120 lines
4.2 KiB
Python
120 lines
4.2 KiB
Python
|
# Licensed under the GPL: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
|
||
|
|
# For details: https://github.com/pylint-dev/pylint/blob/main/LICENSE
|
||
|
|
# Copyright (c) https://github.com/pylint-dev/pylint/blob/main/CONTRIBUTORS.txt
|
||
|
|
|
||
|
|
"""Checks for magic values instead of literals."""
|
||
|
|
|
||
|
|
from __future__ import annotations
|
||
|
|
|
||
|
|
from re import match as regex_match
|
||
|
|
from typing import TYPE_CHECKING
|
||
|
|
|
||
|
|
from astroid import nodes
|
||
|
|
|
||
|
|
from pylint.checkers import BaseChecker, utils
|
||
|
|
from pylint.interfaces import HIGH
|
||
|
|
|
||
|
|
if TYPE_CHECKING:
|
||
|
|
from pylint.lint import PyLinter
|
||
|
|
|
||
|
|
|
||
|
|
class MagicValueChecker(BaseChecker):
|
||
|
|
"""Checks for constants in comparisons."""
|
||
|
|
|
||
|
|
name = "magic-value"
|
||
|
|
msgs = {
|
||
|
|
"R2004": (
|
||
|
|
"Consider using a named constant or an enum instead of '%s'.",
|
||
|
|
"magic-value-comparison",
|
||
|
|
"Using named constants instead of magic values helps improve readability and maintainability of your"
|
||
|
|
" code, try to avoid them in comparisons.",
|
||
|
|
)
|
||
|
|
}
|
||
|
|
|
||
|
|
options = (
|
||
|
|
(
|
||
|
|
"valid-magic-values",
|
||
|
|
{
|
||
|
|
"default": (0, -1, 1, "", "__main__"),
|
||
|
|
"type": "csv",
|
||
|
|
"metavar": "<argument names>",
|
||
|
|
"help": "List of valid magic values that `magic-value-compare` will not detect. "
|
||
|
|
"Supports integers, floats, negative numbers, for empty string enter ``''``,"
|
||
|
|
" for backslash values just use one backslash e.g \\n.",
|
||
|
|
},
|
||
|
|
),
|
||
|
|
)
|
||
|
|
|
||
|
|
def __init__(self, linter: PyLinter) -> None:
|
||
|
|
"""Initialize checker instance."""
|
||
|
|
super().__init__(linter=linter)
|
||
|
|
self.valid_magic_vals: tuple[float | str, ...] = ()
|
||
|
|
|
||
|
|
def open(self) -> None:
|
||
|
|
# Extra manipulation is needed in case of using external configuration like an rcfile
|
||
|
|
if self._magic_vals_ext_configured():
|
||
|
|
self.valid_magic_vals = tuple(
|
||
|
|
self._parse_rcfile_magic_numbers(value)
|
||
|
|
for value in self.linter.config.valid_magic_values
|
||
|
|
)
|
||
|
|
else:
|
||
|
|
self.valid_magic_vals = self.linter.config.valid_magic_values
|
||
|
|
|
||
|
|
def _magic_vals_ext_configured(self) -> bool:
|
||
|
|
return not isinstance(self.linter.config.valid_magic_values, tuple)
|
||
|
|
|
||
|
|
def _check_constants_comparison(self, node: nodes.Compare) -> None:
|
||
|
|
"""
|
||
|
|
Magic values in any side of the comparison should be avoided,
|
||
|
|
Detects comparisons that `comparison-of-constants` core checker cannot detect.
|
||
|
|
"""
|
||
|
|
const_operands = []
|
||
|
|
LEFT_OPERAND = 0
|
||
|
|
RIGHT_OPERAND = 1
|
||
|
|
|
||
|
|
left_operand = node.left
|
||
|
|
const_operands.append(isinstance(left_operand, nodes.Const))
|
||
|
|
|
||
|
|
right_operand = node.ops[0][1]
|
||
|
|
const_operands.append(isinstance(right_operand, nodes.Const))
|
||
|
|
|
||
|
|
if all(const_operands):
|
||
|
|
# `comparison-of-constants` avoided
|
||
|
|
return
|
||
|
|
|
||
|
|
operand_value = None
|
||
|
|
if const_operands[LEFT_OPERAND] and self._is_magic_value(left_operand):
|
||
|
|
operand_value = left_operand.as_string()
|
||
|
|
elif const_operands[RIGHT_OPERAND] and self._is_magic_value(right_operand):
|
||
|
|
operand_value = right_operand.as_string()
|
||
|
|
if operand_value is not None:
|
||
|
|
self.add_message(
|
||
|
|
"magic-value-comparison",
|
||
|
|
node=node,
|
||
|
|
args=(operand_value),
|
||
|
|
confidence=HIGH,
|
||
|
|
)
|
||
|
|
|
||
|
|
def _is_magic_value(self, node: nodes.Const) -> bool:
|
||
|
|
return (not utils.is_singleton_const(node)) and (
|
||
|
|
node.value not in (self.valid_magic_vals)
|
||
|
|
)
|
||
|
|
|
||
|
|
@staticmethod
|
||
|
|
def _parse_rcfile_magic_numbers(parsed_val: str) -> float | str:
|
||
|
|
parsed_val = parsed_val.encode().decode("unicode_escape")
|
||
|
|
|
||
|
|
if parsed_val.startswith("'") and parsed_val.endswith("'"):
|
||
|
|
return parsed_val[1:-1]
|
||
|
|
|
||
|
|
is_number = regex_match(r"[-+]?\d+(\.0*)?$", parsed_val)
|
||
|
|
return float(parsed_val) if is_number else parsed_val
|
||
|
|
|
||
|
|
@utils.only_required_for_messages("magic-comparison")
|
||
|
|
def visit_compare(self, node: nodes.Compare) -> None:
|
||
|
|
self._check_constants_comparison(node)
|
||
|
|
|
||
|
|
|
||
|
|
def register(linter: PyLinter) -> None:
|
||
|
|
linter.register_checker(MagicValueChecker(linter))
|