rust/compiler/rustc_ast/src/ast_like.rs
Nicholas Nethercote 364b908d57 Remove Nonterminal::NtTT.
It's only needed for macro expansion, not as a general element in the
AST. This commit removes it, adds `NtOrTt` for the parser and macro
expansion cases, and renames the variants in `NamedMatch` to better
match the new type.
2022-03-28 10:03:02 +11:00

321 lines
11 KiB
Rust

use super::ptr::P;
use super::token::Nonterminal;
use super::tokenstream::LazyTokenStream;
use super::{Arm, Crate, ExprField, FieldDef, GenericParam, Param, PatField, Variant};
use super::{AssocItem, Expr, ForeignItem, Item, Local, MacCallStmt};
use super::{AttrItem, AttrKind, Block, Pat, Path, Ty, Visibility};
use super::{AttrVec, Attribute, Stmt, StmtKind};
use std::fmt;
use std::marker::PhantomData;
/// An `AstLike` represents an AST node (or some wrapper around
/// and AST node) which stores some combination of attributes
/// and tokens.
pub trait AstLike: Sized + fmt::Debug {
/// This is `true` if this `AstLike` might support 'custom' (proc-macro) inner
/// attributes. Attributes like `#![cfg]` and `#![cfg_attr]` are not
/// considered 'custom' attributes
///
/// If this is `false`, then this `AstLike` definitely does
/// not support 'custom' inner attributes, which enables some optimizations
/// during token collection.
const SUPPORTS_CUSTOM_INNER_ATTRS: bool;
fn attrs(&self) -> &[Attribute];
fn visit_attrs(&mut self, f: impl FnOnce(&mut Vec<Attribute>));
fn tokens_mut(&mut self) -> Option<&mut Option<LazyTokenStream>>;
}
impl<T: AstLike + 'static> AstLike for P<T> {
const SUPPORTS_CUSTOM_INNER_ATTRS: bool = T::SUPPORTS_CUSTOM_INNER_ATTRS;
fn attrs(&self) -> &[Attribute] {
(**self).attrs()
}
fn visit_attrs(&mut self, f: impl FnOnce(&mut Vec<Attribute>)) {
(**self).visit_attrs(f);
}
fn tokens_mut(&mut self) -> Option<&mut Option<LazyTokenStream>> {
(**self).tokens_mut()
}
}
impl AstLike for crate::token::Nonterminal {
const SUPPORTS_CUSTOM_INNER_ATTRS: bool = true;
fn attrs(&self) -> &[Attribute] {
match self {
Nonterminal::NtItem(item) => item.attrs(),
Nonterminal::NtStmt(stmt) => stmt.attrs(),
Nonterminal::NtExpr(expr) | Nonterminal::NtLiteral(expr) => expr.attrs(),
Nonterminal::NtPat(_)
| Nonterminal::NtTy(_)
| Nonterminal::NtMeta(_)
| Nonterminal::NtPath(_)
| Nonterminal::NtVis(_)
| Nonterminal::NtBlock(_)
| Nonterminal::NtIdent(..)
| Nonterminal::NtLifetime(_) => &[],
}
}
fn visit_attrs(&mut self, f: impl FnOnce(&mut Vec<Attribute>)) {
match self {
Nonterminal::NtItem(item) => item.visit_attrs(f),
Nonterminal::NtStmt(stmt) => stmt.visit_attrs(f),
Nonterminal::NtExpr(expr) | Nonterminal::NtLiteral(expr) => expr.visit_attrs(f),
Nonterminal::NtPat(_)
| Nonterminal::NtTy(_)
| Nonterminal::NtMeta(_)
| Nonterminal::NtPath(_)
| Nonterminal::NtVis(_)
| Nonterminal::NtBlock(_)
| Nonterminal::NtIdent(..)
