1 //! A `MutVisitor` represents an AST modification; it accepts an AST piece and
2 //! mutates it in place. So, for instance, macro expansion is a `MutVisitor`
3 //! that walks over an AST and modifies it.
5 //! Note: using a `MutVisitor` (other than the `MacroExpander` `MutVisitor`) on
6 //! an AST before macro expansion is probably a bad idea. For instance,
7 //! a `MutVisitor` renaming item names in a module will miss all of those
8 //! that are created by the expansion of a macro.
12 use crate::token::{self, Token};
13 use crate::tokenstream::*;
15 use rustc_data_structures::map_in_place::MapInPlace;
16 use rustc_data_structures::sync::Lrc;
17 use rustc_data_structures::thin_vec::ThinVec;
18 use rustc_span::source_map::Spanned;
19 use rustc_span::symbol::Ident;
22 use smallvec::{smallvec, Array, SmallVec};
23 use std::ops::DerefMut;
24 use std::{panic, ptr};
26 pub trait ExpectOne<A: Array> {
27 fn expect_one(self, err: &'static str) -> A::Item;
30 impl<A: Array> ExpectOne<A> for SmallVec<A> {
31 fn expect_one(self, err: &'static str) -> A::Item {
32 assert!(self.len() == 1, "{}", err);
33 self.into_iter().next().unwrap()
37 pub trait MutVisitor: Sized {
38 /// Mutable token visiting only exists for the `macro_rules` token marker and should not be
39 /// used otherwise. Token visitor would be entirely separate from the regular visitor if
40 /// the marker didn't have to visit AST fragments in nonterminal tokens.
41 const VISIT_TOKENS: bool = false;
43 // Methods in this trait have one of three forms:
45 // fn visit_t(&mut self, t: &mut T); // common
46 // fn flat_map_t(&mut self, t: T) -> SmallVec<[T; 1]>; // rare
47 // fn filter_map_t(&mut self, t: T) -> Option<T>; // rarest
49 // Any additions to this trait should happen in form of a call to a public
50 // `noop_*` function that only calls out to the visitor again, not other
51 // `noop_*` functions. This is a necessary API workaround to the problem of
52 // not being able to call out to the super default method in an overridden
55 // When writing these methods, it is better to use destructuring like this:
57 // fn visit_abc(&mut self, ABC { a, b, c: _ }: &mut ABC) {
62 // than to use field access like this:
64 // fn visit_abc(&mut self, abc: &mut ABC) {
65 // visit_a(&mut abc.a);
66 // visit_b(&mut abc.b);
70 // As well as being more concise, the former is explicit about which fields
71 // are skipped. Furthermore, if a new field is added, the destructuring
72 // version will cause a compile error, which is good. In comparison, the
73 // field access version will continue working and it would be easy to
74 // forget to add handling for it.
76 fn visit_crate(&mut self, c: &mut Crate) {
77 noop_visit_crate(c, self)
80 fn visit_meta_list_item(&mut self, list_item: &mut NestedMetaItem) {
81 noop_visit_meta_list_item(list_item, self);
84 fn visit_meta_item(&mut self, meta_item: &mut MetaItem) {
85 noop_visit_meta_item(meta_item, self);
88 fn visit_use_tree(&mut self, use_tree: &mut UseTree) {
89 noop_visit_use_tree(use_tree, self);
92 fn flat_map_foreign_item(&mut self, ni: P<ForeignItem>) -> SmallVec<[P<ForeignItem>; 1]> {
93 noop_flat_map_foreign_item(ni, self)
96 fn flat_map_item(&mut self, i: P<Item>) -> SmallVec<[P<Item>; 1]> {
97 noop_flat_map_item(i, self)
100 fn visit_fn_header(&mut self, header: &mut FnHeader) {
101 noop_visit_fn_header(header, self);
104 fn flat_map_field_def(&mut self, fd: FieldDef) -> SmallVec<[FieldDef; 1]> {
105 noop_flat_map_field_def(fd, self)
108 fn visit_item_kind(&mut self, i: &mut ItemKind) {
109 noop_visit_item_kind(i, self);
112 fn flat_map_trait_item(&mut self, i: P<AssocItem>) -> SmallVec<[P<AssocItem>; 1]> {
113 noop_flat_map_assoc_item(i, self)
116 fn flat_map_impl_item(&mut self, i: P<AssocItem>) -> SmallVec<[P<AssocItem>; 1]> {
117 noop_flat_map_assoc_item(i, self)
120 fn visit_fn_decl(&mut self, d: &mut P<FnDecl>) {
121 noop_visit_fn_decl(d, self);
124 fn visit_asyncness(&mut self, a: &mut Async) {
125 noop_visit_asyncness(a, self);
128 fn visit_closure_binder(&mut self, b: &mut ClosureBinder) {
129 noop_visit_closure_binder(b, self);
132 fn visit_block(&mut self, b: &mut P<Block>) {
133 noop_visit_block(b, self);
136 fn flat_map_stmt(&mut self, s: Stmt) -> SmallVec<[Stmt; 1]> {
137 noop_flat_map_stmt(s, self)
140 fn flat_map_arm(&mut self, arm: Arm) -> SmallVec<[Arm; 1]> {
141 noop_flat_map_arm(arm, self)
144 fn visit_pat(&mut self, p: &mut P<Pat>) {
145 noop_visit_pat(p, self);
148 fn visit_anon_const(&mut self, c: &mut AnonConst) {
149 noop_visit_anon_const(c, self);
152 fn visit_expr(&mut self, e: &mut P<Expr>) {
153 noop_visit_expr(e, self);
156 fn filter_map_expr(&mut self, e: P<Expr>) -> Option<P<Expr>> {
157 noop_filter_map_expr(e, self)
160 fn visit_generic_arg(&mut self, arg: &mut GenericArg) {
161 noop_visit_generic_arg(arg, self);
164 fn visit_ty(&mut self, t: &mut P<Ty>) {
165 noop_visit_ty(t, self);
168 fn visit_lifetime(&mut self, l: &mut Lifetime) {
169 noop_visit_lifetime(l, self);
172 fn visit_constraint(&mut self, t: &mut AssocConstraint) {
173 noop_visit_constraint(t, self);
176 fn visit_foreign_mod(&mut self, nm: &mut ForeignMod) {
177 noop_visit_foreign_mod(nm, self);
180 fn flat_map_variant(&mut self, v: Variant) -> SmallVec<[Variant; 1]> {
181 noop_flat_map_variant(v, self)
184 fn visit_ident(&mut self, i: &mut Ident) {
185 noop_visit_ident(i, self);
188 fn visit_path(&mut self, p: &mut Path) {
189 noop_visit_path(p, self);
192 fn visit_qself(&mut self, qs: &mut Option<QSelf>) {
193 noop_visit_qself(qs, self);
196 fn visit_generic_args(&mut self, p: &mut GenericArgs) {
197 noop_visit_generic_args(p, self);
200 fn visit_angle_bracketed_parameter_data(&mut self, p: &mut AngleBracketedArgs) {
