ETS variant of circa

ecirca_ets.erl

-module(ecirca_ets).
-export([new/1,
         set/3,
         get/2,
         push/2,
         slice/3]).

-type res() :: {reference(), integer(), integer()}.

-spec new(pos_integer()) -> {ok, res()}.
new(Sz) ->
    try
        ets:new(circa_tab, [named_table, public])
    catch
        _:_ ->
            ignore % Hack
    end,
    {ok, {make_ref(), 0, Sz}}.

-spec set(res(), pos_integer(), pos_integer()) -> {ok, res()} |
                                                  {error, not_found}.
set({Ref, _C, Sz} = T, I, Val) when I >= 0 andalso I < Sz ->
    ets:insert(circa_tab, {{Ref, I}, Val}),
    {ok, T}.

-spec get(res(), pos_integer()) -> {ok, pos_integer()} |
                                   {error, not_found}.
get({Ref, _C, Sz}, I) when I >= 0 andalso I < Sz ->
    {ok, ets:lookup_element(circa_tab, {Ref, I}, 2)}.

-spec push(res(), pos_integer()) -> {ok, res()}.
push({Ref, C, Sz}, Val) when C > Sz ->
    push({Ref, 0, Sz}, Val);
push({Ref, C, Sz}, Val) ->
    ets:insert(circa_tab, {{Ref, C}, Val}),
    {ok, {Ref, C+1, Sz}}.

-spec slice(res(), pos_integer(), pos_integer()) -> [pos_integer()] |
                                                    {error, slice_too_big}.
slice(_Res, _Start, _End) ->
    todo.