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# Copyright (c) Meta Platforms, Inc. and affiliates.
#
# This source code is licensed under the MIT license found in the
# LICENSE file in the root directory of this source tree.
from typing import Callable, TypeVar
from libcst.matchers._matcher_base import BaseMatcherNode
_CSTVisitFuncT = TypeVar("_CSTVisitFuncT")
VISIT_POSITIVE_MATCHER_ATTR: str = "_call_if_inside_matcher"
VISIT_NEGATIVE_MATCHER_ATTR: str = "_call_if_not_inside_matcher"
CONSTRUCTED_VISIT_MATCHER_ATTR: str = "_visit_matcher"
CONSTRUCTED_LEAVE_MATCHER_ATTR: str = "_leave_matcher"
def call_if_inside(
matcher: BaseMatcherNode,
# pyre-fixme[34]: `Variable[_CSTVisitFuncT]` isn't present in the function's parameters.
) -> Callable[[_CSTVisitFuncT], _CSTVisitFuncT]:
"""
A decorator for visit and leave methods inside a :class:`MatcherDecoratableTransformer`
or a :class:`MatcherDecoratableVisitor`. A method that is decorated with this decorator
will only be called if it or one of its parents matches the supplied matcher.
Use this to selectively gate visit and leave methods to be called only when
inside of another relevant node. Note that this works for both node and attribute
methods, so you can decorate a ``visit_<Node>`` or a ``visit_<Node>_<Attr>`` method.
"""
def inner(original: _CSTVisitFuncT) -> _CSTVisitFuncT:
setattr(
original,
VISIT_POSITIVE_MATCHER_ATTR,
[*getattr(original, VISIT_POSITIVE_MATCHER_ATTR, []), matcher],
)
return original
return inner
def call_if_not_inside(
matcher: BaseMatcherNode,
# pyre-fixme[34]: `Variable[_CSTVisitFuncT]` isn't present in the function's parameters.
) -> Callable[[_CSTVisitFuncT], _CSTVisitFuncT]:
"""
A decorator for visit and leave methods inside a :class:`MatcherDecoratableTransformer`
or a :class:`MatcherDecoratableVisitor`. A method that is decorated with this decorator
will only be called if it or one of its parents does not match the supplied
matcher. Use this to selectively gate visit and leave methods to be called only
when outside of another relevant node. Note that this works for both node and
attribute methods, so you can decorate a ``visit_<Node>`` or a ``visit_<Node>_<Attr>``
method.
"""
def inner(original: _CSTVisitFuncT) -> _CSTVisitFuncT:
setattr(
original,
VISIT_NEGATIVE_MATCHER_ATTR,
[*getattr(original, VISIT_NEGATIVE_MATCHER_ATTR, []), matcher],
)
return original
return inner
# pyre-fixme[34]: `Variable[_CSTVisitFuncT]` isn't present in the function's parameters.
def visit(matcher: BaseMatcherNode) -> Callable[[_CSTVisitFuncT], _CSTVisitFuncT]:
"""
A decorator that allows a method inside a :class:`MatcherDecoratableTransformer`
or a :class:`MatcherDecoratableVisitor` visitor to be called when visiting a node
that matches the provided matcher. Note that you can use this in combination with
:func:`call_if_inside` and :func:`call_if_not_inside` decorators. Unlike explicit
``visit_<Node>`` and ``leave_<Node>`` methods, functions decorated with this
decorator cannot stop child traversal by returning ``False``. Decorated visit
functions should always have a return annotation of ``None``.
There is no restriction on the number of visit decorators allowed on a method.
There is also no restriction on the number of methods that may be decorated
with the same matcher. When multiple visit decorators are found on the same
method, they act as a simple or, and the method will be called when any one
of the contained matches is ``True``.
"""
def inner(original: _CSTVisitFuncT) -> _CSTVisitFuncT:
setattr(
original,
CONSTRUCTED_VISIT_MATCHER_ATTR,
[*getattr(original, CONSTRUCTED_VISIT_MATCHER_ATTR, []), matcher],
)
return original
return inner
# pyre-fixme[34]: `Variable[_CSTVisitFuncT]` isn't present in the function's parameters.
def leave(matcher: BaseMatcherNode) -> Callable[[_CSTVisitFuncT], _CSTVisitFuncT]:
"""
A decorator that allows a method inside a :class:`MatcherDecoratableTransformer`
or a :class:`MatcherDecoratableVisitor` visitor to be called when leaving a node
that matches the provided matcher. Note that you can use this in combination
with :func:`call_if_inside` and :func:`call_if_not_inside` decorators.
There is no restriction on the number of leave decorators allowed on a method.
There is also no restriction on the number of methods that may be decorated
with the same matcher. When multiple leave decorators are found on the same
method, they act as a simple or, and the method will be called when any one
of the contained matches is ``True``.
"""
def inner(original: _CSTVisitFuncT) -> _CSTVisitFuncT:
setattr(
original,
CONSTRUCTED_LEAVE_MATCHER_ATTR,
[*getattr(original, CONSTRUCTED_LEAVE_MATCHER_ATTR, []), matcher],
)
return original
return inner
|
