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Auto merge of #114115 - nnethercote:less-token-tree-cloning, r=petrochenkov

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Less `TokenTree` cloning

`TokenTreeCursor` has this comment on it:
```
// FIXME: Many uses of this can be replaced with by-reference iterator to avoid clones.
```
This PR completes that FIXME. It doesn't have much perf effect, but at least we now know that.

r? `@petrochenkov`
This commit is contained in:
bors 2023-07-28 01:21:27 +00:00
commit 0699d99516
9 changed files with 83 additions and 90 deletions
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6
compiler/rustc_expand/src/config.rs
View file

@ -365,9 +365,9 @@ impl<'a> StripUnconfigured<'a> {
// Use the `#` in `#[cfg_attr(pred, attr)]` as the `#` token
// for `attr` when we expand it to `#[attr]`
let mut orig_trees = orig_tokens.into_trees();
let mut orig_trees = orig_tokens.trees();
let TokenTree::Token(pound_token @ Token { kind: TokenKind::Pound, .. }, _) =
orig_trees.next().unwrap()
orig_trees.next().unwrap().clone()
else {
panic!("Bad tokens for attribute {:?}", attr);
};
@ -377,7 +377,7 @@ impl<'a> StripUnconfigured<'a> {
if attr.style == AttrStyle::Inner {
// For inner attributes, we do the same thing for the `!` in `#![some_attr]`
let TokenTree::Token(bang_token @ Token { kind: TokenKind::Not, .. }, _) =
orig_trees.next().unwrap()
orig_trees.next().unwrap().clone()
else {
panic!("Bad tokens for attribute {:?}", attr);
};

4
compiler/rustc_expand/src/mbe/macro_rules.rs
View file

@ -500,7 +500,7 @@ pub fn compile_declarative_macro(
.map(|m| {
if let MatchedTokenTree(tt) = m {
let tt = mbe::quoted::parse(
TokenStream::new(vec![tt.clone()]),
&TokenStream::new(vec![tt.clone()]),
true,
&sess.parse_sess,
def.id,
@ -524,7 +524,7 @@ pub fn compile_declarative_macro(
.map(|m| {
if let MatchedTokenTree(tt) = m {
return mbe::quoted::parse(
TokenStream::new(vec![tt.clone()]),
&TokenStream::new(vec![tt.clone()]),
false,
&sess.parse_sess,
def.id,

