Parse a HTTP token-list

gistfile1.erl

%%
%% Parse a comma-separated tokenlist
%%
%%  the string:  a, b , "c\" ", , d
%%  gives     :  {ok, [<<"a">>, <<"b">>, <<"c\" >>, <<>>, <<"d">>]}
%%

-spec parse_tokenlist(string()) -> malformed | {ok, [binary()]}.

parse_tokenlist(String) ->
    parse_tokenlist(String, []).

parse_tokenlist([$ |Rest], Out) ->
    parse_tokenlist(Rest, Out);
parse_tokenlist([$,|Rest], Out) ->
    parse_tokenlist(Rest, [<<"">>|Out]);
parse_tokenlist([$"|Rest], Out) ->
    parse_quoted_string(Rest, [], Out);
parse_tokenlist([], Out) ->
    {ok, Out};
parse_tokenlist(Str, Out) ->
    parse_token(Str,[],Out).

parse_token([$,|Rest], Str, Out) ->
    parse_tokenlist(Rest, [list_to_binary(list:reverse(Str)) | Out]);
parse_token([CH|Rest], Str, Out) ->
    parse_token(Rest, [CH|Str], Out);
parse_token([], Str, Out) ->
    {ok, [list_to_binary(lists:reverse(Str)) | Out ]}.

parse_quoted_string([$"|Rest], Str, Out) ->
    parse_after_quoted_string(Rest, [list_to_binary(lists:reverse(Str)) | Out]);
parse_quoted_string([$\, CH|Rest], Str, Out) ->
    parse_quoted_string(Rest, [CH|Str], Out);
parse_quoted_string([CH|Rest], Str, Out) ->
    parse_quoted_string(Rest, [CH|Str], Out);
parse_quoted_string([], _, _) ->
    malformed.

parse_after_quoted_string([$ |Rest], Out) ->
    parse_after_quoted_string(Rest, Out);
parse_after_quoted_string([$,|Rest], Out) ->
    parse_tokenlist(Rest, Out);
parse_after_quoted_string([], Out) ->
    {ok, Out}.