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# copyright 2003-2015 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/>.
from astroid import bases
from astroid import context as contextmod
from astroid import exceptions
from astroid import nodes
from astroid import util
import six
class CallSite(object):
"""Class for understanding arguments passed into a call site
It needs a call context, which contains the arguments and the
keyword arguments that were passed into a given call site.
In order to infer what an argument represents, call
:meth:`infer_argument` with the corresponding function node
and the argument name.
"""
def __init__(self, callcontext):
args = callcontext.args
keywords = callcontext.keywords
self.duplicated_keywords = set()
self._unpacked_args = self._unpack_args(args)
self._unpacked_kwargs = self._unpack_keywords(keywords)
self.positional_arguments = [
arg for arg in self._unpacked_args
if arg is not util.YES
]
self.keyword_arguments = {
key: value for key, value in self._unpacked_kwargs.items()
if value is not util.YES
}
@classmethod
def from_call(cls, call_node):
"""Get a CallSite object from the given Call node."""
callcontext = contextmod.CallContext(call_node.args,
call_node.keywords)
return cls(callcontext)
def has_invalid_arguments(self):
"""Check if in the current CallSite were passed *invalid* arguments
This can mean multiple things. For instance, if an unpacking
of an invalid object was passed, then this method will return True.
Other cases can be when the arguments can't be inferred by astroid,
for example, by passing objects which aren't known statically.
"""
return len(self.positional_arguments) != len(self._unpacked_args)
def has_invalid_keywords(self):
"""Check if in the current CallSite were passed *invalid* keyword arguments
For instance, unpacking a dictionary with integer keys is invalid
(**{1:2}), because the keys must be strings, which will make this
method to return True. Other cases where this might return True if
objects which can't be inferred were passed.
"""
return len(self.keyword_arguments) != len(self._unpacked_kwargs)
def _unpack_keywords(self, keywords):
values = {}
context = contextmod.InferenceContext()
for name, value in keywords:
if name is None:
# Then it's an unpacking operation (**)
try:
inferred = next(value.infer(context=context))
except exceptions.InferenceError:
values[name] = util.YES
continue
if not isinstance(inferred, nodes.Dict):
# Not something we can work with.
values[name] = util.YES
continue
for dict_key, dict_value in inferred.items:
try:
dict_key = next(dict_key.infer(context=context))
except exceptions.InferenceError:
values[name] = util.YES
continue
if not isinstance(dict_key, nodes.Const):
values[name] = util.YES
continue
if not isinstance(dict_key.value, six.string_types):
values[name] = util.YES
continue
if dict_key.value in values:
# The name is already in the dictionary
values[dict_key.value] = util.YES
self.duplicated_keywords.add(dict_key.value)
continue
values[dict_key.value] = dict_value
else:
values[name] = value
return values
@staticmethod
def _unpack_args(args):
values = []
context = contextmod.InferenceContext()
for arg in args:
if isinstance(arg, nodes.Starred):
try:
inferred = next(arg.value.infer(context=context))
except exceptions.InferenceError:
values.append(util.YES)
continue
if inferred is util.YES:
values.append(util.YES)
continue
if not hasattr(inferred, 'elts'):
values.append(util.YES)
continue
values.extend(inferred.elts)
else:
values.append(arg)
return values
def infer_argument(self, funcnode, name, context):
"""infer a function argument value according to the call context"""
if name in self.duplicated_keywords:
raise exceptions.InferenceError(name)
# Look into the keywords first, maybe it's already there.
try:
return self.keyword_arguments[name].infer(context)
except KeyError:
pass
# Too many arguments given and no variable arguments.
if len(self.positional_arguments) > len(funcnode.args.args):
if not funcnode.args.vararg:
raise exceptions.InferenceError(name)
positional = self.positional_arguments[:len(funcnode.args.args)]
vararg = self.positional_arguments[len(funcnode.args.args):]
argindex = funcnode.args.find_argname(name)[0]
kwonlyargs = set(arg.name for arg in funcnode.args.kwonlyargs)
kwargs = {
key: value for key, value in self.keyword_arguments.items()
if key not in kwonlyargs
}
# If there are too few positionals compared to
# what the function expects to receive, check to see
# if the missing positional arguments were passed
# as keyword arguments and if so, place them into the
# positional args list.
if len(positional) < len(funcnode.args.args):
for func_arg in funcnode.args.args:
if func_arg.name in kwargs:
arg = kwargs.pop(func_arg.name)
positional.append(arg)
if argindex is not None:
# 2. first argument of instance/class method
if argindex == 0 and funcnode.type in ('method', 'classmethod'):
if context.boundnode is not None:
boundnode = context.boundnode
else:
# XXX can do better ?
boundnode = funcnode.parent.frame()
if funcnode.type == 'method':
if not isinstance(boundnode, bases.Instance):
boundnode = bases.Instance(boundnode)
return iter((boundnode,))
if funcnode.type == 'classmethod':
return iter((boundnode,))
# if we have a method, extract one position
# from the index, so we'll take in account
# the extra parameter represented by `self` or `cls`
if funcnode.type in ('method', 'classmethod'):
argindex -= 1
# 2. search arg index
try:
return self.positional_arguments[argindex].infer(context)
except IndexError:
pass
if funcnode.args.kwarg == name:
# It wants all the keywords that were passed into
# the call site.
if self.has_invalid_keywords():
raise exceptions.InferenceError
kwarg = nodes.Dict(lineno=funcnode.args.lineno,
col_offset=funcnode.args.col_offset,
parent=funcnode.args)
kwarg.postinit([(nodes.const_factory(key), value)
for key, value in kwargs.items()])
return iter((kwarg, ))
elif funcnode.args.vararg == name:
# It wants all the args that were passed into
# the call site.
if self.has_invalid_arguments():
raise exceptions.InferenceError
args = nodes.Tuple(lineno=funcnode.args.lineno,
col_offset=funcnode.args.col_offset,
parent=funcnode.args)
args.postinit(vararg)
return iter((args, ))
# Check if it's a default parameter.
try:
return funcnode.args.default_value(name).infer(context)
except exceptions.NoDefault:
pass
raise exceptions.InferenceError(name)
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