use regex_syntax; use rustc::hir::*; use rustc::lint::*; use rustc::middle::const_val::ConstVal; use rustc_const_eval::ConstContext; use rustc::ty::subst::Substs; use std::collections::HashSet; use std::error::Error; use syntax::ast::{LitKind, NodeId}; use syntax::codemap::{BytePos, Span}; use syntax::symbol::InternedString; use utils::{is_expn_of, match_def_path, match_type, paths, span_help_and_lint, span_lint, opt_def_id}; /// **What it does:** Checks [regex](https://crates.io/crates/regex) creation /// (with `Regex::new`,`RegexBuilder::new` or `RegexSet::new`) for correct /// regex syntax. /// /// **Why is this bad?** This will lead to a runtime panic. /// /// **Known problems:** None. /// /// **Example:** /// ```rust /// Regex::new("|") /// ``` declare_lint! { pub INVALID_REGEX, Deny, "invalid regular expressions" } /// **What it does:** Checks for trivial [regex] creation (with `Regex::new`, /// `RegexBuilder::new` or `RegexSet::new`). /// /// [regex]: https://crates.io/crates/regex /// /// **Why is this bad?** Matching the regex can likely be replaced by `==` or /// `str::starts_with`, `str::ends_with` or `std::contains` or other `str` /// methods. /// /// **Known problems:** None. /// /// **Example:** /// ```rust /// Regex::new("^foobar") /// ``` declare_lint! { pub TRIVIAL_REGEX, Warn, "trivial regular expressions" } /// **What it does:** Checks for usage of `regex!(_)` which (as of now) is /// usually slower than `Regex::new(_)` unless called in a loop (which is a bad /// idea anyway). /// /// **Why is this bad?** Performance, at least for now. The macro version is /// likely to catch up long-term, but for now the dynamic version is faster. /// /// **Known problems:** None. /// /// **Example:** /// ```rust /// regex!("foo|bar") /// ``` declare_lint! { pub REGEX_MACRO, Warn, "use of `regex!(_)` instead of `Regex::new(_)`" } #[derive(Clone, Default)] pub struct Pass { spans: HashSet, last: Option, } impl LintPass for Pass { fn get_lints(&self) -> LintArray { lint_array!(INVALID_REGEX, REGEX_MACRO, TRIVIAL_REGEX) } } impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass { fn check_crate(&mut self, _: &LateContext<'a, 'tcx>, _: &'tcx Crate) { self.spans.clear(); } fn check_block(&mut self, cx: &LateContext<'a, 'tcx>, block: &'tcx Block) { if_let_chain!{[ self.last.is_none(), let Some(ref expr) = block.expr, match_type(cx, cx.tables.expr_ty(expr), &paths::REGEX), let Some(span) = is_expn_of(expr.span, "regex"), ], { if !self.spans.contains(&span) { span_lint(cx, REGEX_MACRO, span, "`regex!(_)` found. \ Please use `Regex::new(_)`, which is faster for now."); self.spans.insert(span); } self.last = Some(block.id); }} } fn check_block_post(&mut self, _: &LateContext<'a, 'tcx>, block: &'tcx Block) { if self.last.map_or(false, |id| block.id == id) { self.last = None; } } fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) { if_let_chain!{[ let ExprCall(ref fun, ref args) = expr.node, let ExprPath(ref qpath) = fun.node, args.len() == 1, let Some(def_id) = opt_def_id(cx.tables.qpath_def(qpath, fun.hir_id)), ], { if match_def_path(cx.tcx, def_id, &paths::REGEX_NEW) || match_def_path(cx.tcx, def_id, &paths::REGEX_BUILDER_NEW) { check_regex(cx, &args[0], true); } else if match_def_path(cx.tcx, def_id, &paths::REGEX_BYTES_NEW) || match_def_path(cx.tcx, def_id, &paths::REGEX_BYTES_BUILDER_NEW) { check_regex(cx, &args[0], false); } else if match_def_path(cx.tcx, def_id, &paths::REGEX_SET_NEW) { check_set(cx, &args[0], true); } else if match_def_path(cx.tcx, def_id, &paths::REGEX_BYTES_SET_NEW) { check_set(cx, &args[0], false); } }} } } #[allow(cast_possible_truncation)] fn str_span(base: Span, s: &str, c: usize) -> Span { let mut si = s.char_indices().skip(c); match (si.next(), si.next()) { (Some((l, _)), Some((h, _))) => { Span::new(base.lo() + BytePos(l as u32), base.lo() + BytePos(h as u32), base.ctxt()) }, _ => base, } } fn const_str(cx: &LateContext, e: &Expr) -> Option { let parent_item = cx.tcx.hir.get_parent(e.id); let parent_def_id = cx.tcx.hir.local_def_id(parent_item); let substs = Substs::identity_for_item(cx.tcx, parent_def_id); match ConstContext::new(cx.tcx, cx.param_env.and(substs), cx.tables).eval(e) { Ok(ConstVal::Str(r)) => Some(r), _ => None, } } fn is_trivial_regex(s: ®ex_syntax::Expr) -> Option<&'static str> { use regex_syntax::Expr; match *s { Expr::Empty | Expr::StartText | Expr::EndText => Some("the regex is unlikely to be useful as it is"), Expr::Literal { .. } => Some("consider using `str::contains`"), Expr::Concat(ref exprs) => match exprs.len() { 2 => match (&exprs[0], &exprs[1]) { (&Expr::StartText, &Expr::EndText) => Some("consider using `str::is_empty`"), (&Expr::StartText, &Expr::Literal { .. }) => Some("consider using `str::starts_with`"), (&Expr::Literal { .. }, &Expr::EndText) => Some("consider using `str::ends_with`"), _ => None, }, 3 => if let (&Expr::StartText, &Expr::Literal { .. }, &Expr::EndText) = (&exprs[0], &exprs[1], &exprs[2]) { Some("consider using `==` on `str`s") } else { None }, _ => None, }, _ => None, } } fn check_set(cx: &LateContext, expr: &Expr, utf8: bool) { if_let_chain! {[ let ExprAddrOf(_, ref expr) = expr.node, let ExprArray(ref exprs) = expr.node, ], { for expr in exprs { check_regex(cx, expr, utf8); } }} } fn check_regex(cx: &LateContext, expr: &Expr, utf8: bool) { let builder = regex_syntax::ExprBuilder::new().unicode(utf8); if let ExprLit(ref lit) = expr.node { if let LitKind::Str(ref r, _) = lit.node { let r = &r.as_str(); match builder.parse(r) { Ok(r) => if let Some(repl) = is_trivial_regex(&r) { span_help_and_lint( cx, TRIVIAL_REGEX, expr.span, "trivial regex", &format!("consider using {}", repl), ); }, Err(e) => { span_lint( cx, INVALID_REGEX, str_span(expr.span, r, e.position()), &format!("regex syntax error: {}", e.description()), ); }, } } } else if let Some(r) = const_str(cx, expr) { match builder.parse(&r) { Ok(r) => if let Some(repl) = is_trivial_regex(&r) { span_help_and_lint( cx, TRIVIAL_REGEX, expr.span, "trivial regex", &format!("consider using {}", repl), ); }, Err(e) => { span_lint( cx, INVALID_REGEX, expr.span, &format!("regex syntax error on position {}: {}", e.position(), e.description()), ); }, } } }