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173 lines (138 loc) · 5.32 KB
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# Copyright (c) 2015-2016 Cara Vinson <ceridwenv@gmail.com>
# Copyright (c) 2015-2016 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
"""
Various helper utilities.
"""
import six
from astroid import bases
from astroid import context as contextmod
from astroid import exceptions
from astroid import manager
from astroid import nodes
from astroid import raw_building
from astroid import scoped_nodes
from astroid import util
BUILTINS = six.moves.builtins.__name__
def _build_proxy_class(cls_name, builtins):
proxy = raw_building.build_class(cls_name)
proxy.parent = builtins
return proxy
def _function_type(function, builtins):
if isinstance(function, scoped_nodes.Lambda):
if function.root().name == BUILTINS:
cls_name = 'builtin_function_or_method'
else:
cls_name = 'function'
elif isinstance(function, bases.BoundMethod):
if six.PY2:
cls_name = 'instancemethod'
else:
cls_name = 'method'
elif isinstance(function, bases.UnboundMethod):
if six.PY2:
cls_name = 'instancemethod'
else:
cls_name = 'function'
return _build_proxy_class(cls_name, builtins)
def _object_type(node, context=None):
astroid_manager = manager.AstroidManager()
builtins = astroid_manager.astroid_cache[BUILTINS]
context = context or contextmod.InferenceContext()
for inferred in node.infer(context=context):
if isinstance(inferred, scoped_nodes.ClassDef):
if inferred.newstyle:
metaclass = inferred.metaclass()
if metaclass:
yield metaclass
continue
yield builtins.getattr('type')[0]
elif isinstance(inferred, (scoped_nodes.Lambda, bases.UnboundMethod)):
yield _function_type(inferred, builtins)
elif isinstance(inferred, scoped_nodes.Module):
yield _build_proxy_class('module', builtins)
else:
yield inferred._proxied
def object_type(node, context=None):
"""Obtain the type of the given node
This is used to implement the ``type`` builtin, which means that it's
used for inferring type calls, as well as used in a couple of other places
in the inference.
The node will be inferred first, so this function can support all
sorts of objects, as long as they support inference.
"""
try:
types = set(_object_type(node, context))
except exceptions.InferenceError:
return util.Uninferable
if len(types) > 1 or not types:
return util.Uninferable
return list(types)[0]
def safe_infer(node, context=None):
"""Return the inferred value for the given node.
Return None if inference failed or if there is some ambiguity (more than
one node has been inferred).
"""
try:
inferit = node.infer(context=context)
value = next(inferit)
except exceptions.InferenceError:
return
try:
next(inferit)
return # None if there is ambiguity on the inferred node
except exceptions.InferenceError:
return # there is some kind of ambiguity
except StopIteration:
return value
def has_known_bases(klass, context=None):
"""Return true if all base classes of a class could be inferred."""
try:
return klass._all_bases_known
except AttributeError:
pass
for base in klass.bases:
result = safe_infer(base, context=context)
# TODO: check for A->B->A->B pattern in class structure too?
if (not isinstance(result, scoped_nodes.ClassDef) or
result is klass or
not has_known_bases(result, context=context)):
klass._all_bases_known = False
return False
klass._all_bases_known = True
return True
def _type_check(type1, type2):
if not all(map(has_known_bases, (type1, type2))):
raise exceptions._NonDeducibleTypeHierarchy
if not all([type1.newstyle, type2.newstyle]):
return False
try:
return type1 in type2.mro()[:-1]
except exceptions.MroError:
# The MRO is invalid.
raise exceptions._NonDeducibleTypeHierarchy
def is_subtype(type1, type2):
"""Check if *type1* is a subtype of *typ2*."""
return _type_check(type2, type1)
def is_supertype(type1, type2):
"""Check if *type2* is a supertype of *type1*."""
return _type_check(type1, type2)
def class_instance_as_index(node):
"""Get the value as an index for the given instance.
If an instance provides an __index__ method, then it can
be used in some scenarios where an integer is expected,
for instance when multiplying or subscripting a list.
"""
context = contextmod.InferenceContext()
context.callcontext = contextmod.CallContext(args=[node])
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