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
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
|
# copyright 2003-2013 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
#
# This file is part of astroid.
#
# astroid is free software: you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published by the
# Free Software Foundation, either version 2.1 of the License, or (at your
# option) any later version.
#
# astroid is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
# for more details.
#
# You should have received a copy of the GNU Lesser General Public License along
# with astroid. If not, see <http://www.gnu.org/licenses/>.
"""this module contains a set of functions to handle python protocols for nodes
where it makes sense.
"""
import collections
import operator
import sys
import six
from astroid import arguments
from astroid import bases
from astroid import context as contextmod
from astroid import exceptions
from astroid import decorators
from astroid import node_classes
from astroid import nodes
from astroid import util
def _reflected_name(name):
return "__r" + name[2:]
def _augmented_name(name):
return "__i" + name[2:]
_CONTEXTLIB_MGR = 'contextlib.contextmanager'
BIN_OP_METHOD = {'+': '__add__',
'-': '__sub__',
'/': '__div__' if six.PY2 else '__truediv__',
'//': '__floordiv__',
'*': '__mul__',
'**': '__pow__',
'%': '__mod__',
'&': '__and__',
'|': '__or__',
'^': '__xor__',
'<<': '__lshift__',
'>>': '__rshift__',
'@': '__matmul__'
}
REFLECTED_BIN_OP_METHOD = {
key: _reflected_name(value)
for (key, value) in BIN_OP_METHOD.items()
}
AUGMENTED_OP_METHOD = {
key + "=": _augmented_name(value)
for (key, value) in BIN_OP_METHOD.items()
}
UNARY_OP_METHOD = {'+': '__pos__',
'-': '__neg__',
'~': '__invert__',
'not': None, # XXX not '__nonzero__'
}
_UNARY_OPERATORS = {
'+': operator.pos,
'-': operator.neg,
'~': operator.invert,
'not': operator.not_,
}
def _infer_unary_op(obj, op):
func = _UNARY_OPERATORS[op]
value = func(obj)
return nodes.const_factory(value)
nodes.Tuple.infer_unary_op = lambda self, op: _infer_unary_op(tuple(self.elts), op)
nodes.List.infer_unary_op = lambda self, op: _infer_unary_op(self.elts, op)
nodes.Set.infer_unary_op = lambda self, op: _infer_unary_op(set(self.elts), op)
nodes.Const.infer_unary_op = lambda self, op: _infer_unary_op(self.value, op)
nodes.Dict.infer_unary_op = lambda self, op: _infer_unary_op(dict(self.items), op)
# Binary operations
BIN_OP_IMPL = {'+': lambda a, b: a + b,
'-': lambda a, b: a - b,
'/': lambda a, b: a / b,
'//': lambda a, b: a // b,
'*': lambda a, b: a * b,
'**': lambda a, b: a ** b,
'%': lambda a, b: a % b,
'&': lambda a, b: a & b,
'|': lambda a, b: a | b,
'^': lambda a, b: a ^ b,
'<<': lambda a, b: a << b,
'>>': lambda a, b: a >> b,
}
if sys.version_info >= (3, 5):
# MatMult is available since Python 3.5+.
BIN_OP_IMPL['@'] = operator.matmul
for _KEY, _IMPL in list(BIN_OP_IMPL.items()):
BIN_OP_IMPL[_KEY + '='] = _IMPL
@decorators.yes_if_nothing_inferred
def const_infer_binary_op(self, operator, other, context, _):
not_implemented = nodes.Const(NotImplemented)
if isinstance(other, nodes.Const):
try:
impl = BIN_OP_IMPL[operator]
try:
yield nodes.const_factory(impl(self.value, other.value))
except TypeError:
# ArithmeticError is not enough: float >> float is a TypeError
yield not_implemented
except Exception: # pylint: disable=broad-except
yield util.YES
except TypeError:
yield not_implemented
elif isinstance(self.value, six.string_types) and operator == '%':
