optic

%%%-------------------------------------------------------------------

%%% @doc

%%% A set of optics specific to gb_sets.

%%% @end

%%%-------------------------------------------------------------------

-module(optic_gb_sets).

%% API

-export([all/0,

         all/1]).

%%%===================================================================

%%% API

%%%===================================================================


%% @see all/1

-spec all() -> optic:optic().
all() ->
    all(#{}).

%% @doc

%% Focus on all elements of a gb_set.

%%

%% Example:

%%

%% ```

%% > optic:get([optic_gb_sets:all()], gb_sets:from_list([1,2,3])).

%% {ok,[1,2,3]}

%% '''

%% @end

%% @param Options Common optic options.

%% @returns An opaque optic record.

-spec all(Options) -> optic:optic() when

      Options :: optic:variations().
all(Options) ->
    Fold =
    fun (Fun, Acc, Set) ->
            case is_gb_set(Set) of
                true ->
                    {ok, gb_sets:fold(Fun, Acc, Set)};
                false ->
                    {error, undefined}
            end
    end,
    MapFold =
    fun (Fun, Acc, Set) ->
            case is_gb_set(Set) of
                true ->
                    {ok, gb_sets:fold(fun (Elem, {InnerSet, InnerAcc}) ->
                                              {NewElem, NewAcc} = Fun(Elem, InnerAcc),
                                              {gb_sets:add_element(NewElem, InnerSet), NewAcc}
                                      end,
                                      {gb_sets:new(), Acc},
                                      Set)};
                false ->
                    {error, undefined}
            end
    end,
    New =
    fun (_Data, _Template) ->
            gb_sets:new()
    end,
    Optic = optic:new(MapFold, Fold),
    optic:variations(Optic, Options, New).

%%%===================================================================

%%% Internal Functions

%%%===================================================================


is_gb_set(Unknown) ->
    try gb_sets:size(Unknown) of
        _ ->
            true
    catch
        error:function_clause ->
            false
    end.