201 noop_visit_angle_bracketed_parameter_data(p, self);
204 fn visit_parenthesized_parameter_data(&mut self, p: &mut ParenthesizedArgs) {
205 noop_visit_parenthesized_parameter_data(p, self);
208 fn visit_local(&mut self, l: &mut P<Local>) {
209 noop_visit_local(l, self);
212 fn visit_mac_call(&mut self, mac: &mut MacCall) {
213 noop_visit_mac(mac, self);
216 fn visit_macro_def(&mut self, def: &mut MacroDef) {
217 noop_visit_macro_def(def, self);
220 fn visit_label(&mut self, label: &mut Label) {
221 noop_visit_label(label, self);
224 fn visit_attribute(&mut self, at: &mut Attribute) {
225 noop_visit_attribute(at, self);
228 fn flat_map_param(&mut self, param: Param) -> SmallVec<[Param; 1]> {
229 noop_flat_map_param(param, self)
232 fn visit_generics(&mut self, generics: &mut Generics) {
233 noop_visit_generics(generics, self);
236 fn visit_trait_ref(&mut self, tr: &mut TraitRef) {
237 noop_visit_trait_ref(tr, self);
240 fn visit_poly_trait_ref(&mut self, p: &mut PolyTraitRef) {
241 noop_visit_poly_trait_ref(p, self);
244 fn visit_variant_data(&mut self, vdata: &mut VariantData) {
245 noop_visit_variant_data(vdata, self);
248 fn flat_map_generic_param(&mut self, param: GenericParam) -> SmallVec<[GenericParam; 1]> {
249 noop_flat_map_generic_param(param, self)
252 fn visit_param_bound(&mut self, tpb: &mut GenericBound) {
253 noop_visit_param_bound(tpb, self);
256 fn visit_mt(&mut self, mt: &mut MutTy) {
257 noop_visit_mt(mt, self);
260 fn flat_map_expr_field(&mut self, f: ExprField) -> SmallVec<[ExprField; 1]> {
261 noop_flat_map_expr_field(f, self)
264 fn visit_where_clause(&mut self, where_clause: &mut WhereClause) {
265 noop_visit_where_clause(where_clause, self);
268 fn visit_where_predicate(&mut self, where_predicate: &mut WherePredicate) {
269 noop_visit_where_predicate(where_predicate, self);
272 fn visit_vis(&mut self, vis: &mut Visibility) {
273 noop_visit_vis(vis, self);
276 fn visit_id(&mut self, _id: &mut NodeId) {
280 fn visit_span(&mut self, _sp: &mut Span) {
284 fn flat_map_pat_field(&mut self, fp: PatField) -> SmallVec<[PatField; 1]> {
285 noop_flat_map_pat_field(fp, self)
288 fn visit_inline_asm(&mut self, asm: &mut InlineAsm) {
289 noop_visit_inline_asm(asm, self)
292 fn visit_inline_asm_sym(&mut self, sym: &mut InlineAsmSym) {
293 noop_visit_inline_asm_sym(sym, self)
297 /// Use a map-style function (`FnOnce(T) -> T`) to overwrite a `&mut T`. Useful
298 /// when using a `flat_map_*` or `filter_map_*` method within a `visit_`
301 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
302 pub fn visit_clobber<T: DummyAstNode>(t: &mut T, f: impl FnOnce(T) -> T) {
304 // Safe because `t` is used in a read-only fashion by `read()` before
305 // being overwritten by `write()`.
306 let old_t = ptr::read(t);
308 panic::catch_unwind(panic::AssertUnwindSafe(|| f(old_t))).unwrap_or_else(|err| {
309 // Set `t` to some valid but possible meaningless value,
310 // and pass the fatal error further.
311 ptr::write(t, T::dummy());
312 panic::resume_unwind(err);
314 ptr::write(t, new_t);
318 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
320 pub fn visit_vec<T, F>(elems: &mut Vec<T>, mut visit_elem: F)
329 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
331 pub fn visit_opt<T, F>(opt: &mut Option<T>, mut visit_elem: F)
335 if let Some(elem) = opt {
340 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
341 pub fn visit_attrs<T: MutVisitor>(attrs: &mut Vec<Attribute>, vis: &mut T) {
342 visit_vec(attrs, |attr| vis.visit_attribute(attr));
345 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
346 pub fn visit_thin_attrs<T: MutVisitor>(attrs: &mut AttrVec, vis: &mut T) {
347 for attr in attrs.iter_mut() {
348 vis.visit_attribute(attr);
352 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
353 pub fn visit_exprs<T: MutVisitor>(exprs: &mut Vec<P<Expr>>, vis: &mut T) {
354 exprs.flat_map_in_place(|expr| vis.filter_map_expr(expr))
357 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
358 pub fn visit_bounds<T: MutVisitor>(bounds: &mut GenericBounds, vis: &mut T) {
359 visit_vec(bounds, |bound| vis.visit_param_bound(bound));
362 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
363 pub fn visit_fn_sig<T: MutVisitor>(FnSig { header, decl, span }: &mut FnSig, vis: &mut T) {
364 vis.visit_fn_header(header);
365 vis.visit_fn_decl(decl);
366 vis.visit_span(span);
369 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
370 pub fn visit_mac_args<T: MutVisitor>(args: &mut MacArgs, vis: &mut T) {
373 MacArgs::Delimited(dspan, _delim, tokens) => {
374 visit_delim_span(dspan, vis);
375 visit_tts(tokens, vis);
377 MacArgs::Eq(eq_span, MacArgsEq::Ast(expr)) => {
378 vis.visit_span(eq_span);
379 vis.visit_expr(expr);
381 MacArgs::Eq(_, MacArgsEq::Hir(lit)) => {
382 unreachable!("in literal form when visiting mac args eq: {:?}", lit)
387 pub fn visit_delim_span<T: MutVisitor>(dspan: &mut DelimSpan, vis: &mut T) {
388 vis.visit_span(&mut dspan.open);
389 vis.visit_span(&mut dspan.close);
392 pub fn noop_flat_map_pat_field<T: MutVisitor>(
395 ) -> SmallVec<[PatField; 1]> {
396 let PatField { attrs, id, ident, is_placeholder: _, is_shorthand: _, pat, span } = &mut fp;
398 vis.visit_ident(ident);
400 vis.visit_span(span);
401 visit_thin_attrs(attrs, vis);
405 pub fn noop_visit_use_tree<T: MutVisitor>(use_tree: &mut UseTree, vis: &mut T) {
406 let UseTree { prefix, kind, span } = use_tree;
407 vis.visit_path(prefix);
409 UseTreeKind::Simple(rename, id1, id2) => {
410 visit_opt(rename, |rename| vis.visit_ident(rename));
414 UseTreeKind::Nested(items) => {
415 for (tree, id) in items {
416 vis.visit_use_tree(tree);
420 UseTreeKind::Glob => {}
422 vis.visit_span(span);
