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.
11 use crate::source_map::{Spanned, respan};
12 use crate::token::{self, Token};
15 use crate::tokenstream::*;
16 use crate::util::map_in_place::MapInPlace;
18 use smallvec::{smallvec, Array, SmallVec};
21 use rustc_data_structures::sync::Lrc;
22 use std::ops::DerefMut;
23 use std::{panic, process, ptr};
25 pub trait ExpectOne<A: Array> {
26 fn expect_one(self, err: &'static str) -> A::Item;
29 impl<A: Array> ExpectOne<A> for SmallVec<A> {
30 fn expect_one(self, err: &'static str) -> A::Item {
31 assert!(self.len() == 1, err);
32 self.into_iter().next().unwrap()
36 pub trait MutVisitor: Sized {
37 // Methods in this trait have one of three forms:
39 // fn visit_t(&mut self, t: &mut T); // common
40 // fn flat_map_t(&mut self, t: T) -> SmallVec<[T; 1]>; // rare
41 // fn filter_map_t(&mut self, t: T) -> Option<T>; // rarest
43 // Any additions to this trait should happen in form of a call to a public
44 // `noop_*` function that only calls out to the visitor again, not other
45 // `noop_*` functions. This is a necessary API workaround to the problem of
46 // not being able to call out to the super default method in an overridden
49 // When writing these methods, it is better to use destructuring like this:
51 // fn visit_abc(&mut self, ABC { a, b, c: _ }: &mut ABC) {
56 // than to use field access like this:
58 // fn visit_abc(&mut self, abc: &mut ABC) {
59 // visit_a(&mut abc.a);
60 // visit_b(&mut abc.b);
64 // As well as being more concise, the former is explicit about which fields
65 // are skipped. Furthermore, if a new field is added, the destructuring
66 // version will cause a compile error, which is good. In comparison, the
67 // field access version will continue working and it would be easy to
68 // forget to add handling for it.
70 fn visit_crate(&mut self, c: &mut Crate) {
71 noop_visit_crate(c, self)
74 fn visit_meta_list_item(&mut self, list_item: &mut NestedMetaItem) {
75 noop_visit_meta_list_item(list_item, self);
78 fn visit_meta_item(&mut self, meta_item: &mut MetaItem) {
79 noop_visit_meta_item(meta_item, self);
82 fn visit_use_tree(&mut self, use_tree: &mut UseTree) {
83 noop_visit_use_tree(use_tree, self);
86 fn flat_map_foreign_item(&mut self, ni: ForeignItem) -> SmallVec<[ForeignItem; 1]> {
87 noop_flat_map_foreign_item(ni, self)
90 fn flat_map_item(&mut self, i: P<Item>) -> SmallVec<[P<Item>; 1]> {
91 noop_flat_map_item(i, self)
94 fn visit_fn_header(&mut self, header: &mut FnHeader) {
95 noop_visit_fn_header(header, self);
98 fn flat_map_struct_field(&mut self, sf: StructField) -> SmallVec<[StructField; 1]> {
99 noop_flat_map_struct_field(sf, self)
102 fn visit_item_kind(&mut self, i: &mut ItemKind) {
103 noop_visit_item_kind(i, self);
106 fn flat_map_trait_item(&mut self, i: TraitItem) -> SmallVec<[TraitItem; 1]> {
107 noop_flat_map_trait_item(i, self)
110 fn flat_map_impl_item(&mut self, i: ImplItem) -> SmallVec<[ImplItem; 1]> {
111 noop_flat_map_impl_item(i, self)
114 fn visit_fn_decl(&mut self, d: &mut P<FnDecl>) {
115 noop_visit_fn_decl(d, self);
118 fn visit_asyncness(&mut self, a: &mut IsAsync) {
119 noop_visit_asyncness(a, self);
122 fn visit_block(&mut self, b: &mut P<Block>) {
123 noop_visit_block(b, self);
126 fn flat_map_stmt(&mut self, s: Stmt) -> SmallVec<[Stmt; 1]> {
127 noop_flat_map_stmt(s, self)
130 fn flat_map_arm(&mut self, arm: Arm) -> SmallVec<[Arm; 1]> {
131 noop_flat_map_arm(arm, self)
134 fn visit_pat(&mut self, p: &mut P<Pat>) {
135 noop_visit_pat(p, self);
138 fn visit_anon_const(&mut self, c: &mut AnonConst) {
139 noop_visit_anon_const(c, self);
142 fn visit_expr(&mut self, e: &mut P<Expr>) {
143 noop_visit_expr(e, self);
146 fn filter_map_expr(&mut self, e: P<Expr>) -> Option<P<Expr>> {
147 noop_filter_map_expr(e, self)
150 fn visit_generic_arg(&mut self, arg: &mut GenericArg) {
151 noop_visit_generic_arg(arg, self);
154 fn visit_ty(&mut self, t: &mut P<Ty>) {
155 noop_visit_ty(t, self);
158 fn visit_lifetime(&mut self, l: &mut Lifetime) {
159 noop_visit_lifetime(l, self);
162 fn visit_ty_constraint(&mut self, t: &mut AssocTyConstraint) {
163 noop_visit_ty_constraint(t, self);
166 fn visit_mod(&mut self, m: &mut Mod) {
167 noop_visit_mod(m, self);
170 fn visit_foreign_mod(&mut self, nm: &mut ForeignMod) {
171 noop_visit_foreign_mod(nm, self);
174 fn flat_map_variant(&mut self, v: Variant) -> SmallVec<[Variant; 1]> {
175 noop_flat_map_variant(v, self)
178 fn visit_ident(&mut self, i: &mut Ident) {
179 noop_visit_ident(i, self);
182 fn visit_path(&mut self, p: &mut Path) {
183 noop_visit_path(p, self);
186 fn visit_qself(&mut self, qs: &mut Option<QSelf>) {
187 noop_visit_qself(qs, self);
190 fn visit_generic_args(&mut self, p: &mut GenericArgs) {
