1 //! A `MutVisitor` represents an AST modification; it accepts an AST piece and
2 //! and 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::*;
14 use crate::util::map_in_place::MapInPlace;
16 use rustc_data_structures::sync::Lrc;
17 use rustc_span::source_map::{respan, Spanned};
20 use smallvec::{smallvec, Array, SmallVec};
21 use std::ops::DerefMut;
22 use std::{panic, process, ptr};
24 pub trait ExpectOne<A: Array> {
25 fn expect_one(self, err: &'static str) -> A::Item;
28 impl<A: Array> ExpectOne<A> for SmallVec<A> {
29 fn expect_one(self, err: &'static str) -> A::Item {
30 assert!(self.len() == 1, err);
31 self.into_iter().next().unwrap()
35 pub trait MutVisitor: Sized {
36 // Methods in this trait have one of three forms:
38 // fn visit_t(&mut self, t: &mut T); // common
39 // fn flat_map_t(&mut self, t: T) -> SmallVec<[T; 1]>; // rare
40 // fn filter_map_t(&mut self, t: T) -> Option<T>; // rarest
42 // Any additions to this trait should happen in form of a call to a public
43 // `noop_*` function that only calls out to the visitor again, not other
44 // `noop_*` functions. This is a necessary API workaround to the problem of
45 // not being able to call out to the super default method in an overridden
48 // When writing these methods, it is better to use destructuring like this:
50 // fn visit_abc(&mut self, ABC { a, b, c: _ }: &mut ABC) {
55 // than to use field access like this:
57 // fn visit_abc(&mut self, abc: &mut ABC) {
58 // visit_a(&mut abc.a);
59 // visit_b(&mut abc.b);
63 // As well as being more concise, the former is explicit about which fields
64 // are skipped. Furthermore, if a new field is added, the destructuring
65 // version will cause a compile error, which is good. In comparison, the
66 // field access version will continue working and it would be easy to
67 // forget to add handling for it.
69 fn visit_crate(&mut self, c: &mut Crate) {
70 noop_visit_crate(c, self)
73 fn visit_meta_list_item(&mut self, list_item: &mut NestedMetaItem) {
74 noop_visit_meta_list_item(list_item, self);
77 fn visit_meta_item(&mut self, meta_item: &mut MetaItem) {
78 noop_visit_meta_item(meta_item, self);
81 fn visit_use_tree(&mut self, use_tree: &mut UseTree) {
82 noop_visit_use_tree(use_tree, self);
85 fn flat_map_foreign_item(&mut self, ni: ForeignItem) -> SmallVec<[ForeignItem; 1]> {
86 noop_flat_map_foreign_item(ni, self)
89 fn flat_map_item(&mut self, i: P<Item>) -> SmallVec<[P<Item>; 1]> {
90 noop_flat_map_item(i, self)
93 fn visit_fn_header(&mut self, header: &mut FnHeader) {
94 noop_visit_fn_header(header, self);
97 fn flat_map_struct_field(&mut self, sf: StructField) -> SmallVec<[StructField; 1]> {
98 noop_flat_map_struct_field(sf, self)
101 fn visit_item_kind(&mut self, i: &mut ItemKind) {
102 noop_visit_item_kind(i, self);
105 fn flat_map_trait_item(&mut self, i: AssocItem) -> SmallVec<[AssocItem; 1]> {
106 noop_flat_map_assoc_item(i, self)
109 fn flat_map_impl_item(&mut self, i: AssocItem) -> SmallVec<[AssocItem; 1]> {
110 noop_flat_map_assoc_item(i, self)
113 fn visit_fn_decl(&mut self, d: &mut P<FnDecl>) {
114 noop_visit_fn_decl(d, self);
117 fn visit_asyncness(&mut self, a: &mut IsAsync) {
118 noop_visit_asyncness(a, self);
121 fn visit_block(&mut self, b: &mut P<Block>) {
122 noop_visit_block(b, self);
125 fn flat_map_stmt(&mut self, s: Stmt) -> SmallVec<[Stmt; 1]> {
126 noop_flat_map_stmt(s, self)
129 fn flat_map_arm(&mut self, arm: Arm) -> SmallVec<[Arm; 1]> {
130 noop_flat_map_arm(arm, self)
133 fn visit_pat(&mut self, p: &mut P<Pat>) {
134 noop_visit_pat(p, self);
137 fn visit_anon_const(&mut self, c: &mut AnonConst) {
138 noop_visit_anon_const(c, self);
141 fn visit_expr(&mut self, e: &mut P<Expr>) {
142 noop_visit_expr(e, self);
145 fn filter_map_expr(&mut self, e: P<Expr>) -> Option<P<Expr>> {
146 noop_filter_map_expr(e, self)
149 fn visit_generic_arg(&mut self, arg: &mut GenericArg) {
150 noop_visit_generic_arg(arg, self);
153 fn visit_ty(&mut self, t: &mut P<Ty>) {
154 noop_visit_ty(t, self);
157 fn visit_lifetime(&mut self, l: &mut Lifetime) {
158 noop_visit_lifetime(l, self);
161 fn visit_ty_constraint(&mut self, t: &mut AssocTyConstraint) {
162 noop_visit_ty_constraint(t, self);
165 fn visit_mod(&mut self, m: &mut Mod) {
166 noop_visit_mod(m, self);
169 fn visit_foreign_mod(&mut self, nm: &mut ForeignMod) {
170 noop_visit_foreign_mod(nm, self);
173 fn flat_map_variant(&mut self, v: Variant) -> SmallVec<[Variant; 1]> {
174 noop_flat_map_variant(v, self)
177 fn visit_ident(&mut self, i: &mut Ident) {
178 noop_visit_ident(i, self);
181 fn visit_path(&mut self, p: &mut Path) {
182 noop_visit_path(p, self);
185 fn visit_qself(&mut self, qs: &mut Option<QSelf>) {
186 noop_visit_qself(qs, self);
189 fn visit_generic_args(&mut self, p: &mut GenericArgs) {
