Function parseFunction

packages/inline-mod/src/closure/parseFunction.ts:102–134

(funcString: string)

// are represented.  If these change, this will likely break us.
/** @internal */
export function parseFunction(funcString: string): [string, ParsedFunction] {
	const [error, functionCode] = parseFunctionCode(funcString);
	if (error) {
		return [error, undefined as any];
	}

	// In practice it's not guaranteed that a function's toString is parsable by TypeScript.
	// V8 intrinsics are prefixed with a '%' and TypeScript does not consider that to be a valid
	// identifier.
	const [parseError, file] = createSourceFile(functionCode);
	if (parseError) {
		return [parseError, undefined as any];
	}

	const capturedVariables = computeCapturedVariableNames(file!);

	// if we're looking at an arrow function, the it is always using lexical 'this's
	// so we don't have to bother even examining it.
	const usesNonLexicalThis = !functionCode.isArrowFunction && computeUsesNonLexicalThis(file!);

	const result = functionCode as ParsedFunction;
	result.capturedVariables = capturedVariables;
	result.usesNonLexicalThis = usesNonLexicalThis;

	if (result.capturedVariables.required.has('this')) {
		return [
			"arrow function captured 'this'. Assign 'this' to another name outside function and capture that.",
			result,
		];
	}

	return ['', result];
}

function parseFunctionCode(funcString: string): [string, ParsedFunctionCode] {
	if (funcString.startsWith('[Function:')) {