gistfile1.hrl

-record(timestamp, {year, month, day, hour, minute, second, fraction, timezone}).
-record(timezone, {hour, minute}).

parse_iso8601(Time) when is_list(Time) ->
	parse_iso8601( list_to_binary(Time) );

parse_iso8601(Time) when is_binary(Time) ->
    try
        {ok, iso_to_rec(
            year,
            Time,
            #timestamp{
                year = 0,
                day = 0,
                month = 0,
                hour = 0,
                minute = 0,
                second = 0,
                fraction = 0,
                timezone = #timezone{ hour = 0, minute = 0}
            }
        )
        }
    catch
        error:Err -> {error, not_iso8601, Err}
    end.

iso_to_rec( _State, <<>>, R ) -> R;

iso_to_rec(second, <<"-", Rest/bitstring>>, R) ->
    iso_to_rec(tz_hour, Rest, R );
iso_to_rec(fraction, <<"-", Rest/bitstring>>, R) ->
    iso_to_rec(tz_hour, Rest, R );
iso_to_rec(_State, <<"+", Rest/bitstring>>, R) ->
    iso_to_rec(tz_hour, Rest, R );
iso_to_rec( State, <<"-", Rest/bitstring>>, R ) ->
	iso_to_rec( State, Rest, R );
iso_to_rec( State, <<" ", Rest/bitstring>>, R ) ->
	iso_to_rec( State, Rest, R );
iso_to_rec( State, <<"T", Rest/bitstring>>, R ) ->
	iso_to_rec( State, Rest, R );
iso_to_rec( State, <<":", Rest/bitstring>>, R ) ->
	iso_to_rec( State, Rest, R );
iso_to_rec( fraction, <<".", Rest/bitstring>>, R ) ->
    iso_to_rec( fraction, Rest, R );

iso_to_rec( year, <<Year:32/bitstring, Rest/bitstring>>, R ) ->
	iso_to_rec( month, Rest, R#timestamp{ year = Year } );
iso_to_rec( month, <<Month:16/bitstring, Rest/bitstring>>, R ) ->
	iso_to_rec( day, Rest, R#timestamp{ month = Month } );
iso_to_rec( day, <<Day:16/bitstring, Rest/bitstring>>, R ) ->
	iso_to_rec( hour, Rest, R#timestamp{ day = Day } );

iso_to_rec( hour, <<Hour:16/bitstring, Rest/bitstring>>, R ) ->
	iso_to_rec( minute, Rest, R#timestamp{ hour = Hour } );
iso_to_rec( minute, <<Minute:16/bitstring, Rest/bitstring>>, R ) ->
	iso_to_rec( second, Rest, R#timestamp{ minute = Minute } );
iso_to_rec( second, <<Second:16/bitstring, Rest/bitstring>>, R ) ->
	iso_to_rec( fraction, Rest, R#timestamp{ second = Second } );

%% parsing fraction by character, cause we don't know its length
iso_to_rec( fraction, <<C:8/bitstring, Rest/bitstring>>, R) ->
    iso_to_rec( fraction, Rest, R#timestamp{ fraction = R#timestamp.fraction * 10 + list_to_integer(binary_to_list(C))});

iso_to_rec( tz_hour, <<Tz_hour:16/bitstring, Rest/bitstring>>, R) ->
    iso_to_rec(minute, Rest, R#timestamp{ timezone = (R#timestamp.timezone)#timezone{ hour = Tz_hour }} );

iso_to_rec( tz_minute, <<Tz_min:16/bitstring, Rest/bitstring>>, R) ->
    iso_to_rec(minute, Rest, R#timestamp{ timezone = (R#timestamp.timezone)#timezone{ minute = Tz_min }} ).