190 noop_visit_generic_args(p, self);
193 fn visit_angle_bracketed_parameter_data(&mut self, p: &mut AngleBracketedArgs) {
194 noop_visit_angle_bracketed_parameter_data(p, self);
197 fn visit_parenthesized_parameter_data(&mut self, p: &mut ParenthesizedArgs) {
198 noop_visit_parenthesized_parameter_data(p, self);
201 fn visit_local(&mut self, l: &mut P<Local>) {
202 noop_visit_local(l, self);
205 fn visit_mac(&mut self, _mac: &mut Mac) {
206 panic!("visit_mac disabled by default");
207 // N.B., see note about macros above. If you really want a visitor that
208 // works on macros, use this definition in your trait impl:
209 // mut_visit::noop_visit_mac(_mac, self);
212 fn visit_macro_def(&mut self, def: &mut MacroDef) {
213 noop_visit_macro_def(def, self);
216 fn visit_label(&mut self, label: &mut Label) {
217 noop_visit_label(label, self);
220 fn visit_attribute(&mut self, at: &mut Attribute) {
221 noop_visit_attribute(at, self);
224 fn flat_map_param(&mut self, param: Param) -> SmallVec<[Param; 1]> {
225 noop_flat_map_param(param, self)
228 fn visit_generics(&mut self, generics: &mut Generics) {
229 noop_visit_generics(generics, self);
232 fn visit_trait_ref(&mut self, tr: &mut TraitRef) {
233 noop_visit_trait_ref(tr, self);
236 fn visit_poly_trait_ref(&mut self, p: &mut PolyTraitRef) {
237 noop_visit_poly_trait_ref(p, self);
240 fn visit_variant_data(&mut self, vdata: &mut VariantData) {
241 noop_visit_variant_data(vdata, self);
244 fn flat_map_generic_param(&mut self, param: GenericParam) -> SmallVec<[GenericParam; 1]> {
245 noop_flat_map_generic_param(param, self)
248 fn visit_tt(&mut self, tt: &mut TokenTree) {
249 noop_visit_tt(tt, self);
252 fn visit_tts(&mut self, tts: &mut TokenStream) {
253 noop_visit_tts(tts, self);
256 fn visit_token(&mut self, t: &mut Token) {
257 noop_visit_token(t, self);
260 fn visit_interpolated(&mut self, nt: &mut token::Nonterminal) {
261 noop_visit_interpolated(nt, self);
264 fn visit_param_bound(&mut self, tpb: &mut GenericBound) {
265 noop_visit_param_bound(tpb, self);
268 fn visit_mt(&mut self, mt: &mut MutTy) {
269 noop_visit_mt(mt, self);
272 fn flat_map_field(&mut self, f: Field) -> SmallVec<[Field; 1]> {
273 noop_flat_map_field(f, self)
276 fn visit_where_clause(&mut self, where_clause: &mut WhereClause) {
277 noop_visit_where_clause(where_clause, self);
280 fn visit_where_predicate(&mut self, where_predicate: &mut WherePredicate) {
281 noop_visit_where_predicate(where_predicate, self);
284 fn visit_vis(&mut self, vis: &mut Visibility) {
285 noop_visit_vis(vis, self);
288 fn visit_id(&mut self, _id: &mut NodeId) {
292 fn visit_span(&mut self, _sp: &mut Span) {
296 fn flat_map_field_pattern(&mut self, fp: FieldPat) -> SmallVec<[FieldPat; 1]> {
297 noop_flat_map_field_pattern(fp, self)
301 /// Use a map-style function (`FnOnce(T) -> T`) to overwrite a `&mut T`. Useful
302 /// when using a `flat_map_*` or `filter_map_*` method within a `visit_`
303 /// method. Abort the program if the closure panics.
305 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
306 pub fn visit_clobber<T, F>(t: &mut T, f: F)
311 // Safe because `t` is used in a read-only fashion by `read()` before
312 // being overwritten by `write()`.
313 let old_t = ptr::read(t);
314 let new_t = panic::catch_unwind(panic::AssertUnwindSafe(|| f(old_t)))
315 .unwrap_or_else(|_| process::abort());
316 ptr::write(t, new_t);
320 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
322 pub fn visit_vec<T, F>(elems: &mut Vec<T>, mut visit_elem: F)
331 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
333 pub fn visit_opt<T, F>(opt: &mut Option<T>, mut visit_elem: F)
337 if let Some(elem) = opt {
342 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
343 pub fn visit_attrs<T: MutVisitor>(attrs: &mut Vec<Attribute>, vis: &mut T) {
344 visit_vec(attrs, |attr| vis.visit_attribute(attr));
347 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
348 pub fn visit_thin_attrs<T: MutVisitor>(attrs: &mut AttrVec, vis: &mut T) {
349 for attr in attrs.iter_mut() {
350 vis.visit_attribute(attr);
354 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
355 pub fn visit_exprs<T: MutVisitor>(exprs: &mut Vec<P<Expr>>, vis: &mut T) {
356 exprs.flat_map_in_place(|expr| vis.filter_map_expr(expr))
359 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
360 pub fn visit_bounds<T: MutVisitor>(bounds: &mut GenericBounds, vis: &mut T) {
361 visit_vec(bounds, |bound| vis.visit_param_bound(bound));
364 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
365 pub fn visit_fn_sig<T: MutVisitor>(FnSig { header, decl }: &mut FnSig, vis: &mut T) {
366 vis.visit_fn_header(header);
367 vis.visit_fn_decl(decl);
370 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
