rust/compiler/rustc_ast/src/mut_visit.rs

611 lines
17 KiB
Rust

//! A `MutVisitor` represents an AST modification; it accepts an AST piece and
//! mutates it in place. So, for instance, macro expansion is a `MutVisitor`
//! that walks over an AST and modifies it.
//!
//! Note: using a `MutVisitor` (other than the `MacroExpander` `MutVisitor`) on
//! an AST before macro expansion is probably a bad idea. For instance,
//! a `MutVisitor` renaming item names in a module will miss all of those
//! that are created by the expansion of a macro.
use std::ops::DerefMut;
use std::panic;
use rustc_data_structures::flat_map_in_place::FlatMapInPlace;
use rustc_span::source_map::Spanned;
use rustc_span::{Ident, Span};
use smallvec::{Array, SmallVec, smallvec};
use thin_vec::ThinVec;
use crate::ast::*;
use crate::ptr::P;
use crate::tokenstream::*;
use crate::visit::{AssocCtxt, BoundKind, FnCtxt, VisitorResult, try_visit, visit_opt, walk_list};
pub trait ExpectOne<A: Array> {
fn expect_one(self, err: &'static str) -> A::Item;
}
impl<A: Array> ExpectOne<A> for SmallVec<A> {
fn expect_one(self, err: &'static str) -> A::Item {
assert!(self.len() == 1, "{}", err);
self.into_iter().next().unwrap()
}
}
mod sealed {
use rustc_ast_ir::visit::VisitorResult;
/// This is for compatibility with the regular `Visitor`.
pub trait MutVisitorResult {
type Result: VisitorResult;
}
impl<T> MutVisitorResult for T {
type Result = ();
}
}
use sealed::MutVisitorResult;
pub trait MutVisitor: Sized + MutVisitorResult<Result = ()> {
// Methods in this trait have one of three forms:
//
// fn visit_t(&mut self, t: &mut T); // common
// fn flat_map_t(&mut self, t: T) -> SmallVec<[T; 1]>; // rare
// fn filter_map_t(&mut self, t: T) -> Option<T>; // rarest
//
// When writing these methods, it is better to use destructuring like this:
//
// fn visit_abc(&mut self, ABC { a, b, c: _ }: &mut ABC) {
// visit_a(a);
// visit_b(b);
// }
//
// than to use field access like this:
//
// fn visit_abc(&mut self, abc: &mut ABC) {
// visit_a(&mut abc.a);
// visit_b(&mut abc.b);
// // ignore abc.c
// }
//
// As well as being more concise, the former is explicit about which fields
// are skipped. Furthermore, if a new field is added, the destructuring
// version will cause a compile error, which is good. In comparison, the
// field access version will continue working and it would be easy to
// forget to add handling for it.
fn visit_crate(&mut self, c: &mut Crate) {
walk_crate(self, c)
}
fn visit_meta_list_item(&mut self, list_item: &mut MetaItemInner) {
walk_meta_list_item(self, list_item);
}
fn visit_meta_item(&mut self, meta_item: &mut MetaItem) {
walk_meta_item(self, meta_item);
}
fn visit_use_tree(&mut self, use_tree: &mut UseTree) {
walk_use_tree(self, use_tree);
}
fn visit_foreign_item(&mut self, ni: &mut ForeignItem) {
walk_item(self, ni);
}
fn flat_map_foreign_item(&mut self, ni: P<ForeignItem>) -> SmallVec<[P<ForeignItem>; 1]> {
walk_flat_map_foreign_item(self, ni)
}
fn visit_item(&mut self, i: &mut Item) {
walk_item(self, i);
}
fn flat_map_item(&mut self, i: P<Item>) -> SmallVec<[P<Item>; 1]> {
walk_flat_map_item(self, i)
}
fn visit_fn_header(&mut self, header: &mut FnHeader) {
walk_fn_header(self, header);
}
fn visit_field_def(&mut self, fd: &mut FieldDef) {
walk_field_def(self, fd);
}
fn flat_map_field_def(&mut self, fd: FieldDef) -> SmallVec<[FieldDef; 1]> {
walk_flat_map_field_def(self, fd)
}
fn visit_assoc_item(&mut self, i: &mut AssocItem, ctxt: AssocCtxt) {
walk_assoc_item(self, i, ctxt)
}
fn flat_map_assoc_item(
&mut self,
i: P<AssocItem>,
ctxt: AssocCtxt,
) -> SmallVec<[P<AssocItem>; 1]> {
walk_flat_map_assoc_item(self, i, ctxt)
}
fn visit_contract(&mut self, c: &mut FnContract) {
walk_contract(self, c);
}
fn visit_fn_decl(&mut self, d: &mut FnDecl) {
walk_fn_decl(self, d);
}
/// `Span` and `NodeId` are mutated at the caller site.
