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perf(es/lexer): Apply various optimizations #9095

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merged 6 commits into from
Jun 21, 2024
+123 −117
Merged

perf(es/lexer): Apply various optimizations #9095

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28c0dd7
Lexer.next_token
kdy1 Jun 21, 2024
5db4506
fix
kdy1 Jun 21, 2024
3ef77fa
#[cold]
kdy1 Jun 21, 2024
f787f2d
Small tidy
kdy1 Jun 21, 2024
e605cf7
Use smallvec
kdy1 Jun 21, 2024
3c4a0ea
Merge branch 'main' into perf-parser
swc-bot Jun 21, 2024
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1 change: 1 addition & 0 deletions crates/swc_ecma_parser/src/lexer/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1210,6 +1210,7 @@ impl<'a> Lexer<'a> {
Ok(Token::Regex(content, flags))
}

#[cold]
fn read_shebang(&mut self) -> LexResult<Option<Atom>> {
if self.input.cur() != Some('#') || self.input.peek() != Some('!') {
return Ok(None);
Expand Down
237 changes: 121 additions & 116 deletions crates/swc_ecma_parser/src/lexer/state.rs
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
use std::mem::take;

use smallvec::{smallvec, SmallVec};
use swc_common::{BytePos, Span};
use tracing::trace;

Expand Down Expand Up @@ -192,145 +193,149 @@ impl Tokens for Lexer<'_> {
}
}

impl<'a> Iterator for Lexer<'a> {
type Item = TokenAndSpan;

fn next(&mut self) -> Option<Self::Item> {
let mut start = self.cur_pos();

let res = (|| -> Result<Option<_>, _> {
if let Some(start) = self.state.next_regexp {
return Ok(Some(self.read_regexp(start)?));
}
impl Lexer<'_> {
fn next_token(&mut self, start: &mut BytePos) -> Result<Option<Token>, Error> {
if let Some(start) = self.state.next_regexp {
return Ok(Some(self.read_regexp(start)?));
}

if self.state.is_first {
if let Some(shebang) = self.read_shebang()? {
return Ok(Some(Token::Shebang(shebang)));
}
if self.state.is_first {
if let Some(shebang) = self.read_shebang()? {
return Ok(Some(Token::Shebang(shebang)));
}
}

self.state.had_line_break = self.state.is_first;
self.state.is_first = false;
self.state.had_line_break = self.state.is_first;
self.state.is_first = false;

// skip spaces before getting next character, if we are allowed to.
if self.state.can_skip_space() {
self.skip_space::<true>()?;
start = self.input.cur_pos();
};
// skip spaces before getting next character, if we are allowed to.
if self.state.can_skip_space() {
self.skip_space::<true>()?;
*start = self.input.cur_pos();
};

match self.input.cur() {
Some(..) => {}
// End of input.
None => {
if let Some(comments) = self.comments.as_mut() {
let comments_buffer = self.comments_buffer.as_mut().unwrap();
let last = self.state.prev_hi;

// move the pending to the leading or trailing
for c in comments_buffer.take_pending_leading() {
// if the file had no tokens and no shebang, then treat any
// comments in the leading comments buffer as leading.
// Otherwise treat them as trailing.
if last == self.start_pos {
comments_buffer.push(BufferedComment {
kind: BufferedCommentKind::Leading,
pos: last,
comment: c,
});
} else {
comments_buffer.push(BufferedComment {
kind: BufferedCommentKind::Trailing,
pos: last,
comment: c,
});
}
match self.input.cur() {
Some(..) => {}
// End of input.
None => {
if let Some(comments) = self.comments.as_mut() {
let comments_buffer = self.comments_buffer.as_mut().unwrap();
let last = self.state.prev_hi;

// move the pending to the leading or trailing
for c in comments_buffer.take_pending_leading() {
// if the file had no tokens and no shebang, then treat any
// comments in the leading comments buffer as leading.
// Otherwise treat them as trailing.
if last == self.start_pos {
comments_buffer.push(BufferedComment {
kind: BufferedCommentKind::Leading,
pos: last,
comment: c,
});
} else {
comments_buffer.push(BufferedComment {
kind: BufferedCommentKind::Trailing,
pos: last,
comment: c,
});
}
}

// now fill the user's passed in comments
for comment in comments_buffer.take_comments() {
match comment.kind {
BufferedCommentKind::Leading => {
comments.add_leading(comment.pos, comment.comment);
}
BufferedCommentKind::Trailing => {
comments.add_trailing(comment.pos, comment.comment);
}
// now fill the user's passed in comments
for comment in comments_buffer.take_comments() {
match comment.kind {
BufferedCommentKind::Leading => {
comments.add_leading(comment.pos, comment.comment);
}
BufferedCommentKind::Trailing => {
comments.add_trailing(comment.pos, comment.comment);
}
}
}

return Ok(None);
}
};

