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idna

1.0.2
7.1.0 6.1.1 6.1.0 6.0.1 6.0.0 5.1.2 5.1.1 5.1.0 5.0.2 5.0.1 5.0.0 4.0.0 3.0.0 2.0.0 1.2.0 1.1.0 1.0.3 1.0.2 1.0.1

A pure Erlang IDNA implementation

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idna src idna.erl
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src/idna.erl 

-module(idna).



-export([to_ascii/1,

         utf8_to_ascii/1,

         from_ascii/1]).



-define(ACE_PREFIX, "xn--").



to_ascii(Domain) ->

    to_ascii(string:tokens(idna_unicode:downcase(Domain), "."), []).



utf8_to_ascii(Domain) ->

    to_ascii(idna_ucs:from_utf8(Domain)).



-spec from_ascii(nonempty_string()) -> nonempty_string().

from_ascii(Domain) ->

    from_ascii(string:tokens(Domain, "."), []).



%% Helper functions

%%

to_ascii([], Acc) ->

    lists:reverse(Acc);

to_ascii([Label|Labels], []) ->

    to_ascii(Labels, lists:reverse(label_to_ascii(Label)));

to_ascii([Label|Labels], Acc) ->

    to_ascii(Labels, lists:reverse(label_to_ascii(Label), [$.|Acc])).



label_to_ascii(Label) ->

    case lists:all(fun(C) -> idna_ucs:is_ascii(C) end, Label) of

        true ->

            Label;

        false ->

            ?ACE_PREFIX ++ punycode:encode(idna_unicode:normalize_kc(Label))

    end.



from_ascii([], Acc) ->

    lists:reverse(Acc);

from_ascii([Label|Labels], []) ->

    from_ascii(Labels, lists:reverse(label_from_ascii(Label)));

from_ascii([Label|Labels], Acc) ->

    from_ascii(Labels, lists:reverse(label_from_ascii(Label), [$.|Acc])).



label_from_ascii(?ACE_PREFIX ++ Label) ->

    punycode:decode(Label);

label_from_ascii(Label) ->

    Label.