tctx/tracestate.mjs

W3C Trace Contexts made simple

class Tracestate extends Map {
	set(key, value) {
		if (!valid_key(key) || !valid_value(value)) throw new TypeError("Invalid key or value");
		key = key.trim();
		if (this.has(key)) this.delete(key);
else if (this.size >= 32) this.delete([...this.keys()][0]);
		return super.set(key, value);
	}
	toString() {
		let o = "", c = 0;
		let els = [...this].reverse();
		while (c < Math.min(32, els.length) && (o += `${els[c][0]}=${els[c++][1]},`));
		return o.slice(0, -1);
	}
}
export function make(initial) {
	return new Tracestate(initial);
}
export function parse(value) {
	let i = 0, c = 0, v = [];
	let pair, pairs = value.split(",");
	while (i < pairs.length) {
		pair = pairs[i++];
		let idx = pair.indexOf("=");
		if (!~idx) continue;
		let key = pair.slice(0, idx).toLowerCase().trim();
		let value = pair.slice(idx + 1).trimRight();
		if (valid_key(key) && valid_value(value)) {
			v.unshift([key, value]);
			++c;
		}
	}
	return make(v);
}
function valid_value(value) {
	let v = String(value);
	return /^[ -~]{0,255}[!-~]$/.test(v) && !(~v.indexOf(",") || ~v.indexOf("="));
}
function valid_key(key) {
	return /^[a-z0-9][_0-9a-z-*/]{0,255}$/.test(key) || /^[a-z0-9][_0-9a-z-*/]{0,240}@[a-z][_0-9a-z-*/]{0,13}$/.test(key);
}