in ast.walk(node):
if isinstance(sub_node, ast.Yield):
self.add_violation(YieldInComprehensionViolation(node))
def _post_visit(self) -> None:
for node, for_count in self._fors.items():
if for_count > self._max_fors:
self.add_violation(TooManyForsInComprehensionViolation(node))
@final
@decorators.alias('visit_any_loop', (
'visit_For',
'visit_While',
'visit_AsyncFor',
))
class WrongLoopVisitor(base.BaseNodeVisitor):
"""Responsible for examining loops."""
def visit_any_loop(self, node: _AnyLoop) -> None:
"""
Checks ``for`` and ``while`` loops.
Raises:
UselessLoopElseViolation
LambdaInsideLoopViolation
MultilineLoopViolation
"""
self._check_loop_needs_else(node)
self._check_lambda_inside_loop(node)
self._check_useless_continue(node)
self._check_multiline_loop(node)
self.generic_visit(node)
def _does_loop_contain_node( # TODO: move, reuse in annotations.py
self,
loop: Optional[_AnyLoop],
to_check: ast.Break,
) -> bool:
if loop is None:
return False
for inner_node in ast.walk(loop):
# We are checking this specific node, not just any `break`:
if to_check is inner_node:
return True
return False
def _has_break(self, node: _AnyLoop) -> bool:
closest_loop = None
for subnode in ast.walk(node):
if isinstance(subnode, (*ForNodes, ast.While)):
if subnode is not node:
closest_loop = subnode
if isinstance(subnode, ast.Break):
is_nested_break = self._does_loop_contain_node(
closest_loop, subnode,
)
if not is_nested_break:
return True
return False
def _check_loop_needs_else(self, node: _AnyLoop) -> None:
if node.orelse and not self._has_break(node):
self.add_violation(UselessLoopElseViolation(node))
def _check_lambda_inside_loop(self, node: _AnyLoop) -> None:
for subnode in node.body:
if is_contained(subnode, (ast.Lambda,)):
self.add_violation(LambdaInsideLoopViolation(node))
def _check_useless_continue(self, node: _AnyLoop) -> None:
nodes_at_line: DefaultDict[int, List[ast.AST]] = defaultdict(list)
for sub_node in ast.walk(node):
lineno = getattr(sub_node, 'lineno', None)
if lineno is not None:
nodes_at_line[lineno].append(sub_node)
last_line = nodes_at_line[sorted(nodes_at_line.keys())[-1]]
if any(isinstance(last, ast.Continue) for last in last_line):
self.add_violation(UselessContinueViolation(node))
def _check_multiline_loop(self, node: _AnyLoop) -> None:
start_lineno = getattr(node, 'lineno', None)
if isinstance(node, ast.While):
node_to_check = node.test
else:
node_to_check = node.iter
for sub_node in ast.walk(node_to_check):
sub_lineno = getattr(sub_node, 'lineno', None)
if sub_lineno is not None and sub_lineno > start_lineno:
self.add_violation(MultilineLoopViolation(node))
break
@final
@decorators.alias('visit_any_for', (
'visit_For',
'visit_AsyncFor',
))
class WrongLoopDefinitionVisitor(base.BaseNodeVisitor):
"""Responsible for ``for`` loops and comprehensions definitions."""
_forbidden_for_iters: ClassVar[AnyNodes] = (
ast.List,
ast.ListComp,
ast.Dict,
ast.DictComp,
ast.Set,
ast.SetComp,
ast.GeneratorExp,
ast.Num,
ast.NameConstant,
)
def visit_any_for(self, node: AnyFor) -> None:
"""
Ensures that ``for`` loop definitions are correct.
Raises:
LoopVariableDefinitionViolation
WrongLoopIterTypeViolation
ImplicitSumViolation
"""
self._check_variable_definitions(node.target)
self._check_explicit_iter_type(node)
self._check_implicit_sum(node)
self.generic_visit(node)
def visit_comprehension(self, node: ast.comprehension) -> None:
"""
Ensures that comprehension definitions are correct.
Raises:
LoopVariableDefinitionViolation
"""
self._check_variable_definitions(node.target)
self._check_explicit_iter_type(node)
self.generic_visit(node)
def _check_variable_definitions(self, node: ast.AST) -> None:
if not is_valid_block_variable_definition(node):
self.add_violation(LoopVariableDefinitionViolation(node))
def _check_explicit_iter_type(
self,
node: Union[AnyFor, ast.comprehension],
) -> None:
node_iter = unwrap_unary_node(node.iter)
is_wrong = isinstance(node_iter, self._forbidden_for_iters)
is_empty = isinstance(node_iter, ast.Tuple) and not node_iter.elts
if is_wrong or is_empty:
self.add_violation(WrongLoopIterTypeViolation(node_iter))
def _check_implicit_sum(self, node: AnyFor) -> None:
is_implicit_sum = (
len(node.body) == 1 and
isinstance(node.body[0], ast.AugAssign) and
isinstance(node.body[0].op, ast.Add) and
isinstance(node.body[0].target, ast.Name)
)
if is_implicit_sum:
self.add_violation(ImplicitSumViolation(node))