100 lines
3.8 KiB
Rust
100 lines
3.8 KiB
Rust
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use clippy_utils::diagnostics::span_lint_and_sugg;
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use clippy_utils::source::{snippet_with_applicability, snippet_with_context};
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use clippy_utils::sugg::Sugg;
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use clippy_utils::ty::{is_type_diagnostic_item, is_type_lang_item, match_type};
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use clippy_utils::{is_expr_path_def_path, paths};
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use if_chain::if_chain;
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use rustc_ast::LitKind;
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use rustc_errors::Applicability;
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use rustc_hir::{Expr, ExprKind, LangItem};
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use rustc_lint::LateContext;
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use rustc_middle::ty::{self, Ty, TyS};
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use rustc_span::symbol::sym;
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use std::borrow::Cow;
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use super::MANUAL_STR_REPEAT;
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enum RepeatKind {
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String,
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Char(char),
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}
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fn get_ty_param(ty: Ty<'_>) -> Option<Ty<'_>> {
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if let ty::Adt(_, subs) = ty.kind() {
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subs.types().next()
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} else {
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None
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}
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}
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fn parse_repeat_arg(cx: &LateContext<'_>, e: &Expr<'_>) -> Option<RepeatKind> {
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if let ExprKind::Lit(lit) = &e.kind {
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match lit.node {
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LitKind::Str(..) => Some(RepeatKind::String),
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LitKind::Char(c) => Some(RepeatKind::Char(c)),
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_ => None,
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}
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} else {
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let ty = cx.typeck_results().expr_ty(e);
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if is_type_diagnostic_item(cx, ty, sym::string_type)
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|| (is_type_lang_item(cx, ty, LangItem::OwnedBox) && get_ty_param(ty).map_or(false, TyS::is_str))
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|| (match_type(cx, ty, &paths::COW) && get_ty_param(ty).map_or(false, TyS::is_str))
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{
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Some(RepeatKind::String)
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} else {
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let ty = ty.peel_refs();
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(ty.is_str() || is_type_diagnostic_item(cx, ty, sym::string_type)).then(|| RepeatKind::String)
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}
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}
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}
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pub(super) fn check(
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cx: &LateContext<'_>,
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collect_expr: &Expr<'_>,
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take_expr: &Expr<'_>,
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take_self_arg: &Expr<'_>,
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take_arg: &Expr<'_>,
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) {
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if_chain! {
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if let ExprKind::Call(repeat_fn, [repeat_arg]) = take_self_arg.kind;
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if is_expr_path_def_path(cx, repeat_fn, &paths::ITER_REPEAT);
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if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(collect_expr), sym::string_type);
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if let Some(collect_id) = cx.typeck_results().type_dependent_def_id(collect_expr.hir_id);
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if let Some(take_id) = cx.typeck_results().type_dependent_def_id(take_expr.hir_id);
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if let Some(iter_trait_id) = cx.tcx.get_diagnostic_item(sym::Iterator);
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if cx.tcx.trait_of_item(collect_id) == Some(iter_trait_id);
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if cx.tcx.trait_of_item(take_id) == Some(iter_trait_id);
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if let Some(repeat_kind) = parse_repeat_arg(cx, repeat_arg);
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let ctxt = collect_expr.span.ctxt();
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if ctxt == take_expr.span.ctxt();
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if ctxt == take_self_arg.span.ctxt();
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then {
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let mut app = Applicability::MachineApplicable;
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let count_snip = snippet_with_context(cx, take_arg.span, ctxt, "..", &mut app).0;
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let val_str = match repeat_kind {
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RepeatKind::Char(_) if repeat_arg.span.ctxt() != ctxt => return,
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RepeatKind::Char('\'') => r#""'""#.into(),
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RepeatKind::Char('"') => r#""\"""#.into(),
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RepeatKind::Char(_) =>
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match snippet_with_applicability(cx, repeat_arg.span, "..", &mut app) {
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Cow::Owned(s) => Cow::Owned(format!("\"{}\"", &s[1..s.len() - 1])),
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s @ Cow::Borrowed(_) => s,
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},
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RepeatKind::String =>
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Sugg::hir_with_context(cx, repeat_arg, ctxt, "..", &mut app).maybe_par().to_string().into(),
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};
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span_lint_and_sugg(
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cx,
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MANUAL_STR_REPEAT,
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collect_expr.span,
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"manual implementation of `str::repeat` using iterators",
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"try this",
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format!("{}.repeat({})", val_str, count_snip),
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app
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)
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}
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}
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}
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