-module(gsc_ntree).

-export([
    nstem/2, meta/1, kids/1,
    flatten_tree/1, flatten_forest/1
]).


-include("$gsc_include/gsc.hrl").


%%=====================================================
%% API: functions
%%=====================================================

-spec nstem(Root, Forest) -> Tree when
        Root   :: S,
        Forest :: nforest(S, L),
        Tree   :: ntree(S, L),
        S      :: any(),
        L      :: any().

nstem(Root, List) ->
    {ns, Root, List}.


meta(#ns{meta = M}) -> M.
kids(#ns{kids = K}) -> K.



-spec flatten_tree(Tree) -> Leafs when
        Tree  :: ntree(_, L),
        Leafs :: [L],
        L     :: any().

flatten_tree(T) ->
    lists:flatten(ft(T)).



-spec flatten_forest(Forest) -> Leafs when
        Forest :: nforest(_, L),
        Leafs  :: [L],
        L      :: any().

flatten_forest(F) ->
    lists:flatten(ff(F)).


ft(#ns{kids = F}) -> ff(F);
ft(Leaf)          -> [Leaf].

ff(F) ->
    [ft(T) || T <- F].