Function isEscaped

src/pkg/utils/regex_to_glob.ts:138–146

(s: string, idx: number)

    return [...r].reverse().join("");
  }
  function isEscaped(s: string, idx: number): boolean {
    let k = idx - 1,
      cnt = 0;
    while (k >= 0 && s[k] === "\\") {
      cnt++;
      k--;
    }
    return cnt % 2 === 1;
  }

  // 提取字面头/尾（解转义）及其源长度
  function literalHeadInfo(s: string): { lit: string; srcLen: number } {