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zotonic_stdlib src z_string_normalize.erl
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src/z_string_normalize.erl 

% -*- coding: utf-8; Mode: erlang; tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*-

% ex: set softtabstop=4 tabstop=4 shiftwidth=4 expandtab fileencoding=utf-8:

%% coding: utf-8



%% @author Marc Worrell <marc@worrell.nl>

%% @copyright 2009-2025 Marc Worrell

%% @doc String normalization, used for search indices. Takes a string, lowercases

%% it and then transliterates to ASCII.

%% @end



-module(z_string_normalize).



-export([ normalize/1 ]).



%% File with all the word mappings in the priv folder.

-define(WORD_MAPPING_FILE, "normalize-words-mapping.csv").



%% Separators in a lowercased string.

-define(is_sep(C),

        C < $0

        orelse (C > $9 andalso C < $a)

        orelse (C > $z andalso C < 127)

        orelse C =:= 160    % non breaking space

        orelse C =:= 8220   % left double quote

        orelse C =:= 8221   % right double quote

        orelse C =:= 8216   % left single quote

        orelse C =:= 8217   % right single quote

        orelse C =:= 8230   % ellipsis

        orelse C =:= 8232   % line separator

        orelse C =:= 8233   % paragraph separator

        orelse C =:= 8212   % mdash

        orelse C =:= 8211   % ndash

    ).



-define(is_map_space(C),

               C =:= 65279  % byte order mark

        orelse C =:= 8232   % line separator

        orelse C =:= 8233   % paragraph separator

        orelse C =:= 8203   % zero width space

        orelse C =:= 8204   % zero width non-joiner

        orelse C =:= 8239   % narrow no-break space

    ).



-define(is_word_ignore_char(C),

               C =:= 8205   % zero width joiner

        orelse C =:= 8288   % word joiner

        orelse C =:= 173    % soft hyphen

    ).









%% @doc Transliterate an unicode string to an ascii string with lowercase characters.

%% Tries to transliterate some characters to a..z

-spec normalize(string() | binary() | atom() | {trans, list()} | undefined) -> binary().

normalize(undefined) ->

    <<>>;

normalize(A) when is_atom(A) ->

    normalize(atom_to_binary(A, utf8));

normalize(L) when is_list(L) ->

    normalize(unicode:characters_to_binary(L));

normalize(B) when is_binary(B)  ->

    B1 = z_string:sanitize_utf8(B),

    B2 = unicode:characters_to_nfc_binary(B1),

    B3 = string:casefold(B2),

    normalize_words(B3);

normalize({trans, []}) ->

    <<>>;

normalize({trans, [{_, First} | _] = Tr}) ->

    V = proplists:get_value(en, Tr, First),

    normalize(V).



%% Normalize specific words using custom mappings from CSV file.

%% This allows language-specific transliterations that differ from

%% standard romanization rules.

normalize_words(B) when is_binary(B) ->

    Ws = normalize_words_word(B, <<>>, []),

    normalize(erlang:iolist_to_binary(Ws), <<>>).



normalize_words_word(<<>>, W, Acc) ->

    lists:reverse([map_word(W)|Acc]);

normalize_words_word(<<C/utf8, T/binary>>, W, Acc) when ?is_word_ignore_char(C) ->

    normalize_words_word(T, W, Acc);

normalize_words_word(<<C/utf8, T/binary>>, W, Acc) when ?is_sep(C) orelse ?is_map_space(C) ->

    normalize_words_sep(T, <<C/utf8>>, [map_word(W)|Acc]);

normalize_words_word(<<C/utf8, T/binary>>, W, Acc) ->

    normalize_words_word(T, <<W/binary, C/utf8>>, Acc);

normalize_words_word(<<_Byte, T/binary>>, W, Acc) ->

    % Skip invalid UTF-8 byte

    normalize_words_word(T, W, Acc).



