# copyright 2003-2013 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
# contact http://www.logilab.fr/ -- mailto:[email protected]
#
# 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 inference on astroid trees
"""
__doctype__ = "restructuredtext en"
from itertools import chain
from astroid import nodes
from astroid.manager import AstroidManager
from astroid.exceptions import (AstroidError, InferenceError, NoDefault,
NotFoundError, UnresolvableName)
from astroid.bases import (YES, Instance, InferenceContext,
_infer_stmts, path_wrapper,
raise_if_nothing_infered)
from astroid.protocols import (
_arguments_infer_argname,
BIN_OP_METHOD, UNARY_OP_METHOD)
MANAGER = AstroidManager()
class CallContext(object):
"""when inferring a function call, this class is used to remember values
given as argument
"""
def __init__(self, args, starargs, dstarargs):
self.args = []
self.nargs = {}
for arg in args:
if isinstance(arg, nodes.Keyword):
self.nargs[arg.arg] = arg.value
else:
self.args.append(arg)
self.starargs = starargs
self.dstarargs = dstarargs
def infer_argument(self, funcnode, name, context):
"""infer a function argument value according to the call context"""
# 1. search in named keywords
try:
return self.nargs[name].infer(context)
except KeyError:
# Function.args.args can be None in astroid (means that we don't have
# information on argnames)
argindex = funcnode.args.find_argname(name)[0]
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, Instance):
boundnode = 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.args[argindex].infer(context)
except IndexError:
pass
# 3. search in *args (.starargs)
if self.starargs is not None:
its = []
for infered in self.starargs.infer(context):
if infered is YES:
its.append((YES,))
continue
try:
its.append(infered.getitem(argindex, context).infer(context))
except (InferenceError, AttributeError):
its.append((YES,))
except (IndexError, TypeError):
continue
if its:
return chain(*its)
# 4. XXX search in **kwargs (.dstarargs)
if self.dstarargs is not None:
its = []
for infered in self.dstarargs.infer(context):
if infered is YES:
its.append((YES,))
continue
try:
its.append(infered.getitem(name, context).infer(context))
except (InferenceError, AttributeError):
its.append((YES,))
except (IndexError, TypeError):
continue
if its:
return chain(*its)
# 5. */** argument, (Tuple or Dict)
if name == funcnode.args.vararg:
return iter((nodes.const_factory(())))
if name == funcnode.args.kwarg:
return iter((nodes.const_factory({})))
# 6. return default value if any
try:
return funcnode.args.default_value(name).infer(context)
except NoDefault:
raise InferenceError(name)
# .infer method ###############################################################
def infer_end(self, context=None):
"""inference's end for node such as Module, Class, Function, Const...
"""
yield self
nodes.Module._infer = infer_end
nodes.Class._infer = infer_end
nodes.Function._infer = infer_end
nodes.Lambda._infer = infer_end
nodes.Const._infer = infer_end
nodes.List._infer = infer_end
nodes.Tuple._infer = infer_end
nodes.Dict._infer = infer_end
nodes.Set._infer = infer_end
def _higher_function_scope(node):
""" Search for the first function which encloses the given
scope. This can be used for looking up in that function's
scope, in case looking up in a lower scope for a particular
name fails.
:param node: A scope node.
:returns:
``None``, if no parent function scope was found,
otherwise an instance of :class:`astroid.scoped_nodes.Function`,
which encloses the given node.
"""
current = node
while current.parent and not isinstance(current.parent, nodes.Function):
current = current.parent
if current and current.parent:
return current.parent
def infer_name(self, context=None):
"""infer a Name: use name lookup rules"""
frame, stmts = self.lookup(self.name)
if not stmts:
# Try to see if the name is enclosed in a nested function
# and use the higher (first function) scope for searching.
# TODO: should this be promoted to other nodes as well?
parent_function = _higher_function_scope(self.scope())
if parent_function:
_, stmts = parent_function.lookup(self.name)
if not stmts:
raise UnresolvableName(self.name)
return _infer_stmts(stmts, context, frame, self.name)
nodes.Name._infer = path_wrapper(infer_name)
nodes.AssName.infer_lhs = infer_name # won't work with a path wrapper
def infer_callfunc(self, context=None):
"""infer a CallFunc node by trying to guess what the function returns"""
if context is None:
context = InferenceContext()
for callee in self.func.infer(context):
with context.scope(
callcontext=CallContext(self.args, self.starargs, self.kwargs),
boundnode=None,
):
if callee is YES:
yield callee
continue
try:
if hasattr(callee, 'infer_call_result'):
for infered in callee.infer_call_result(self, context):
yield infered
except InferenceError:
