// goes well with the stage {} macro (see tok_stages)

srecord Stages2(L<Stages2.Stage> stages) is Steppable, Runnable {

  int iStage;

  Stage stage;

  // set this to record timing for each stage

  settable transient FunctionTimings<S> timings;

  { stages = new L; }

  record noeq Stage(S name, Runnable body) {

    run {

      if (timings != null)

        timings.do(name, body);

      else

        callF(body);

    }

    toString { ret or2(name, "Unnamed stage"); }

  }

  public bool step() {

    if (iStage >= l(stages)) false;

    var stage = stages.get(iStage++);

    stage.run();

    true;

  }

  Stage stage(Stage stage) {

    stages.add(stage);

    ret stage;

  }

  Stage stage(S name, Runnable body) {

    ret stage(new Stage(name, body));

  }

  run { stepAll(this); }

  int indexOfStage(Stage stage) {

    ret stages.indexOf(stage);

  }

  void stepUntilStage(Stage stage) {

    int index = indexOfStage(stage);

    while (iStage <= index && step()) {}

  }

  L<Stage> completedStages() {

    ret cloneTakeFirst(stages, iStage);

  }

  L<Stage> remainingStages() {

    ret cloneDropFirst(stages, iStage);

  }

}