371 pub fn visit_mac_args<T: MutVisitor>(args: &mut MacArgs, vis: &mut T) {
374 MacArgs::Delimited(dspan, _delim, tokens) => {
375 visit_delim_span(dspan, vis);
376 vis.visit_tts(tokens);
378 MacArgs::Eq(eq_span, tokens) => {
379 vis.visit_span(eq_span);
380 vis.visit_tts(tokens);
385 pub fn visit_delim_span<T: MutVisitor>(dspan: &mut DelimSpan, vis: &mut T) {
386 vis.visit_span(&mut dspan.open);
387 vis.visit_span(&mut dspan.close);
390 pub fn noop_flat_map_field_pattern<T: MutVisitor>(
393 ) -> SmallVec<[FieldPat; 1]> {
394 let FieldPat { attrs, id, ident, is_placeholder: _, is_shorthand: _, pat, span } = &mut fp;
396 vis.visit_ident(ident);
398 vis.visit_span(span);
399 visit_thin_attrs(attrs, vis);
403 pub fn noop_visit_use_tree<T: MutVisitor>(use_tree: &mut UseTree, vis: &mut T) {
404 let UseTree { prefix, kind, span } = use_tree;
405 vis.visit_path(prefix);
407 UseTreeKind::Simple(rename, id1, id2) => {
408 visit_opt(rename, |rename| vis.visit_ident(rename));
412 UseTreeKind::Nested(items) => {
413 for (tree, id) in items {
414 vis.visit_use_tree(tree);
418 UseTreeKind::Glob => {}
420 vis.visit_span(span);
423 pub fn noop_flat_map_arm<T: MutVisitor>(mut arm: Arm, vis: &mut T) -> SmallVec<[Arm; 1]> {
424 let Arm { attrs, pat, guard, body, span, id, is_placeholder: _ } = &mut arm;
425 visit_attrs(attrs, vis);
428 visit_opt(guard, |guard| vis.visit_expr(guard));
429 vis.visit_expr(body);
430 vis.visit_span(span);
434 pub fn noop_visit_ty_constraint<T: MutVisitor>(
435 AssocTyConstraint { id, ident, kind, span }: &mut AssocTyConstraint,
439 vis.visit_ident(ident);
441 AssocTyConstraintKind::Equality { ref mut ty } => {
444 AssocTyConstraintKind::Bound { ref mut bounds } => {
445 visit_bounds(bounds, vis);
448 vis.visit_span(span);
451 pub fn noop_visit_ty<T: MutVisitor>(ty: &mut P<Ty>, vis: &mut T) {
452 let Ty { id, kind, span } = ty.deref_mut();
455 TyKind::Infer | TyKind::ImplicitSelf | TyKind::Err | TyKind::Never | TyKind::CVarArgs => {}
456 TyKind::Slice(ty) => vis.visit_ty(ty),
457 TyKind::Ptr(mt) => vis.visit_mt(mt),
458 TyKind::Rptr(lt, mt) => {
459 visit_opt(lt, |lt| noop_visit_lifetime(lt, vis));
462 TyKind::BareFn(bft) => {
463 let BareFnTy { unsafety: _, ext: _, generic_params, decl } = bft.deref_mut();
464 generic_params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
465 vis.visit_fn_decl(decl);
467 TyKind::Tup(tys) => visit_vec(tys, |ty| vis.visit_ty(ty)),
468 TyKind::Paren(ty) => vis.visit_ty(ty),
469 TyKind::Path(qself, path) => {
470 vis.visit_qself(qself);
471 vis.visit_path(path);
473 TyKind::Array(ty, length) => {
475 vis.visit_anon_const(length);
477 TyKind::Typeof(expr) => vis.visit_anon_const(expr),
478 TyKind::TraitObject(bounds, _syntax) => {
479 visit_vec(bounds, |bound| vis.visit_param_bound(bound))
481 TyKind::ImplTrait(id, bounds) => {
483 visit_vec(bounds, |bound| vis.visit_param_bound(bound));
485 TyKind::Mac(mac) => vis.visit_mac(mac),
487 vis.visit_span(span);
490 pub fn noop_visit_foreign_mod<T: MutVisitor>(foreign_mod: &mut ForeignMod, vis: &mut T) {
491 let ForeignMod { abi: _, items } = foreign_mod;
492 items.flat_map_in_place(|item| vis.flat_map_foreign_item(item));
495 pub fn noop_flat_map_variant<T: MutVisitor>(
496 mut variant: Variant,
498 ) -> SmallVec<[Variant; 1]> {
499 let Variant { ident, vis, attrs, id, data, disr_expr, span, is_placeholder: _ } = &mut variant;
500 visitor.visit_ident(ident);
501 visitor.visit_vis(vis);
502 visit_attrs(attrs, visitor);
503 visitor.visit_id(id);
504 visitor.visit_variant_data(data);
505 visit_opt(disr_expr, |disr_expr| visitor.visit_anon_const(disr_expr));
506 visitor.visit_span(span);
510 pub fn noop_visit_ident<T: MutVisitor>(Ident { name: _, span }: &mut Ident, vis: &mut T) {
511 vis.visit_span(span);
514 pub fn noop_visit_path<T: MutVisitor>(Path { segments, span }: &mut Path, vis: &mut T) {
515 vis.visit_span(span);
516 for PathSegment { ident, id, args } in segments {
517 vis.visit_ident(ident);
519 visit_opt(args, |args| vis.visit_generic_args(args));
523 pub fn noop_visit_qself<T: MutVisitor>(qself: &mut Option<QSelf>, vis: &mut T) {
524 visit_opt(qself, |QSelf { ty, path_span, position: _ }| {
526 vis.visit_span(path_span);
530 pub fn noop_visit_generic_args<T: MutVisitor>(generic_args: &mut GenericArgs, vis: &mut T) {
532 GenericArgs::AngleBracketed(data) => vis.visit_angle_bracketed_parameter_data(data),
533 GenericArgs::Parenthesized(data) => vis.visit_parenthesized_parameter_data(data),
537 pub fn noop_visit_generic_arg<T: MutVisitor>(arg: &mut GenericArg, vis: &mut T) {
539 GenericArg::Lifetime(lt) => vis.visit_lifetime(lt),
540 GenericArg::Type(ty) => vis.visit_ty(ty),
541 GenericArg::Const(ct) => vis.visit_anon_const(ct),
545 pub fn noop_visit_angle_bracketed_parameter_data<T: MutVisitor>(
546 data: &mut AngleBracketedArgs,