191 noop_visit_generic_args(p, self);
194 fn visit_angle_bracketed_parameter_data(&mut self, p: &mut AngleBracketedArgs) {
195 noop_visit_angle_bracketed_parameter_data(p, self);
198 fn visit_parenthesized_parameter_data(&mut self, p: &mut ParenthesizedArgs) {
199 noop_visit_parenthesized_parameter_data(p, self);
202 fn visit_local(&mut self, l: &mut P<Local>) {
203 noop_visit_local(l, self);
206 fn visit_mac(&mut self, _mac: &mut Mac) {
207 panic!("visit_mac disabled by default");
208 // N.B., see note about macros above. If you really want a visitor that
209 // works on macros, use this definition in your trait impl:
210 // mut_visit::noop_visit_mac(_mac, self);
213 fn visit_macro_def(&mut self, def: &mut MacroDef) {
214 noop_visit_macro_def(def, self);
217 fn visit_label(&mut self, label: &mut Label) {
218 noop_visit_label(label, self);
221 fn visit_attribute(&mut self, at: &mut Attribute) {
222 noop_visit_attribute(at, self);
225 fn flat_map_param(&mut self, param: Param) -> SmallVec<[Param; 1]> {
226 noop_flat_map_param(param, self)
229 fn visit_generics(&mut self, generics: &mut Generics) {
230 noop_visit_generics(generics, self);
233 fn visit_trait_ref(&mut self, tr: &mut TraitRef) {
234 noop_visit_trait_ref(tr, self);
237 fn visit_poly_trait_ref(&mut self, p: &mut PolyTraitRef) {
238 noop_visit_poly_trait_ref(p, self);
241 fn visit_variant_data(&mut self, vdata: &mut VariantData) {
242 noop_visit_variant_data(vdata, self);
245 fn flat_map_generic_param(&mut self, param: GenericParam) -> SmallVec<[GenericParam; 1]> {
246 noop_flat_map_generic_param(param, self)
249 fn visit_tt(&mut self, tt: &mut TokenTree) {
250 noop_visit_tt(tt, self);
253 fn visit_tts(&mut self, tts: &mut TokenStream) {
254 noop_visit_tts(tts, self);
257 fn visit_token(&mut self, t: &mut Token) {
258 noop_visit_token(t, self);
261 fn visit_interpolated(&mut self, nt: &mut token::Nonterminal) {
262 noop_visit_interpolated(nt, self);
265 fn visit_param_bound(&mut self, tpb: &mut GenericBound) {
266 noop_visit_param_bound(tpb, self);
269 fn visit_mt(&mut self, mt: &mut MutTy) {
270 noop_visit_mt(mt, self);
273 fn flat_map_field(&mut self, f: Field) -> SmallVec<[Field; 1]> {
274 noop_flat_map_field(f, self)
277 fn visit_where_clause(&mut self, where_clause: &mut WhereClause) {
278 noop_visit_where_clause(where_clause, self);
281 fn visit_where_predicate(&mut self, where_predicate: &mut WherePredicate) {
282 noop_visit_where_predicate(where_predicate, self);
285 fn visit_vis(&mut self, vis: &mut Visibility) {
286 noop_visit_vis(vis, self);
289 fn visit_id(&mut self, _id: &mut NodeId) {
293 fn visit_span(&mut self, _sp: &mut Span) {
297 fn flat_map_field_pattern(&mut self, fp: FieldPat) -> SmallVec<[FieldPat; 1]> {
298 noop_flat_map_field_pattern(fp, self)
302 /// Use a map-style function (`FnOnce(T) -> T`) to overwrite a `&mut T`. Useful
303 /// when using a `flat_map_*` or `filter_map_*` method within a `visit_`
304 /// method. Abort the program if the closure panics.
306 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
307 pub fn visit_clobber<T, F>(t: &mut T, f: F) where F: FnOnce(T) -> T {
309 // Safe because `t` is used in a read-only fashion by `read()` before
310 // being overwritten by `write()`.
311 let old_t = ptr::read(t);
312 let new_t = panic::catch_unwind(panic::AssertUnwindSafe(|| f(old_t)))
313 .unwrap_or_else(|_| process::abort());
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) where F: FnMut(&mut T) {
326 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
328 pub fn visit_opt<T, F>(opt: &mut Option<T>, mut visit_elem: F) where F: FnMut(&mut T) {
329 if let Some(elem) = opt {
334 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
335 pub fn visit_attrs<T: MutVisitor>(attrs: &mut Vec<Attribute>, vis: &mut T) {
336 visit_vec(attrs, |attr| vis.visit_attribute(attr));
339 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
340 pub fn visit_thin_attrs<T: MutVisitor>(attrs: &mut ThinVec<Attribute>, vis: &mut T) {
341 for attr in attrs.iter_mut() {
342 vis.visit_attribute(attr);
346 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
347 pub fn visit_exprs<T: MutVisitor>(exprs: &mut Vec<P<Expr>>, vis: &mut T) {
348 exprs.flat_map_in_place(|expr| vis.filter_map_expr(expr))
351 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
352 pub fn visit_bounds<T: MutVisitor>(bounds: &mut GenericBounds, vis: &mut T) {
353 visit_vec(bounds, |bound| vis.visit_param_bound(bound));
356 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
357 pub fn visit_fn_sig<T: MutVisitor>(FnSig { header, decl }: &mut FnSig, vis: &mut T) {
358 vis.visit_fn_header(header);
359 vis.visit_fn_decl(decl);
362 // No `noop_` prefix because there isn't a corresponding method in `MutVisitor`.
