[refurb] Implement math-constant (FURB152) (#8727) · astral-sh/ruff@2faac1e (original) (raw)
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use anyhow::Result;
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use ruff_diagnostics::{Diagnostic, Edit, Fix, FixAvailability, Violation};
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use ruff_macros::{derive_message_formats, violation};
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use ruff_python_ast::{self as ast, Number};
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use ruff_text_size::Ranged;
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use crate::checkers::ast::Checker;
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use crate::importer::ImportRequest;
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/// ## What it does
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/// Checks for literals that are similar to constants in math module.
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///
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/// ## Why is this bad?
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/// Hard-coding mathematical constants like π increases code duplication,
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/// reduces readability, and may lead to a lack of precision.
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///
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/// ## Example
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/// ```python
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/// A = 3.141592 * r**2
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/// ```
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///
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/// Use instead:
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/// ```python
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/// A = math.pi * r**2
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/// ```
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///
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/// ## References
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/// - Python documentation: math constants
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#[violation]
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pub struct MathConstant {
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literal: String,
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constant: &'static str,
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}
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impl Violation for MathConstant {
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const FIX_AVAILABILITY: FixAvailability = FixAvailability::Sometimes;
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#[derive_message_formats]
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fn message(&self) -> String {
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let MathConstant { literal, constant } = self;
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format!("Replace {literal} with math.{constant}")
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}
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fn fix_title(&self) -> Option {
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let MathConstant { constant, .. } = self;
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Some(format!("Use math.{constant}"))
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}
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}
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/// FURB152
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pub(crate) fn math_constant(checker: &mut Checker, literal: &ast::ExprNumberLiteral) {
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let Number::Float(value) = literal.value else {
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return;
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};
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for (real_value, constant) in [
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(std::f64::consts::PI, "pi"),
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(std::f64::consts::E, "e"),
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(std::f64::consts::TAU, "tau"),
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] {
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if (value - real_value).abs() < 1e-2 {
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let mut diagnostic = Diagnostic::new(
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MathConstant {
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literal: checker.locator().slice(literal).into(),
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constant,
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},
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literal.range(),
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);
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diagnostic.try_set_fix(|| convert_to_constant(literal, constant, checker));
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checker.diagnostics.push(diagnostic);
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return;
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}
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}
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}
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fn convert_to_constant(
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literal: &ast::ExprNumberLiteral,
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constant: &'static str,
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checker: &Checker,
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) -> Result {
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let (edit, binding) = checker.importer().get_or_import_symbol(
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&ImportRequest::import("math", constant),
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literal.start(),
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checker.semantic(),
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)?;
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Ok(Fix::safe_edits(
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Edit::range_replacement(binding, literal.range()),
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[edit],
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))
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}
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