sclass SimpleLeftToRightParser {
  S text;
  LS tok;
  ListAndIndex<S> ptr, mainLoopPtr;
  S currentToken;
  bool caseInsensitive;
  
  *(S *text) {}
  *(LS *tok) {}
  
  S t() { ret currentToken; }
  S tpp() { var t = t(); next(); ret t; }
  
  bool is(S t) { ret eqOrEqic(caseInsensitive, currentToken, t); }
  
  bool isInteger() { ret isInteger(t()); }
  bool isInteger(S s) { ret main isInteger(s); }
  
  void next { if (!endOfText()) ptr(ptr.plus(2)); }
  
  void ptr(ListAndIndex<S> ptr) { this.ptr = ptr; fetch(); }

  bool atEnd aka endOfText() { ret ptr.atEnd(); }
    
  void fetch { currentToken = ptr!; }
  
  void init {
    tok if null = javaTok(text);
    ptr(ListAndIndex(tok, 1));
  }
  
  bool mainLoop() {
    if (atEnd()) false;
    if (eq(mainLoopPtr, ptr))
      fail("main loop didn't advance");
    mainLoopPtr = ptr;
    true;
  }
  
  void unknownToken {
    warn("Unknown token: " + t());
  }
}