549 let AngleBracketedArgs { args, constraints, span } = data;
550 visit_vec(args, |arg| vis.visit_generic_arg(arg));
551 visit_vec(constraints, |constraint| vis.visit_ty_constraint(constraint));
552 vis.visit_span(span);
555 pub fn noop_visit_parenthesized_parameter_data<T: MutVisitor>(
556 args: &mut ParenthesizedArgs,
559 let ParenthesizedArgs { inputs, output, span } = args;
560 visit_vec(inputs, |input| vis.visit_ty(input));
561 noop_visit_fn_ret_ty(output, vis);
562 vis.visit_span(span);
565 pub fn noop_visit_local<T: MutVisitor>(local: &mut P<Local>, vis: &mut T) {
566 let Local { id, pat, ty, init, span, attrs } = local.deref_mut();
569 visit_opt(ty, |ty| vis.visit_ty(ty));
570 visit_opt(init, |init| vis.visit_expr(init));
571 vis.visit_span(span);
572 visit_thin_attrs(attrs, vis);
575 pub fn noop_visit_attribute<T: MutVisitor>(attr: &mut Attribute, vis: &mut T) {
576 let Attribute { kind, id: _, style: _, span } = attr;
578 AttrKind::Normal(AttrItem { path, args }) => {
579 vis.visit_path(path);
580 visit_mac_args(args, vis);
582 AttrKind::DocComment(_) => {}
584 vis.visit_span(span);
587 pub fn noop_visit_mac<T: MutVisitor>(mac: &mut Mac, vis: &mut T) {
588 let Mac { path, args, prior_type_ascription: _ } = mac;
589 vis.visit_path(path);
590 visit_mac_args(args, vis);
593 pub fn noop_visit_macro_def<T: MutVisitor>(macro_def: &mut MacroDef, vis: &mut T) {
594 let MacroDef { body, legacy: _ } = macro_def;
595 visit_mac_args(body, vis);
598 pub fn noop_visit_meta_list_item<T: MutVisitor>(li: &mut NestedMetaItem, vis: &mut T) {
600 NestedMetaItem::MetaItem(mi) => vis.visit_meta_item(mi),
601 NestedMetaItem::Literal(_lit) => {}
605 pub fn noop_visit_meta_item<T: MutVisitor>(mi: &mut MetaItem, vis: &mut T) {
606 let MetaItem { path: _, kind, span } = mi;
608 MetaItemKind::Word => {}
609 MetaItemKind::List(mis) => visit_vec(mis, |mi| vis.visit_meta_list_item(mi)),
610 MetaItemKind::NameValue(_s) => {}
612 vis.visit_span(span);
615 pub fn noop_flat_map_param<T: MutVisitor>(mut param: Param, vis: &mut T) -> SmallVec<[Param; 1]> {
616 let Param { attrs, id, pat, span, ty, is_placeholder: _ } = &mut param;
618 visit_thin_attrs(attrs, vis);
620 vis.visit_span(span);
625 pub fn noop_visit_tt<T: MutVisitor>(tt: &mut TokenTree, vis: &mut T) {
627 TokenTree::Token(token) => {
628 vis.visit_token(token);
630 TokenTree::Delimited(DelimSpan { open, close }, _delim, tts) => {
631 vis.visit_span(open);
632 vis.visit_span(close);
638 pub fn noop_visit_tts<T: MutVisitor>(TokenStream(tts): &mut TokenStream, vis: &mut T) {
639 let tts = Lrc::make_mut(tts);
640 visit_vec(tts, |(tree, _is_joint)| vis.visit_tt(tree));
643 // Applies ident visitor if it's an ident; applies other visits to interpolated nodes.
644 // In practice the ident part is not actually used by specific visitors right now,
645 // but there's a test below checking that it works.
646 pub fn noop_visit_token<T: MutVisitor>(t: &mut Token, vis: &mut T) {
647 let Token { kind, span } = t;
649 token::Ident(name, _) | token::Lifetime(name) => {
650 let mut ident = Ident::new(*name, *span);
651 vis.visit_ident(&mut ident);
654 return; // Avoid visiting the span for the second time.
656 token::Interpolated(nt) => {
657 let mut nt = Lrc::make_mut(nt);
658 vis.visit_interpolated(&mut nt);
662 vis.visit_span(span);
665 /// Applies the visitor to elements of interpolated nodes.
667 // N.B., this can occur only when applying a visitor to partially expanded
668 // code, where parsed pieces have gotten implanted ito *other* macro
669 // invocations. This is relevant for macro hygiene, but possibly not elsewhere.
671 // One problem here occurs because the types for flat_map_item, flat_map_stmt,
672 // etc., allow the visitor to return *multiple* items; this is a problem for the
673 // nodes here, because they insist on having exactly one piece. One solution
674 // would be to mangle the MutVisitor trait to include one-to-many and
675 // one-to-one versions of these entry points, but that would probably confuse a
676 // lot of people and help very few. Instead, I'm just going to put in dynamic
677 // checks. I think the performance impact of this will be pretty much
678 // nonexistent. The danger is that someone will apply a `MutVisitor` to a
679 // partially expanded node, and will be confused by the fact that their
680 // `flat_map_item` or `flat_map_stmt` isn't getting called on `NtItem` or `NtStmt`
681 // nodes. Hopefully they'll wind up reading this comment, and doing something
684 // BTW, design choice: I considered just changing the type of, e.g., `NtItem` to
685 // contain multiple items, but decided against it when I looked at
686 // `parse_item_or_view_item` and tried to figure out what I would do with
687 // multiple items there....