363 pub fn visit_mac_args<T: MutVisitor>(args: &mut MacArgs, vis: &mut T) {
366 MacArgs::Delimited(dspan, _delim, tokens) => {
367 visit_delim_span(dspan, vis);
368 vis.visit_tts(tokens);
370 MacArgs::Eq(eq_span, tokens) => {
371 vis.visit_span(eq_span);
372 vis.visit_tts(tokens);
377 pub fn visit_delim_span<T: MutVisitor>(dspan: &mut DelimSpan, vis: &mut T) {
378 vis.visit_span(&mut dspan.open);
379 vis.visit_span(&mut dspan.close);
382 pub fn noop_flat_map_field_pattern<T: MutVisitor>(
385 ) -> SmallVec<[FieldPat; 1]> {
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 |
456 TyKind::Never | TyKind::CVarArgs => {}
457 TyKind::Slice(ty) => vis.visit_ty(ty),
458 TyKind::Ptr(mt) => vis.visit_mt(mt),
459 TyKind::Rptr(lt, mt) => {
460 visit_opt(lt, |lt| noop_visit_lifetime(lt, vis));
463 TyKind::BareFn(bft) => {
464 let BareFnTy { unsafety: _, ext: _, generic_params, decl } = bft.deref_mut();
465 generic_params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
466 vis.visit_fn_decl(decl);
468 TyKind::Tup(tys) => visit_vec(tys, |ty| vis.visit_ty(ty)),
469 TyKind::Paren(ty) => vis.visit_ty(ty),
470 TyKind::Path(qself, path) => {
471 vis.visit_qself(qself);
472 vis.visit_path(path);
474 TyKind::Array(ty, length) => {
476 vis.visit_anon_const(length);
478 TyKind::Typeof(expr) => vis.visit_anon_const(expr),
479 TyKind::TraitObject(bounds, _syntax) =>
480 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>(mut variant: Variant, visitor: &mut T)
496 -> SmallVec<[Variant; 1]>
498 let Variant { ident, vis, attrs, id, data, disr_expr, span, is_placeholder: _ } = &mut variant;
499 visitor.visit_ident(ident);
500 visitor.visit_vis(vis);
501 visit_attrs(attrs, visitor);
502 visitor.visit_id(id);
503 visitor.visit_variant_data(data);
504 visit_opt(disr_expr, |disr_expr| visitor.visit_anon_const(disr_expr));
505 visitor.visit_span(span);
509 pub fn noop_visit_ident<T: MutVisitor>(Ident { name: _, span }: &mut Ident, vis: &mut T) {
510 vis.visit_span(span);
513 pub fn noop_visit_path<T: MutVisitor>(Path { segments, span }: &mut Path, vis: &mut T) {
514 vis.visit_span(span);
515 for PathSegment { ident, id, args } in segments {
516 vis.visit_ident(ident);
518 visit_opt(args, |args| vis.visit_generic_args(args));
522 pub fn noop_visit_qself<T: MutVisitor>(qself: &mut Option<QSelf>, vis: &mut T) {
523 visit_opt(qself, |QSelf { ty, path_span, position: _ }| {
525 vis.visit_span(path_span);
529 pub fn noop_visit_generic_args<T: MutVisitor>(generic_args: &mut GenericArgs, vis: &mut T) {
531 GenericArgs::AngleBracketed(data) => vis.visit_angle_bracketed_parameter_data(data),
532 GenericArgs::Parenthesized(data) => vis.visit_parenthesized_parameter_data(data),
536 pub fn noop_visit_generic_arg<T: MutVisitor>(arg: &mut GenericArg, vis: &mut T) {
538 GenericArg::Lifetime(lt) => vis.visit_lifetime(lt),
539 GenericArg::Type(ty) => vis.visit_ty(ty),
540 GenericArg::Const(ct) => vis.visit_anon_const(ct),
544 pub fn noop_visit_angle_bracketed_parameter_data<T: MutVisitor>(data: &mut AngleBracketedArgs,
546 let AngleBracketedArgs { args, constraints, span } = data;
547 visit_vec(args, |arg| vis.visit_generic_arg(arg));
548 visit_vec(constraints, |constraint| vis.visit_ty_constraint(constraint));
549 vis.visit_span(span);
552 pub fn noop_visit_parenthesized_parameter_data<T: MutVisitor>(args: &mut ParenthesizedArgs,
554 let ParenthesizedArgs { inputs, output, span } = args;
555 visit_vec(inputs, |input| vis.visit_ty(input));
556 visit_opt(output, |output| vis.visit_ty(output));
557 vis.visit_span(span);
560 pub fn noop_visit_local<T: MutVisitor>(local: &mut P<Local>, vis: &mut T) {
561 let Local { id, pat, ty, init, span, attrs } = local.deref_mut();
564 visit_opt(ty, |ty| vis.visit_ty(ty));
565 visit_opt(init, |init| vis.visit_expr(init));
566 vis.visit_span(span);
567 visit_thin_attrs(attrs, vis);
570 pub fn noop_visit_attribute<T: MutVisitor>(attr: &mut Attribute, vis: &mut T) {
571 let Attribute { kind, id: _, style: _, span } = attr;
573 AttrKind::Normal(AttrItem { path, args }) => {
574 vis.visit_path(path);
575 visit_mac_args(args, vis);
577 AttrKind::DocComment(_) => {}
579 vis.visit_span(span);
582 pub fn noop_visit_mac<T: MutVisitor>(mac: &mut Mac, vis: &mut T) {
583 let Mac { path, args, prior_type_ascription: _ } = mac;
584 vis.visit_path(path);
585 visit_mac_args(args, vis);
588 pub fn noop_visit_macro_def<T: MutVisitor>(macro_def: &mut MacroDef, vis: &mut T) {
589 let MacroDef { body, legacy: _ } = macro_def;
590 visit_mac_args(body, vis);
593 pub fn noop_visit_meta_list_item<T: MutVisitor>(li: &mut NestedMetaItem, vis: &mut T) {
595 NestedMetaItem::MetaItem(mi) => vis.visit_meta_item(mi),
596 NestedMetaItem::Literal(_lit) => {}