| Nonterminal::NtLifetime(_) => {}
}
}
fn tokens_mut(&mut self) -> Option<&mut Option<LazyTokenStream>> {
match self {
Nonterminal::NtItem(item) => item.tokens_mut(),
Nonterminal::NtStmt(stmt) => stmt.tokens_mut(),
Nonterminal::NtExpr(expr) | Nonterminal::NtLiteral(expr) => expr.tokens_mut(),
Nonterminal::NtPat(pat) => pat.tokens_mut(),
Nonterminal::NtTy(ty) => ty.tokens_mut(),
Nonterminal::NtMeta(attr_item) => attr_item.tokens_mut(),
Nonterminal::NtPath(path) => path.tokens_mut(),
Nonterminal::NtVis(vis) => vis.tokens_mut(),
Nonterminal::NtBlock(block) => block.tokens_mut(),
Nonterminal::NtIdent(..) | Nonterminal::NtLifetime(..) => None,
}
}
}
fn visit_attrvec(attrs: &mut AttrVec, f: impl FnOnce(&mut Vec<Attribute>)) {
crate::mut_visit::visit_clobber(attrs, |attrs| {
let mut vec = attrs.into();
f(&mut vec);
vec.into()
});
}
impl AstLike for StmtKind {
// This might be an `StmtKind::Item`, which contains
// an item that supports inner attrs
const SUPPORTS_CUSTOM_INNER_ATTRS: bool = true;
fn attrs(&self) -> &[Attribute] {
match self {
StmtKind::Local(local) => local.attrs(),
StmtKind::Expr(expr) | StmtKind::Semi(expr) => expr.attrs(),
StmtKind::Item(item) => item.attrs(),
StmtKind::Empty => &[],
StmtKind::MacCall(mac) => &mac.attrs,
}
}
fn visit_attrs(&mut self, f: impl FnOnce(&mut Vec<Attribute>)) {
match self {
StmtKind::Local(local) => local.visit_attrs(f),
StmtKind::Expr(expr) | StmtKind::Semi(expr) => expr.visit_attrs(f),
StmtKind::Item(item) => item.visit_attrs(f),
StmtKind::Empty => {}
StmtKind::MacCall(mac) => visit_attrvec(&mut mac.attrs, f),
}
}
fn tokens_mut(&mut self) -> Option<&mut Option<LazyTokenStream>> {
Some(match self {
StmtKind::Local(local) => &mut local.tokens,
StmtKind::Item(item) => &mut item.tokens,
StmtKind::Expr(expr) | StmtKind::Semi(expr) => &mut expr.tokens,
StmtKind::Empty => return None,
StmtKind::MacCall(mac) => &mut mac.tokens,
})
}
}
impl AstLike for Stmt {
const SUPPORTS_CUSTOM_INNER_ATTRS: bool = StmtKind::SUPPORTS_CUSTOM_INNER_ATTRS;
fn attrs(&self) -> &[Attribute] {
self.kind.attrs()
}
fn visit_attrs(&mut self, f: impl FnOnce(&mut Vec<Attribute>)) {
self.kind.visit_attrs(f);
}
fn tokens_mut(&mut self) -> Option<&mut Option<LazyTokenStream>> {
self.kind.tokens_mut()
}
}
impl AstLike for Attribute {
const SUPPORTS_CUSTOM_INNER_ATTRS: bool = false;
fn attrs(&self) -> &[Attribute] {
&[]
}
fn visit_attrs(&mut self, _f: impl FnOnce(&mut Vec<Attribute>)) {}
fn tokens_mut(&mut self) -> Option<&mut Option<LazyTokenStream>> {
Some(match &mut self.kind {
AttrKind::Normal(_, tokens) => tokens,
kind @ AttrKind::DocComment(..) => {
panic!("Called tokens_mut on doc comment attr {:?}", kind)
}
})
}
}
impl<T: AstLike> AstLike for Option<T> {
const SUPPORTS_CUSTOM_INNER_ATTRS: bool = T::SUPPORTS_CUSTOM_INNER_ATTRS;
fn attrs(&self) -> &[Attribute] {
self.as_ref().map(|inner| inner.attrs()).unwrap_or(&[])
}
fn visit_attrs(&mut self, f: impl FnOnce(&mut Vec<Attribute>)) {
if let Some(inner) = self.as_mut() {
inner.visit_attrs(f);
}
}
fn tokens_mut(&mut self) -> Option<&mut Option<LazyTokenStream>> {
self.as_mut().and_then(|inner| inner.tokens_mut())
}
}
/// Helper trait for the macros below. Abstracts over
/// the two types of attribute fields that AST nodes
/// may have (`Vec<Attribute>` or `AttrVec`)
trait VecOrAttrVec {