fn visit_fn(&mut self, fk: FnKind<'_>, _: Span, _: NodeId) {
walk_fn(self, fk)
}
fn visit_coroutine_kind(&mut self, a: &mut CoroutineKind) {
walk_coroutine_kind(self, a);
}
fn visit_closure_binder(&mut self, b: &mut ClosureBinder) {
walk_closure_binder(self, b);
}
fn visit_block(&mut self, b: &mut Block) {
walk_block(self, b);
}
fn flat_map_stmt(&mut self, s: Stmt) -> SmallVec<[Stmt; 1]> {
walk_flat_map_stmt(self, s)
}
fn visit_arm(&mut self, arm: &mut Arm) {
walk_arm(self, arm);
}
fn flat_map_arm(&mut self, arm: Arm) -> SmallVec<[Arm; 1]> {
walk_flat_map_arm(self, arm)
}
fn visit_pat(&mut self, p: &mut P<Pat>) {
walk_pat(self, p);
}
fn visit_anon_const(&mut self, c: &mut AnonConst) {
walk_anon_const(self, c);
}
fn visit_expr(&mut self, e: &mut P<Expr>) {
walk_expr(self, e);
}
/// This method is a hack to workaround unstable of `stmt_expr_attributes`.
/// It can be removed once that feature is stabilized.
fn visit_method_receiver_expr(&mut self, ex: &mut P<Expr>) {
self.visit_expr(ex)
}
fn filter_map_expr(&mut self, e: P<Expr>) -> Option<P<Expr>> {
walk_filter_map_expr(self, e)
}
fn visit_generic_arg(&mut self, arg: &mut GenericArg) {
walk_generic_arg(self, arg);
}
fn visit_ty(&mut self, t: &mut P<Ty>) {
walk_ty(self, t);
}
fn visit_ty_pat(&mut self, t: &mut TyPat) {
walk_ty_pat(self, t);
}
fn visit_lifetime(&mut self, l: &mut Lifetime) {
walk_lifetime(self, l);
}
fn visit_assoc_item_constraint(&mut self, c: &mut AssocItemConstraint) {
walk_assoc_item_constraint(self, c);
}
fn visit_foreign_mod(&mut self, nm: &mut ForeignMod) {
walk_foreign_mod(self, nm);
}
fn visit_variant(&mut self, v: &mut Variant) {
walk_variant(self, v);
}
fn flat_map_variant(&mut self, v: Variant) -> SmallVec<[Variant; 1]> {
walk_flat_map_variant(self, v)
}
fn visit_ident(&mut self, i: &mut Ident) {
self.visit_span(&mut i.span);
}
fn visit_path(&mut self, p: &mut Path) {
walk_path(self, p);
}
fn visit_path_segment(&mut self, p: &mut PathSegment) {
walk_path_segment(self, p)
}
fn visit_qself(&mut self, qs: &mut Option<P<QSelf>>) {
walk_qself(self, qs);
}
fn visit_generic_args(&mut self, p: &mut GenericArgs) {
walk_generic_args(self, p);
}
fn visit_local(&mut self, l: &mut Local) {
walk_local(self, l);
}
fn visit_mac_call(&mut self, mac: &mut MacCall) {
walk_mac(self, mac);
}
fn visit_macro_def(&mut self, def: &mut MacroDef) {
walk_macro_def(self, def);
}
fn visit_label(&mut self, label: &mut Label) {
walk_label(self, label);
}
fn visit_attribute(&mut self, at: &mut Attribute) {
walk_attribute(self, at);
}
fn visit_param(&mut self, param: &mut Param) {
walk_param(self, param);
}
fn flat_map_param(&mut self, param: Param) -> SmallVec<[Param; 1]> {
walk_flat_map_param(self, param)
}
fn visit_generics(&mut self, generics: &mut Generics) {
