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