425 pub fn noop_flat_map_arm<T: MutVisitor>(mut arm: Arm, vis: &mut T) -> SmallVec<[Arm; 1]> {
426 let Arm { attrs, pat, guard, body, span, id, is_placeholder: _ } = &mut arm;
427 visit_thin_attrs(attrs, vis);
430 visit_opt(guard, |guard| vis.visit_expr(guard));
431 vis.visit_expr(body);
432 vis.visit_span(span);
436 pub fn noop_visit_constraint<T: MutVisitor>(
437 AssocConstraint { id, ident, gen_args, kind, span }: &mut AssocConstraint,
441 vis.visit_ident(ident);
442 if let Some(ref mut gen_args) = gen_args {
443 vis.visit_generic_args(gen_args);
446 AssocConstraintKind::Equality { ref mut term } => match term {
447 Term::Ty(ty) => vis.visit_ty(ty),
448 Term::Const(c) => vis.visit_anon_const(c),
450 AssocConstraintKind::Bound { ref mut bounds } => visit_bounds(bounds, vis),
452 vis.visit_span(span);
455 pub fn noop_visit_ty<T: MutVisitor>(ty: &mut P<Ty>, vis: &mut T) {
456 let Ty { id, kind, span, tokens } = ty.deref_mut();
459 TyKind::Infer | TyKind::ImplicitSelf | TyKind::Err | TyKind::Never | TyKind::CVarArgs => {}
460 TyKind::Slice(ty) => vis.visit_ty(ty),
461 TyKind::Ptr(mt) => vis.visit_mt(mt),
462 TyKind::Rptr(lt, mt) => {
463 visit_opt(lt, |lt| noop_visit_lifetime(lt, vis));
466 TyKind::BareFn(bft) => {
467 let BareFnTy { unsafety, ext: _, generic_params, decl, decl_span } = bft.deref_mut();
468 visit_unsafety(unsafety, vis);
469 generic_params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
470 vis.visit_fn_decl(decl);
471 vis.visit_span(decl_span);
473 TyKind::Tup(tys) => visit_vec(tys, |ty| vis.visit_ty(ty)),
474 TyKind::Paren(ty) => vis.visit_ty(ty),
475 TyKind::Path(qself, path) => {
476 vis.visit_qself(qself);
477 vis.visit_path(path);
479 TyKind::Array(ty, length) => {
481 vis.visit_anon_const(length);
483 TyKind::Typeof(expr) => vis.visit_anon_const(expr),
484 TyKind::TraitObject(bounds, _syntax) => {
485 visit_vec(bounds, |bound| vis.visit_param_bound(bound))
487 TyKind::ImplTrait(id, bounds) => {
489 visit_vec(bounds, |bound| vis.visit_param_bound(bound));
491 TyKind::MacCall(mac) => vis.visit_mac_call(mac),
493 vis.visit_span(span);
494 visit_lazy_tts(tokens, vis);
497 pub fn noop_visit_foreign_mod<T: MutVisitor>(foreign_mod: &mut ForeignMod, vis: &mut T) {
498 let ForeignMod { unsafety, abi: _, items } = foreign_mod;
499 visit_unsafety(unsafety, vis);
500 items.flat_map_in_place(|item| vis.flat_map_foreign_item(item));
503 pub fn noop_flat_map_variant<T: MutVisitor>(
504 mut variant: Variant,
506 ) -> SmallVec<[Variant; 1]> {
507 let Variant { ident, vis, attrs, id, data, disr_expr, span, is_placeholder: _ } = &mut variant;
508 visitor.visit_ident(ident);
509 visitor.visit_vis(vis);
510 visit_thin_attrs(attrs, visitor);
511 visitor.visit_id(id);
512 visitor.visit_variant_data(data);
513 visit_opt(disr_expr, |disr_expr| visitor.visit_anon_const(disr_expr));
514 visitor.visit_span(span);
518 pub fn noop_visit_ident<T: MutVisitor>(Ident { name: _, span }: &mut Ident, vis: &mut T) {
519 vis.visit_span(span);
522 pub fn noop_visit_path<T: MutVisitor>(Path { segments, span, tokens }: &mut Path, vis: &mut T) {
523 vis.visit_span(span);
524 for PathSegment { ident, id, args } in segments {
525 vis.visit_ident(ident);
527 visit_opt(args, |args| vis.visit_generic_args(args));
529 visit_lazy_tts(tokens, vis);
532 pub fn noop_visit_qself<T: MutVisitor>(qself: &mut Option<QSelf>, vis: &mut T) {
533 visit_opt(qself, |QSelf { ty, path_span, position: _ }| {
535 vis.visit_span(path_span);
539 pub fn noop_visit_generic_args<T: MutVisitor>(generic_args: &mut GenericArgs, vis: &mut T) {
541 GenericArgs::AngleBracketed(data) => vis.visit_angle_bracketed_parameter_data(data),
542 GenericArgs::Parenthesized(data) => vis.visit_parenthesized_parameter_data(data),
546 pub fn noop_visit_generic_arg<T: MutVisitor>(arg: &mut GenericArg, vis: &mut T) {
548 GenericArg::Lifetime(lt) => vis.visit_lifetime(lt),
549 GenericArg::Type(ty) => vis.visit_ty(ty),
550 GenericArg::Const(ct) => vis.visit_anon_const(ct),
554 pub fn noop_visit_angle_bracketed_parameter_data<T: MutVisitor>(
555 data: &mut AngleBracketedArgs,
558 let AngleBracketedArgs { args, span } = data;
559 visit_vec(args, |arg| match arg {
560 AngleBracketedArg::Arg(arg) => vis.visit_generic_arg(arg),
561 AngleBracketedArg::Constraint(constraint) => vis.visit_constraint(constraint),
563 vis.visit_span(span);
566 pub fn noop_visit_parenthesized_parameter_data<T: MutVisitor>(
567 args: &mut ParenthesizedArgs,
570 let ParenthesizedArgs { inputs, output, span, .. } = args;
571 visit_vec(inputs, |input| vis.visit_ty(input));
572 noop_visit_fn_ret_ty(output, vis);
573 vis.visit_span(span);
576 pub fn noop_visit_local<T: MutVisitor>(local: &mut P<Local>, vis: &mut T) {
577 let Local { id, pat, ty, kind, span, attrs, tokens } = local.deref_mut();
580 visit_opt(ty, |ty| vis.visit_ty(ty));
582 LocalKind::Decl => {}
583 LocalKind::Init(init) => {
584 vis.visit_expr(init);
586 LocalKind::InitElse(init, els) => {
587 vis.visit_expr(init);
588 vis.visit_block(els);
591 vis.visit_span(span);
592 visit_thin_attrs(attrs, vis);
593 visit_lazy_tts(tokens, vis);
596 pub fn noop_visit_attribute<T: MutVisitor>(attr: &mut Attribute, vis: &mut T) {
597 let Attribute { kind, id: _, style: _, span } = attr;
599 AttrKind::Normal(AttrItem { path, args, tokens }, attr_tokens) => {
600 vis.visit_path(path);
601 visit_mac_args(args, vis);
602 visit_lazy_tts(tokens, vis);
603 visit_lazy_tts(attr_tokens, vis);
605 AttrKind::DocComment(..) => {}
607 vis.visit_span(span);
610 pub fn noop_visit_mac<T: MutVisitor>(mac: &mut MacCall, vis: &mut T) {
611 let MacCall { path, args, prior_type_ascription: _ } = mac;
612 vis.visit_path(path);
613 visit_mac_args(args, vis);
