# screen_class.ludic - a Ludic component shown as a whole screen
# a Ludic component shown as a screen: an instance at the top, keyed by its name
function fr_class_nodes(ui_st: mut UiState, cls: UiClass) -> UiNode {
  pl_begin(ui_st, cls.name)
  ui_st.uv_on = true
  lc_begin(ui_st)
  ui_st.in_build += 1
  ui_st.ui_view = null
  uc_load(ui_st, cls)
  let root = fr_root(ui_st, cls.name, cls.sheet)
  if cls.use == null { fr_class_use(cls) }
  let use = cls.use
  let e = env_new(ui_st, null)
  e.model = cls.none
  root.env = e
  bd_class(ui_st, use, e, cls.name, root.children)
  in_sweep(ui_st, cls.name)
  cs_tree(ui_st, root)
  ui_st.uv_on = false
  return root
}
function fr_root(ui_st: mut UiState, key: string, sheet: UiSheet) -> UiNode {
  let root = nd_take(ui_st)
  root.key = key
  root.tag = "screen"
  root.sheet = sheet
  return root
}

@alloc_ok("once per component class: the tag that shows it as a screen")
function fr_class_use(cls: UiClass) -> void {
  let use = new UiTpl
  use.tag = cls.name
  use.cls = cls
  use.keys = new []string
  use.vals = new []UiExpr
  use.on_keys = new []string
  use.on_acts = new []UiAct
  use.kids = new []UiTpl
  cls.use = use
  cls.none = Value.object()
}