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perf: Fix performance regression for generator #17627

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68832fb
fix
liuxingbaoyu Dec 2, 2025
1fb11ab
fix
liuxingbaoyu Dec 2, 2025
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176 changes: 80 additions & 96 deletions packages/babel-generator/src/generators/deprecated.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -8,112 +8,96 @@ export type DeprecatedBabel7ASTTypes =
| "RecordExpression"
| "TupleExpression";

export function addDeprecatedGenerators(PrinterClass: typeof Printer) {
// Add Babel 7 generator methods that is removed in Babel 8
if (!process.env.BABEL_8_BREAKING) {
const deprecatedBabel7Generators = {
Noop(this: Printer) {},
export function Noop(this: Printer) {}

TSExpressionWithTypeArguments(
this: Printer,
// @ts-ignore(Babel 7 vs Babel 8) Babel 7 AST
node: t.TSExpressionWithTypeArguments,
) {
this.print(node.expression);
this.print(node.typeParameters);
},

DecimalLiteral(this: Printer, node: any) {
const raw = this.getPossibleRaw(node);
if (!this.format.minified && raw !== undefined) {
this.word(raw);
return;
}
this.word(node.value + "m");
},
export function TSExpressionWithTypeArguments(
this: Printer,
// @ts-ignore(Babel 7 vs Babel 8) Babel 7 AST
node: t.TSExpressionWithTypeArguments,
) {
this.print(node.expression);
this.print(node.typeParameters);
}

// @ts-ignore(Babel 7 vs Babel 8) - t.RecordExpression only exists in Babel 7
RecordExpression(this: Printer, node: t.RecordExpression) {
const props = node.properties;
export function DecimalLiteral(this: Printer, node: any) {
const raw = this.getPossibleRaw(node);
if (!this.format.minified && raw !== undefined) {
this.word(raw);
return;
}
this.word(node.value + "m");
}

let startToken;
let endToken;
// @ts-ignore(Babel 7 vs Babel 8) - t.RecordExpression only exists in Babel 7
export function RecordExpression(this: Printer, node: t.RecordExpression) {
const props = node.properties;

if (this.format.recordAndTupleSyntaxType === "bar") {
startToken = "{|";
endToken = "|}";
} else if (
this.format.recordAndTupleSyntaxType !== "hash" &&
this.format.recordAndTupleSyntaxType != null
) {
throw new Error(
`The "recordAndTupleSyntaxType" generator option must be "bar" or "hash" (${JSON.stringify(
this.format.recordAndTupleSyntaxType,
)} received).`,
);
} else {
startToken = "#{";
endToken = "}";
}
let startToken;
let endToken;

this.token(startToken);
if (this.format.recordAndTupleSyntaxType === "bar") {
startToken = "{|";
endToken = "|}";
} else if (
this.format.recordAndTupleSyntaxType !== "hash" &&
this.format.recordAndTupleSyntaxType != null
) {
throw new Error(
`The "recordAndTupleSyntaxType" generator option must be "bar" or "hash" (${JSON.stringify(
this.format.recordAndTupleSyntaxType,
)} received).`,
);
} else {
startToken = "#{";
endToken = "}";
}

if (props.length) {
this.space();
this.printList(
props,
this.shouldPrintTrailingComma(endToken),
true,
true,
);
this.space();
}
this.token(endToken);
},
this.token(startToken);

// @ts-ignore(Babel 7 vs Babel 8) - t.TupleExpression only exists in Babel 7
TupleExpression(this: Printer, node: t.TupleExpression) {
const elems = node.elements;
const len = elems.length;
if (props.length) {
this.space();
this.printList(props, this.shouldPrintTrailingComma(endToken), true, true);
this.space();
}
this.token(endToken);
}

let startToken;
let endToken;
if (process.env.BABEL_8_BREAKING) {
startToken = "#[";
endToken = "]";
} else {
if (this.format.recordAndTupleSyntaxType === "bar") {
startToken = "[|";
endToken = "|]";
} else if (this.format.recordAndTupleSyntaxType === "hash") {
startToken = "#[";
endToken = "]";
} else {
throw new Error(
`${this.format.recordAndTupleSyntaxType} is not a valid recordAndTuple syntax type`,
);
}
}
// @ts-ignore(Babel 7 vs Babel 8) - t.TupleExpression only exists in Babel 7
export function TupleExpression(this: Printer, node: t.TupleExpression) {
const elems = node.elements;
const len = elems.length;

this.token(startToken);
let startToken;
let endToken;
if (process.env.BABEL_8_BREAKING) {
startToken = "#[";
endToken = "]";
} else {
if (this.format.recordAndTupleSyntaxType === "bar") {
startToken = "[|";
endToken = "|]";
} else if (this.format.recordAndTupleSyntaxType === "hash") {
startToken = "#[";
endToken = "]";
} else {
throw new Error(
`${this.format.recordAndTupleSyntaxType} is not a valid recordAndTuple syntax type`,
);
}
}

for (let i = 0; i < elems.length; i++) {
const elem = elems[i];
if (elem) {
if (i > 0) this.space();
this.print(elem);
if (i < len - 1 || this.shouldPrintTrailingComma(endToken)) {
this.token(",", false, i);
}
}
}
this.token(startToken);

this.token(endToken);
},
} satisfies Record<
DeprecatedBabel7ASTTypes,
(this: Printer, node: any) => void
>;
Object.assign(PrinterClass.prototype, deprecatedBabel7Generators);
for (let i = 0; i < elems.length; i++) {
const elem = elems[i];
if (elem) {
if (i > 0) this.space();
this.print(elem);
if (i < len - 1 || this.shouldPrintTrailingComma(endToken)) {
this.token(",", false, i);
}
}
}

this.token(endToken);
}
8 changes: 3 additions & 5 deletions packages/babel-generator/src/printer.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -15,10 +15,8 @@ import type { Opts as jsescOptions } from "jsesc";
import { TokenMap } from "./token-map.ts";
import type { GeneratorOptions } from "./index.ts";
import * as generatorFunctions from "./generators/index.ts";
import {
addDeprecatedGenerators,
type DeprecatedBabel7ASTTypes,
} from "./generators/deprecated.ts";
import type { DeprecatedBabel7ASTTypes } from "./generators/deprecated.ts";
import * as deprecatedGeneratorFunctions from "./generators/deprecated.ts" with { if: "!process.env.BABEL_8_BREAKING" };
import type SourceMap from "./source-map.ts";
import type { TraceMap } from "@jridgewell/trace-mapping";
import type { Token } from "@babel/parser";
Expand Down Expand Up @@ -1420,7 +1418,7 @@ class Printer {
Object.assign(Printer.prototype, generatorFunctions);

if (!process.env.BABEL_8_BREAKING) {
addDeprecatedGenerators(Printer);
Object.assign(Printer.prototype, deprecatedGeneratorFunctions);
}

type GeneratorFunctions = typeof generatorFunctions;
Expand Down
10 changes: 0 additions & 10 deletions packages/babel-runtime-corejs3/helpers/esm/regeneratorDefineIM.js
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14 changes: 0 additions & 14 deletions packages/babel-runtime-corejs3/helpers/esm/tryCatch.js
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