688 pub fn noop_visit_interpolated<T: MutVisitor>(nt: &mut token::Nonterminal, vis: &mut T) {
690 token::NtItem(item) => visit_clobber(item, |item| {
691 // This is probably okay, because the only visitors likely to
692 // peek inside interpolated nodes will be renamings/markings,
693 // which map single items to single items.
694 vis.flat_map_item(item).expect_one("expected visitor to produce exactly one item")
696 token::NtBlock(block) => vis.visit_block(block),
697 token::NtStmt(stmt) => visit_clobber(stmt, |stmt| {
698 // See reasoning above.
699 vis.flat_map_stmt(stmt).expect_one("expected visitor to produce exactly one item")
701 token::NtPat(pat) => vis.visit_pat(pat),
702 token::NtExpr(expr) => vis.visit_expr(expr),
703 token::NtTy(ty) => vis.visit_ty(ty),
704 token::NtIdent(ident, _is_raw) => vis.visit_ident(ident),
705 token::NtLifetime(ident) => vis.visit_ident(ident),
706 token::NtLiteral(expr) => vis.visit_expr(expr),
707 token::NtMeta(AttrItem { path, args }) => {
708 vis.visit_path(path);
709 visit_mac_args(args, vis);
711 token::NtPath(path) => vis.visit_path(path),
712 token::NtTT(tt) => vis.visit_tt(tt),
713 token::NtImplItem(item) => visit_clobber(item, |item| {
714 // See reasoning above.
715 vis.flat_map_impl_item(item).expect_one("expected visitor to produce exactly one item")
717 token::NtTraitItem(item) => visit_clobber(item, |item| {
718 // See reasoning above.
719 vis.flat_map_trait_item(item).expect_one("expected visitor to produce exactly one item")
721 token::NtVis(visib) => vis.visit_vis(visib),
722 token::NtForeignItem(item) => visit_clobber(item, |item| {
723 // See reasoning above.
724 vis.flat_map_foreign_item(item)
725 .expect_one("expected visitor to produce exactly one item")
730 pub fn noop_visit_asyncness<T: MutVisitor>(asyncness: &mut IsAsync, vis: &mut T) {
732 IsAsync::Async { closure_id, return_impl_trait_id } => {
733 vis.visit_id(closure_id);
734 vis.visit_id(return_impl_trait_id);
736 IsAsync::NotAsync => {}
740 pub fn noop_visit_fn_decl<T: MutVisitor>(decl: &mut P<FnDecl>, vis: &mut T) {
741 let FnDecl { inputs, output } = decl.deref_mut();
742 inputs.flat_map_in_place(|param| vis.flat_map_param(param));
743 noop_visit_fn_ret_ty(output, vis);
746 pub fn noop_visit_fn_ret_ty<T: MutVisitor>(fn_ret_ty: &mut FunctionRetTy, vis: &mut T) {
748 FunctionRetTy::Default(span) => vis.visit_span(span),
749 FunctionRetTy::Ty(ty) => vis.visit_ty(ty),
753 pub fn noop_visit_param_bound<T: MutVisitor>(pb: &mut GenericBound, vis: &mut T) {
755 GenericBound::Trait(ty, _modifier) => vis.visit_poly_trait_ref(ty),
756 GenericBound::Outlives(lifetime) => noop_visit_lifetime(lifetime, vis),
760 pub fn noop_flat_map_generic_param<T: MutVisitor>(
761 mut param: GenericParam,
763 ) -> SmallVec<[GenericParam; 1]> {
764 let GenericParam { id, ident, attrs, bounds, kind, is_placeholder: _ } = &mut param;
766 vis.visit_ident(ident);
767 visit_thin_attrs(attrs, vis);
768 visit_vec(bounds, |bound| noop_visit_param_bound(bound, vis));
770 GenericParamKind::Lifetime => {}
771 GenericParamKind::Type { default } => {
772 visit_opt(default, |default| vis.visit_ty(default));
774 GenericParamKind::Const { ty } => {
781 pub fn noop_visit_label<T: MutVisitor>(Label { ident }: &mut Label, vis: &mut T) {
782 vis.visit_ident(ident);
785 fn noop_visit_lifetime<T: MutVisitor>(Lifetime { id, ident }: &mut Lifetime, vis: &mut T) {
787 vis.visit_ident(ident);
790 pub fn noop_visit_generics<T: MutVisitor>(generics: &mut Generics, vis: &mut T) {
791 let Generics { params, where_clause, span } = generics;
792 params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
793 vis.visit_where_clause(where_clause);
794 vis.visit_span(span);
797 pub fn noop_visit_where_clause<T: MutVisitor>(wc: &mut WhereClause, vis: &mut T) {
798 let WhereClause { predicates, span } = wc;
799 visit_vec(predicates, |predicate| vis.visit_where_predicate(predicate));
800 vis.visit_span(span);
803 pub fn noop_visit_where_predicate<T: MutVisitor>(pred: &mut WherePredicate, vis: &mut T) {
805 WherePredicate::BoundPredicate(bp) => {
806 let WhereBoundPredicate { span, bound_generic_params, bounded_ty, bounds } = bp;
807 vis.visit_span(span);
808 bound_generic_params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
809 vis.visit_ty(bounded_ty);
810 visit_vec(bounds, |bound| vis.visit_param_bound(bound));
812 WherePredicate::RegionPredicate(rp) => {
813 let WhereRegionPredicate { span, lifetime, bounds } = rp;
814 vis.visit_span(span);
815 noop_visit_lifetime(lifetime, vis);
816 visit_vec(bounds, |bound| noop_visit_param_bound(bound, vis));
818 WherePredicate::EqPredicate(ep) => {
819 let WhereEqPredicate { id, span, lhs_ty, rhs_ty } = ep;
821 vis.visit_span(span);
822 vis.visit_ty(lhs_ty);
823 vis.visit_ty(rhs_ty);
828 pub fn noop_visit_variant_data<T: MutVisitor>(vdata: &mut VariantData, vis: &mut T) {
830 VariantData::Struct(fields, ..) => {
831 fields.flat_map_in_place(|field| vis.flat_map_struct_field(field));
833 VariantData::Tuple(fields, id) => {
834 fields.flat_map_in_place(|field| vis.flat_map_struct_field(field));
