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import { dirname, delimiter } from './std/path.ts'import xArgs, { FlagDescriptor, BinaryFlag, MAIN_COMMAND } from './x/args.ts'import getWasiPath from './wasi-path.ts'
/** * Extract names of files and folders from an array of CLI arguments * @param args CLI arguments * @returns Either `null` or an array *   * `null`: When filenames and dirnames are judged to be unnecessary *     (i.e. when user asks for `--help` or `--version`) *   * an array of names: When filenames and dirnames are necessary */function getTargetFiles(args: readonly string[]) {  const flagAlias = (x: string): FlagDescriptor => ({ alias: [x] })
  const res = xArgs    .with(BinaryFlag('help', flagAlias('h')))    .with(BinaryFlag('version', flagAlias('V')))    .with(BinaryFlag('stdio'))    .parse(args)
  if (res.tag !== MAIN_COMMAND) {    throw new Error('Something goes wrong.')  }
  // when the following flags present, sane-fmt won't touch the filesystem,  // preopens become an unnecessary burden on performance  const { help, version, stdio } = res.value  if (help || version || stdio) return null
  return res.remaining().rawValues()}
/** * Convert a `PATH`-like string into an object to add to `preopens` * @param env Value of `SANE_FMT_DENO_PREOPENS` environment variable * @returns Object compatible with `preopens` */function parsePreopensEnv(env?: string): Record<string, string> {  if (!env) return {}  const entries = env.split(delimiter).map(path => [getWasiPath(path), path])  return Object.fromEntries(entries)}
/** * Create a `preopens` object * @param args CLI arguments * @param env Value of `SANE_FMT_DENO_PREOPENS` environment variable * @returns Promise that resolves to a `preopens` object */export async function preopens(args: readonly string[], env?: string): Promise<Record<string, string>> {  const preopens: Record<string, string> = parsePreopensEnv(env)
  const targetFiles = getTargetFiles(args)  if (!targetFiles) return preopens
  if (!targetFiles.length) return { '.': '.', ...preopens }
  const directories = await Promise.all(    targetFiles.map(async name => {      try {        const stats = await Deno.lstat(name)        return stats.isDirectory ? name : dirname(name)      } catch (error) {        if (error instanceof Deno.errors.NotFound) {          return null        }        throw error      }    }),  )
  for (const name of directories) {    if (name === null) continue    preopens[getWasiPath(name)] = name  }
  return preopens}
export default preopens