94 lines
3.4 KiB
Python
94 lines
3.4 KiB
Python
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# Licensed under the GPL: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
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# For details: https://github.com/pylint-dev/pylint/blob/main/LICENSE
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# Copyright (c) https://github.com/pylint-dev/pylint/blob/main/CONTRIBUTORS.txt
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from __future__ import annotations
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from itertools import zip_longest
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from typing import TYPE_CHECKING
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from astroid import nodes
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from pylint.checkers import BaseChecker
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from pylint.interfaces import HIGH
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if TYPE_CHECKING:
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from pylint.lint import PyLinter
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class LambdaExpressionChecker(BaseChecker):
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"""Check for unnecessary usage of lambda expressions."""
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name = "lambda-expressions"
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msgs = {
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"C3001": (
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"Lambda expression assigned to a variable. "
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'Define a function using the "def" keyword instead.',
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"unnecessary-lambda-assignment",
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"Used when a lambda expression is assigned to variable "
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'rather than defining a standard function with the "def" keyword.',
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),
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"C3002": (
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"Lambda expression called directly. Execute the expression inline instead.",
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"unnecessary-direct-lambda-call",
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"Used when a lambda expression is directly called "
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"rather than executing its contents inline.",
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),
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}
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options = ()
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def visit_assign(self, node: nodes.Assign) -> None:
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"""Check if lambda expression is assigned to a variable."""
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if isinstance(node.targets[0], nodes.AssignName) and isinstance(
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node.value, nodes.Lambda
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):
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self.add_message(
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"unnecessary-lambda-assignment",
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node=node.value,
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confidence=HIGH,
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)
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elif isinstance(node.targets[0], nodes.Tuple) and isinstance(
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node.value, (nodes.Tuple, nodes.List)
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):
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# Iterate over tuple unpacking assignment elements and
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# see if any lambdas are assigned to a variable.
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# N.B. We may encounter W0632 (unbalanced-tuple-unpacking)
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# and still need to flag the lambdas that are being assigned.
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for lhs_elem, rhs_elem in zip_longest(
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node.targets[0].elts, node.value.elts
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):
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if lhs_elem is None or rhs_elem is None:
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# unbalanced tuple unpacking. stop checking.
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break
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if isinstance(lhs_elem, nodes.AssignName) and isinstance(
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rhs_elem, nodes.Lambda
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):
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self.add_message(
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"unnecessary-lambda-assignment",
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node=rhs_elem,
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confidence=HIGH,
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)
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def visit_namedexpr(self, node: nodes.NamedExpr) -> None:
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if isinstance(node.target, nodes.AssignName) and isinstance(
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node.value, nodes.Lambda
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):
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self.add_message(
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"unnecessary-lambda-assignment",
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node=node.value,
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confidence=HIGH,
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)
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def visit_call(self, node: nodes.Call) -> None:
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"""Check if lambda expression is called directly."""
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if isinstance(node.func, nodes.Lambda):
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self.add_message(
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"unnecessary-direct-lambda-call",
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node=node,
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confidence=HIGH,
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)
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def register(linter: PyLinter) -> None:
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linter.register_checker(LambdaExpressionChecker(linter))
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