normalize_words_sep(<<>>, W, Acc) ->

    lists:reverse([W|Acc]);

normalize_words_sep(<<C/utf8, T/binary>>, W, Acc) when ?is_word_ignore_char(C) ->

    normalize_words_sep(T, W, Acc);

normalize_words_sep(<<C/utf8, T/binary>>, W, Acc) when not (?is_sep(C) orelse ?is_map_space(C)) ->

    normalize_words_word(T, <<C/utf8>>, [W|Acc]);

normalize_words_sep(<<C/utf8, T/binary>>, W, Acc) ->

    normalize_words_sep(T, <<W/binary, C/utf8>>, Acc);

normalize_words_sep(<<_Byte, T/binary>>, W, Acc) ->

    % Skip invalid UTF-8 byte

    normalize_words_sep(T, W, Acc).



%% Specific word normalizations. The mappings are loaded from a CSV file

%% and stored in the persistent term storage for efficiency.

map_word(<<>>) ->

    <<>>;

map_word(W) ->

    try

        Mapping = persistent_term:get(z_string_normalize_word_mapping),

        maps:get(W, Mapping, W)

    catch

        error:badarg ->

            Filename = filename:join(code:priv_dir(zotonic_stdlib), ?WORD_MAPPING_FILE),

            {ok, Data} = file:read_file(Filename),

            Lines = binary:split(Data, [ <<"\n">>, <<"\r">> ], [ global, trim_all ]),

            NewMapping = lists:foldl(

                fun

                    (<<"#", _/binary>>, Acc) ->

                        Acc;

                    (Line, Acc) ->

                        case binary:split(Line, [ <<",">>, <<";">>, <<"\t">> ]) of

                            [From, To] ->

                                From1 = string:casefold(z_string:trim(From)),

                                To1 = string:casefold(z_string:trim(To)),

                                Acc#{ From1 => To1 };

                            _ ->

                                Acc

                        end

                end,

                #{},

                Lines),

            persistent_term:put(z_string_normalize_word_mapping, NewMapping),

            maps:get(W, NewMapping, W)

end.



normalize(<<>>, Acc) ->

    Acc;

normalize(<<C,T/binary>>, Acc)

    when       (C >= $a andalso C =< $z)

        orelse (C >= $0 andalso C =< $9)

        orelse C =:= 32

        orelse C =:= $\n

        orelse C =:= $\t

        orelse C =:= $-

        orelse C =:= $_ ->

    % Usual ascii characters - just for efficiency at the top

    normalize(T, <<Acc/binary,C>>);

normalize(<<"ä"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$a>>);

normalize(<<"ë"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$e>>);

normalize(<<"ï"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$i>>);

normalize(<<"ü"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$u>>);

normalize(<<"ö"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$o>>);

normalize(<<"é"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$e>>);

normalize(<<"è"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$e>>);

normalize(<<"í"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$i>>);

normalize(<<"ì"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$i>>);

normalize(<<"ú"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$u>>);

normalize(<<"ù"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$u>>);

normalize(<<"ó"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$o>>);

normalize(<<"ò"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$o>>);

normalize(<<"ô"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$o>>);

normalize(<<"ß"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$s,$s>>);

normalize(<<"ç"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$c>>);

normalize(<<"ø"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$o>>);

normalize(<<"å"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$a>>);

normalize(<<"€"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$e>>);

normalize(<<"ÿ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$y>>);

normalize(<<"ã"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$a>>);

normalize(<<"ñ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$n>>);

normalize(<<"õ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$o>>);

% Cyrillic support (from http://en.wikipedia.org/wiki/Romanization_of_Russian)

% See also the rules for Russian passports (2013, ICAO).

