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-module(dets_test).

-export([start/0]).

-import(dets, []).
-import(lib, []).
-import(io, []).
-import(file, [] ).

start() ->
        open(myfile),
        fill(myfile, "test.txt"),
        walk(myfile),
        dets:close(myfile).

open(TBL) ->
        case dets:open_file(TBL, [{type, bag},
                                  {repair, true},
                                  {file, "test.dets"}] ) of
          {ok, TBL} -> {ok, TBL};
          {error, Reason} -> lib:error_message("Dets returned error: ~p", [Reason]),
                                {error, Reason};
          Else -> lib:error_message("Dets unknown result when opening ~s: ~p",
                                        ["test.dets", Else]),
                        {error, Else}
        end.

fill(TBL, Textfile) ->
        case file:open(Textfile, [read]) of
                {ok, FHandle} -> fill_loop(TBL, FHandle), file:close(FHandle);
                {error, Reason} -> lib:error_message("File ~s open error: ~p",
                                        [Textfile, Reason]),
                        {error, Reason};
                Else -> lib:error_message("File ~s unknown open result: ~p",
                                [Textfile, Else]),
                        {error, "Unknown result"}
        end.

fill_loop(TBL, FHandle) ->
        case file:read_line(FHandle) of
                {ok, String} -> case dets:insert(TBL, {String}) of
                                ok -> fill_loop(TBL, FHandle);
                                Else -> lib:error_message("Dets insertion error ~p",
                                                [Else]),
                                        fill_loop(TBL, FHandle)
                                end;
                eof -> ok;
                {error, Reason} -> lib:error_message("File read error ~p", [Reason]),
                        {error, Reason}
        end.

walk(TBL) ->
        case dets:first(TBL) of
                '$end_of_table' -> ok;
                Key -> io:format("First key is ~p~n", [Key]),
                        walk_loop(TBL, Key)
        end.
walk_loop(TBL, PrevKey) ->
        case dets:next(TBL, PrevKey) of
                '$end_of_table' -> ok;
                Key -> io:format("Next key is ~p~n", [Key]),
                        walk_loop(TBL, Key)
        end.