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- # Copyright (c) 2016 Claudiu Popa <pcmanticore@gmail.com>
- # Licensed under the LGPL: https://www.gnu.org/licenses/old-licenses/lgpl-2.1.en.html
- # For details: https://github.com/PyCQA/astroid/blob/master/COPYING.LESSER
-
- """Contains logic for retrieving special methods.
-
- This implementation does not rely on the dot attribute access
- logic, found in ``.getattr()``. The difference between these two
- is that the dunder methods are looked with the type slots
- (you can find more about these here
- http://lucumr.pocoo.org/2014/8/16/the-python-i-would-like-to-see/)
- As such, the lookup for the special methods is actually simpler than
- the dot attribute access.
- """
- import itertools
-
- import astroid
- from astroid import exceptions
-
-
- def _lookup_in_mro(node, name):
- attrs = node.locals.get(name, [])
-
- nodes = itertools.chain.from_iterable(
- ancestor.locals.get(name, [])
- for ancestor in node.ancestors(recurs=True)
- )
- values = list(itertools.chain(attrs, nodes))
- if not values:
- raise exceptions.AttributeInferenceError(
- attribute=name,
- target=node
- )
-
- return values
-
-
- def lookup(node, name):
- """Lookup the given special method name in the given *node*
-
- If the special method was found, then a list of attributes
- will be returned. Otherwise, `astroid.AttributeInferenceError`
- is going to be raised.
- """
- if isinstance(node, (astroid.List,
- astroid.Tuple,
- astroid.Const,
- astroid.Dict,
- astroid.Set)):
- return _builtin_lookup(node, name)
- elif isinstance(node, astroid.Instance):
- return _lookup_in_mro(node, name)
- elif isinstance(node, astroid.ClassDef):
- return _class_lookup(node, name)
-
- raise exceptions.AttributeInferenceError(
- attribute=name,
- target=node
- )
-
-
- def _class_lookup(node, name):
- metaclass = node.metaclass()
- if metaclass is None:
- raise exceptions.AttributeInferenceError(
- attribute=name,
- target=node
- )
-
- return _lookup_in_mro(metaclass, name)
-
-
- def _builtin_lookup(node, name):
- values = node.locals.get(name, [])
- if not values:
- raise exceptions.AttributeInferenceError(
- attribute=name,
- target=node
- )
-
- return values
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