Function unionLeaves

javascript/selenium-webdriver/project_bidi_schema.mjs:323–332

(ref, types, seen = new Set())

// Resolve a union member to its leaf record names, following nested unions and
// single-ref aliases. Every BiDi union bottoms out in records, so this is total.
function unionLeaves(ref, types, seen = new Set()) {
  if (seen.has(ref)) return []
  seen.add(ref)
  const t = types[ref]
  if (!t) return []
  if (t.kind === 'record') return [ref]
  if (t.kind === 'union') return t.variants.flatMap((v) => unionLeaves(v, types, seen))
  if (t.kind === 'alias' && t.type?.ref) return unionLeaves(t.type.ref, types, seen)
  return []
}

// Whether a union variant is an object (record) type — following aliases and nested
// unions to their leaves. An enum, or an alias to a primitive/list/map (or an inline