// TODO: line comments inside of /* */ comments (super-special case)
static LS getJavaLineComments(S s) {
  ret getJavaLineComments(javaTok(s));
}

static LS getJavaLineComments(LS tok) {
  new LS out;
  for (int i = 0; i < l(tok); i += 2)
    addAll(out, regexpAllFirstGroups("//([^\r\n]*)", tok.get(i)));
  ret out;
}