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Remove NtIdent and NtLifetime.

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The extra span is now recorded in the new `TokenKind::NtIdent` and
`TokenKind::NtLifetime`. These both consist of a single token, and so
there's no operator precedence problems with inserting them directly
into the token stream.

The other way to do this would be to wrap the ident/lifetime in invisible
delimiters, but there's a lot of code that assumes an interpolated
ident/lifetime fits in a single token, and changing all that code to work with
invisible delimiters would have been a pain. (Maybe it could be done in a
follow-up.)

This change might not seem like much of a win, but it's a first step toward the
much bigger and long-desired removal of `Nonterminal` and
`TokenKind::Interpolated`. That change is big and complex enough that it's
worth doing this piece separately. (Indeed, this commit is based on part of a
late commit in #114647, a prior attempt at that big and complex change.)
This commit is contained in:
Nicholas Nethercote 2024-04-22 19:46:51 +10:00
parent 9a63a42cb7
commit 95e519ecbf
11 changed files with 131 additions and 104 deletions
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77
compiler/rustc_ast/src/token.rs
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@ -318,11 +318,20 @@ pub enum TokenKind {
/// It's recommended to use `Token::(ident,uninterpolate,uninterpolated_span)` to
/// treat regular and interpolated identifiers in the same way.
Ident(Symbol, IdentIsRaw),
/// This identifier (and its span) is the identifier passed to the
/// declarative macro. The span in the surrounding `Token` is the span of
/// the `ident` metavariable in the macro's RHS.
NtIdent(Ident, IdentIsRaw),
/// Lifetime identifier token.
/// Do not forget about `NtLifetime` when you want to match on lifetime identifiers.
/// It's recommended to use `Token::(lifetime,uninterpolate,uninterpolated_span)` to
/// treat regular and interpolated lifetime identifiers in the same way.
Lifetime(Symbol),
/// This identifier (and its span) is the lifetime passed to the
/// declarative macro. The span in the surrounding `Token` is the span of
/// the `lifetime` metavariable in the macro's RHS.
NtLifetime(Ident),
/// An embedded AST node, as produced by a macro. This only exists for
/// historical reasons. We'd like to get rid of it, for multiple reasons.
@ -444,8 +453,9 @@ impl Token {
/// Note that keywords are also identifiers, so they should use this
/// if they keep spans or perform edition checks.
pub fn uninterpolated_span(&self) -> Span {
match &self.kind {
Interpolated(nt) => nt.use_span(),
match self.kind {
NtIdent(ident, _) | NtLifetime(ident) => ident.span,
Interpolated(ref nt) => nt.use_span(),
_ => self.span,
}
}
@ -463,7 +473,7 @@ impl Token {
}
OpenDelim(..) | CloseDelim(..) | Literal(..) | DocComment(..) | Ident(..)
| Lifetime(..) | Interpolated(..) | Eof => false,
| NtIdent(..) | Lifetime(..) | NtLifetime(..) | Interpolated(..) | Eof => false,
}
}
@ -613,14 +623,9 @@ impl Token {
/// into the regular identifier or lifetime token it refers to,
/// otherwise returns the original token.
pub fn uninterpolate(&self) -> Cow<'_, Token> {
match &self.kind {
Interpolated(nt) => match &**nt {
NtIdent(ident, is_raw) => {
Cow::Owned(Token::new(Ident(ident.name, *is_raw), ident.span))
}
NtLifetime(ident) => Cow::Owned(Token::new(Lifetime(ident.name), ident.span)),
_ => Cow::Borrowed(self),
},
match self.kind {
NtIdent(ident, is_raw) => Cow::Owned(Token::new(Ident(ident.name, is_raw), ident.span)),
NtLifetime(ident) => Cow::Owned(Token::new(Lifetime(ident.name), ident.span)),
_ => Cow::Borrowed(self),