# TODO(cpopa): implement string interpolation later on.
yield util.YES
else:
yield not_implemented
nodes.Const.infer_binary_op = const_infer_binary_op
def _multiply_seq_by_int(self, other, context):
node = self.__class__()
elts = [n for elt in self.elts for n in elt.infer(context)
if not n is util.YES] * other.value
node.elts = elts
return node
@decorators.yes_if_nothing_inferred
def tl_infer_binary_op(self, operator, other, context, method):
not_implemented = nodes.Const(NotImplemented)
if isinstance(other, self.__class__) and operator == '+':
node = self.__class__()
elts = [n for elt in self.elts for n in elt.infer(context)
if not n is util.YES]
elts += [n for elt in other.elts for n in elt.infer(context)
if not n is util.YES]
node.elts = elts
yield node
elif isinstance(other, nodes.Const) and operator == '*':
if not isinstance(other.value, int):
yield not_implemented
return
yield _multiply_seq_by_int(self, other, context)
elif isinstance(other, bases.Instance) and operator == '*':
# Verify if the instance supports __index__.
as_index = class_as_index(other, context)
if not as_index:
yield util.YES
else:
yield _multiply_seq_by_int(self, as_index, context)
else:
yield not_implemented
nodes.Tuple.infer_binary_op = tl_infer_binary_op
nodes.List.infer_binary_op = tl_infer_binary_op
@decorators.yes_if_nothing_inferred
def instance_infer_binary_op(self, operator, other, context, method):
return method.infer_call_result(self, context)
bases.Instance.infer_binary_op = instance_infer_binary_op
# assignment ##################################################################
"""the assigned_stmts method is responsible to return the assigned statement
(e.g. not inferred) according to the assignment type.
The `asspath` argument is used to record the lhs path of the original node.
For instance if we want assigned statements for 'c' in 'a, (b,c)', asspath
will be [1, 1] once arrived to the Assign node.
The `context` argument is the current inference context which should be given
to any intermediary inference necessary.
"""
def _resolve_looppart(parts, asspath, context):
"""recursive function to resolve multiple assignments on loops"""
asspath = asspath[:]
index = asspath.pop(0)
for part in parts:
if part is util.YES:
continue
# XXX handle __iter__ and log potentially detected errors
if not hasattr(part, 'itered'):
continue
try:
itered = part.itered()
except TypeError:
continue # XXX log error
for stmt in itered:
try:
assigned = stmt.getitem(index, context)
except (AttributeError, IndexError):
continue
except TypeError: # stmt is unsubscriptable Const
continue
if not asspath:
# we achieved to resolved the assignment path,
# don't infer the last part
yield assigned
elif assigned is util.YES:
break
else:
# we are not yet on the last part of the path
# search on each possibly inferred value
try:
for inferred in _resolve_looppart(assigned.infer(context),
asspath, context):
yield inferred
except exceptions.InferenceError:
break
@decorators.raise_if_nothing_inferred
def for_assigned_stmts(self, node, context=None, asspath=None):
if asspath is None:
for lst in self.iter.infer(context):
if isinstance(lst, (nodes.Tuple, nodes.List)):
for item in lst.elts:
yield item
else:
for inferred in _resolve_looppart(self.iter.infer(context),
asspath, context):
yield inferred
nodes.For.assigned_stmts = for_assigned_stmts
nodes.Comprehension.assigned_stmts = for_assigned_stmts
def mulass_assigned_stmts(self, node, context=None, asspath=None):
if asspath is None:
asspath = []
asspath.insert(0, self.elts.index(node))
return self.parent.assigned_stmts(self, context, asspath)
nodes.Tuple.assigned_stmts = mulass_assigned_stmts
nodes.List.assigned_stmts = mulass_assigned_stmts
def assend_assigned_stmts(self, context=None):
return self.parent.assigned_stmts(self, context=context)
nodes.AssignName.assigned_stmts = assend_assigned_stmts
nodes.AssignAttr.assigned_stmts = assend_assigned_stmts
def _arguments_infer_argname(self, name, context):
# arguments information may be missing, in which case we can't do anything
# more
if not (self.args or self.vararg or self.kwarg):
yield util.YES
return
# first argument of instance/class method
if self.args and getattr(self.args[0], 'name', None) == name:
functype = self.parent.type
if functype == 'method':
yield bases.Instance(self.parent.parent.frame())
return
if functype == 'classmethod':
yield self.parent.parent.frame()
return
if context and context.callcontext:
call_site = arguments.CallSite(context.callcontext)
for value in call_site.infer_argument(self.parent, name, context):