normalize(<<"а"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$a>>);

normalize(<<"б"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$b>>);

normalize(<<"в"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$v>>);

normalize(<<"г"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$g>>);

normalize(<<"д"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$d>>);

normalize(<<"е"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$e>>);

normalize(<<"ё"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$e>>);

normalize(<<"ж"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$z,$h>>);

normalize(<<"з"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$z>>);

normalize(<<"и"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$i>>);

normalize(<<"й"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$j>>);

normalize(<<"к"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$k>>);

normalize(<<"л"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$l>>);

normalize(<<"м"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$m>>);

normalize(<<"н"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$n>>);

normalize(<<"о"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$o>>);

normalize(<<"п"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$p>>);

normalize(<<"р"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$r>>);

normalize(<<"с"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$s>>);

normalize(<<"т"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$t>>);

normalize(<<"у"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$u>>);

normalize(<<"ф"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$f>>);

normalize(<<"х"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$k,$h>>);

normalize(<<"ц"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$c>>);

normalize(<<"ч"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$c,$h>>);

normalize(<<"ш"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$s,$h>>);

normalize(<<"щ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$s,$h,$c,$h>>);

normalize(<<"ъ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$_>>);

normalize(<<"ы"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$y>>);

normalize(<<"ь"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$_>>);

normalize(<<"э"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$e>>);

normalize(<<"ю"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$i,$u>>);

normalize(<<"я"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$i,$a>>);

% Ukrainian support

normalize(<<"ґ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$g>>);

normalize(<<"ї"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$i>>);

normalize(<<"і"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$i>>);

normalize(<<"є"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$e,$y>>);

% Polish support

normalize(<<"ą"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$a>>);

normalize(<<"ę"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$e>>);

normalize(<<"ć"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$c>>);

normalize(<<"ł"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$l>>);

normalize(<<"ń"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$n>>);

normalize(<<"ś"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$s>>);

normalize(<<"ź"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$z>>);

normalize(<<"ż"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$z>>);

% Turkish support

normalize(<<"ş"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$s>>);

normalize(<<"ğ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$g>>);

normalize(<<"ı"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$i>>);



% Hebrew support (simplified) https://en.wikipedia.org/wiki/Romanization_of_Hebrew

% TODO: check this, as it seems quite broken/incomplete

normalize(<<"א"/utf8,T/binary>>, Acc) -> normalize(T, Acc);

normalize(<<"ב"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$v>>);

normalize(<<"בּ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$b>>);

normalize(<<"ג"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$g>>);

normalize(<<"גּ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$g>>);

normalize(<<"ג׳"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$j>>);

normalize(<<"ד"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$d>>);

normalize(<<"דּ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$d>>);

normalize(<<"ד׳"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$d,$h>>);

normalize(<<"ה"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$h>>);

normalize(<<"הּ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$h>>);

normalize(<<"ו"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$v>>);

normalize(<<"וּ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$v>>);

normalize(<<"ז"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$z>>);

normalize(<<"זּ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$z>>);

normalize(<<"ז׳"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$z,$h>>);

normalize(<<"ח"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$c,$h>>);

normalize(<<"ט"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$t>>);

normalize(<<"טּ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$t>>);

normalize(<<"י"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$y>>);

normalize(<<"יּ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$y>>);

normalize(<<"ךכ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$c,$h>>);

normalize(<<"ךּ כּ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$k>>);

normalize(<<"ל"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$l>>);

normalize(<<"לּ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$l>>);

normalize(<<"םמ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$m>>);

normalize(<<"מּ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$m>>);

normalize(<<"ןנ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$n>>);

normalize(<<"נּ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$n>>);

normalize(<<"ס"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$s>>);

normalize(<<"סּ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$s>>);

normalize(<<"ע"/utf8,T/binary>>, Acc) -> normalize(T, Acc);

normalize(<<"ףפ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$f>>);

normalize(<<"ףּ פּ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$p>>);

normalize(<<"ץצ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$t,$z>>);

normalize(<<"צּ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$t,$z>>);

normalize(<<"ץ׳צ׳"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$t,$s,$h>>);

normalize(<<"ק"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$k>>);

normalize(<<"קּ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$k>>);

normalize(<<"ר"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$r>>);

normalize(<<"רּ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$r>>);

normalize(<<"ש"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$s,$h>>);

normalize(<<"שׁ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$s,$h>>);

normalize(<<"שּׁ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$s,$h>>);

normalize(<<"שׂ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$s>>);

normalize(<<"שּׂ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$s>>);

normalize(<<"ת"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$t>>);

normalize(<<"תּ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$t>>);

normalize(<<"ת׳"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$t,$h>>);