}
}
@ -629,12 +634,9 @@ impl Token {
#[inline]
pub fn ident(&self) -> Option<(Ident, IdentIsRaw)> {
// We avoid using `Token::uninterpolate` here because it's slow.
match &self.kind {
&Ident(name, is_raw) => Some((Ident::new(name, self.span), is_raw)),
Interpolated(nt) => match &**nt {
NtIdent(ident, is_raw) => Some((*ident, *is_raw)),
_ => None,
},
match self.kind {
Ident(name, is_raw) => Some((Ident::new(name, self.span), is_raw)),
NtIdent(ident, is_raw) => Some((ident, is_raw)),
_ => None,
}
}
@ -643,12 +645,9 @@ impl Token {
#[inline]
pub fn lifetime(&self) -> Option<Ident> {
// We avoid using `Token::uninterpolate` here because it's slow.
match &self.kind {
&Lifetime(name) => Some(Ident::new(name, self.span)),
Interpolated(nt) => match &**nt {
NtLifetime(ident) => Some(*ident),
_ => None,
},
match self.kind {
Lifetime(name) => Some(Ident::new(name, self.span)),
NtLifetime(ident) => Some(ident),
_ => None,
}
}
@ -837,8 +836,10 @@ impl Token {
Le | EqEq | Ne | Ge | AndAnd | OrOr | Tilde | BinOpEq(..) | At | DotDotDot
| DotDotEq | Comma | Semi | PathSep | RArrow | LArrow | FatArrow | Pound | Dollar
| Question | OpenDelim(..) | CloseDelim(..) | Literal(..) | Ident(..)
| Lifetime(..) | Interpolated(..) | DocComment(..) | Eof => return None,
| Question | OpenDelim(..) | CloseDelim(..) | Literal(..) | Ident(..) | NtIdent(..)
| Lifetime(..) | NtLifetime(..) | Interpolated(..) | DocComment(..) | Eof => {
return None;
}
};
Some(Token::new(kind, self.span.to(joint.span)))
@ -861,9 +862,6 @@ pub enum Nonterminal {
NtPat(P<ast::Pat>),
NtExpr(P<ast::Expr>),
NtTy(P<ast::Ty>),
/// The span is for the identifier argument passed to the macro.
NtIdent(Ident, IdentIsRaw),
NtLifetime(Ident),
NtLiteral(P<ast::Expr>),
/// Stuff inside brackets for attributes
NtMeta(P<ast::AttrItem>),
@ -958,7 +956,6 @@ impl Nonterminal {
NtPat(pat) => pat.span,
NtExpr(expr) | NtLiteral(expr) => expr.span,
NtTy(ty) => ty.span,
NtIdent(ident, _) | NtLifetime(ident) => ident.span,
NtMeta(attr_item) => attr_item.span(),
NtPath(path) => path.span,
NtVis(vis) => vis.span,
@ -974,8 +971,6 @@ impl Nonterminal {
NtExpr(..) => "expression",
NtLiteral(..) => "literal",
NtTy(..) => "type",
NtIdent(..) => "identifier",
NtLifetime(..) => "lifetime",
NtMeta(..) => "attribute",
NtPath(..) => "path",
NtVis(..) => "visibility",
@ -984,18 +979,12 @@ impl Nonterminal {
}
impl PartialEq for Nonterminal {
fn eq(&self, rhs: &Self) -> bool {
match (self, rhs) {
(NtIdent(ident_lhs, is_raw_lhs), NtIdent(ident_rhs, is_raw_rhs)) => {
ident_lhs == ident_rhs && is_raw_lhs == is_raw_rhs
}
(NtLifetime(ident_lhs), NtLifetime(ident_rhs)) => ident_lhs == ident_rhs,
// FIXME: Assume that all "complex" nonterminal are not equal, we can't compare them
// correctly based on data from AST. This will prevent them from matching each other
// in macros. The comparison will become possible only when each nonterminal has an
// attached token stream from which it was parsed.
_ => false,
}
fn eq(&self, _rhs: &Self) -> bool {
// FIXME: Assume that all nonterminals are not equal, we can't compare them
// correctly based on data from AST. This will prevent them from matching each other
// in macros. The comparison will become possible only when each nonterminal has an
// attached token stream from which it was parsed.
false
}
}
@ -1008,12 +997,10 @@ impl fmt::Debug for Nonterminal {
NtPat(..) => f.pad("NtPat(..)"),
NtExpr(..) => f.pad("NtExpr(..)"),
NtTy(..) => f.pad("NtTy(..)"),
NtIdent(..) => f.pad("NtIdent(..)"),
NtLiteral(..) => f.pad("NtLiteral(..)"),
NtMeta(..) => f.pad("NtMeta(..)"),
NtPath(..) => f.pad("NtPath(..)"),
NtVis(..) => f.pad("NtVis(..)"),
NtLifetime(..) => f.pad("NtLifetime(..)"),
}
}
}