837 VariantData::Unit(id) => vis.visit_id(id),
841 pub fn noop_visit_trait_ref<T: MutVisitor>(tr: &mut TraitRef, vis: &mut T) {
842 let TraitRef { path, ref_id, constness: _ } = tr;
843 vis.visit_path(path);
844 vis.visit_id(ref_id);
847 pub fn noop_visit_poly_trait_ref<T: MutVisitor>(p: &mut PolyTraitRef, vis: &mut T) {
848 let PolyTraitRef { bound_generic_params, trait_ref, span } = p;
849 bound_generic_params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
850 vis.visit_trait_ref(trait_ref);
851 vis.visit_span(span);
854 pub fn noop_flat_map_struct_field<T: MutVisitor>(
857 ) -> SmallVec<[StructField; 1]> {
858 let StructField { span, ident, vis, id, ty, attrs, is_placeholder: _ } = &mut sf;
859 visitor.visit_span(span);
860 visit_opt(ident, |ident| visitor.visit_ident(ident));
861 visitor.visit_vis(vis);
862 visitor.visit_id(id);
863 visitor.visit_ty(ty);
864 visit_attrs(attrs, visitor);
868 pub fn noop_flat_map_field<T: MutVisitor>(mut f: Field, vis: &mut T) -> SmallVec<[Field; 1]> {
869 let Field { ident, expr, span, is_shorthand: _, attrs, id, is_placeholder: _ } = &mut f;
870 vis.visit_ident(ident);
871 vis.visit_expr(expr);
873 vis.visit_span(span);
874 visit_thin_attrs(attrs, vis);
878 pub fn noop_visit_mt<T: MutVisitor>(MutTy { ty, mutbl: _ }: &mut MutTy, vis: &mut T) {
882 pub fn noop_visit_block<T: MutVisitor>(block: &mut P<Block>, vis: &mut T) {
883 let Block { id, stmts, rules: _, span } = block.deref_mut();
885 stmts.flat_map_in_place(|stmt| vis.flat_map_stmt(stmt));
886 vis.visit_span(span);
889 pub fn noop_visit_item_kind<T: MutVisitor>(kind: &mut ItemKind, vis: &mut T) {
891 ItemKind::ExternCrate(_orig_name) => {}
892 ItemKind::Use(use_tree) => vis.visit_use_tree(use_tree),
893 ItemKind::Static(ty, _mut, expr) => {
895 vis.visit_expr(expr);
897 ItemKind::Const(ty, expr) => {
899 vis.visit_expr(expr);
901 ItemKind::Fn(sig, generics, body) => {
902 visit_fn_sig(sig, vis);
903 vis.visit_generics(generics);
904 vis.visit_block(body);
906 ItemKind::Mod(m) => vis.visit_mod(m),
907 ItemKind::ForeignMod(nm) => vis.visit_foreign_mod(nm),
908 ItemKind::GlobalAsm(_ga) => {}
909 ItemKind::TyAlias(ty, generics) => {
911 vis.visit_generics(generics);
913 ItemKind::Enum(EnumDef { variants }, generics) => {
914 variants.flat_map_in_place(|variant| vis.flat_map_variant(variant));
915 vis.visit_generics(generics);
917 ItemKind::Struct(variant_data, generics) | ItemKind::Union(variant_data, generics) => {
918 vis.visit_variant_data(variant_data);
919 vis.visit_generics(generics);
930 vis.visit_generics(generics);
931 visit_opt(of_trait, |trait_ref| vis.visit_trait_ref(trait_ref));
932 vis.visit_ty(self_ty);
933 items.flat_map_in_place(|item| vis.flat_map_impl_item(item));
935 ItemKind::Trait(_is_auto, _unsafety, generics, bounds, items) => {
936 vis.visit_generics(generics);
937 visit_bounds(bounds, vis);
938 items.flat_map_in_place(|item| vis.flat_map_trait_item(item));
940 ItemKind::TraitAlias(generics, bounds) => {
941 vis.visit_generics(generics);
942 visit_bounds(bounds, vis);
944 ItemKind::Mac(m) => vis.visit_mac(m),
945 ItemKind::MacroDef(def) => vis.visit_macro_def(def),
949 pub fn noop_flat_map_assoc_item<T: MutVisitor>(
952 ) -> SmallVec<[AssocItem; 1]> {
953 let AssocItem { id, ident, vis, defaultness: _, attrs, generics, kind, span, tokens: _ } =
955 visitor.visit_id(id);
956 visitor.visit_ident(ident);
957 visitor.visit_vis(vis);
958 visit_attrs(attrs, visitor);
959 visitor.visit_generics(generics);
961 AssocItemKind::Const(ty, expr) => {
962 visitor.visit_ty(ty);
963 visit_opt(expr, |expr| visitor.visit_expr(expr));
965 AssocItemKind::Fn(sig, body) => {
966 visit_fn_sig(sig, visitor);
967 visit_opt(body, |body| visitor.visit_block(body));
969 AssocItemKind::TyAlias(bounds, ty) => {
970 visit_bounds(bounds, visitor);
971 visit_opt(ty, |ty| visitor.visit_ty(ty));
973 AssocItemKind::Macro(mac) => visitor.visit_mac(mac),
975 visitor.visit_span(span);
980 pub fn noop_visit_fn_header<T: MutVisitor>(header: &mut FnHeader, vis: &mut T) {
981 let FnHeader { unsafety: _, asyncness, constness: _, ext: _ } = header;
982 vis.visit_asyncness(&mut asyncness.node);
985 pub fn noop_visit_mod<T: MutVisitor>(Mod { inner, items, inline: _ }: &mut Mod, vis: &mut T) {
986 vis.visit_span(inner);
987 items.flat_map_in_place(|item| vis.flat_map_item(item));
990 pub fn noop_visit_crate<T: MutVisitor>(krate: &mut Crate, vis: &mut T) {
991 visit_clobber(krate, |Crate { module, attrs, span }| {
993 ident: Ident::invalid(),
996 vis: respan(span.shrink_to_lo(), VisibilityKind::Public),
998 kind: ItemKind::Mod(module),
1001 let items = vis.flat_map_item(item);
1003 let len = items.len();
1005 let module = Mod { inner: span, items: vec![], inline: true };
1006 Crate { module, attrs: vec![], span }
1007 } else if len == 1 {
1008 let Item { attrs, span, kind, .. } = items.into_iter().next().unwrap().into_inner();
1010 ItemKind::Mod(module) => Crate { module, attrs, span },
1011 _ => panic!("visitor converted a module to not a module"),
1014 panic!("a crate cannot expand to more than one item");
1019 // Mutates one item into possibly many items.