616 pub fn noop_visit_macro_def<T: MutVisitor>(macro_def: &mut MacroDef, vis: &mut T) {
617 let MacroDef { body, macro_rules: _ } = macro_def;
618 visit_mac_args(body, vis);
621 pub fn noop_visit_meta_list_item<T: MutVisitor>(li: &mut NestedMetaItem, vis: &mut T) {
623 NestedMetaItem::MetaItem(mi) => vis.visit_meta_item(mi),
624 NestedMetaItem::Literal(_lit) => {}
628 pub fn noop_visit_meta_item<T: MutVisitor>(mi: &mut MetaItem, vis: &mut T) {
629 let MetaItem { path: _, kind, span } = mi;
631 MetaItemKind::Word => {}
632 MetaItemKind::List(mis) => visit_vec(mis, |mi| vis.visit_meta_list_item(mi)),
633 MetaItemKind::NameValue(_s) => {}
635 vis.visit_span(span);
638 pub fn noop_flat_map_param<T: MutVisitor>(mut param: Param, vis: &mut T) -> SmallVec<[Param; 1]> {
639 let Param { attrs, id, pat, span, ty, is_placeholder: _ } = &mut param;
641 visit_thin_attrs(attrs, vis);
643 vis.visit_span(span);
648 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
649 pub fn visit_attr_annotated_tt<T: MutVisitor>(tt: &mut AttrAnnotatedTokenTree, vis: &mut T) {
651 AttrAnnotatedTokenTree::Token(token) => {
652 visit_token(token, vis);
654 AttrAnnotatedTokenTree::Delimited(DelimSpan { open, close }, _delim, tts) => {
655 vis.visit_span(open);
656 vis.visit_span(close);
657 visit_attr_annotated_tts(tts, vis);
659 AttrAnnotatedTokenTree::Attributes(data) => {
660 for attr in &mut *data.attrs {
661 match &mut attr.kind {
662 AttrKind::Normal(_, attr_tokens) => {
663 visit_lazy_tts(attr_tokens, vis);
665 AttrKind::DocComment(..) => {
666 vis.visit_span(&mut attr.span);
670 visit_lazy_tts_opt_mut(Some(&mut data.tokens), vis);
675 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
676 pub fn visit_tt<T: MutVisitor>(tt: &mut TokenTree, vis: &mut T) {
678 TokenTree::Token(token, _) => {
679 visit_token(token, vis);
681 TokenTree::Delimited(DelimSpan { open, close }, _delim, tts) => {
682 vis.visit_span(open);
683 vis.visit_span(close);
689 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
690 pub fn visit_tts<T: MutVisitor>(TokenStream(tts): &mut TokenStream, vis: &mut T) {
691 if T::VISIT_TOKENS && !tts.is_empty() {
692 let tts = Lrc::make_mut(tts);
693 visit_vec(tts, |tree| visit_tt(tree, vis));
697 pub fn visit_attr_annotated_tts<T: MutVisitor>(
698 AttrAnnotatedTokenStream(tts): &mut AttrAnnotatedTokenStream,
701 if T::VISIT_TOKENS && !tts.is_empty() {
702 let tts = Lrc::make_mut(tts);
703 visit_vec(tts, |(tree, _is_joint)| visit_attr_annotated_tt(tree, vis));
707 pub fn visit_lazy_tts_opt_mut<T: MutVisitor>(lazy_tts: Option<&mut LazyTokenStream>, vis: &mut T) {
709 if let Some(lazy_tts) = lazy_tts {
710 let mut tts = lazy_tts.create_token_stream();
711 visit_attr_annotated_tts(&mut tts, vis);
712 *lazy_tts = LazyTokenStream::new(tts);
717 pub fn visit_lazy_tts<T: MutVisitor>(lazy_tts: &mut Option<LazyTokenStream>, vis: &mut T) {
718 visit_lazy_tts_opt_mut(lazy_tts.as_mut(), vis);
721 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
722 // Applies ident visitor if it's an ident; applies other visits to interpolated nodes.
723 // In practice the ident part is not actually used by specific visitors right now,
724 // but there's a test below checking that it works.
725 pub fn visit_token<T: MutVisitor>(t: &mut Token, vis: &mut T) {
726 let Token { kind, span } = t;
728 token::Ident(name, _) | token::Lifetime(name) => {
729 let mut ident = Ident::new(*name, *span);
730 vis.visit_ident(&mut ident);
733 return; // Avoid visiting the span for the second time.
735 token::Interpolated(nt) => {
736 let mut nt = Lrc::make_mut(nt);
737 visit_nonterminal(&mut nt, vis);
741 vis.visit_span(span);
744 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
745 /// Applies the visitor to elements of interpolated nodes.
747 // N.B., this can occur only when applying a visitor to partially expanded
748 // code, where parsed pieces have gotten implanted ito *other* macro
749 // invocations. This is relevant for macro hygiene, but possibly not elsewhere.
751 // One problem here occurs because the types for flat_map_item, flat_map_stmt,
752 // etc., allow the visitor to return *multiple* items; this is a problem for the
753 // nodes here, because they insist on having exactly one piece. One solution
754 // would be to mangle the MutVisitor trait to include one-to-many and
755 // one-to-one versions of these entry points, but that would probably confuse a
756 // lot of people and help very few. Instead, I'm just going to put in dynamic
757 // checks. I think the performance impact of this will be pretty much
758 // nonexistent. The danger is that someone will apply a `MutVisitor` to a
759 // partially expanded node, and will be confused by the fact that their
760 // `flat_map_item` or `flat_map_stmt` isn't getting called on `NtItem` or `NtStmt`
761 // nodes. Hopefully they'll wind up reading this comment, and doing something
764 // BTW, design choice: I considered just changing the type of, e.g., `NtItem` to
765 // contain multiple items, but decided against it when I looked at
766 // `parse_item_or_view_item` and tried to figure out what I would do with
767 // multiple items there....
768 pub fn visit_nonterminal<T: MutVisitor>(nt: &mut token::Nonterminal, vis: &mut T) {
770 token::NtItem(item) => visit_clobber(item, |item| {
771 // This is probably okay, because the only visitors likely to
772 // peek inside interpolated nodes will be renamings/markings,
773 // which map single items to single items.
774 vis.flat_map_item(item).expect_one("expected visitor to produce exactly one item")
776 token::NtBlock(block) => vis.visit_block(block),
777 token::NtStmt(stmt) => visit_clobber(stmt, |stmt| {
778 // See reasoning above.
