type Punctuation = { readonly ch: string; readonly at: number; readonly paren: number; readonly brace: number }

export function* jsPunctuation(text: string): Generator<Punctuation> {
	let quote = ""
	let template = false
	let paren = 0
	let brace = 0
	const interpolations: number[] = []
	for (let at = 0; at < text.length; at++) {
		const ch = text[at] ?? ""
		if (quote) {
			if (ch === "\\") at++
			else if (ch === quote) quote = ""
			continue
		}
		if (template && interpolations.length === 0) {
			if (ch === "\\") at++
			else if (ch === "$" && text[at + 1] === "{") { interpolations.push(++brace); at++ }
			else if (ch === "`") template = false
			continue
		}
		if (ch === '"' || ch === "'") { quote = ch; continue }
		if (ch === "`") { template = true; continue }
		if (ch === "(") { paren++; continue }
		if (ch === ")") { paren--; continue }
		if (ch === "{") { brace++; continue }
		if (ch === "}") {
			brace--
			if (interpolations.length > 0 && brace < (interpolations.at(-1) ?? 0)) interpolations.pop()
			continue
		}
		yield { ch, at, paren, brace }
	}
}