fn visit(&mut self, f: impl FnOnce(&mut Vec<Attribute>));
}
impl VecOrAttrVec for Vec<Attribute> {
fn visit(&mut self, f: impl FnOnce(&mut Vec<Attribute>)) {
f(self)
}
}
impl VecOrAttrVec for AttrVec {
fn visit(&mut self, f: impl FnOnce(&mut Vec<Attribute>)) {
visit_attrvec(self, f)
}
}
macro_rules! derive_has_tokens_and_attrs {
(
const SUPPORTS_CUSTOM_INNER_ATTRS: bool = $inner_attrs:literal;
$($ty:path),*
) => { $(
impl AstLike for $ty {
const SUPPORTS_CUSTOM_INNER_ATTRS: bool = $inner_attrs;
fn attrs(&self) -> &[Attribute] {
&self.attrs
}
fn visit_attrs(&mut self, f: impl FnOnce(&mut Vec<Attribute>)) {
VecOrAttrVec::visit(&mut self.attrs, f)
}
fn tokens_mut(&mut self) -> Option<&mut Option<LazyTokenStream>> {
Some(&mut self.tokens)
}
}
)* }
}
macro_rules! derive_has_attrs_no_tokens {
($($ty:path),*) => { $(
impl AstLike for $ty {
const SUPPORTS_CUSTOM_INNER_ATTRS: bool = false;
fn attrs(&self) -> &[Attribute] {
&self.attrs
}
fn visit_attrs(&mut self, f: impl FnOnce(&mut Vec<Attribute>)) {
VecOrAttrVec::visit(&mut self.attrs, f)
}
fn tokens_mut(&mut self) -> Option<&mut Option<LazyTokenStream>> {
None
}
}
)* }
}
macro_rules! derive_has_tokens_no_attrs {
($($ty:path),*) => { $(
impl AstLike for $ty {
const SUPPORTS_CUSTOM_INNER_ATTRS: bool = false;
fn attrs(&self) -> &[Attribute] {
&[]
}
fn visit_attrs(&mut self, _f: impl FnOnce(&mut Vec<Attribute>)) {}
fn tokens_mut(&mut self) -> Option<&mut Option<LazyTokenStream>> {
Some(&mut self.tokens)
}
}
)* }
}
// These ast nodes support both active and inert attributes,
// so they have tokens collected to pass to proc macros
derive_has_tokens_and_attrs! {
// Both `Item` and `AssocItem` can have bodies, which
// can contain inner attributes
const SUPPORTS_CUSTOM_INNER_ATTRS: bool = true;
Item, AssocItem, ForeignItem
}
derive_has_tokens_and_attrs! {
const SUPPORTS_CUSTOM_INNER_ATTRS: bool = false;
Local, MacCallStmt, Expr
}
// These ast nodes only support inert attributes, so they don't
// store tokens (since nothing can observe them)
derive_has_attrs_no_tokens! {
FieldDef, Arm, ExprField, PatField, Variant, Param, GenericParam, Crate
}
// These AST nodes don't support attributes, but can
// be captured by a `macro_rules!` matcher. Therefore,
// they need to store tokens.
derive_has_tokens_no_attrs! {
Ty, Block, AttrItem, Pat, Path, Visibility
}
/// A newtype around an `AstLike` node that implements `AstLike` itself.
pub struct AstLikeWrapper<Wrapped, Tag> {
pub wrapped: Wrapped,
pub tag: PhantomData<Tag>,
}
impl<Wrapped, Tag> AstLikeWrapper<Wrapped, Tag> {
pub fn new(wrapped: Wrapped, _tag: Tag) -> AstLikeWrapper<Wrapped, Tag> {
AstLikeWrapper { wrapped, tag: Default::default() }
}
}
impl<Wrapped: fmt::Debug, Tag> fmt::Debug for AstLikeWrapper<Wrapped, Tag> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("AstLikeWrapper")
.field("wrapped", &self.wrapped)
.field("tag", &self.tag)
.finish()
}
}
impl<Wrapped: AstLike, Tag> AstLike for AstLikeWrapper<Wrapped, Tag> {
const SUPPORTS_CUSTOM_INNER_ATTRS: bool = Wrapped::SUPPORTS_CUSTOM_INNER_ATTRS;
fn attrs(&self) -> &[Attribute] {
self.wrapped.attrs()
}
fn visit_attrs(&mut self, f: impl FnOnce(&mut Vec<Attribute>)) {
self.wrapped.visit_attrs(f)
}
fn tokens_mut(&mut self) -> Option<&mut Option<LazyTokenStream>> {
self.wrapped.tokens_mut()
}
}