780 vis.flat_map_stmt(stmt).expect_one("expected visitor to produce exactly one item")
783 token::NtPat(pat) => vis.visit_pat(pat),
784 token::NtExpr(expr) => vis.visit_expr(expr),
785 token::NtTy(ty) => vis.visit_ty(ty),
786 token::NtIdent(ident, _is_raw) => vis.visit_ident(ident),
787 token::NtLifetime(ident) => vis.visit_ident(ident),
788 token::NtLiteral(expr) => vis.visit_expr(expr),
789 token::NtMeta(item) => {
790 let AttrItem { path, args, tokens } = item.deref_mut();
791 vis.visit_path(path);
792 visit_mac_args(args, vis);
793 visit_lazy_tts(tokens, vis);
795 token::NtPath(path) => vis.visit_path(path),
796 token::NtVis(visib) => vis.visit_vis(visib),
800 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
801 pub fn visit_defaultness<T: MutVisitor>(defaultness: &mut Defaultness, vis: &mut T) {
803 Defaultness::Default(span) => vis.visit_span(span),
804 Defaultness::Final => {}
808 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
809 pub fn visit_unsafety<T: MutVisitor>(unsafety: &mut Unsafe, vis: &mut T) {
811 Unsafe::Yes(span) => vis.visit_span(span),
816 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
817 pub fn visit_polarity<T: MutVisitor>(polarity: &mut ImplPolarity, vis: &mut T) {
819 ImplPolarity::Positive => {}
820 ImplPolarity::Negative(span) => vis.visit_span(span),
824 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
825 pub fn visit_constness<T: MutVisitor>(constness: &mut Const, vis: &mut T) {
827 Const::Yes(span) => vis.visit_span(span),
832 pub fn noop_visit_closure_binder<T: MutVisitor>(binder: &mut ClosureBinder, vis: &mut T) {
834 ClosureBinder::NotPresent => {}
835 ClosureBinder::For { span: _, generic_params } => {
836 let mut vec = std::mem::take(generic_params).into_vec();
837 vec.flat_map_in_place(|param| vis.flat_map_generic_param(param));
838 *generic_params = P::from_vec(vec);
843 pub fn noop_visit_asyncness<T: MutVisitor>(asyncness: &mut Async, vis: &mut T) {
845 Async::Yes { span: _, closure_id, return_impl_trait_id } => {
846 vis.visit_id(closure_id);
847 vis.visit_id(return_impl_trait_id);
853 pub fn noop_visit_fn_decl<T: MutVisitor>(decl: &mut P<FnDecl>, vis: &mut T) {
854 let FnDecl { inputs, output } = decl.deref_mut();
855 inputs.flat_map_in_place(|param| vis.flat_map_param(param));
856 noop_visit_fn_ret_ty(output, vis);
859 pub fn noop_visit_fn_ret_ty<T: MutVisitor>(fn_ret_ty: &mut FnRetTy, vis: &mut T) {
861 FnRetTy::Default(span) => vis.visit_span(span),
862 FnRetTy::Ty(ty) => vis.visit_ty(ty),
866 pub fn noop_visit_param_bound<T: MutVisitor>(pb: &mut GenericBound, vis: &mut T) {
868 GenericBound::Trait(ty, _modifier) => vis.visit_poly_trait_ref(ty),
869 GenericBound::Outlives(lifetime) => noop_visit_lifetime(lifetime, vis),
873 pub fn noop_flat_map_generic_param<T: MutVisitor>(
874 mut param: GenericParam,
876 ) -> SmallVec<[GenericParam; 1]> {
877 let GenericParam { id, ident, attrs, bounds, kind, colon_span, is_placeholder: _ } = &mut param;
879 vis.visit_ident(ident);
880 if let Some(ref mut colon_span) = colon_span {
881 vis.visit_span(colon_span);
883 visit_thin_attrs(attrs, vis);
884 visit_vec(bounds, |bound| noop_visit_param_bound(bound, vis));
886 GenericParamKind::Lifetime => {}
887 GenericParamKind::Type { default } => {
888 visit_opt(default, |default| vis.visit_ty(default));
890 GenericParamKind::Const { ty, kw_span: _, default } => {
892 visit_opt(default, |default| vis.visit_anon_const(default));
898 pub fn noop_visit_label<T: MutVisitor>(Label { ident }: &mut Label, vis: &mut T) {
899 vis.visit_ident(ident);
902 fn noop_visit_lifetime<T: MutVisitor>(Lifetime { id, ident }: &mut Lifetime, vis: &mut T) {
904 vis.visit_ident(ident);
907 pub fn noop_visit_generics<T: MutVisitor>(generics: &mut Generics, vis: &mut T) {
908 let Generics { params, where_clause, span } = generics;
909 params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
910 vis.visit_where_clause(where_clause);
911 vis.visit_span(span);
914 pub fn noop_visit_where_clause<T: MutVisitor>(wc: &mut WhereClause, vis: &mut T) {
915 let WhereClause { has_where_token: _, predicates, span } = wc;
916 visit_vec(predicates, |predicate| vis.visit_where_predicate(predicate));
917 vis.visit_span(span);
920 pub fn noop_visit_where_predicate<T: MutVisitor>(pred: &mut WherePredicate, vis: &mut T) {
922 WherePredicate::BoundPredicate(bp) => {
923 let WhereBoundPredicate { span, bound_generic_params, bounded_ty, bounds } = bp;
924 vis.visit_span(span);
925 bound_generic_params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
926 vis.visit_ty(bounded_ty);
927 visit_vec(bounds, |bound| vis.visit_param_bound(bound));
929 WherePredicate::RegionPredicate(rp) => {
930 let WhereRegionPredicate { span, lifetime, bounds } = rp;
931 vis.visit_span(span);
932 noop_visit_lifetime(lifetime, vis);
933 visit_vec(bounds, |bound| noop_visit_param_bound(bound, vis));
935 WherePredicate::EqPredicate(ep) => {
936 let WhereEqPredicate { id, span, lhs_ty, rhs_ty } = ep;
938 vis.visit_span(span);
939 vis.visit_ty(lhs_ty);
940 vis.visit_ty(rhs_ty);
945 pub fn noop_visit_variant_data<T: MutVisitor>(vdata: &mut VariantData, vis: &mut T) {
947 VariantData::Struct(fields, ..) => {
948 fields.flat_map_in_place(|field| vis.flat_map_field_def(field));
950 VariantData::Tuple(fields, id) => {
951 fields.flat_map_in_place(|field| vis.flat_map_field_def(field));
954 VariantData::Unit(id) => vis.visit_id(id),
958 pub fn noop_visit_trait_ref<T: MutVisitor>(TraitRef { path, ref_id }: &mut TraitRef, vis: &mut T) {
959 vis.visit_path(path);
960 vis.visit_id(ref_id);
963 pub fn noop_visit_poly_trait_ref<T: MutVisitor>(p: &mut PolyTraitRef, vis: &mut T) {
964 let PolyTraitRef { bound_generic_params, trait_ref, span } = p;
965 bound_generic_params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
966 vis.visit_trait_ref(trait_ref);
967 vis.visit_span(span);
970 pub fn noop_flat_map_field_def<T: MutVisitor>(
973 ) -> SmallVec<[FieldDef; 1]> {
974 let FieldDef { span, ident, vis, id, ty, attrs, is_placeholder: _ } = &mut fd;
975 visitor.visit_span(span);
976 visit_opt(ident, |ident| visitor.visit_ident(ident));
977 visitor.visit_vis(vis);
978 visitor.visit_id(id);
979 visitor.visit_ty(ty);
980 visit_thin_attrs(attrs, visitor);
984 pub fn noop_flat_map_expr_field<T: MutVisitor>(
987 ) -> SmallVec<[ExprField; 1]> {
988 let ExprField { ident, expr, span, is_shorthand: _, attrs, id, is_placeholder: _ } = &mut f;
989 vis.visit_ident(ident);
990 vis.visit_expr(expr);
992 vis.visit_span(span);
993 visit_thin_attrs(attrs, vis);
997 pub fn noop_visit_mt<T: MutVisitor>(MutTy { ty, mutbl: _ }: &mut MutTy, vis: &mut T) {
1001 pub fn noop_visit_block<T: MutVisitor>(block: &mut P<Block>, vis: &mut T) {
1002 let Block { id, stmts, rules: _, span, tokens, could_be_bare_literal: _ } = block.deref_mut();
1004 stmts.flat_map_in_place(|stmt| vis.flat_map_stmt(stmt));
1005 vis.visit_span(span);
1006 visit_lazy_tts(tokens, vis);
1009 pub fn noop_visit_item_kind<T: MutVisitor>(kind: &mut ItemKind, vis: &mut T) {
1011 ItemKind::ExternCrate(_orig_name) => {}
1012 ItemKind::Use(use_tree) => vis.visit_use_tree(use_tree),
1013 ItemKind::Static(ty, _, expr) => {
1015 visit_opt(expr, |expr| vis.visit_expr(expr));
1017 ItemKind::Const(defaultness, ty, expr) => {
1018 visit_defaultness(defaultness, vis);
1020 visit_opt(expr, |expr| vis.visit_expr(expr));
1022 ItemKind::Fn(box Fn { defaultness, generics, sig, body }) => {
1023 visit_defaultness(defaultness, vis);
1024 visit_fn_sig(sig, vis);
1025 vis.visit_generics(generics);
1026 visit_opt(body, |body| vis.visit_block(body));
1028 ItemKind::Mod(unsafety, mod_kind) => {
1029 visit_unsafety(unsafety, vis);
1031 ModKind::Loaded(items, _inline, ModSpans { inner_span, inject_use_span }) => {
1032 vis.visit_span(inner_span);
1033 vis.visit_span(inject_use_span);
1034 items.flat_map_in_place(|item| vis.flat_map_item(item));
1036 ModKind::Unloaded => {}
1039 ItemKind::ForeignMod(nm) => vis.visit_foreign_mod(nm),
1040 ItemKind::GlobalAsm(asm) => vis.visit_inline_asm(asm),
1041 ItemKind::TyAlias(box TyAlias {
1042 defaultness, generics, where_clauses, bounds, ty, ..
