unnecessary_comprehension_any_all.rs

use ruff_python_ast::{self as ast, Expr, Keyword};

use ruff_diagnostics::Violation;
use ruff_diagnostics::{Diagnostic, FixAvailability};
use ruff_macros::{derive_message_formats, violation};
use ruff_python_ast::helpers::any_over_expr;
use ruff_text_size::Ranged;

use crate::checkers::ast::Checker;
use crate::registry::AsRule;
use crate::rules::flake8_comprehensions::fixes;

/// ## What it does
/// Checks for unnecessary list comprehensions passed to `any` and `all`.
///
/// ## Why is this bad?
/// `any` and `all` take any iterators, including generators. Converting a generator to a list
/// by way of a list comprehension is unnecessary and reduces performance due to the
/// overhead of creating the list.
///
/// For example, compare the performance of `all` with a list comprehension against that
/// of a generator (~40x faster here):
///
/// ```console
/// In [1]: %timeit all([i for i in range(1000)])
/// 8.14 µs ± 25.4 ns per loop (mean ± std. dev. of 7 runs, 100,000 loops each)
///
/// In [2]: %timeit all(i for i in range(1000))
/// 212 ns ± 0.892 ns per loop (mean ± std. dev. of 7 runs, 1,000,000 loops each)
/// ```
///
/// ## Examples
/// ```python
/// any([x.id for x in bar])
/// all([x.id for x in bar])
/// ```
///
/// Use instead:
/// ```python
/// any(x.id for x in bar)
/// all(x.id for x in bar)
/// ```
#[violation]
pub struct UnnecessaryComprehensionAnyAll;

impl Violation for UnnecessaryComprehensionAnyAll {
    const FIX_AVAILABILITY: FixAvailability = FixAvailability::Sometimes;

    #[derive_message_formats]
    fn message(&self) -> String {
        format!("Unnecessary list comprehension.")
    }

    fn fix_title(&self) -> Option<String> {
        Some("Remove unnecessary list comprehension".to_string())
    }
}

/// C419
pub(crate) fn unnecessary_comprehension_any_all(
    checker: &mut Checker,
    expr: &Expr,
    func: &Expr,
    args: &[Expr],
    keywords: &[Keyword],
) {
    if !keywords.is_empty() {
        return;
    }
    let Expr::Name(ast::ExprName { id, .. }) = func else {
        return;
    };
    if !matches!(id.as_str(), "all" | "any") {
        return;
    }
    let [arg] = args else {
        return;
    };
    let (Expr::ListComp(ast::ExprListComp { elt, .. })
    | Expr::SetComp(ast::ExprSetComp { elt, .. })) = arg
    else {
        return;
    };
    if contains_await(elt) {
        return;
    }
    if !checker.semantic().is_builtin(id) {
        return;
    }

    let mut diagnostic = Diagnostic::new(UnnecessaryComprehensionAnyAll, arg.range());
    if checker.patch(diagnostic.kind.rule()) {
        diagnostic.try_set_fix(|| {
            fixes::fix_unnecessary_comprehension_any_all(expr, checker.locator(), checker.stylist())
        });
    }
    checker.diagnostics.push(diagnostic);
}

/// Return `true` if the [`Expr`] contains an `await` expression.
fn contains_await(expr: &Expr) -> bool {
    any_over_expr(expr, &Expr::is_await_expr)
}