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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 Set, Tuple, Union
from libcst import Import, ImportFrom, ImportStar, Module
from libcst.codemod import CodemodContext, VisitorBasedCodemodCommand
from libcst.codemod.visitors import GatherCommentsVisitor, RemoveImportsVisitor
from libcst.helpers import get_absolute_module_from_package_for_import
from libcst.metadata import PositionProvider, ProviderT
DEFAULT_SUPPRESS_COMMENT_REGEX = (
r".*\W(noqa|lint-ignore: ?unused-import|lint-ignore: ?F401)(\W.*)?$"
)
class RemoveUnusedImportsCommand(VisitorBasedCodemodCommand):
"""
Remove all unused imports from a file based on scope analysis.
This command analyses individual files in isolation and does not attempt
to track cross-references between them. If a symbol is imported in a file
but otherwise unused in it, that import will be removed even if it is being
referenced from another file.
"""
DESCRIPTION: str = (
"Remove all imports that are not used in a file. "
+ "Note: only considers the file in isolation. "
)
METADATA_DEPENDENCIES: Tuple[ProviderT] = (PositionProvider,)
def __init__(self, context: CodemodContext) -> None:
super().__init__(context)
self._ignored_lines: Set[int] = set()
def visit_Module(self, node: Module) -> bool:
comment_visitor = GatherCommentsVisitor(
self.context, DEFAULT_SUPPRESS_COMMENT_REGEX
)
node.visit(comment_visitor)
self._ignored_lines = set(comment_visitor.comments.keys())
return True
def visit_Import(self, node: Import) -> bool:
self._handle_import(node)
return False
def visit_ImportFrom(self, node: ImportFrom) -> bool:
self._handle_import(node)
return False
def _handle_import(self, node: Union[Import, ImportFrom]) -> None:
node_start = self.get_metadata(PositionProvider, node).start.line
if node_start in self._ignored_lines:
return
names = node.names
if isinstance(names, ImportStar):
return
for alias in names:
position = self.get_metadata(PositionProvider, alias)
lines = set(range(position.start.line, position.end.line + 1))
if lines.isdisjoint(self._ignored_lines):
if isinstance(node, Import):
RemoveImportsVisitor.remove_unused_import(
self.context,
module=alias.evaluated_name,
asname=alias.evaluated_alias,
)
else:
module_name = get_absolute_module_from_package_for_import(
self.context.full_package_name, node
)
if module_name is None:
raise ValueError(
f"Couldn't get absolute module name for {alias.evaluated_name}"
)
RemoveImportsVisitor.remove_unused_import(
self.context,
module=module_name,
obj=alias.evaluated_name,
asname=alias.evaluated_alias,
)
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