code: public int getDepth() {
      String path = mUri.getPath();
      if (path.isEmpty() || CUR_DIR.equals(path)) {
        return 0;
      }
      if (hasWindowsDrive(path, true)) {
        path = path.substring(3);
      }
  
      int depth = 0;
  
      int slash = path.length() == 1 && path.charAt(0) == '/' ? -1 : 0;
      while (slash != -1) {
        depth++;
        slash = path.indexOf(SEPARATOR, slash + 1);
      }
      return depth;
    }
docs: Returns the number of elements of the path component of the {@link AlluxioURI}.
  
  <pre>
  /                                  = 0
  .                                  = 0
  /a                                 = 1
  /a/b/c.txt                         = 3
  /a/b/                              = 3
  a/b                                = 2
  a\b                                = 2
  alluxio://localhost:19998/         = 0
  alluxio://localhost:19998/a        = 1
  alluxio://localhost:19998/a/b.txt  = 2
  C:\a                               = 1
  C:                                 = 0
  </pre>
  
  @return the depth