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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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25
compiler/rustc_ast/src/tokenstream.rs
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@@ -466,12 +466,6 @@ impl TokenStream {
pub fn from_nonterminal_ast(nt: &Nonterminal) -> TokenStream {
match nt {
Nonterminal::NtIdent(ident, is_raw) => {
TokenStream::token_alone(token::Ident(ident.name, *is_raw), ident.span)
}
Nonterminal::NtLifetime(ident) => {
TokenStream::token_alone(token::Lifetime(ident.name), ident.span)
}
Nonterminal::NtItem(item) => TokenStream::from_ast(item),
Nonterminal::NtBlock(block) => TokenStream::from_ast(block),
Nonterminal::NtStmt(stmt) if let StmtKind::Empty = stmt.kind => {
@@ -489,11 +483,17 @@ impl TokenStream {
}
fn flatten_token(token: &Token, spacing: Spacing) -> TokenTree {
match &token.kind {
token::Interpolated(nt) if let token::NtIdent(ident, is_raw) = &**nt => {
TokenTree::Token(Token::new(token::Ident(ident.name, *is_raw), ident.span), spacing)
match token.kind {
token::NtIdent(ident, is_raw) => {
TokenTree::Token(Token::new(token::Ident(ident.name, is_raw), ident.span), spacing)
}
token::Interpolated(nt) => TokenTree::Delimited(
token::NtLifetime(ident) => TokenTree::Delimited(
DelimSpan::from_single(token.span),
DelimSpacing::new(Spacing::JointHidden, spacing),
Delimiter::Invisible,
TokenStream::token_alone(token::Lifetime(ident.name), ident.span),
),
token::Interpolated(ref nt) => TokenTree::Delimited(
DelimSpan::from_single(token.span),
DelimSpacing::new(Spacing::JointHidden, spacing),
Delimiter::Invisible,
@@ -516,7 +516,10 @@ impl TokenStream {
pub fn flattened(&self) -> TokenStream {
fn can_skip(stream: &TokenStream) -> bool {
stream.trees().all(|tree| match tree {
TokenTree::Token(token, _) => !matches!(token.kind, token::Interpolated(_)),
TokenTree::Token(token, _) => !matches!(
token.kind,
token::NtIdent(..) | token::NtLifetime(..) | token::Interpolated(..)
),
TokenTree::Delimited(.., inner) => can_skip(inner),
})
}