600 pub fn noop_visit_meta_item<T: MutVisitor>(mi: &mut MetaItem, vis: &mut T) {
601 let MetaItem { path: _, kind, span } = mi;
603 MetaItemKind::Word => {}
604 MetaItemKind::List(mis) => visit_vec(mis, |mi| vis.visit_meta_list_item(mi)),
605 MetaItemKind::NameValue(_s) => {}
607 vis.visit_span(span);
610 pub fn noop_flat_map_param<T: MutVisitor>(mut param: Param, vis: &mut T) -> SmallVec<[Param; 1]> {
611 let Param { attrs, id, pat, span, ty, is_placeholder: _ } = &mut param;
613 visit_thin_attrs(attrs, vis);
615 vis.visit_span(span);
620 pub fn noop_visit_tt<T: MutVisitor>(tt: &mut TokenTree, vis: &mut T) {
622 TokenTree::Token(token) => {
623 vis.visit_token(token);
625 TokenTree::Delimited(DelimSpan { open, close }, _delim, tts) => {
626 vis.visit_span(open);
627 vis.visit_span(close);
633 pub fn noop_visit_tts<T: MutVisitor>(TokenStream(tts): &mut TokenStream, vis: &mut T) {
634 let tts = Lrc::make_mut(tts);
635 visit_vec(tts, |(tree, _is_joint)| vis.visit_tt(tree));
638 // Applies ident visitor if it's an ident; applies other visits to interpolated nodes.
639 // In practice the ident part is not actually used by specific visitors right now,
640 // but there's a test below checking that it works.
641 pub fn noop_visit_token<T: MutVisitor>(t: &mut Token, vis: &mut T) {
642 let Token { kind, span } = t;
644 token::Ident(name, _) | token::Lifetime(name) => {
645 let mut ident = Ident::new(*name, *span);
646 vis.visit_ident(&mut ident);
649 return; // Avoid visiting the span for the second time.
651 token::Interpolated(nt) => {
652 let mut nt = Lrc::make_mut(nt);
653 vis.visit_interpolated(&mut nt);
657 vis.visit_span(span);
660 /// Applies the visitor to elements of interpolated nodes.
662 // N.B., this can occur only when applying a visitor to partially expanded
663 // code, where parsed pieces have gotten implanted ito *other* macro
664 // invocations. This is relevant for macro hygiene, but possibly not elsewhere.
666 // One problem here occurs because the types for flat_map_item, flat_map_stmt,
667 // etc., allow the visitor to return *multiple* items; this is a problem for the
668 // nodes here, because they insist on having exactly one piece. One solution
669 // would be to mangle the MutVisitor trait to include one-to-many and
670 // one-to-one versions of these entry points, but that would probably confuse a
671 // lot of people and help very few. Instead, I'm just going to put in dynamic
672 // checks. I think the performance impact of this will be pretty much
673 // nonexistent. The danger is that someone will apply a `MutVisitor` to a
674 // partially expanded node, and will be confused by the fact that their
675 // `flat_map_item` or `flat_map_stmt` isn't getting called on `NtItem` or `NtStmt`
676 // nodes. Hopefully they'll wind up reading this comment, and doing something
679 // BTW, design choice: I considered just changing the type of, e.g., `NtItem` to
680 // contain multiple items, but decided against it when I looked at
681 // `parse_item_or_view_item` and tried to figure out what I would do with
682 // multiple items there....
683 pub fn noop_visit_interpolated<T: MutVisitor>(nt: &mut token::Nonterminal, vis: &mut T) {
685 token::NtItem(item) =>
686 visit_clobber(item, |item| {
687 // This is probably okay, because the only visitors likely to
688 // peek inside interpolated nodes will be renamings/markings,
689 // which map single items to single items.
690 vis.flat_map_item(item).expect_one("expected visitor to produce exactly one item")
692 token::NtBlock(block) => vis.visit_block(block),
693 token::NtStmt(stmt) =>
694 visit_clobber(stmt, |stmt| {
695 // See reasoning above.
696 vis.flat_map_stmt(stmt).expect_one("expected visitor to produce exactly one item")
698 token::NtPat(pat) => vis.visit_pat(pat),
699 token::NtExpr(expr) => vis.visit_expr(expr),
700 token::NtTy(ty) => vis.visit_ty(ty),
701 token::NtIdent(ident, _is_raw) => vis.visit_ident(ident),
702 token::NtLifetime(ident) => vis.visit_ident(ident),
703 token::NtLiteral(expr) => vis.visit_expr(expr),
704 token::NtMeta(AttrItem { path, args }) => {
705 vis.visit_path(path);
706 visit_mac_args(args, vis);
708 token::NtPath(path) => vis.visit_path(path),
709 token::NtTT(tt) => vis.visit_tt(tt),
710 token::NtImplItem(item) =>
711 visit_clobber(item, |item| {
712 // See reasoning above.
713 vis.flat_map_impl_item(item)
714 .expect_one("expected visitor to produce exactly one item")
716 token::NtTraitItem(item) =>
717 visit_clobber(item, |item| {
718 // See reasoning above.
719 vis.flat_map_trait_item(item)
720 .expect_one("expected visitor to produce exactly one item")
722 token::NtVis(visib) => vis.visit_vis(visib),
723 token::NtForeignItem(item) =>
724 visit_clobber(item, |item| {
725 // See reasoning above.
