# Copyright (c) 2012-2015 LOGILAB S.A. (Paris, FRANCE) <contact@logilab.fr>
# Copyright (c) 2014-2016 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
"""Astroid hooks for the Python standard library."""
import functools
import sys
import keyword
from textwrap import dedent
from astroid import (
MANAGER, UseInferenceDefault, inference_tip,
InferenceError)
from astroid import arguments
from astroid import exceptions
from astroid import nodes
from astroid.builder import AstroidBuilder, extract_node
from astroid import util
PY3K = sys.version_info > (3, 0)
PY33 = sys.version_info >= (3, 3)
PY34 = sys.version_info >= (3, 4)
# general function
def infer_func_form(node, base_type, context=None, enum=False):
"""Specific inference function for namedtuple or Python 3 enum. """
def infer_first(node):
if node is util.Uninferable:
raise UseInferenceDefault
try:
value = next(node.infer(context=context))
if value is util.Uninferable:
raise UseInferenceDefault()
else:
return value
except StopIteration:
raise InferenceError()
# node is a Call node, class name as first argument and generated class
# attributes as second argument
if len(node.args) != 2:
# something weird here, go back to class implementation
raise UseInferenceDefault()
# namedtuple or enums list of attributes can be a list of strings or a
# whitespace-separate string
try:
name = infer_first(node.args[0]).value
names = infer_first(node.args[1])
try:
attributes = names.value.replace(',', ' ').split()
except AttributeError:
if not enum:
attributes = [infer_first(const).value for const in names.elts]
else:
# Enums supports either iterator of (name, value) pairs
# or mappings.
# TODO: support only list, tuples and mappings.
if hasattr(names, 'items') and isinstance(names.items, list):
attributes = [infer_first(const[0]).value
for const in names.items
if isinstance(const[0], nodes.Const)]
elif hasattr(names, 'elts'):
# Enums can support either ["a", "b", "c"]
# or [("a", 1), ("b", 2), ...], but they can't
# be mixed.
if all(isinstance(const, nodes.Tuple)
for const in names.elts):
attributes = [infer_first(const.elts[0]).value
for const in names.elts
if isinstance(const, nodes.Tuple)]
else:
attributes = [infer_first(const).value
for const in names.elts]
else:
raise AttributeError
if not attributes:
raise AttributeError
except (AttributeError, exceptions.InferenceError):
raise UseInferenceDefault()
# If we can't infer the name of the class, don't crash, up to this point
# we know it is a namedtuple anyway.
name = name or 'Uninferable'
# we want to return a Class node instance with proper attributes set
class_node = nodes.ClassDef(name, 'docstring')
class_node.parent = node.parent
# set base class=tuple
class_node.bases.append(base_type)
# XXX add __init__(*attributes) method
for attr in attributes:
fake_node = nodes.EmptyNode()
fake_node.parent = class_node
fake_node.attrname = attr
class_node.instance_attrs[attr] = [fake_node]
return class_node, name, attributes
def _looks_like(node, name):
func = node.func
if isinstance(func, nodes.Attribute):
return func.attrname == name
if isinstance(func, nodes.Name):
return func.name == name
return False
_looks_like_namedtuple = functools.partial(_looks_like, name='namedtuple')
_looks_like_enum = functools.partial(_looks_like, name='Enum')
def infer_named_tuple(node, context=None):
"""Specific inference function for namedtuple Call node"""
class_node, name, attributes = infer_func_form(node, nodes.Tuple._proxied,
context=context)
call_site = arguments.CallSite.from_call(node)
func = next(extract_node('import collections; collections.namedtuple').infer())
try:
rename = next(call_site.infer_argument(func, 'rename', context)).bool_value()
except InferenceError:
rename = False
if rename:
attributes = _get_renamed_namedtuple_atributes(attributes)
field_def = (" {name} = property(lambda self: self[{index:d}], "
"doc='Alias for field number {index:d}')")
field_defs = '\n'.join(field_def.format(name=name, index=index)
for index, name in enumerate(attributes))
fake = AstroidBuilder(MANAGER).string_build('''
class %(name)s(tuple):
__slots__ = ()
_fields = %(fields)r
def _asdict(self):
return self.__dict__
@classmethod
def _make(cls, iterable, new=tuple.__new__, len=len):
return new(cls, iterable)
def _replace(self, **kwds):
return self
def __getnewargs__(self):
return tuple(self)
%(field_defs)s
''' % {'name': name, 'fields': attributes, 'field_defs': field_defs})
class_node.locals['_asdict'] = fake.body[0].locals['_asdict']
class_node.locals['_make'] = fake.body[0].locals['_make']
class_node.locals['_replace'] = fake.body[0].locals['_replace']
class_node.locals['_fields'] = fake.body[0].locals['_fields']
for attr in attributes:
class_node.locals[attr] = fake.body[0].locals[attr]
# we use UseInferenceDefault, we can't be a generator so return an iterator
return iter([class_node])
def _get_renamed_namedtuple_atributes(field_names):
names = list(field_names)
seen = set()
for i, name in enumerate(field_names):
if (not all(c.isalnum() or c == '_' for c in name) or keyword.iskeyword(name)
or not name or name[0].isdigit() or name.startswith('_') or name in seen):
names[i] = '_%d' % i
seen.add(name)
return tuple(names)
def infer_enum(node, context=None):
""" Specific inference function for enum Call node. """
enum_meta = extract_node('''
class EnumMeta(object):
'docstring'
def __call__(self, node):
class EnumAttribute(object):
name = ''
value = 0
return EnumAttribute()
''')
class_node = infer_func_form(node, enum_meta,
context=context, enum=True)[0]
return iter([class_node.instantiate_class()])
def infer_enum_class(node):
""" Specific inference for enums. """
names = set(('Enum', 'IntEnum', 'enum.Enum', 'enum.IntEnum'))
for basename in node.basenames:
# TODO: doesn't handle subclasses yet. This implementation
# is a hack to support enums.
if basename not in names:
continue
if node.root().name == 'enum':
# Skip if the class is directly from enum module.
break
for local, values in node.locals.items():
if any(not isinstance(value, nodes.AssignName)
for value in values):
continue
stmt = values[0].statement()
if isinstance(stmt.targets[0], nodes.Tuple):
targets = stmt.targets[0].itered()
else:
targets = stmt.targets
new_targets = []
for target in targets:
# Replace all the assignments with our mocked class.
classdef = dedent('''
class %(name)s(%(types)s):
@property
def value(self):
# Not the best return.
return None
@property
def name(self):
return %(name)r
''' % {'name': target.name, 'types': ', '.join(node.basenames)})
fake = AstroidBuilder(MANAGER).string_build(classdef)[target.name]
fake.parent = target.parent
for method in node.mymethods():
fake.locals[method.name] = [method]
new_targets.append(fake.instantiate_class())
node.locals[local] = new_targets
break
return node
MANAGER.register_transform(nodes.Call, inference_tip(infer_named_tuple),
_looks_like_namedtuple)
MANAGER.register_transform(nodes.Call, inference_tip(infer_enum),
_looks_like_enum)
MANAGER.register_transform(nodes.ClassDef, infer_enum_class)