walk_generics(self, generics);
}
fn visit_trait_ref(&mut self, tr: &mut TraitRef) {
walk_trait_ref(self, tr);
}
fn visit_poly_trait_ref(&mut self, p: &mut PolyTraitRef) {
walk_poly_trait_ref(self, p);
}
fn visit_variant_data(&mut self, vdata: &mut VariantData) {
walk_variant_data(self, vdata);
}
fn visit_generic_param(&mut self, param: &mut GenericParam) {
walk_generic_param(self, param)
}
fn flat_map_generic_param(&mut self, param: GenericParam) -> SmallVec<[GenericParam; 1]> {
walk_flat_map_generic_param(self, param)
}
fn visit_param_bound(&mut self, tpb: &mut GenericBound, _ctxt: BoundKind) {
walk_param_bound(self, tpb);
}
fn visit_precise_capturing_arg(&mut self, arg: &mut PreciseCapturingArg) {
walk_precise_capturing_arg(self, arg);
}
fn visit_expr_field(&mut self, f: &mut ExprField) {
walk_expr_field(self, f);
}
fn flat_map_expr_field(&mut self, f: ExprField) -> SmallVec<[ExprField; 1]> {
walk_flat_map_expr_field(self, f)
}
fn flat_map_where_predicate(
&mut self,
where_predicate: WherePredicate,
) -> SmallVec<[WherePredicate; 1]> {
walk_flat_map_where_predicate(self, where_predicate)
}
fn visit_where_predicate_kind(&mut self, kind: &mut WherePredicateKind) {
walk_where_predicate_kind(self, kind)
}
fn visit_vis(&mut self, vis: &mut Visibility) {
walk_vis(self, vis);
}
fn visit_id(&mut self, _id: &mut NodeId) {
// Do nothing.
}
// Span visiting is no longer used, but we keep it for now,
// in case it's needed for something like #127241.
fn visit_span(&mut self, _sp: &mut Span) {
// Do nothing.
}
fn visit_pat_field(&mut self, fp: &mut PatField) {
walk_pat_field(self, fp)
}
fn flat_map_pat_field(&mut self, fp: PatField) -> SmallVec<[PatField; 1]> {
walk_flat_map_pat_field(self, fp)
}
fn visit_inline_asm(&mut self, asm: &mut InlineAsm) {
walk_inline_asm(self, asm)
}
fn visit_inline_asm_sym(&mut self, sym: &mut InlineAsmSym) {
walk_inline_asm_sym(self, sym)
}
fn visit_format_args(&mut self, fmt: &mut FormatArgs) {
walk_format_args(self, fmt)
}
fn visit_capture_by(&mut self, capture_by: &mut CaptureBy) {
walk_capture_by(self, capture_by)
}
fn visit_fn_ret_ty(&mut self, fn_ret_ty: &mut FnRetTy) {
walk_fn_ret_ty(self, fn_ret_ty)
}
}
super::common_visitor_and_walkers!((mut) MutVisitor);
macro_rules! generate_flat_map_visitor_fns {
($($name:ident, $Ty:ty, $flat_map_fn:ident$(, $param:ident: $ParamTy:ty)*;)+) => {
$(
fn $name<V: MutVisitor>(
vis: &mut V,
values: &mut ThinVec<$Ty>,
$(
$param: $ParamTy,
)*
) {
values.flat_map_in_place(|value| vis.$flat_map_fn(value$(,$param)*));
}
)+
}
}
generate_flat_map_visitor_fns! {
visit_items, P<Item>, flat_map_item;
visit_foreign_items, P<ForeignItem>, flat_map_foreign_item;
visit_generic_params, GenericParam, flat_map_generic_param;
visit_stmts, Stmt, flat_map_stmt;
visit_exprs, P<Expr>, filter_map_expr;