1044 visit_defaultness(defaultness, vis);
1045 vis.visit_generics(generics);
1046 vis.visit_span(&mut where_clauses.0.1);
1047 vis.visit_span(&mut where_clauses.1.1);
1048 visit_bounds(bounds, vis);
1049 visit_opt(ty, |ty| vis.visit_ty(ty));
1051 ItemKind::Enum(EnumDef { variants }, generics) => {
1052 variants.flat_map_in_place(|variant| vis.flat_map_variant(variant));
1053 vis.visit_generics(generics);
1055 ItemKind::Struct(variant_data, generics) | ItemKind::Union(variant_data, generics) => {
1056 vis.visit_variant_data(variant_data);
1057 vis.visit_generics(generics);
1059 ItemKind::Impl(box Impl {
1069 visit_defaultness(defaultness, vis);
1070 visit_unsafety(unsafety, vis);
1071 vis.visit_generics(generics);
1072 visit_constness(constness, vis);
1073 visit_polarity(polarity, vis);
1074 visit_opt(of_trait, |trait_ref| vis.visit_trait_ref(trait_ref));
1075 vis.visit_ty(self_ty);
1076 items.flat_map_in_place(|item| vis.flat_map_impl_item(item));
1078 ItemKind::Trait(box Trait { unsafety, is_auto: _, generics, bounds, items }) => {
1079 visit_unsafety(unsafety, vis);
1080 vis.visit_generics(generics);
1081 visit_bounds(bounds, vis);
1082 items.flat_map_in_place(|item| vis.flat_map_trait_item(item));
1084 ItemKind::TraitAlias(generics, bounds) => {
1085 vis.visit_generics(generics);
1086 visit_bounds(bounds, vis);
1088 ItemKind::MacCall(m) => vis.visit_mac_call(m),
1089 ItemKind::MacroDef(def) => vis.visit_macro_def(def),
1093 pub fn noop_flat_map_assoc_item<T: MutVisitor>(
1094 mut item: P<AssocItem>,
1096 ) -> SmallVec<[P<AssocItem>; 1]> {
1097 let Item { id, ident, vis, attrs, kind, span, tokens } = item.deref_mut();
1098 visitor.visit_id(id);
1099 visitor.visit_ident(ident);
1100 visitor.visit_vis(vis);
1101 visit_attrs(attrs, visitor);
1103 AssocItemKind::Const(defaultness, ty, expr) => {
1104 visit_defaultness(defaultness, visitor);
1105 visitor.visit_ty(ty);
1106 visit_opt(expr, |expr| visitor.visit_expr(expr));
1108 AssocItemKind::Fn(box Fn { defaultness, generics, sig, body }) => {
1109 visit_defaultness(defaultness, visitor);
1110 visitor.visit_generics(generics);
1111 visit_fn_sig(sig, visitor);
1112 visit_opt(body, |body| visitor.visit_block(body));
1114 AssocItemKind::TyAlias(box TyAlias {
1122 visit_defaultness(defaultness, visitor);
1123 visitor.visit_generics(generics);
1124 visitor.visit_span(&mut where_clauses.0.1);
1125 visitor.visit_span(&mut where_clauses.1.1);
1126 visit_bounds(bounds, visitor);
1127 visit_opt(ty, |ty| visitor.visit_ty(ty));
1129 AssocItemKind::MacCall(mac) => visitor.visit_mac_call(mac),
1131 visitor.visit_span(span);
1132 visit_lazy_tts(tokens, visitor);
1136 pub fn noop_visit_fn_header<T: MutVisitor>(header: &mut FnHeader, vis: &mut T) {
1137 let FnHeader { unsafety, asyncness, constness, ext: _ } = header;
1138 visit_constness(constness, vis);
1139 vis.visit_asyncness(asyncness);
1140 visit_unsafety(unsafety, vis);
1143 pub fn noop_visit_crate<T: MutVisitor>(krate: &mut Crate, vis: &mut T) {
1144 let Crate { attrs, items, spans, id, is_placeholder: _ } = krate;
1146 visit_attrs(attrs, vis);
1147 items.flat_map_in_place(|item| vis.flat_map_item(item));
1148 let ModSpans { inner_span, inject_use_span } = spans;
1149 vis.visit_span(inner_span);
1150 vis.visit_span(inject_use_span);
1153 // Mutates one item into possibly many items.
