sclass TokScanner {
  LS tok;
  int idx = 1; // always points to code token
  
  *() {}
  *(LS *tok) {}
  *(LS *tok, int *idx) { idx |= 1; }
  *(S s) { this(javaTok(s)); }
  
  S get(int ofs default 0) { ret _get(tok, idx+ofs*2); }
  S consume() { ret atEnd() ? null : tok.get((idx += 2)-2); }
  void consume(int n) { idx += n*2; }
  void skipTo(int idx) { this.idx = idx | 1; }
  
  bool atEnd() { ret idx >= l(tok); }
  
  S consumeBracketPart() {
    int idx2 = findEndOfBracketPart(tok, idx);
    S result = joinSubList(tok, idx, idx2);
    skipTo(idx2);
    ret result;
  }
}