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[Babel 8] Improve generator performance #17718

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Merged
nicolo-ribaudo merged 1 commit into from
Jan 23, 2026
Merged

[Babel 8] Improve generator performance #17718

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19 changes: 13 additions & 6 deletions Gulpfile.mts
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Original file line number Diff line number Diff line change
Expand Up @@ -474,7 +474,9 @@ function buildRollup(packages: PackageInfo[], buildStandalone?: boolean) {
preferBuiltins: !buildStandalone,
}),
rollupJson(),
src === "packages/babel-parser" &&
["packages/babel-parser", "packages/babel-generator"].includes(
src
) &&
getBabelOutputPlugin({
configFile: false,
babelrc: false,
Expand Down Expand Up @@ -517,14 +519,19 @@ function buildRollup(packages: PackageInfo[], buildStandalone?: boolean) {
!vals.has(node.property.name)
) {
all = false;
return;
}
parentPath.replaceWith(
t.numericLiteral(vals.get(node.property.name))
);
});

if (all) path.remove();
if (all) {
binding.referencePaths.forEach(({ parentPath }) => {
const { node } = parentPath;
parentPath.replaceWith(
// @ts-expect-error checked above
t.numericLiteral(vals.get(node.property.name))
);
});
path.remove();
}
},
},
};
Expand Down
51 changes: 43 additions & 8 deletions babel.config.js
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Original file line number Diff line number Diff line change
Expand Up @@ -182,7 +182,7 @@ module.exports = function (api) {
plugins: ["babel-plugin-transform-charcodes"],
},
{
test: ["packages/babel-generator"].map(normalize),
test: ["packages/babel-generator/src"].map(normalize),
plugins: [pluginGeneratorOptimization],
},
{
Expand Down Expand Up @@ -549,25 +549,60 @@ function pluginBabelParserTokenType({
* @returns {import("@babel/core").PluginObject}
*/
function pluginGeneratorOptimization({ types: t }) {
const generatorNames = [];
fs.globSync(
pathUtils.join(__dirname, "./packages/babel-generator/src/generators/*.ts")
).forEach(file => {
if (file.endsWith("deprecated.ts")) return;
const content = fs.readFileSync(file, "utf8");
const ast = parseSync(content, {
configFile: false,
parserOpts: { plugins: ["typescript"] },
});
t.traverseFast(ast, node => {
let name;
if (t.isExportSpecifier(node)) {
name = t.isStringLiteral(node.exported)
? node.exported.value
: node.exported.name;
} else if (
t.isExportNamedDeclaration(node) &&
t.isFunctionDeclaration(node.declaration)
) {
name = node.declaration.id.name;
}
if (name && !name.startsWith("_")) generatorNames.push(name);
});
});
generatorNames.sort();
return {
visitor: {
CallExpression: {
exit(path) {
const node = path.node;
const { callee, arguments: args } = path.node;
if (t.isIdentifier(callee) && callee.name === "__node") {
t.assertStringLiteral(args[0]);
const type = args[0].value;
const generatorIndex = generatorNames.indexOf(type);
if (generatorIndex === -1) {
throw path.buildCodeFrameError(`Unknown generator type: ${type}`);
}
path.replaceWith(t.numericLiteral(generatorIndex));
return;
}

if (
t.isMemberExpression(node.callee) &&
t.isThisExpression(node.callee.object)
t.isMemberExpression(callee) &&
t.isThisExpression(callee.object)
) {
const args = node.arguments;

if (
node.callee.property.name === "token" &&
callee.property.name === "token" &&
args.length === 1 &&
t.isStringLiteral(args[0])
) {
const str = args[0].value;
if (str.length === 1) {
node.callee.property.name = "tokenChar";
callee.property.name = "tokenChar";
args[0] = t.numericLiteral(str.charCodeAt(0));
}
}
Expand Down
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