glob-negate.ts

/**
 * For vscode globs that can't just do `!`, but do have negative char classes
 *
 * turn `test` into `{[^t]*,?[^e]*,??[^s]*,???[^t]*}`
 *                  `{[^t]*,?{,[^r]*,?{,[^a]*,?[^p]*}}}`
 *
 * two directories need to be excluded, the following would be needed:
 * (ex. for negating 'test' or 'glob')
 *
 * `{[^tg]*,?[^el]*,??[^so]*,???[^tb]*,te{sb,ob,ot},t{ls,lo,eo}t,{tl,ge,gl}st,gl{ot,sb,st},g{es,ls,eo}b,{ge,tl,te}ob`
 *
 * @see https://github.com/microsoft/vscode/issues/869?ts=2#issuecomment-804615384
 */
function globNegate(s: string): string {
  switch (s.length) {
    case 0:
      return '';
    case 1:
      return `{[^${s}]*,??*}`;
    case 2:
      return `{[^${s[0]}]*,?[${s[1]}]*,???*}`;
  }
  return [...s]
    .reduceRight((p, c) => `{,[^${c}]*,?${p}}`, `?*`)
    .replace(/^\{,/, '{');
}