yield value
return
# TODO: just provide the type here, no need to have an empty Dict.
if name == self.vararg:
vararg = nodes.const_factory(())
vararg.parent = self
yield vararg
return
if name == self.kwarg:
kwarg = nodes.const_factory({})
kwarg.parent = self
yield kwarg
return
# if there is a default value, yield it. And then yield YES to reflect
# we can't guess given argument value
try:
context = contextmod.copy_context(context)
for inferred in self.default_value(name).infer(context):
yield inferred
yield util.YES
except exceptions.NoDefault:
yield util.YES
def arguments_assigned_stmts(self, node, context, asspath=None):
if context.callcontext:
# reset call context/name
callcontext = context.callcontext
context = contextmod.copy_context(context)
context.callcontext = None
args = arguments.CallSite(callcontext)
return args.infer_argument(self.parent, node.name, context)
return _arguments_infer_argname(self, node.name, context)
nodes.Arguments.assigned_stmts = arguments_assigned_stmts
@decorators.raise_if_nothing_inferred
def assign_assigned_stmts(self, node, context=None, asspath=None):
if not asspath:
yield self.value
return
for inferred in _resolve_asspart(self.value.infer(context), asspath, context):
yield inferred
nodes.Assign.assigned_stmts = assign_assigned_stmts
nodes.AugAssign.assigned_stmts = assign_assigned_stmts
def _resolve_asspart(parts, asspath, context):
"""recursive function to resolve multiple assignments"""
asspath = asspath[:]
index = asspath.pop(0)
for part in parts:
if hasattr(part, 'getitem'):
try:
assigned = part.getitem(index, context)
# XXX raise a specific exception to avoid potential hiding of
# unexpected exception ?
except (TypeError, IndexError):
return
if not asspath:
# we achieved to resolved the assignment path, don't infer the
# last part
yield assigned
elif assigned is util.YES:
return
else:
# we are not yet on the last part of the path search on each
# possibly inferred value
try:
for inferred in _resolve_asspart(assigned.infer(context),
asspath, context):
yield inferred
except exceptions.InferenceError:
return
@decorators.raise_if_nothing_inferred
def excepthandler_assigned_stmts(self, node, context=None, asspath=None):
for assigned in node_classes.unpack_infer(self.type):
if isinstance(assigned, nodes.ClassDef):
assigned = bases.Instance(assigned)
yield assigned
nodes.ExceptHandler.assigned_stmts = excepthandler_assigned_stmts
def _infer_context_manager(self, mgr, context):
try:
inferred = next(mgr.infer(context=context))
except exceptions.InferenceError:
return
if isinstance(inferred, bases.Generator):
# Check if it is decorated with contextlib.contextmanager.
func = inferred.parent
if not func.decorators:
return
for decorator_node in func.decorators.nodes:
decorator = next(decorator_node.infer(context))
if isinstance(decorator, nodes.FunctionDef):
if decorator.qname() == _CONTEXTLIB_MGR:
break
else:
# It doesn't interest us.
return
# Get the first yield point. If it has multiple yields,
# then a RuntimeError will be raised.
# TODO(cpopa): Handle flows.
yield_point = next(func.nodes_of_class(nodes.Yield), None)
if yield_point:
if not yield_point.value:
# TODO(cpopa): an empty yield. Should be wrapped to Const.
const = nodes.Const(None)
const.parent = yield_point
const.lineno = yield_point.lineno
yield const
else:
for inferred in yield_point.value.infer(context=context):
yield inferred
elif isinstance(inferred, bases.Instance):
try:
enter = next(inferred.igetattr('__enter__', context=context))
except (exceptions.InferenceError, exceptions.NotFoundError):
return
if not isinstance(enter, bases.BoundMethod):
return
for result in enter.infer_call_result(self, context):
yield result
@decorators.raise_if_nothing_inferred
def with_assigned_stmts(self, node, context=None, asspath=None):
"""Infer names and other nodes from a *with* statement.
This enables only inference for name binding in a *with* statement.
For instance, in the following code, inferring `func` will return
the `ContextManager` class, not whatever ``__enter__`` returns.
We are doing this intentionally, because we consider that the context
manager result is whatever __enter__ returns and what it is binded
using the ``as`` keyword.
class ContextManager(object):
def __enter__(self):
return 42
with ContextManager() as f:
pass
# ContextManager().infer() will return ContextManager
# f.infer() will return 42.
"""
mgr = next(mgr for (mgr, vars) in self.items if vars == node)
if asspath is None:
for result in _infer_context_manager(self, mgr, context):
yield result
else:
for result in _infer_context_manager(self, mgr, context):
# Walk the asspath and get the item at the final index.
obj = result
for index in asspath:
if not hasattr(obj, 'elts'):
raise exceptions.InferenceError
try:
obj = obj.elts[index]
except IndexError:
util.reraise(exceptions.InferenceError())
yield obj
nodes.With.assigned_stmts = with_assigned_stmts
@decorators.yes_if_nothing_inferred
def starred_assigned_stmts(self, node=None, context=None, asspath=None):
stmt = self.statement()
if not isinstance(stmt, (nodes.Assign, nodes.For)):
raise exceptions.InferenceError()
if isinstance(stmt, nodes.Assign):
value = stmt.value
lhs = stmt.targets[0]
if sum(1 for node in lhs.nodes_of_class(nodes.Starred)) > 1:
# Too many starred arguments in the expression.
raise exceptions.InferenceError()
if context is None:
context = contextmod.InferenceContext()
try:
rhs = next(value.infer(context))
except exceptions.InferenceError:
yield util.YES
return
if rhs is util.YES or not hasattr(rhs, 'elts'):
# Not interested in inferred values without elts.
yield util.YES
return
elts = collections.deque(rhs.elts[:])
if len(lhs.elts) > len(rhs.elts):
# a, *b, c = (1, 2)
raise exceptions.InferenceError()
# Unpack iteratively the values from the rhs of the assignment,
# until the find the starred node. What will remain will
# be the list of values which the Starred node will represent
# This is done in two steps, from left to right to remove
# anything before the starred node and from right to left
# to remvoe anything after the starred node.
for index, node in enumerate(lhs.elts):
if not isinstance(node, nodes.Starred):
elts.popleft()
continue
lhs_elts = collections.deque(reversed(lhs.elts[index:]))
for node in lhs_elts:
if not isinstance(node, nodes.Starred):
elts.pop()
continue
# We're done
packed = nodes.List()
packed.elts = elts
packed.parent = self
yield packed
break
nodes.Starred.assigned_stmts = starred_assigned_stmts
def class_as_index(node, context):
"""Get the value as an index for the given node
It is expected that the node is an Instance. If it provides
an *__index__* method, we'll try to return its int value.
"""
try:
for inferred in node.igetattr('__index__', context=context):
if not isinstance(inferred, bases.BoundMethod):
continue
for result in inferred.infer_call_result(node, context=context):
if (isinstance(result, nodes.Const)
and isinstance(result.value, int)):
return result
except exceptions.InferenceError:
pass
|