% Hebrew forms used in transliteration from Arabic

normalize(<<"ח׳"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$n>>);

normalize(<<"ט׳"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$z>>);

normalize(<<"ע׳ר׳"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$g>>);

% Hebrew vowels

normalize(<<"צ"/utf8, T/binary>>, Acc) -> normalize(T, <<Acc/binary,$a,$a>>);

normalize(<<"טְ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$e>>);

normalize(<<"חֱ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$e>>);

normalize(<<"חֲ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$a>>);

normalize(<<"חֳ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$o>>);

normalize(<<"טִ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$i>>);

normalize(<<"טֵ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$e>>);

normalize(<<"טֶ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$e>>);

normalize(<<"טַ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$a>>);

normalize(<<"טָ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$o>>);

normalize(<<"טֹ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$o>>);

normalize(<<"טֻ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$u>>);

normalize(<<"טוּ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$u>>);

normalize(<<"טֵי"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$e,$i>>);

normalize(<<"טֶי"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$e,$i>>);

normalize(<<"טַיטַיְ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$a,$i>>);

normalize(<<"טָיטָיְ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$a,$i>>);

normalize(<<"טֹיטֹיְ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$o,$i>>);

normalize(<<"טֻיטֻיְ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$u,$i>>);

normalize(<<"טוּיטוּיְ"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,$u,$i>>);



% Some entities - we might want to add generic code here, depends

% on where normalize/1 is used (can we assume that the input is always html?)

normalize(<<"&amp;", T/binary>>, Acc) -> normalize(T, <<Acc/binary," ">>);

normalize(<<"&lt;",  T/binary>>, Acc) -> normalize(T, <<Acc/binary," ">>);

normalize(<<"&gt;",  T/binary>>, Acc) -> normalize(T, <<Acc/binary," ">>);

normalize(<<"&#39;", T/binary>>, Acc) -> normalize(T, <<Acc/binary," ">>);

normalize(<<"&quot;",T/binary>>, Acc) -> normalize(T, <<Acc/binary," ">>);

normalize(<<"&nbsp;",T/binary>>, Acc) -> normalize(T, <<Acc/binary," ">>);

normalize(<<"&mdash;",T/binary>>, Acc) -> normalize(T, <<Acc/binary,"-">>);

normalize(<<"&ndash;",T/binary>>, Acc) -> normalize(T, <<Acc/binary,"-">>);

normalize(<<"—"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,"-">>);

normalize(<<"–"/utf8,T/binary>>, Acc) -> normalize(T, <<Acc/binary,"-">>);

normalize(<<C/utf8,T/binary>>, Acc) when C >= 32, C =< 126 ->

    % ASCII characters

    normalize(T, <<Acc/binary, C/utf8>>);

normalize(<<C, T/binary>>, Acc) when C =:= $\n; C =:= $\t ->

    % Keep newlines and tabs

    normalize(T, <<Acc/binary, " ">>);

normalize(<<C/utf8,T/binary>>, Acc) when ?is_map_space(C) ->

    % Replace control or space-like characters with spaces

    normalize(T, <<Acc/binary, " ">>);

normalize(<<C/utf8,T/binary>>, Acc) when ?is_word_ignore_char(C) ->

    % Zero width space et al

    normalize(T, Acc);

normalize(<<C/utf8,T/binary>>, Acc) ->

    % Try to remove any accents.

    C1 = z_string:unaccent(<<C/utf8>>),

    normalize(T, <<Acc/binary, C1/binary>>);

normalize(<<_C,T/binary>>, Acc) ->

    % Drop non-utf8

    normalize(T, Acc).