1020 pub fn noop_flat_map_item<T: MutVisitor>(
1023 ) -> SmallVec<[P<Item>; 1]> {
1024 let Item { ident, attrs, id, kind, vis, span, tokens: _ } = item.deref_mut();
1025 visitor.visit_ident(ident);
1026 visit_attrs(attrs, visitor);
1027 visitor.visit_id(id);
1028 visitor.visit_item_kind(kind);
1029 visitor.visit_vis(vis);
1030 visitor.visit_span(span);
1032 // FIXME: if `tokens` is modified with a call to `vis.visit_tts` it causes
1033 // an ICE during resolve... odd!
1038 pub fn noop_flat_map_foreign_item<T: MutVisitor>(
1039 mut item: ForeignItem,
1041 ) -> SmallVec<[ForeignItem; 1]> {
1042 let ForeignItem { ident, attrs, id, kind, vis, span, tokens: _ } = &mut item;
1043 visitor.visit_ident(ident);
1044 visit_attrs(attrs, visitor);
1046 ForeignItemKind::Fn(fdec, generics) => {
1047 visitor.visit_fn_decl(fdec);
1048 visitor.visit_generics(generics);
1050 ForeignItemKind::Static(t, _m) => visitor.visit_ty(t),
1051 ForeignItemKind::Ty => {}
1052 ForeignItemKind::Macro(mac) => visitor.visit_mac(mac),
1054 visitor.visit_id(id);
1055 visitor.visit_span(span);
1056 visitor.visit_vis(vis);
1061 pub fn noop_visit_pat<T: MutVisitor>(pat: &mut P<Pat>, vis: &mut T) {
1062 let Pat { id, kind, span } = pat.deref_mut();
1065 PatKind::Wild | PatKind::Rest => {}
1066 PatKind::Ident(_binding_mode, ident, sub) => {
1067 vis.visit_ident(ident);
1068 visit_opt(sub, |sub| vis.visit_pat(sub));
1070 PatKind::Lit(e) => vis.visit_expr(e),
1071 PatKind::TupleStruct(path, elems) => {
1072 vis.visit_path(path);
1073 visit_vec(elems, |elem| vis.visit_pat(elem));
1075 PatKind::Path(qself, path) => {
1076 vis.visit_qself(qself);
1077 vis.visit_path(path);
1079 PatKind::Struct(path, fields, _etc) => {
1080 vis.visit_path(path);
1081 fields.flat_map_in_place(|field| vis.flat_map_field_pattern(field));
1083 PatKind::Box(inner) => vis.visit_pat(inner),
1084 PatKind::Ref(inner, _mutbl) => vis.visit_pat(inner),
1085 PatKind::Range(e1, e2, Spanned { span: _, node: _ }) => {
1086 visit_opt(e1, |e| vis.visit_expr(e));
1087 visit_opt(e2, |e| vis.visit_expr(e));
1088 vis.visit_span(span);
1090 PatKind::Tuple(elems) | PatKind::Slice(elems) | PatKind::Or(elems) => {
1091 visit_vec(elems, |elem| vis.visit_pat(elem))
1093 PatKind::Paren(inner) => vis.visit_pat(inner),
1094 PatKind::Mac(mac) => vis.visit_mac(mac),
1096 vis.visit_span(span);
1099 pub fn noop_visit_anon_const<T: MutVisitor>(AnonConst { id, value }: &mut AnonConst, vis: &mut T) {
1101 vis.visit_expr(value);
1104 pub fn noop_visit_expr<T: MutVisitor>(Expr { kind, id, span, attrs }: &mut Expr, vis: &mut T) {
1106 ExprKind::Box(expr) => vis.visit_expr(expr),
1107 ExprKind::Array(exprs) => visit_exprs(exprs, vis),
1108 ExprKind::Repeat(expr, count) => {
1109 vis.visit_expr(expr);
1110 vis.visit_anon_const(count);
1112 ExprKind::Tup(exprs) => visit_exprs(exprs, vis),
1113 ExprKind::Call(f, args) => {
1115 visit_exprs(args, vis);
1117 ExprKind::MethodCall(PathSegment { ident, id, args }, exprs) => {
1118 vis.visit_ident(ident);
1120 visit_opt(args, |args| vis.visit_generic_args(args));
1121 visit_exprs(exprs, vis);
1123 ExprKind::Binary(_binop, lhs, rhs) => {
1124 vis.visit_expr(lhs);
1125 vis.visit_expr(rhs);
1127 ExprKind::Unary(_unop, ohs) => vis.visit_expr(ohs),
1128 ExprKind::Cast(expr, ty) => {
1129 vis.visit_expr(expr);
1132 ExprKind::Type(expr, ty) => {
1133 vis.visit_expr(expr);
1136 ExprKind::AddrOf(_, _, ohs) => vis.visit_expr(ohs),
1137 ExprKind::Let(pat, scrutinee) => {
1139 vis.visit_expr(scrutinee);
1141 ExprKind::If(cond, tr, fl) => {
1142 vis.visit_expr(cond);
1143 vis.visit_block(tr);
1144 visit_opt(fl, |fl| vis.visit_expr(fl));
1146 ExprKind::While(cond, body, label) => {
1147 vis.visit_expr(cond);
1148 vis.visit_block(body);
1149 visit_opt(label, |label| vis.visit_label(label));
1151 ExprKind::ForLoop(pat, iter, body, label) => {
1153 vis.visit_expr(iter);
