# Licensed under the GPL: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
# For details: https://github.com/PyCQA/pylint/blob/main/LICENSE
# Copyright (c) https://github.com/PyCQA/pylint/blob/main/CONTRIBUTORS.txt
from __future__ import annotations
import tokenize
from tokenize import TokenInfo
from typing import TYPE_CHECKING
from astroid import nodes
from pylint.checkers import BaseTokenChecker
from pylint.checkers.utils import only_required_for_messages
from pylint.interfaces import HIGH
if TYPE_CHECKING:
from pylint.lint import PyLinter
class ElseifUsedChecker(BaseTokenChecker):
"""Checks for use of "else if" when an "elif" could be used."""
name = "else_if_used"
msgs = {
"R5501": (
'Consider using "elif" instead of "else" then "if" to remove one indentation level',
"else-if-used",
"Used when an else statement is immediately followed by "
"an if statement and does not contain statements that "
"would be unrelated to it.",
)
}
def __init__(self, linter: PyLinter) -> None:
super().__init__(linter)
self._init()
def _init(self) -> None:
self._elifs: dict[tokenize._Position, str] = {}
def process_tokens(self, tokens: list[TokenInfo]) -> None:
"""Process tokens and look for 'if' or 'elif'."""
self._elifs = {
begin: token for _, token, begin, _, _ in tokens if token in {"elif", "if"}
}
def leave_module(self, _: nodes.Module) -> None:
self._init()
@only_required_for_messages("else-if-used")
def visit_if(self, node: nodes.If) -> None:
"""Current if node must directly follow an 'else'."""
if (
isinstance(node.parent, nodes.If)
and node.parent.orelse == [node]
and (node.lineno, node.col_offset) in self._elifs
and self._elifs[(node.lineno, node.col_offset)] == "if"
):
self.add_message("else-if-used", node=node, confidence=HIGH)
def register(linter: PyLinter) -> None:
linter.register_checker(ElseifUsedChecker(linter))
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