## XXX log error ?
continue
nodes.CallFunc._infer = path_wrapper(raise_if_nothing_infered(infer_callfunc))
def infer_import(self, context=None, asname=True, lookupname=None):
"""infer an Import node: return the imported module/object"""
if lookupname is None:
raise InferenceError()
if asname:
yield self.do_import_module(self.real_name(lookupname))
else:
yield self.do_import_module(lookupname)
nodes.Import._infer = path_wrapper(infer_import)
def infer_name_module(self, name):
context = InferenceContext()
return self.infer(context, asname=False, lookupname=name)
nodes.Import.infer_name_module = infer_name_module
def infer_from(self, context=None, asname=True, lookupname=None):
"""infer a From nodes: return the imported module/object"""
if lookupname is None:
raise InferenceError()
if asname:
lookupname = self.real_name(lookupname)
module = self.do_import_module()
try:
return _infer_stmts(module.getattr(lookupname, ignore_locals=module is self.root()), context, lookupname=lookupname)
except NotFoundError:
raise InferenceError(lookupname)
nodes.From._infer = path_wrapper(infer_from)
def infer_getattr(self, context=None):
"""infer a Getattr node by using getattr on the associated object"""
if not context:
context = InferenceContext()
for owner in self.expr.infer(context):
if owner is YES:
yield owner
continue
try:
with context.scope(boundnode=owner):
for obj in owner.igetattr(self.attrname, context):
yield obj
except (NotFoundError, InferenceError):
pass
except AttributeError:
# XXX method / function
pass
nodes.Getattr._infer = path_wrapper(raise_if_nothing_infered(infer_getattr))
nodes.AssAttr.infer_lhs = raise_if_nothing_infered(infer_getattr) # # won't work with a path wrapper
def infer_global(self, context=None, lookupname=None):
if lookupname is None:
raise InferenceError()
try:
return _infer_stmts(self.root().getattr(lookupname), context)
except NotFoundError:
raise InferenceError()
nodes.Global._infer = path_wrapper(infer_global)
def infer_subscript(self, context=None):
"""infer simple subscription such as [1,2,3][0] or (1,2,3)[-1]"""
value = next(self.value.infer(context))
if value is YES:
yield YES
return
index = next(self.slice.infer(context))
if index is YES:
yield YES
return
if isinstance(index, nodes.Const):
try:
assigned = value.getitem(index.value, context)
except AttributeError:
raise InferenceError()
except (IndexError, TypeError):
yield YES
return
# Prevent inferring if the infered subscript
# is the same as the original subscripted object.
if self is assigned:
yield YES
return
for infered in assigned.infer(context):
yield infered
else:
raise InferenceError()
nodes.Subscript._infer = path_wrapper(infer_subscript)
nodes.Subscript.infer_lhs = raise_if_nothing_infered(infer_subscript)
def infer_unaryop(self, context=None):
for operand in self.operand.infer(context):
try:
yield operand.infer_unary_op(self.op)
except TypeError:
continue
except AttributeError:
meth = UNARY_OP_METHOD[self.op]
if meth is None:
yield YES
else:
try:
# XXX just suppose if the type implement meth, returned type
# will be the same
operand.getattr(meth)
yield operand
except GeneratorExit:
raise
except:
yield YES
nodes.UnaryOp._infer = path_wrapper(infer_unaryop)
def _infer_binop(operator, operand1, operand2, context, failures=None):
if operand1 is YES:
yield operand1
return
try:
for valnode in operand1.infer_binary_op(operator, operand2, context):
yield valnode
except AttributeError:
try:
# XXX just suppose if the type implement meth, returned type
# will be the same
operand1.getattr(BIN_OP_METHOD[operator])
yield operand1
except:
if failures is None:
yield YES
else:
failures.append(operand1)
def infer_binop(self, context=None):
failures = []
for lhs in self.left.infer(context):
for val in _infer_binop(self.op, lhs, self.right, context, failures):
yield val
for lhs in failures:
for rhs in self.right.infer(context):
for val in _infer_binop(self.op, rhs, lhs, context):
yield val
nodes.BinOp._infer = path_wrapper(infer_binop)
def infer_arguments(self, context=None, lookupname=None):
if lookupname is None:
raise InferenceError()
return _arguments_infer_argname(self, lookupname, context)
nodes.Arguments._infer = infer_arguments
def infer_ass(self, context=None):
"""infer a AssName/AssAttr: need to inspect the RHS part of the
assign node
"""
stmt = self.statement()
if isinstance(stmt, nodes.AugAssign):
return stmt.infer(context)
stmts = list(self.assigned_stmts(context=context))
return _infer_stmts(stmts, context)
nodes.AssName._infer = path_wrapper(infer_ass)
nodes.AssAttr._infer = path_wrapper(infer_ass)
def infer_augassign(self, context=None):
failures = []
for lhs in self.target.infer_lhs(context):
for val in _infer_binop(self.op, lhs, self.value, context, failures):
yield val
for lhs in failures:
for rhs in self.value.infer(context):
for val in _infer_binop(self.op, rhs, lhs, context):
yield val
nodes.AugAssign._infer = path_wrapper(infer_augassign)
# no infer method on DelName and DelAttr (expected InferenceError)
def infer_empty_node(self, context=None):
if not self.has_underlying_object():
yield YES
else:
try:
for infered in MANAGER.infer_ast_from_something(self.object,
context=context):
yield infered
except AstroidError:
yield YES
nodes.EmptyNode._infer = path_wrapper(infer_empty_node)
def infer_index(self, context=None):
return self.value.infer(context)
nodes.Index._infer = infer_index
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