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# Copyright (c) 2015-2016, 2018 Claudiu Popa <pcmanticore@gmail.com>
# Copyright (c) 2015-2016 Ceridwen <ceridwenv@gmail.com>
# Copyright (c) 2015 Florian Bruhin <me@the-compiler.org>
# Copyright (c) 2016 Derek Gustafson <degustaf@gmail.com>
# Copyright (c) 2018 Nick Drozd <nicholasdrozd@gmail.com>
# Copyright (c) 2018 Ashley Whetter <ashley@awhetter.co.uk>
# Copyright (c) 2018 HoverHell <hoverhell@gmail.com>
# Copyright (c) 2018 Bryce Guinta <bryce.paul.guinta@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
""" A few useful function/method decorators."""
import functools
import wrapt
from astroid import context as contextmod
from astroid import exceptions
from astroid import util
@wrapt.decorator
def cached(func, instance, args, kwargs):
"""Simple decorator to cache result of method calls without args."""
cache = getattr(instance, "__cache", None)
if cache is None:
instance.__cache = cache = {}
try:
return cache[func]
except KeyError:
cache[func] = result = func(*args, **kwargs)
return result
class cachedproperty:
""" Provides a cached property equivalent to the stacking of
@cached and @property, but more efficient.
After first usage, the <property_name> becomes part of the object's
__dict__. Doing:
del obj.<property_name> empties the cache.
Idea taken from the pyramid_ framework and the mercurial_ project.
.. _pyramid: http://pypi.python.org/pypi/pyramid
.. _mercurial: http://pypi.python.org/pypi/Mercurial
"""
__slots__ = ("wrapped",)
def __init__(self, wrapped):
try:
wrapped.__name__
except AttributeError as exc:
raise TypeError("%s must have a __name__ attribute" % wrapped) from exc
self.wrapped = wrapped
@property
def __doc__(self):
doc = getattr(self.wrapped, "__doc__", None)
return "<wrapped by the cachedproperty decorator>%s" % (
"\n%s" % doc if doc else ""
)
def __get__(self, inst, objtype=None):
if inst is None:
return self
val = self.wrapped(inst)
setattr(inst, self.wrapped.__name__, val)
return val
def path_wrapper(func):
"""return the given infer function wrapped to handle the path
Used to stop inference if the node has already been looked
at for a given `InferenceContext` to prevent infinite recursion
"""
@functools.wraps(func)
def wrapped(node, context=None, _func=func, **kwargs):
"""wrapper function handling context"""
if context is None:
context = contextmod.InferenceContext()
if context.push(node):
return None
yielded = set()
generator = _func(node, context, **kwargs)
try:
while True:
res = next(generator)
# unproxy only true instance, not const, tuple, dict...
if res.__class__.__name__ == "Instance":
ares = res._proxied
else:
ares = res
if ares not in yielded:
yield res
yielded.add(ares)
except StopIteration as error:
if error.args:
return error.args[0]
return None
return wrapped
@wrapt.decorator
def yes_if_nothing_inferred(func, instance, args, kwargs):
generator = func(*args, **kwargs)
try:
yield next(generator)
except StopIteration:
# generator is empty
yield util.Uninferable
return
yield from generator
@wrapt.decorator
def raise_if_nothing_inferred(func, instance, args, kwargs):
generator = func(*args, **kwargs)
try:
yield next(generator)
except StopIteration as error:
# generator is empty
if error.args:
# pylint: disable=not-a-mapping
raise exceptions.InferenceError(**error.args[0])
raise exceptions.InferenceError(
"StopIteration raised without any error information."
)
yield from generator