-module(ts_common).
-export([list/3]).

-include_lib("stdlib/include/qlc.hrl").

%% list <Length> number of records, skipping the first <Start>
list(Table, Start, Length)
when is_atom(Table) and is_integer(Start) and is_integer(Length) ->
    list(qlc:q([A || A <- mnesia:table(Table)]), Start, Length);

list(Query, Start, Length) ->
    {atomic, Result} = mnesia:transaction(fun() ->
        % create a cursor for the query
        C = qlc:cursor(Query),

        % skip the first Start records
        if Start > 0 -> qlc:next_answers(C, Start);
            true -> ok
        end,

        % return Length records
        List = qlc:next_answers(C, Length),

        % free cursor
        ok = qlc:delete_cursor(C),

        List
    end),
    Result.