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perf(transformer/jsx): use ArenaString to store decoded JSX text #10249

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perf(transformer/jsx): use ArenaString to store decoded JSX text #10249

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39 changes: 26 additions & 13 deletions crates/oxc_transformer/src/jsx/jsx_impl.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -88,7 +88,7 @@
//!
//! * Babel plugin implementation: <https://github.com/babel/babel/tree/v7.26.2/packages/babel-helper-builder-react-jsx>

use oxc_allocator::{Box as ArenaBox, TakeIn, Vec as ArenaVec};
use oxc_allocator::{Box as ArenaBox, String as ArenaString, TakeIn, Vec as ArenaVec};
use oxc_ast::{AstBuilder, NONE, ast::*};
use oxc_ecmascript::PropName;
use oxc_span::{Atom, SPAN, Span};
Expand Down Expand Up @@ -860,7 +860,7 @@ impl<'a> JsxImpl<'a, '_> {
) -> Expression<'a> {
match value {
Some(JSXAttributeValue::StringLiteral(s)) => {
let jsx_text = Self::decode_entities(s.value.as_str());
let jsx_text = Self::decode_entities(s.value.as_str(), ctx).into_bump_str();
ctx.ast.expression_string_literal(s.span, jsx_text, None)
}
Some(JSXAttributeValue::Element(e)) => self.transform_jsx_element(e, ctx),
Expand Down Expand Up @@ -948,8 +948,8 @@ impl<'a> JsxImpl<'a, '_> {
}

fn transform_jsx_text(text: &JSXText<'a>, ctx: &TraverseCtx<'a>) -> Option<Expression<'a>> {
Self::fixup_whitespace_and_decode_entities(text.value.as_str())
.map(|s| ctx.ast.expression_string_literal(text.span, s, None))
Self::fixup_whitespace_and_decode_entities(text.value.as_str(), ctx)
.map(|s| ctx.ast.expression_string_literal(text.span, s.into_bump_str(), None))
}

/// JSX trims whitespace at the end and beginning of lines, except that the
Expand All @@ -967,14 +967,17 @@ impl<'a> JsxImpl<'a, '_> {
/// - Remove empty lines and join the rest with " ".
///
/// <https://github.com/microsoft/TypeScript/blob/f0374ce2a9c465e27a15b7fa4a347e2bd9079450/src/compiler/transformers/jsx.ts#L557-L608>
fn fixup_whitespace_and_decode_entities(text: &str) -> Option<String> {
let mut acc: Option<String> = None;
fn fixup_whitespace_and_decode_entities(
text: &str,
ctx: &TraverseCtx<'a>,
) -> Option<ArenaString<'a>> {
let mut acc: Option<ArenaString<'a>> = None;
let mut first_non_whitespace: Option<usize> = Some(0);
let mut last_non_whitespace: Option<usize> = None;
for (index, c) in text.char_indices() {
if is_line_terminator(c) {
if let (Some(first), Some(last)) = (first_non_whitespace, last_non_whitespace) {
acc = Some(Self::add_line_of_jsx_text(acc, &text[first..last]));
acc = Some(Self::add_line_of_jsx_text(acc, &text[first..last], ctx));
}
first_non_whitespace = None;
} else if !is_white_space_single_line(c) {
Expand All @@ -985,22 +988,32 @@ impl<'a> JsxImpl<'a, '_> {
}
}
if let Some(first) = first_non_whitespace {
Some(Self::add_line_of_jsx_text(acc, &text[first..]))
Some(Self::add_line_of_jsx_text(acc, &text[first..], ctx))
} else {
acc
}
}

fn add_line_of_jsx_text(acc: Option<String>, trimmed_line: &str) -> String {
let decoded = Self::decode_entities(trimmed_line);
if let Some(acc) = acc { format!("{acc} {decoded}") } else { decoded }
fn add_line_of_jsx_text(
acc: Option<ArenaString<'a>>,
trimmed_line: &str,
ctx: &TraverseCtx<'a>,
) -> ArenaString<'a> {
let decoded = Self::decode_entities(trimmed_line, ctx);
if let Some(mut acc) = acc {
acc.push(' ');
acc.push_str(&decoded);
acc
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@Dunqing Dunqing Apr 5, 2025

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decoded as part of AST at the end, so I think it is okay here.

} else {
decoded
}
}

/// Replace entities like "&nbsp;", "&#123;", and "&#xDEADBEEF;" with the characters they encode.
/// * See <https://en.wikipedia.org/wiki/List_of_XML_and_HTML_character_entity_references>
/// Code adapted from <https://github.com/microsoft/TypeScript/blob/514f7e639a2a8466c075c766ee9857a30ed4e196/src/compiler/transformers/jsx.ts#L617C1-L635>
fn decode_entities(s: &str) -> String {
let mut buffer = String::new();
fn decode_entities(s: &str, ctx: &TraverseCtx<'a>) -> ArenaString<'a> {
let mut buffer = ArenaString::new_in(ctx.ast.allocator);
let mut chars = s.char_indices();
let mut prev = 0;
while let Some((i, c)) = chars.next() {
Expand Down
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