726 vis.flat_map_foreign_item(item)
727 .expect_one("expected visitor to produce exactly one item")
732 pub fn noop_visit_asyncness<T: MutVisitor>(asyncness: &mut IsAsync, vis: &mut T) {
734 IsAsync::Async { closure_id, return_impl_trait_id } => {
735 vis.visit_id(closure_id);
736 vis.visit_id(return_impl_trait_id);
738 IsAsync::NotAsync => {}
742 pub fn noop_visit_fn_decl<T: MutVisitor>(decl: &mut P<FnDecl>, vis: &mut T) {
743 let FnDecl { inputs, output } = decl.deref_mut();
744 inputs.flat_map_in_place(|param| vis.flat_map_param(param));
746 FunctionRetTy::Default(span) => vis.visit_span(span),
747 FunctionRetTy::Ty(ty) => vis.visit_ty(ty),
751 pub fn noop_visit_param_bound<T: MutVisitor>(pb: &mut GenericBound, vis: &mut T) {
753 GenericBound::Trait(ty, _modifier) => vis.visit_poly_trait_ref(ty),
754 GenericBound::Outlives(lifetime) => noop_visit_lifetime(lifetime, vis),
758 pub fn noop_flat_map_generic_param<T: MutVisitor>(
759 mut param: GenericParam,
761 ) -> SmallVec<[GenericParam; 1]>
763 let GenericParam { id, ident, attrs, bounds, kind, is_placeholder: _ } = &mut param;
765 vis.visit_ident(ident);
766 visit_thin_attrs(attrs, vis);
767 visit_vec(bounds, |bound| noop_visit_param_bound(bound, vis));
769 GenericParamKind::Lifetime => {}
770 GenericParamKind::Type { default } => {
771 visit_opt(default, |default| vis.visit_ty(default));
773 GenericParamKind::Const { ty } => {
780 pub fn noop_visit_label<T: MutVisitor>(Label { ident }: &mut Label, vis: &mut T) {
781 vis.visit_ident(ident);
784 fn noop_visit_lifetime<T: MutVisitor>(Lifetime { id, ident }: &mut Lifetime, vis: &mut T) {
786 vis.visit_ident(ident);
789 pub fn noop_visit_generics<T: MutVisitor>(generics: &mut Generics, vis: &mut T) {
790 let Generics { params, where_clause, span } = generics;
791 params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
792 vis.visit_where_clause(where_clause);
793 vis.visit_span(span);
796 pub fn noop_visit_where_clause<T: MutVisitor>(wc: &mut WhereClause, vis: &mut T) {
797 let WhereClause { predicates, span } = wc;
798 visit_vec(predicates, |predicate| vis.visit_where_predicate(predicate));
799 vis.visit_span(span);
802 pub fn noop_visit_where_predicate<T: MutVisitor>(pred: &mut WherePredicate, vis: &mut T) {
804 WherePredicate::BoundPredicate(bp) => {
805 let WhereBoundPredicate { span, bound_generic_params, bounded_ty, bounds } = bp;
806 vis.visit_span(span);
807 bound_generic_params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
808 vis.visit_ty(bounded_ty);
809 visit_vec(bounds, |bound| vis.visit_param_bound(bound));
811 WherePredicate::RegionPredicate(rp) => {
812 let WhereRegionPredicate { span, lifetime, bounds } = rp;
813 vis.visit_span(span);
814 noop_visit_lifetime(lifetime, vis);
815 visit_vec(bounds, |bound| noop_visit_param_bound(bound, vis));
817 WherePredicate::EqPredicate(ep) => {
818 let WhereEqPredicate { id, span, lhs_ty, rhs_ty } = ep;
820 vis.visit_span(span);
821 vis.visit_ty(lhs_ty);
822 vis.visit_ty(rhs_ty);
827 pub fn noop_visit_variant_data<T: MutVisitor>(vdata: &mut VariantData, vis: &mut T) {
829 VariantData::Struct(fields, ..) => {
830 fields.flat_map_in_place(|field| vis.flat_map_struct_field(field));
832 VariantData::Tuple(fields, id) => {
833 fields.flat_map_in_place(|field| vis.flat_map_struct_field(field));
836 VariantData::Unit(id) => vis.visit_id(id),
840 pub fn noop_visit_trait_ref<T: MutVisitor>(TraitRef { path, ref_id }: &mut TraitRef, vis: &mut T) {
841 vis.visit_path(path);
842 vis.visit_id(ref_id);
845 pub fn noop_visit_poly_trait_ref<T: MutVisitor>(p: &mut PolyTraitRef, vis: &mut T) {
846 let PolyTraitRef { bound_generic_params, trait_ref, span } = p;
847 bound_generic_params.flat_map_in_place(|param| vis.flat_map_generic_param(param));
848 vis.visit_trait_ref(trait_ref);
849 vis.visit_span(span);
852 pub fn noop_flat_map_struct_field<T: MutVisitor>(mut sf: StructField, visitor: &mut T)
853 -> SmallVec<[StructField; 1]>
855 let StructField { span, ident, vis, id, ty, attrs, is_placeholder: _ } = &mut sf;
856 visitor.visit_span(span);
857 visit_opt(ident, |ident| visitor.visit_ident(ident));
858 visitor.visit_vis(vis);
859 visitor.visit_id(id);
860 visitor.visit_ty(ty);
861 visit_attrs(attrs, visitor);
865 pub fn noop_flat_map_field<T: MutVisitor>(mut f: Field, vis: &mut T) -> SmallVec<[Field; 1]> {
866 let Field { ident, expr, span, is_shorthand: _, attrs, id, is_placeholder: _ } = &mut f;
867 vis.visit_ident(ident);
868 vis.visit_expr(expr);
870 vis.visit_span(span);
871 visit_thin_attrs(attrs, vis);
875 pub fn noop_visit_mt<T: MutVisitor>(MutTy { ty, mutbl: _ }: &mut MutTy, vis: &mut T) {
