Skip to content

perf: fast native UTF-16 source copy into Wasm memory on Node #224

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
guybedford merged 1 commit into from
Jul 12, 2026
+6 −1
Merged

perf: fast native UTF-16 source copy into Wasm memory on Node #224

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
7 changes: 6 additions & 1 deletion src/lexer.ts
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -252,7 +252,12 @@ export function parse (source: string, name = '@'): readonly [
wasm.memory.grow(Math.ceil(extraMem / 65536));

const addr = wasm.sa(len - 1);
(isLE ? copyLE : copyBE)(source, new Uint16Array(wasm.memory.buffer, addr, len));
// Node's Buffer blits UTF-16 straight into Wasm memory ~10x faster than the
// charCodeAt fallback, in explicit LE matching Wasm regardless of host.
if (typeof Buffer !== 'undefined')
Buffer.from(wasm.memory.buffer, addr, (len - 1) * 2).write(source, 'utf16le');
else
(isLE ? copyLE : copyBE)(source, new Uint16Array(wasm.memory.buffer, addr, len));

if (!wasm.parse())
throw Object.assign(new Error(`Parse error ${name}:${source.slice(0, wasm.e()).split('\n').length}:${wasm.e() - source.lastIndexOf('\n', wasm.e() - 1)}`), { idx: wasm.e() });
Expand Down
Loading