1154 vis.visit_block(body);
1155 visit_opt(label, |label| vis.visit_label(label));
1157 ExprKind::Loop(body, label) => {
1158 vis.visit_block(body);
1159 visit_opt(label, |label| vis.visit_label(label));
1161 ExprKind::Match(expr, arms) => {
1162 vis.visit_expr(expr);
1163 arms.flat_map_in_place(|arm| vis.flat_map_arm(arm));
1165 ExprKind::Closure(_capture_by, asyncness, _movability, decl, body, span) => {
1166 vis.visit_asyncness(asyncness);
1167 vis.visit_fn_decl(decl);
1168 vis.visit_expr(body);
1169 vis.visit_span(span);
1171 ExprKind::Block(blk, label) => {
1172 vis.visit_block(blk);
1173 visit_opt(label, |label| vis.visit_label(label));
1175 ExprKind::Async(_capture_by, node_id, body) => {
1176 vis.visit_id(node_id);
1177 vis.visit_block(body);
1179 ExprKind::Await(expr) => vis.visit_expr(expr),
1180 ExprKind::Assign(el, er, _) => {
1184 ExprKind::AssignOp(_op, el, er) => {
1188 ExprKind::Field(el, ident) => {
1190 vis.visit_ident(ident);
1192 ExprKind::Index(el, er) => {
1196 ExprKind::Range(e1, e2, _lim) => {
1197 visit_opt(e1, |e1| vis.visit_expr(e1));
1198 visit_opt(e2, |e2| vis.visit_expr(e2));
1200 ExprKind::Path(qself, path) => {
1201 vis.visit_qself(qself);
1202 vis.visit_path(path);
1204 ExprKind::Break(label, expr) => {
1205 visit_opt(label, |label| vis.visit_label(label));
1206 visit_opt(expr, |expr| vis.visit_expr(expr));
1208 ExprKind::Continue(label) => {
1209 visit_opt(label, |label| vis.visit_label(label));
1211 ExprKind::Ret(expr) => {
1212 visit_opt(expr, |expr| vis.visit_expr(expr));
1214 ExprKind::InlineAsm(asm) => {
1224 } = asm.deref_mut();
1225 for out in outputs {
1226 let InlineAsmOutput { constraint: _, expr, is_rw: _, is_indirect: _ } = out;
1227 vis.visit_expr(expr);
1229 visit_vec(inputs, |(_c, expr)| vis.visit_expr(expr));
1231 ExprKind::Mac(mac) => vis.visit_mac(mac),
1232 ExprKind::Struct(path, fields, expr) => {
1233 vis.visit_path(path);
1234 fields.flat_map_in_place(|field| vis.flat_map_field(field));
1235 visit_opt(expr, |expr| vis.visit_expr(expr));
1237 ExprKind::Paren(expr) => {
1238 vis.visit_expr(expr);
1240 // Nodes that are equal modulo `Paren` sugar no-ops should have the same IDs.
1242 vis.visit_span(span);
1243 visit_thin_attrs(attrs, vis);
1246 ExprKind::Yield(expr) => {
1247 visit_opt(expr, |expr| vis.visit_expr(expr));
1249 ExprKind::Try(expr) => vis.visit_expr(expr),
1250 ExprKind::TryBlock(body) => vis.visit_block(body),
1251 ExprKind::Lit(_) | ExprKind::Err => {}
1254 vis.visit_span(span);
1255 visit_thin_attrs(attrs, vis);
1258 pub fn noop_filter_map_expr<T: MutVisitor>(mut e: P<Expr>, vis: &mut T) -> Option<P<Expr>> {
1260 vis.visit_expr(&mut e);
1265 pub fn noop_flat_map_stmt<T: MutVisitor>(
1266 Stmt { kind, mut span, mut id }: Stmt,
1268 ) -> SmallVec<[Stmt; 1]> {
1269 vis.visit_id(&mut id);
1270 vis.visit_span(&mut span);
1271 noop_flat_map_stmt_kind(kind, vis).into_iter().map(|kind| Stmt { id, kind, span }).collect()
1274 pub fn noop_flat_map_stmt_kind<T: MutVisitor>(
1277 ) -> SmallVec<[StmtKind; 1]> {
1279 StmtKind::Local(mut local) => smallvec![StmtKind::Local({
1280 vis.visit_local(&mut local);
1283 StmtKind::Item(item) => vis.flat_map_item(item).into_iter().map(StmtKind::Item).collect(),
1284 StmtKind::Expr(expr) => vis.filter_map_expr(expr).into_iter().map(StmtKind::Expr).collect(),
1285 StmtKind::Semi(expr) => vis.filter_map_expr(expr).into_iter().map(StmtKind::Semi).collect(),
1286 StmtKind::Mac(mut mac) => {
1287 let (mac_, _semi, attrs) = mac.deref_mut();
1288 vis.visit_mac(mac_);
1289 visit_thin_attrs(attrs, vis);
1290 smallvec![StmtKind::Mac(mac)]
1295 pub fn noop_visit_vis<T: MutVisitor>(Spanned { node, span }: &mut Visibility, vis: &mut T) {
1297 VisibilityKind::Public | VisibilityKind::Crate(_) | VisibilityKind::Inherited => {}
1298 VisibilityKind::Restricted { path, id } => {
1299 vis.visit_path(path);
1303 vis.visit_span(span);