879 pub fn noop_visit_block<T: MutVisitor>(block: &mut P<Block>, vis: &mut T) {
880 let Block { id, stmts, rules: _, span } = block.deref_mut();
882 stmts.flat_map_in_place(|stmt| vis.flat_map_stmt(stmt));
883 vis.visit_span(span);
886 pub fn noop_visit_item_kind<T: MutVisitor>(kind: &mut ItemKind, vis: &mut T) {
888 ItemKind::ExternCrate(_orig_name) => {}
889 ItemKind::Use(use_tree) => vis.visit_use_tree(use_tree),
890 ItemKind::Static(ty, _mut, expr) => {
892 vis.visit_expr(expr);
894 ItemKind::Const(ty, expr) => {
896 vis.visit_expr(expr);
898 ItemKind::Fn(sig, generics, body) => {
899 visit_fn_sig(sig, vis);
900 vis.visit_generics(generics);
901 vis.visit_block(body);
903 ItemKind::Mod(m) => vis.visit_mod(m),
904 ItemKind::ForeignMod(nm) => vis.visit_foreign_mod(nm),
905 ItemKind::GlobalAsm(_ga) => {}
906 ItemKind::TyAlias(ty, generics) => {
908 vis.visit_generics(generics);
910 ItemKind::Enum(EnumDef { variants }, generics) => {
911 variants.flat_map_in_place(|variant| vis.flat_map_variant(variant));
912 vis.visit_generics(generics);
914 ItemKind::Struct(variant_data, generics) |
915 ItemKind::Union(variant_data, generics) => {
916 vis.visit_variant_data(variant_data);
917 vis.visit_generics(generics);
919 ItemKind::Impl(_unsafety, _polarity, _defaultness, generics, trait_ref, ty, items) => {
920 vis.visit_generics(generics);
921 visit_opt(trait_ref, |trait_ref| vis.visit_trait_ref(trait_ref));
923 items.flat_map_in_place(|item| vis.flat_map_impl_item(item));
925 ItemKind::Trait(_is_auto, _unsafety, generics, bounds, items) => {
926 vis.visit_generics(generics);
927 visit_bounds(bounds, vis);
928 items.flat_map_in_place(|item| vis.flat_map_trait_item(item));
930 ItemKind::TraitAlias(generics, bounds) => {
931 vis.visit_generics(generics);
932 visit_bounds(bounds, vis);
934 ItemKind::Mac(m) => vis.visit_mac(m),
935 ItemKind::MacroDef(def) => vis.visit_macro_def(def),
939 pub fn noop_flat_map_trait_item<T: MutVisitor>(mut item: TraitItem, visitor: &mut T)
940 -> SmallVec<[TraitItem; 1]>
942 let TraitItem { id, ident, vis, attrs, generics, kind, span, tokens: _ } = &mut item;
943 visitor.visit_id(id);
944 visitor.visit_ident(ident);
945 visitor.visit_vis(vis);
946 visit_attrs(attrs, visitor);
947 visitor.visit_generics(generics);
949 TraitItemKind::Const(ty, default) => {
950 visitor.visit_ty(ty);
951 visit_opt(default, |default| visitor.visit_expr(default));
953 TraitItemKind::Method(sig, body) => {
954 visit_fn_sig(sig, visitor);
955 visit_opt(body, |body| visitor.visit_block(body));
957 TraitItemKind::Type(bounds, default) => {
958 visit_bounds(bounds, visitor);
959 visit_opt(default, |default| visitor.visit_ty(default));
961 TraitItemKind::Macro(mac) => {
962 visitor.visit_mac(mac);
965 visitor.visit_span(span);
970 pub fn noop_flat_map_impl_item<T: MutVisitor>(mut item: ImplItem, visitor: &mut T)
971 -> SmallVec<[ImplItem; 1]>
973 let ImplItem { id, ident, vis, defaultness: _, attrs, generics, kind, span, tokens: _ } =
975 visitor.visit_id(id);
976 visitor.visit_ident(ident);
977 visitor.visit_vis(vis);
978 visit_attrs(attrs, visitor);
979 visitor.visit_generics(generics);
981 ImplItemKind::Const(ty, expr) => {
982 visitor.visit_ty(ty);
983 visitor.visit_expr(expr);
985 ImplItemKind::Method(sig, body) => {
986 visit_fn_sig(sig, visitor);
987 visitor.visit_block(body);
989 ImplItemKind::TyAlias(ty) => visitor.visit_ty(ty),
990 ImplItemKind::Macro(mac) => visitor.visit_mac(mac),
992 visitor.visit_span(span);
997 pub fn noop_visit_fn_header<T: MutVisitor>(header: &mut FnHeader, vis: &mut T) {
998 let FnHeader { unsafety: _, asyncness, constness: _, ext: _ } = header;
999 vis.visit_asyncness(&mut asyncness.node);
1002 pub fn noop_visit_mod<T: MutVisitor>(Mod { inner, items, inline: _ }: &mut Mod, vis: &mut T) {
1003 vis.visit_span(inner);
1004 items.flat_map_in_place(|item| vis.flat_map_item(item));
1007 pub fn noop_visit_crate<T: MutVisitor>(krate: &mut Crate, vis: &mut T) {
1008 visit_clobber(krate, |Crate { module, attrs, span }| {
1010 ident: Ident::invalid(),
1013 vis: respan(span.shrink_to_lo(), VisibilityKind::Public),
1015 kind: ItemKind::Mod(module),
1018 let items = vis.flat_map_item(item);
1020 let len = items.len();
1022 let module = Mod { inner: span, items: vec![], inline: true };
1023 Crate { module, attrs: vec![], span }
1024 } else if len == 1 {
1025 let Item { attrs, span, kind, .. } = items.into_iter().next().unwrap().into_inner();
1027 ItemKind::Mod(module) => Crate { module, attrs, span },
1028 _ => panic!("visitor converted a module to not a module"),
1031 panic!("a crate cannot expand to more than one item");
1036 // Mutates one item into possibly many items.