1154 pub fn noop_flat_map_item<T: MutVisitor>(
1157 ) -> SmallVec<[P<Item>; 1]> {
1158 let Item { ident, attrs, id, kind, vis, span, tokens } = item.deref_mut();
1159 visitor.visit_ident(ident);
1160 visit_attrs(attrs, visitor);
1161 visitor.visit_id(id);
1162 visitor.visit_item_kind(kind);
1163 visitor.visit_vis(vis);
1164 visitor.visit_span(span);
1165 visit_lazy_tts(tokens, visitor);
1170 pub fn noop_flat_map_foreign_item<T: MutVisitor>(
1171 mut item: P<ForeignItem>,
1173 ) -> SmallVec<[P<ForeignItem>; 1]> {
1174 let Item { ident, attrs, id, kind, vis, span, tokens } = item.deref_mut();
1175 visitor.visit_id(id);
1176 visitor.visit_ident(ident);
1177 visitor.visit_vis(vis);
1178 visit_attrs(attrs, visitor);
1180 ForeignItemKind::Static(ty, _, expr) => {
1181 visitor.visit_ty(ty);
1182 visit_opt(expr, |expr| visitor.visit_expr(expr));
1184 ForeignItemKind::Fn(box Fn { defaultness, generics, sig, body }) => {
1185 visit_defaultness(defaultness, visitor);
1186 visitor.visit_generics(generics);
1187 visit_fn_sig(sig, visitor);
1188 visit_opt(body, |body| visitor.visit_block(body));
1190 ForeignItemKind::TyAlias(box TyAlias {
1198 visit_defaultness(defaultness, visitor);
1199 visitor.visit_generics(generics);
1200 visitor.visit_span(&mut where_clauses.0.1);
1201 visitor.visit_span(&mut where_clauses.1.1);
1202 visit_bounds(bounds, visitor);
1203 visit_opt(ty, |ty| visitor.visit_ty(ty));
1205 ForeignItemKind::MacCall(mac) => visitor.visit_mac_call(mac),
1207 visitor.visit_span(span);
1208 visit_lazy_tts(tokens, visitor);
1212 pub fn noop_visit_pat<T: MutVisitor>(pat: &mut P<Pat>, vis: &mut T) {
1213 let Pat { id, kind, span, tokens } = pat.deref_mut();
1216 PatKind::Wild | PatKind::Rest => {}
1217 PatKind::Ident(_binding_mode, ident, sub) => {
1218 vis.visit_ident(ident);
1219 visit_opt(sub, |sub| vis.visit_pat(sub));
1221 PatKind::Lit(e) => vis.visit_expr(e),
1222 PatKind::TupleStruct(qself, path, elems) => {
1223 vis.visit_qself(qself);
1224 vis.visit_path(path);
1225 visit_vec(elems, |elem| vis.visit_pat(elem));
1227 PatKind::Path(qself, path) => {
1228 vis.visit_qself(qself);
1229 vis.visit_path(path);
1231 PatKind::Struct(qself, path, fields, _etc) => {
1232 vis.visit_qself(qself);
1233 vis.visit_path(path);
1234 fields.flat_map_in_place(|field| vis.flat_map_pat_field(field));
1236 PatKind::Box(inner) => vis.visit_pat(inner),
1237 PatKind::Ref(inner, _mutbl) => vis.visit_pat(inner),
1238 PatKind::Range(e1, e2, Spanned { span: _, node: _ }) => {
1239 visit_opt(e1, |e| vis.visit_expr(e));
1240 visit_opt(e2, |e| vis.visit_expr(e));
1241 vis.visit_span(span);
1243 PatKind::Tuple(elems) | PatKind::Slice(elems) | PatKind::Or(elems) => {
1244 visit_vec(elems, |elem| vis.visit_pat(elem))
1246 PatKind::Paren(inner) => vis.visit_pat(inner),
1247 PatKind::MacCall(mac) => vis.visit_mac_call(mac),
1249 vis.visit_span(span);
1250 visit_lazy_tts(tokens, vis);
1253 pub fn noop_visit_anon_const<T: MutVisitor>(AnonConst { id, value }: &mut AnonConst, vis: &mut T) {
1255 vis.visit_expr(value);
1258 pub fn noop_visit_inline_asm<T: MutVisitor>(asm: &mut InlineAsm, vis: &mut T) {
1259 for (op, _) in &mut asm.operands {
1261 InlineAsmOperand::In { expr, .. }
1262 | InlineAsmOperand::Out { expr: Some(expr), .. }
1263 | InlineAsmOperand::InOut { expr, .. } => vis.visit_expr(expr),
1264 InlineAsmOperand::Out { expr: None, .. } => {}
1265 InlineAsmOperand::SplitInOut { in_expr, out_expr, .. } => {
1266 vis.visit_expr(in_expr);
1267 if let Some(out_expr) = out_expr {
1268 vis.visit_expr(out_expr);
1271 InlineAsmOperand::Const { anon_const } => vis.visit_anon_const(anon_const),
1272 InlineAsmOperand::Sym { sym } => vis.visit_inline_asm_sym(sym),
1277 pub fn noop_visit_inline_asm_sym<T: MutVisitor>(
1278 InlineAsmSym { id, qself, path }: &mut InlineAsmSym,
1282 vis.visit_qself(qself);
1283 vis.visit_path(path);
1286 pub fn noop_visit_expr<T: MutVisitor>(
1287 Expr { kind, id, span, attrs, tokens }: &mut Expr,
1291 ExprKind::Box(expr) => vis.visit_expr(expr),
1292 ExprKind::Array(exprs) => visit_exprs(exprs, vis),
1293 ExprKind::ConstBlock(anon_const) => {
1294 vis.visit_anon_const(anon_const);
1296 ExprKind::Repeat(expr, count) => {
1297 vis.visit_expr(expr);
1298 vis.visit_anon_const(count);
1300 ExprKind::Tup(exprs) => visit_exprs(exprs, vis),
1301 ExprKind::Call(f, args) => {
1303 visit_exprs(args, vis);
1305 ExprKind::MethodCall(PathSegment { ident, id, args }, exprs, span) => {
1306 vis.visit_ident(ident);
1308 visit_opt(args, |args| vis.visit_generic_args(args));
1309 visit_exprs(exprs, vis);
1310 vis.visit_span(span);
1312 ExprKind::Binary(_binop, lhs, rhs) => {
1313 vis.visit_expr(lhs);
1314 vis.visit_expr(rhs);
1316 ExprKind::Unary(_unop, ohs) => vis.visit_expr(ohs),
1317 ExprKind::Cast(expr, ty) => {
1318 vis.visit_expr(expr);
1321 ExprKind::Type(expr, ty) => {
1322 vis.visit_expr(expr);
1325 ExprKind::AddrOf(_, _, ohs) => vis.visit_expr(ohs),
1326 ExprKind::Let(pat, scrutinee, _) => {
1328 vis.visit_expr(scrutinee);
1330 ExprKind::If(cond, tr, fl) => {
1331 vis.visit_expr(cond);
1332 vis.visit_block(tr);
1333 visit_opt(fl, |fl| vis.visit_expr(fl));
1335 ExprKind::While(cond, body, label) => {
1336 vis.visit_expr(cond);
1337 vis.visit_block(body);
1338 visit_opt(label, |label| vis.visit_label(label));
1340 ExprKind::ForLoop(pat, iter, body, label) => {
1342 vis.visit_expr(iter);
1343 vis.visit_block(body);
1344 visit_opt(label, |label| vis.visit_label(label));
1346 ExprKind::Loop(body, label) => {
1347 vis.visit_block(body);
1348 visit_opt(label, |label| vis.visit_label(label));
1350 ExprKind::Match(expr, arms) => {
1351 vis.visit_expr(expr);