42
compiler/rustc_expand/src/mbe/quoted.rs
View file

@ -36,7 +36,7 @@ const VALID_FRAGMENT_NAMES_MSG: &str = "valid fragment specifiers are \
///
/// A collection of `self::TokenTree`. There may also be some errors emitted to `sess`.
pub(super) fn parse(
input: tokenstream::TokenStream,
input: &tokenstream::TokenStream,
parsing_patterns: bool,
sess: &ParseSess,
node_id: NodeId,
@ -48,7 +48,7 @@ pub(super) fn parse(
// For each token tree in `input`, parse the token into a `self::TokenTree`, consuming
// additional trees if need be.
let mut trees = input.into_trees();
let mut trees = input.trees();
while let Some(tree) = trees.next() {
// Given the parsed tree, if there is a metavar and we are expecting matchers, actually
// parse out the matcher (i.e., in `$id:ident` this would parse the `:` and `ident`).
@ -56,7 +56,7 @@ pub(super) fn parse(
match tree {
TokenTree::MetaVar(start_sp, ident) if parsing_patterns => {
let span = match trees.next() {
Some(tokenstream::TokenTree::Token(Token { kind: token::Colon, span }, _)) => {
Some(&tokenstream::TokenTree::Token(Token { kind: token::Colon, span }, _)) => {
match trees.next() {
Some(tokenstream::TokenTree::Token(token, _)) => match token.ident() {
Some((frag, _)) => {
@ -96,10 +96,10 @@ pub(super) fn parse(
}
_ => token.span,
},
tree => tree.as_ref().map_or(span, tokenstream::TokenTree::span),
tree => tree.map_or(span, tokenstream::TokenTree::span),
}
}
tree => tree.as_ref().map_or(start_sp, tokenstream::TokenTree::span),
tree => tree.map_or(start_sp, tokenstream::TokenTree::span),
};
result.push(TokenTree::MetaVarDecl(span, ident, None));
@ -134,9 +134,9 @@ fn maybe_emit_macro_metavar_expr_feature(features: &Features, sess: &ParseSess,
/// - `parsing_patterns`: same as [parse].
/// - `sess`: the parsing session. Any errors will be emitted to this session.
/// - `features`: language features so we can do feature gating.
fn parse_tree(
tree: tokenstream::TokenTree,
outer_trees: &mut impl Iterator<Item = tokenstream::TokenTree>,
fn parse_tree<'a>(
tree: &'a tokenstream::TokenTree,
outer_trees: &mut impl Iterator<Item = &'a tokenstream::TokenTree>,
parsing_patterns: bool,
sess: &ParseSess,
node_id: NodeId,
@ -146,13 +146,13 @@ fn parse_tree(
// Depending on what `tree` is, we could be parsing different parts of a macro
match tree {
// `tree` is a `$` token. Look at the next token in `trees`
tokenstream::TokenTree::Token(Token { kind: token::Dollar, span }, _) => {
&tokenstream::TokenTree::Token(Token { kind: token::Dollar, span }, _) => {
// FIXME: Handle `Invisible`-delimited groups in a more systematic way
// during parsing.
let mut next = outer_trees.next();
let mut trees: Box<dyn Iterator<Item = tokenstream::TokenTree>>;
let mut trees: Box<dyn Iterator<Item = &tokenstream::TokenTree>>;
if let Some(tokenstream::TokenTree::Delimited(_, Delimiter::Invisible, tts)) = next {
trees = Box::new(tts.into_trees());
trees = Box::new(tts.trees());
next = trees.next();
} else {
trees = Box::new(outer_trees);
@ -160,7 +160,7 @@ fn parse_tree(
match next {
// `tree` is followed by a delimited set of token trees.
Some(tokenstream::TokenTree::Delimited(delim_span, delim, tts)) => {
Some(&tokenstream::TokenTree::Delimited(delim_span, delim, ref tts)) => {
if parsing_patterns {
if delim != Delimiter::Parenthesis {
span_dollar_dollar_or_metavar_in_the_lhs_err(
@ -228,7 +228,7 @@ fn parse_tree(
}
// `tree` is followed by another `$`. This is an escaped `$`.
Some(tokenstream::TokenTree::Token(Token { kind: token::Dollar, span }, _)) => {
Some(&tokenstream::TokenTree::Token(Token { kind: token::Dollar, span }, _)) => {
if parsing_patterns {
span_dollar_dollar_or_metavar_in_the_lhs_err(
sess,
@ -256,11 +256,11 @@ fn parse_tree(
}
// `tree` is an arbitrary token. Keep it.
tokenstream::TokenTree::Token(token, _) => TokenTree::Token(token),
tokenstream::TokenTree::Token(token, _) => TokenTree::Token(token.clone()),
// `tree` is the beginning of a delimited set of tokens (e.g., `(` or `{`). We need to
// descend into the delimited set and further parse it.
tokenstream::TokenTree::Delimited(span, delim, tts) => TokenTree::Delimited(
&tokenstream::TokenTree::Delimited(span, delim, ref tts) => TokenTree::Delimited(
span,
Delimited {
delim,
@ -286,16 +286,16 @@ fn kleene_op(token: &Token) -> Option<KleeneOp> {
/// - Ok(Ok((op, span))) if the next token tree is a KleeneOp
/// - Ok(Err(tok, span)) if the next token tree is a token but not a KleeneOp
/// - Err(span) if the next token tree is not a token
fn parse_kleene_op(
input: &mut impl Iterator<Item = tokenstream::TokenTree>,
fn parse_kleene_op<'a>(
input: &mut impl Iterator<Item = &'a tokenstream::TokenTree>,
span: Span,
) -> Result<Result<(KleeneOp, Span), Token>, Span> {
match input.next() {
Some(tokenstream::TokenTree::Token(token, _)) => match kleene_op(&token) {
Some(op) => Ok(Ok((op, token.span))),
None => Ok(Err(token)),
None => Ok(Err(token.clone())),
},
tree => Err(tree.as_ref().map_or(span, tokenstream::TokenTree::span)),
tree => Err(tree.map_or(span, tokenstream::TokenTree::span)),
}
}
@ -311,8 +311,8 @@ fn parse_kleene_op(
/// session `sess`. If the next one (or possibly two) tokens in `input` correspond to a Kleene
/// operator and separator, then a tuple with `(separator, KleeneOp)` is returned. Otherwise, an
/// error with the appropriate span is emitted to `sess` and a dummy value is returned.
fn parse_sep_and_kleene_op(
input: &mut impl Iterator<Item = tokenstream::TokenTree>,
fn parse_sep_and_kleene_op<'a>(
input: &mut impl Iterator<Item = &'a tokenstream::TokenTree>,
span: Span,
sess: &ParseSess,
) -> (Option<Token>, KleeneToken) {

9
compiler/rustc_expand/src/parse/tests.rs
View file

@ -69,9 +69,8 @@ fn bad_path_expr_1() {
#[test]
fn string_to_tts_macro() {
create_default_session_globals_then(|| {
let tts: Vec<_> =
string_to_stream("macro_rules! zip (($a)=>($a))".to_string()).into_trees().collect();
let tts: &[TokenTree] = &tts[..];
let stream = string_to_stream("macro_rules! zip (($a)=>($a))".to_string());
let tts = &stream.trees().collect::<Vec<_>>()[..];
match tts {
[
@ -300,9 +299,7 @@ fn ttdelim_span() {
.unwrap();
let ast::ExprKind::MacCall(mac) = &expr.kind else { panic!("not a macro") };
let tts: Vec<_> = mac.args.tokens.clone().into_trees().collect();
let span = tts.iter().rev().next().unwrap().span();
let span = mac.args.tokens.trees().last().unwrap().span();
match sess.source_map().span_to_snippet(span) {
Ok(s) => assert_eq!(&s[..], "{ body }"),

4
compiler/rustc_expand/src/proc_macro_server.rs
View file

@ -94,10 +94,10 @@ impl FromInternal<(TokenStream, &mut Rustc<'_, '_>)> for Vec<TokenTree<TokenStre
// Estimate the capacity as `stream.len()` rounded up to the next power
// of two to limit the number of required reallocations.
let mut trees = Vec::with_capacity(stream.len().next_power_of_two());
let mut cursor = stream.into_trees();
let mut cursor = stream.trees();
while let Some(tree) = cursor.next() {
let (Token { kind, span }, joint) = match tree {
let (Token { kind, span }, joint) = match tree.clone() {
tokenstream::TokenTree::Delimited(span, delim, tts) => {
let delimiter = pm::Delimiter::from_internal(delim);
trees.push(TokenTree::Group(Group {