1037 pub fn noop_flat_map_item<T: MutVisitor>(mut item: P<Item>, visitor: &mut T)
1038 -> SmallVec<[P<Item>; 1]> {
1039 let Item { ident, attrs, id, kind, vis, span, tokens: _ } = item.deref_mut();
1040 visitor.visit_ident(ident);
1041 visit_attrs(attrs, visitor);
1042 visitor.visit_id(id);
1043 visitor.visit_item_kind(kind);
1044 visitor.visit_vis(vis);
1045 visitor.visit_span(span);
1047 // FIXME: if `tokens` is modified with a call to `vis.visit_tts` it causes
1048 // an ICE during resolve... odd!
1053 pub fn noop_flat_map_foreign_item<T: MutVisitor>(mut item: ForeignItem, visitor: &mut T)
1054 -> SmallVec<[ForeignItem; 1]>
1056 let ForeignItem { ident, attrs, id, kind, vis, span, tokens: _ } = &mut item;
1057 visitor.visit_ident(ident);
1058 visit_attrs(attrs, visitor);
1060 ForeignItemKind::Fn(fdec, generics) => {
1061 visitor.visit_fn_decl(fdec);
1062 visitor.visit_generics(generics);
1064 ForeignItemKind::Static(t, _m) => visitor.visit_ty(t),
1065 ForeignItemKind::Ty => {}
1066 ForeignItemKind::Macro(mac) => visitor.visit_mac(mac),
1068 visitor.visit_id(id);
1069 visitor.visit_span(span);
1070 visitor.visit_vis(vis);
1075 pub fn noop_visit_pat<T: MutVisitor>(pat: &mut P<Pat>, vis: &mut T) {
1076 let Pat { id, kind, span } = pat.deref_mut();
1079 PatKind::Wild | PatKind::Rest => {}
1080 PatKind::Ident(_binding_mode, ident, sub) => {
1081 vis.visit_ident(ident);
1082 visit_opt(sub, |sub| vis.visit_pat(sub));
1084 PatKind::Lit(e) => vis.visit_expr(e),
1085 PatKind::TupleStruct(path, elems) => {
1086 vis.visit_path(path);
1087 visit_vec(elems, |elem| vis.visit_pat(elem));
1089 PatKind::Path(qself, path) => {
1090 vis.visit_qself(qself);
1091 vis.visit_path(path);
1093 PatKind::Struct(path, fields, _etc) => {
1094 vis.visit_path(path);
1095 fields.flat_map_in_place(|field| vis.flat_map_field_pattern(field));
1097 PatKind::Box(inner) => vis.visit_pat(inner),
1098 PatKind::Ref(inner, _mutbl) => vis.visit_pat(inner),
1099 PatKind::Range(e1, e2, Spanned { span: _, node: _ }) => {
1102 vis.visit_span(span);
1104 PatKind::Tuple(elems)
1105 | PatKind::Slice(elems)
1106 | PatKind::Or(elems) => visit_vec(elems, |elem| vis.visit_pat(elem)),
1107 PatKind::Paren(inner) => vis.visit_pat(inner),
1108 PatKind::Mac(mac) => vis.visit_mac(mac),
1110 vis.visit_span(span);
1113 pub fn noop_visit_anon_const<T: MutVisitor>(AnonConst { id, value }: &mut AnonConst, vis: &mut T) {
1115 vis.visit_expr(value);
1118 pub fn noop_visit_expr<T: MutVisitor>(Expr { kind, id, span, attrs }: &mut Expr, vis: &mut T) {
1120 ExprKind::Box(expr) => vis.visit_expr(expr),
1121 ExprKind::Array(exprs) => visit_exprs(exprs, vis),
1122 ExprKind::Repeat(expr, count) => {
1123 vis.visit_expr(expr);
1124 vis.visit_anon_const(count);
1126 ExprKind::Tup(exprs) => visit_exprs(exprs, vis),
1127 ExprKind::Call(f, args) => {
1129 visit_exprs(args, vis);
1131 ExprKind::MethodCall(PathSegment { ident, id, args }, exprs) => {
1132 vis.visit_ident(ident);
1134 visit_opt(args, |args| vis.visit_generic_args(args));
1135 visit_exprs(exprs, vis);
1137 ExprKind::Binary(_binop, lhs, rhs) => {
1138 vis.visit_expr(lhs);
1139 vis.visit_expr(rhs);
1141 ExprKind::Unary(_unop, ohs) => vis.visit_expr(ohs),
1142 ExprKind::Cast(expr, ty) => {
1143 vis.visit_expr(expr);
1146 ExprKind::Type(expr, ty) => {
1147 vis.visit_expr(expr);
1150 ExprKind::AddrOf(_, _, ohs) => vis.visit_expr(ohs),
1151 ExprKind::Let(pat, scrutinee) => {
1153 vis.visit_expr(scrutinee);
1155 ExprKind::If(cond, tr, fl) => {
1156 vis.visit_expr(cond);
1157 vis.visit_block(tr);
1158 visit_opt(fl, |fl| vis.visit_expr(fl));
1160 ExprKind::While(cond, body, label) => {
1161 vis.visit_expr(cond);
1162 vis.visit_block(body);
1163 visit_opt(label, |label| vis.visit_label(label));
1165 ExprKind::ForLoop(pat, iter, body, label) => {
1167 vis.visit_expr(iter);
1168 vis.visit_block(body);
1169 visit_opt(label, |label| vis.visit_label(label));
1171 ExprKind::Loop(body, label) => {