1352 arms.flat_map_in_place(|arm| vis.flat_map_arm(arm));
1354 ExprKind::Closure(binder, _capture_by, asyncness, _movability, decl, body, span) => {
1355 vis.visit_closure_binder(binder);
1356 vis.visit_asyncness(asyncness);
1357 vis.visit_fn_decl(decl);
1358 vis.visit_expr(body);
1359 vis.visit_span(span);
1361 ExprKind::Block(blk, label) => {
1362 vis.visit_block(blk);
1363 visit_opt(label, |label| vis.visit_label(label));
1365 ExprKind::Async(_capture_by, node_id, body) => {
1366 vis.visit_id(node_id);
1367 vis.visit_block(body);
1369 ExprKind::Await(expr) => vis.visit_expr(expr),
1370 ExprKind::Assign(el, er, _) => {
1374 ExprKind::AssignOp(_op, el, er) => {
1378 ExprKind::Field(el, ident) => {
1380 vis.visit_ident(ident);
1382 ExprKind::Index(el, er) => {
1386 ExprKind::Range(e1, e2, _lim) => {
1387 visit_opt(e1, |e1| vis.visit_expr(e1));
1388 visit_opt(e2, |e2| vis.visit_expr(e2));
1390 ExprKind::Underscore => {}
1391 ExprKind::Path(qself, path) => {
1392 vis.visit_qself(qself);
1393 vis.visit_path(path);
1395 ExprKind::Break(label, expr) => {
1396 visit_opt(label, |label| vis.visit_label(label));
1397 visit_opt(expr, |expr| vis.visit_expr(expr));
1399 ExprKind::Continue(label) => {
1400 visit_opt(label, |label| vis.visit_label(label));
1402 ExprKind::Ret(expr) => {
1403 visit_opt(expr, |expr| vis.visit_expr(expr));
1405 ExprKind::Yeet(expr) => {
1406 visit_opt(expr, |expr| vis.visit_expr(expr));
1408 ExprKind::InlineAsm(asm) => vis.visit_inline_asm(asm),
1409 ExprKind::MacCall(mac) => vis.visit_mac_call(mac),
1410 ExprKind::Struct(se) => {
1411 let StructExpr { qself, path, fields, rest } = se.deref_mut();
1412 vis.visit_qself(qself);
1413 vis.visit_path(path);
1414 fields.flat_map_in_place(|field| vis.flat_map_expr_field(field));
1416 StructRest::Base(expr) => vis.visit_expr(expr),
1417 StructRest::Rest(_span) => {}
1418 StructRest::None => {}
1421 ExprKind::Paren(expr) => {
1422 vis.visit_expr(expr);
1424 ExprKind::Yield(expr) => {
1425 visit_opt(expr, |expr| vis.visit_expr(expr));
1427 ExprKind::Try(expr) => vis.visit_expr(expr),
1428 ExprKind::TryBlock(body) => vis.visit_block(body),
1429 ExprKind::Lit(_) | ExprKind::Err => {}
1432 vis.visit_span(span);
1433 visit_thin_attrs(attrs, vis);
1434 visit_lazy_tts(tokens, vis);
1437 pub fn noop_filter_map_expr<T: MutVisitor>(mut e: P<Expr>, vis: &mut T) -> Option<P<Expr>> {
1439 vis.visit_expr(&mut e);
1444 pub fn noop_flat_map_stmt<T: MutVisitor>(
1445 Stmt { kind, mut span, mut id }: Stmt,
1447 ) -> SmallVec<[Stmt; 1]> {
1448 vis.visit_id(&mut id);
1449 vis.visit_span(&mut span);
1450 let stmts: SmallVec<_> = noop_flat_map_stmt_kind(kind, vis)
1452 .map(|kind| Stmt { id, kind, span })
1454 if stmts.len() > 1 {
1456 "cloning statement `NodeId`s is prohibited by default, \
1457 the visitor should implement custom statement visiting"
1463 pub fn noop_flat_map_stmt_kind<T: MutVisitor>(
1466 ) -> SmallVec<[StmtKind; 1]> {
1468 StmtKind::Local(mut local) => smallvec![StmtKind::Local({
1469 vis.visit_local(&mut local);
1472 StmtKind::Item(item) => vis.flat_map_item(item).into_iter().map(StmtKind::Item).collect(),
1473 StmtKind::Expr(expr) => vis.filter_map_expr(expr).into_iter().map(StmtKind::Expr).collect(),
1474 StmtKind::Semi(expr) => vis.filter_map_expr(expr).into_iter().map(StmtKind::Semi).collect(),
1475 StmtKind::Empty => smallvec![StmtKind::Empty],
1476 StmtKind::MacCall(mut mac) => {
1477 let MacCallStmt { mac: mac_, style: _, attrs, tokens } = mac.deref_mut();
1478 vis.visit_mac_call(mac_);
1479 visit_thin_attrs(attrs, vis);
1480 visit_lazy_tts(tokens, vis);
1481 smallvec![StmtKind::MacCall(mac)]
1486 pub fn noop_visit_vis<T: MutVisitor>(visibility: &mut Visibility, vis: &mut T) {
1487 match &mut visibility.kind {
1488 VisibilityKind::Public | VisibilityKind::Inherited => {}
1489 VisibilityKind::Restricted { path, id } => {
1490 vis.visit_path(path);
1494 vis.visit_span(&mut visibility.span);
1497 /// Some value for the AST node that is valid but possibly meaningless.
1498 pub trait DummyAstNode {
1502 impl<T> DummyAstNode for Option<T> {
1503 fn dummy() -> Self {
1508 impl<T: DummyAstNode + 'static> DummyAstNode for P<T> {
1509 fn dummy() -> Self {
1510 P(DummyAstNode::dummy())
1514 impl<T> DummyAstNode for ThinVec<T> {
1515 fn dummy() -> Self {
1520 impl DummyAstNode for Item {
1521 fn dummy() -> Self {
1523 attrs: Default::default(),
1525 span: Default::default(),
1527 kind: VisibilityKind::Public,
1528 span: Default::default(),
1529 tokens: Default::default(),
1531 ident: Ident::empty(),
1532 kind: ItemKind::ExternCrate(None),
1533 tokens: Default::default(),
1538 impl DummyAstNode for Expr {
1539 fn dummy() -> Self {
1542 kind: ExprKind::Err,
1543 span: Default::default(),
1544 attrs: Default::default(),
1545 tokens: Default::default(),
1550 impl DummyAstNode for Ty {
1551 fn dummy() -> Self {
1555 span: Default::default(),
1556 tokens: Default::default(),
1561 impl DummyAstNode for Pat {
1562 fn dummy() -> Self {
1565 kind: PatKind::Wild,
1566 span: Default::default(),
1567 tokens: Default::default(),
1572 impl DummyAstNode for Stmt {
1573 fn dummy() -> Self {
1574 Stmt { id: DUMMY_NODE_ID, kind: StmtKind::Empty, span: Default::default() }
1578 impl DummyAstNode for Block {
1579 fn dummy() -> Self {
1581 stmts: Default::default(),
1583 rules: BlockCheckMode::Default,
1584 span: Default::default(),
1585 tokens: Default::default(),
1586 could_be_bare_literal: Default::default(),
1591 impl DummyAstNode for Crate {
1592 fn dummy() -> Self {
1594 attrs: Default::default(),
1595 items: Default::default(),
1596 spans: Default::default(),
1598 is_placeholder: Default::default(),