visit_expr_fields, ExprField, flat_map_expr_field;
visit_pat_fields, PatField, flat_map_pat_field;
visit_variants, Variant, flat_map_variant;
visit_assoc_items, P<AssocItem>, flat_map_assoc_item, ctxt: AssocCtxt;
visit_where_predicates, WherePredicate, flat_map_where_predicate;
visit_params, Param, flat_map_param;
visit_field_defs, FieldDef, flat_map_field_def;
visit_arms, Arm, flat_map_arm;
}
#[inline]
fn visit_thin_vec<T, F>(elems: &mut ThinVec<T>, mut visit_elem: F)
where
F: FnMut(&mut T),
{
for elem in elems {
visit_elem(elem);
}
}
fn visit_attrs<T: MutVisitor>(vis: &mut T, attrs: &mut AttrVec) {
for attr in attrs.iter_mut() {
vis.visit_attribute(attr);
}
}
pub fn walk_flat_map_pat_field<T: MutVisitor>(
vis: &mut T,
mut fp: PatField,
) -> SmallVec<[PatField; 1]> {
vis.visit_pat_field(&mut fp);
smallvec![fp]
}
fn visit_nested_use_tree<V: MutVisitor>(
vis: &mut V,
nested_tree: &mut UseTree,
nested_id: &mut NodeId,
) {
vis.visit_id(nested_id);
vis.visit_use_tree(nested_tree);
}
pub fn walk_flat_map_arm<T: MutVisitor>(vis: &mut T, mut arm: Arm) -> SmallVec<[Arm; 1]> {
vis.visit_arm(&mut arm);
smallvec![arm]
}
pub fn walk_flat_map_variant<T: MutVisitor>(
vis: &mut T,
mut variant: Variant,
) -> SmallVec<[Variant; 1]> {
vis.visit_variant(&mut variant);
smallvec![variant]
}
fn walk_meta_list_item<T: MutVisitor>(vis: &mut T, li: &mut MetaItemInner) {
match li {
MetaItemInner::MetaItem(mi) => vis.visit_meta_item(mi),
MetaItemInner::Lit(_lit) => {}
}
}
fn walk_meta_item<T: MutVisitor>(vis: &mut T, mi: &mut MetaItem) {
let MetaItem { unsafety: _, path: _, kind, span } = mi;
match kind {
MetaItemKind::Word => {}
MetaItemKind::List(mis) => visit_thin_vec(mis, |mi| vis.visit_meta_list_item(mi)),
MetaItemKind::NameValue(_s) => {}
}
vis.visit_span(span);
}
pub fn walk_flat_map_param<T: MutVisitor>(vis: &mut T, mut param: Param) -> SmallVec<[Param; 1]> {
vis.visit_param(&mut param);
smallvec![param]
}
pub fn walk_flat_map_generic_param<T: MutVisitor>(
vis: &mut T,
mut param: GenericParam,
) -> SmallVec<[GenericParam; 1]> {
vis.visit_generic_param(&mut param);
smallvec![param]
}
fn walk_ty_alias_where_clauses<T: MutVisitor>(vis: &mut T, tawcs: &mut TyAliasWhereClauses) {
let TyAliasWhereClauses { before, after, split: _ } = tawcs;
let TyAliasWhereClause { has_where_token: _, span: span_before } = before;
let TyAliasWhereClause { has_where_token: _, span: span_after } = after;
vis.visit_span(span_before);
vis.visit_span(span_after);
}
pub fn walk_flat_map_where_predicate<T: MutVisitor>(
vis: &mut T,
mut pred: WherePredicate,
) -> SmallVec<[WherePredicate; 1]> {
walk_where_predicate(vis, &mut pred);
smallvec![pred]
}
pub fn walk_flat_map_field_def<T: MutVisitor>(
vis: &mut T,
mut fd: FieldDef,
) -> SmallVec<[FieldDef; 1]> {