1172 vis.visit_block(body);
1173 visit_opt(label, |label| vis.visit_label(label));
1175 ExprKind::Match(expr, arms) => {
1176 vis.visit_expr(expr);
1177 arms.flat_map_in_place(|arm| vis.flat_map_arm(arm));
1179 ExprKind::Closure(_capture_by, asyncness, _movability, decl, body, span) => {
1180 vis.visit_asyncness(asyncness);
1181 vis.visit_fn_decl(decl);
1182 vis.visit_expr(body);
1183 vis.visit_span(span);
1185 ExprKind::Block(blk, label) => {
1186 vis.visit_block(blk);
1187 visit_opt(label, |label| vis.visit_label(label));
1189 ExprKind::Async(_capture_by, node_id, body) => {
1190 vis.visit_id(node_id);
1191 vis.visit_block(body);
1193 ExprKind::Await(expr) => vis.visit_expr(expr),
1194 ExprKind::Assign(el, er) => {
1198 ExprKind::AssignOp(_op, el, er) => {
1202 ExprKind::Field(el, ident) => {
1204 vis.visit_ident(ident);
1206 ExprKind::Index(el, er) => {
1210 ExprKind::Range(e1, e2, _lim) => {
1211 visit_opt(e1, |e1| vis.visit_expr(e1));
1212 visit_opt(e2, |e2| vis.visit_expr(e2));
1214 ExprKind::Path(qself, path) => {
1215 vis.visit_qself(qself);
1216 vis.visit_path(path);
1218 ExprKind::Break(label, expr) => {
1219 visit_opt(label, |label| vis.visit_label(label));
1220 visit_opt(expr, |expr| vis.visit_expr(expr));
1222 ExprKind::Continue(label) => {
1223 visit_opt(label, |label| vis.visit_label(label));
1225 ExprKind::Ret(expr) => {
1226 visit_opt(expr, |expr| vis.visit_expr(expr));
1228 ExprKind::InlineAsm(asm) => {
1229 let InlineAsm { asm: _, asm_str_style: _, outputs, inputs, clobbers: _, volatile: _,
1230 alignstack: _, dialect: _ } = asm.deref_mut();
1231 for out in outputs {
1232 let InlineAsmOutput { constraint: _, expr, is_rw: _, is_indirect: _ } = out;
1233 vis.visit_expr(expr);
1235 visit_vec(inputs, |(_c, expr)| vis.visit_expr(expr));
1237 ExprKind::Mac(mac) => vis.visit_mac(mac),
1238 ExprKind::Struct(path, fields, expr) => {
1239 vis.visit_path(path);
1240 fields.flat_map_in_place(|field| vis.flat_map_field(field));
1241 visit_opt(expr, |expr| vis.visit_expr(expr));
1243 ExprKind::Paren(expr) => {
1244 vis.visit_expr(expr);
1246 // Nodes that are equal modulo `Paren` sugar no-ops should have the same IDs.
1248 vis.visit_span(span);
1249 visit_thin_attrs(attrs, vis);
1252 ExprKind::Yield(expr) => {
1253 visit_opt(expr, |expr| vis.visit_expr(expr));
1255 ExprKind::Try(expr) => vis.visit_expr(expr),
1256 ExprKind::TryBlock(body) => vis.visit_block(body),
1257 ExprKind::Lit(_) | ExprKind::Err => {}
1260 vis.visit_span(span);
1261 visit_thin_attrs(attrs, vis);
1264 pub fn noop_filter_map_expr<T: MutVisitor>(mut e: P<Expr>, vis: &mut T) -> Option<P<Expr>> {
1265 Some({ vis.visit_expr(&mut e); e })
1268 pub fn noop_flat_map_stmt<T: MutVisitor>(Stmt { kind, mut span, mut id }: Stmt, vis: &mut T)
1269 -> SmallVec<[Stmt; 1]>
1271 vis.visit_id(&mut id);
1272 vis.visit_span(&mut span);
1273 noop_flat_map_stmt_kind(kind, vis).into_iter().map(|kind| {
1274 Stmt { id, kind, span }
1278 pub fn noop_flat_map_stmt_kind<T: MutVisitor>(kind: StmtKind, vis: &mut T)
1279 -> SmallVec<[StmtKind; 1]> {
1281 StmtKind::Local(mut local) =>
1282 smallvec![StmtKind::Local({ vis.visit_local(&mut local); local })],
1283 StmtKind::Item(item) => vis.flat_map_item(item).into_iter().map(StmtKind::Item).collect(),
1284 StmtKind::Expr(expr) => {
1285 vis.filter_map_expr(expr).into_iter().map(StmtKind::Expr).collect()
1287 StmtKind::Semi(expr) => {
1288 vis.filter_map_expr(expr).into_iter().map(StmtKind::Semi).collect()
1290 StmtKind::Mac(mut mac) => {
1291 let (mac_, _semi, attrs) = mac.deref_mut();
1292 vis.visit_mac(mac_);
1293 visit_thin_attrs(attrs, vis);
1294 smallvec![StmtKind::Mac(mac)]
1299 pub fn noop_visit_vis<T: MutVisitor>(Spanned { node, span }: &mut Visibility, vis: &mut T) {
1301 VisibilityKind::Public | VisibilityKind::Crate(_) | VisibilityKind::Inherited => {}
1302 VisibilityKind::Restricted { path, id } => {
1303 vis.visit_path(path);
1307 vis.visit_span(span);