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# Licensed under the LGPL: https://www.gnu.org/licenses/old-licenses/lgpl-2.1.en.html
# For details: https://github.com/PyCQA/astroid/blob/main/LICENSE
"""Transform utilities (filters and decorator)"""
import itertools
import typing
import wrapt
# pylint: disable=dangerous-default-value
from astroid.exceptions import InferenceOverwriteError
from astroid.nodes import NodeNG
@wrapt.decorator
def _inference_tip_cached(func, instance, args, kwargs, _cache={}): # noqa:B006
"""Cache decorator used for inference tips"""
node = args[0]
try:
return iter(_cache[func, node])
except KeyError:
result = func(*args, **kwargs)
# Need to keep an iterator around
original, copy = itertools.tee(result)
_cache[func, node] = list(copy)
return original
# pylint: enable=dangerous-default-value
def inference_tip(
infer_function: typing.Callable, raise_on_overwrite: bool = False
) -> typing.Callable:
"""Given an instance specific inference function, return a function to be
given to AstroidManager().register_transform to set this inference function.
:param bool raise_on_overwrite: Raise an `InferenceOverwriteError`
if the inference tip will overwrite another. Used for debugging
Typical usage
.. sourcecode:: python
AstroidManager().register_transform(Call, inference_tip(infer_named_tuple),
predicate)
.. Note::
Using an inference tip will override
any previously set inference tip for the given
node. Use a predicate in the transform to prevent
excess overwrites.
"""
def transform(
node: NodeNG, infer_function: typing.Callable = infer_function
) -> NodeNG:
if (
raise_on_overwrite
and node._explicit_inference is not None
and node._explicit_inference is not infer_function
):
raise InferenceOverwriteError(
"Inference already set to {existing_inference}. "
"Trying to overwrite with {new_inference} for {node}".format(
existing_inference=infer_function,
new_inference=node._explicit_inference,
node=node,
)
)
# pylint: disable=no-value-for-parameter
node._explicit_inference = _inference_tip_cached(infer_function)
return node
return transform
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