vis.visit_field_def(&mut fd);
smallvec![fd]
}
pub fn walk_flat_map_expr_field<T: MutVisitor>(
vis: &mut T,
mut f: ExprField,
) -> SmallVec<[ExprField; 1]> {
vis.visit_expr_field(&mut f);
smallvec![f]
}
pub fn walk_item_kind<K: WalkItemKind>(
kind: &mut K,
span: Span,
id: NodeId,
visibility: &mut Visibility,
ctxt: K::Ctxt,
vis: &mut impl MutVisitor,
) {
kind.walk(span, id, visibility, ctxt, vis)
}
pub fn walk_flat_map_item(vis: &mut impl MutVisitor, mut item: P<Item>) -> SmallVec<[P<Item>; 1]> {
vis.visit_item(&mut item);
smallvec![item]
}
pub fn walk_flat_map_foreign_item(
vis: &mut impl MutVisitor,
mut item: P<ForeignItem>,
) -> SmallVec<[P<ForeignItem>; 1]> {
vis.visit_foreign_item(&mut item);
smallvec![item]
}
pub fn walk_flat_map_assoc_item(
vis: &mut impl MutVisitor,
mut item: P<AssocItem>,
ctxt: AssocCtxt,
) -> SmallVec<[P<AssocItem>; 1]> {
vis.visit_assoc_item(&mut item, ctxt);
smallvec![item]
}
pub fn walk_filter_map_expr<T: MutVisitor>(vis: &mut T, mut e: P<Expr>) -> Option<P<Expr>> {
vis.visit_expr(&mut e);
Some(e)
}
pub fn walk_flat_map_stmt<T: MutVisitor>(
vis: &mut T,
Stmt { kind, span, mut id }: Stmt,
) -> SmallVec<[Stmt; 1]> {
vis.visit_id(&mut id);
let mut stmts: SmallVec<[Stmt; 1]> = walk_flat_map_stmt_kind(vis, kind)
.into_iter()
.map(|kind| Stmt { id, kind, span })
.collect();
match &mut stmts[..] {
[] => {}
[stmt] => vis.visit_span(&mut stmt.span),
_ => panic!(
"cloning statement `NodeId`s is prohibited by default, \
the visitor should implement custom statement visiting"
),
}
stmts
}
fn walk_flat_map_stmt_kind<T: MutVisitor>(vis: &mut T, kind: StmtKind) -> SmallVec<[StmtKind; 1]> {
match kind {
StmtKind::Let(mut local) => smallvec![StmtKind::Let({
vis.visit_local(&mut local);
local
})],
StmtKind::Item(item) => vis.flat_map_item(item).into_iter().map(StmtKind::Item).collect(),
StmtKind::Expr(expr) => vis.filter_map_expr(expr).into_iter().map(StmtKind::Expr).collect(),
StmtKind::Semi(expr) => vis.filter_map_expr(expr).into_iter().map(StmtKind::Semi).collect(),
StmtKind::Empty => smallvec![StmtKind::Empty],
StmtKind::MacCall(mut mac) => {
let MacCallStmt { mac: mac_, style: _, attrs, tokens: _ } = mac.deref_mut();
visit_attrs(vis, attrs);
vis.visit_mac_call(mac_);
smallvec![StmtKind::MacCall(mac)]
}
}
}
fn walk_capture_by<T: MutVisitor>(vis: &mut T, capture_by: &mut CaptureBy) {
match capture_by {
CaptureBy::Ref => {}
CaptureBy::Value { move_kw } => {
vis.visit_span(move_kw);
}
CaptureBy::Use { use_kw } => {
vis.visit_span(use_kw);
}
}
}
#[derive(Debug)]
pub enum FnKind<'a> {
/// E.g., `fn foo()`, `fn foo(&self)`, or `extern "Abi" fn foo()`.
Fn(FnCtxt, &'a mut Visibility, &'a mut Fn),
/// E.g., `|x, y| body`.
Closure(
&'a mut ClosureBinder,
&'a mut Option<CoroutineKind>,
&'a mut P<FnDecl>,
&'a mut P<Expr>,
),
}