// println!(
// "\tContext: ({:?}) {:?}",
// self.input.cur().unwrap(),
// self.state.context.0
// );

self.state.start = start;
return Ok(None);
}
};

if self.syntax.jsx() && !self.ctx.in_property_name && !self.ctx.in_type {
//jsx
if self.state.context.current() == Some(TokenContext::JSXExpr) {
return self.read_jsx_token();
}
// println!(
// "\tContext: ({:?}) {:?}",
// self.input.cur().unwrap(),
// self.state.context.0
// );

let c = self.cur();
if let Some(c) = c {
if self.state.context.current() == Some(TokenContext::JSXOpeningTag)
|| self.state.context.current() == Some(TokenContext::JSXClosingTag)
{
if c.is_ident_start() {
return self.read_jsx_word().map(Some);
}
self.state.start = *start;

if c == '>' {
unsafe {
// Safety: cur() is Some('>')
self.input.bump();
}
return Ok(Some(Token::JSXTagEnd));
}
if self.syntax.jsx() && !self.ctx.in_property_name && !self.ctx.in_type {
//jsx
if self.state.context.current() == Some(TokenContext::JSXExpr) {
return self.read_jsx_token();
}

if (c == '\'' || c == '"')
&& self.state.context.current() == Some(TokenContext::JSXOpeningTag)
{
return self.read_jsx_str(c).map(Some);
}
let c = self.cur();
if let Some(c) = c {
if self.state.context.current() == Some(TokenContext::JSXOpeningTag)
|| self.state.context.current() == Some(TokenContext::JSXClosingTag)
{
if c.is_ident_start() {
return self.read_jsx_word().map(Some);
}

if c == '<' && self.state.is_expr_allowed && self.input.peek() != Some('!') {
let had_line_break_before_last = self.had_line_break_before_last();
let cur_pos = self.input.cur_pos();

if c == '>' {
unsafe {
// Safety: cur() is Some('<')
// Safety: cur() is Some('>')
self.input.bump();
}
return Ok(Some(Token::JSXTagEnd));
}

if had_line_break_before_last && self.is_str("<<<<<< ") {
let span = Span::new(cur_pos, cur_pos + BytePos(7), Default::default());
if (c == '\'' || c == '"')
&& self.state.context.current() == Some(TokenContext::JSXOpeningTag)
{
return self.read_jsx_str(c).map(Some);
}
}

self.emit_error_span(span, SyntaxError::TS1185);
self.skip_line_comment(6);
self.skip_space::<true>()?;
return self.read_token();
}
if c == '<' && self.state.is_expr_allowed && self.input.peek() != Some('!') {
let had_line_break_before_last = self.had_line_break_before_last();
let cur_pos = self.input.cur_pos();

unsafe {
// Safety: cur() is Some('<')
self.input.bump();
}

if had_line_break_before_last && self.is_str("<<<<<< ") {
let span = Span::new(cur_pos, cur_pos + BytePos(7), Default::default());

return Ok(Some(Token::JSXTagStart));
self.emit_error_span(span, SyntaxError::TS1185);
self.skip_line_comment(6);
self.skip_space::<true>()?;
return self.read_token();
}

return Ok(Some(Token::JSXTagStart));
}
}
}

if let Some(TokenContext::Tpl {}) = self.state.context.current() {
let start = self.state.tpl_start;
return self.read_tmpl_token(start).map(Some);
}
if let Some(TokenContext::Tpl {}) = self.state.context.current() {
let start = self.state.tpl_start;
return self.read_tmpl_token(start).map(Some);
}

self.read_token()
}
}

impl<'a> Iterator for Lexer<'a> {
type Item = TokenAndSpan;

fn next(&mut self) -> Option<Self::Item> {
let mut start = self.cur_pos();

self.read_token()
})();
let res = self.next_token(&mut start);

let token = match res.map_err(Token::Error).map_err(Some) {
Ok(t) => t,
Expand Down Expand Up @@ -367,7 +372,7 @@ impl<'a> Iterator for Lexer<'a> {

impl State {
pub fn new(syntax: Syntax, start_pos: BytePos) -> Self {
let context = TokenContexts(vec![TokenContext::BraceStmt]);
let context = TokenContexts(smallvec![TokenContext::BraceStmt]);

State {
is_expr_allowed: true,
Expand Down Expand Up @@ -642,7 +647,7 @@ impl State {
}

#[derive(Clone, Default)]
pub struct TokenContexts(pub(crate) Vec<TokenContext>);
pub struct TokenContexts(pub(crate) SmallVec<[TokenContext; 32]>);

impl TokenContexts {
/// Returns true if following `LBrace` token is `block statement` according
Expand Down Expand Up @@ -783,7 +788,7 @@ impl TokenContext {
Self::BraceExpr
| Self::TplQuasi
| Self::ParenExpr
| Self::Tpl { .. }
| Self::Tpl
| Self::FnExpr
| Self::ClassExpr
| Self::JSXExpr
Expand All @@ -792,7 +797,7 @@ impl TokenContext {

pub(crate) const fn preserve_space(&self) -> bool {
match self {
Self::Tpl { .. } | Self::JSXExpr => true,
Self::Tpl | Self::JSXExpr => true,
_ => false,
}
}
Expand All @@ -813,9 +818,9 @@ where
let res = f(&mut l);

#[cfg(debug_assertions)]
let c = vec![TokenContext::BraceStmt];
let c = TokenContexts(smallvec![TokenContext::BraceStmt]);
#[cfg(debug_assertions)]
debug_assert_eq!(l.state.context.0, c);
debug_assert_eq!(l.state.context.0, c.0);

res
})
Expand Down
2 changes: 1 addition & 1 deletion crates/swc_ecma_parser/src/parser/typescript.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2771,7 +2771,7 @@ impl<I: Tokens> Parser<I> {
let cloned = self.input.token_context().clone();

self.input
.set_token_context(TokenContexts(vec![cloned.0[0]]));
.set_token_context(TokenContexts(smallvec::smallvec![cloned.0[0]]));
let res = op(self);
self.input.set_token_context(cloned);

Expand Down
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