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67 lines
2.1 KiB
Python
67 lines
2.1 KiB
Python
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# Copyright (c) 2016-2018 Claudiu Popa <pcmanticore@gmail.com>
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# Licensed under the LGPL: https://www.gnu.org/licenses/old-licenses/lgpl-2.1.en.html
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# For details: https://github.com/PyCQA/astroid/blob/master/COPYING.LESSER
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"""Contains logic for retrieving special methods.
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This implementation does not rely on the dot attribute access
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logic, found in ``.getattr()``. The difference between these two
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is that the dunder methods are looked with the type slots
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(you can find more about these here
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http://lucumr.pocoo.org/2014/8/16/the-python-i-would-like-to-see/)
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As such, the lookup for the special methods is actually simpler than
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the dot attribute access.
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"""
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import itertools
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import astroid
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from astroid import exceptions
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def _lookup_in_mro(node, name):
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attrs = node.locals.get(name, [])
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nodes = itertools.chain.from_iterable(
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ancestor.locals.get(name, []) for ancestor in node.ancestors(recurs=True)
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)
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values = list(itertools.chain(attrs, nodes))
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if not values:
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raise exceptions.AttributeInferenceError(attribute=name, target=node)
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return values
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def lookup(node, name):
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"""Lookup the given special method name in the given *node*
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If the special method was found, then a list of attributes
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will be returned. Otherwise, `astroid.AttributeInferenceError`
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is going to be raised.
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"""
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if isinstance(
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node, (astroid.List, astroid.Tuple, astroid.Const, astroid.Dict, astroid.Set)
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):
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return _builtin_lookup(node, name)
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if isinstance(node, astroid.Instance):
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return _lookup_in_mro(node, name)
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if isinstance(node, astroid.ClassDef):
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return _class_lookup(node, name)
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raise exceptions.AttributeInferenceError(attribute=name, target=node)
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def _class_lookup(node, name):
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metaclass = node.metaclass()
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if metaclass is None:
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raise exceptions.AttributeInferenceError(attribute=name, target=node)
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return _lookup_in_mro(metaclass, name)
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def _builtin_lookup(node, name):
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values = node.locals.get(name, [])
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if not values:
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raise exceptions.AttributeInferenceError(attribute=name, target=node)
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return values
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