srecord noeq GazelleVScript(S text) {
  LS tok;
  
  class Run is Steppable {
    ListAndIndex<S> ptr;
    
    // main variables
    settable IBWIntegralImage integralImage;
    settable BWImage bwImage;
      
    *() {
      parse();
      ptr = ListAndIndex(tok, 1);
    }
    
    public bool step() {
      S token = ptr!;
      if (token == null) false;
      next();
      if (isInteger(token)) {
        int i = parseInt(token);
        S token2 = tpp();
        if (eqic(token2, "p"))
          scaleToHeight(i);
        else if (eqic(token2, "c"))
          posterize(i);
        else
          warn("Unknown token: " + token);
      } else {
        warn("Unknown token: " + token);
      }
      true;
    }
    
    S tpp() { var token = ptr!; next(); ret token; }
    void next { if (!ptr.atEnd()) ptr = ptr.plus(2); }
    
    // operations
    
    void scaleToHeight(int pixelRows) {
      pixelRows = min(pixelRows, 512);
      if (integralImage == null)
        ret with warn("No integral image to scale down");
      bwImage = scaledBWImageFromBWIntegralImage_withMeta(pixelRows, integralImage);
    }
    
    void posterize(int colors) {
      colors = clamp(colors, 2, 256);
      if (bwImage == null)
        ret with warn("No image to posterize");
      else
        bwImage = posterizeBWImage_withMeta(colors, bwImage);
    }
    
    // end of operations
    
    O result() {
      ret or(bwImage, integralImage);
    }
    
    run { stepAll(this); }
  }
  
  void parse() {
    tok if null = javaTok(text);
  }
}