Function getDirectoryNamesAsync

src/hooks/fileSuggestions.ts:403–418

(
  files: string[],
)

 * the main thread for >10ms at a time.
 */
export async function getDirectoryNamesAsync(
  files: string[],
): Promise<string[]> {
  const directoryNames = new Set<string>()
  // Time-based chunking: yield after CHUNK_MS of work so slow machines get
  // smaller chunks and stay responsive.
  let chunkStart = performance.now()
  for (let i = 0; i < files.length; i++) {
    collectDirectoryNames(files, i, i + 1, directoryNames)
    if ((i & 0xff) === 0xff && performance.now() - chunkStart > CHUNK_MS) {
      await yieldToEventLoop()
      chunkStart = performance.now()
    }
  }
  return [...directoryNames].map(d => d + path.sep)
}

function collectDirectoryNames(
  files: string[],