247 lines
7.2 KiB
Erlang
247 lines
7.2 KiB
Erlang
%%%----------------------------------------------------------------------
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%%% File : xml.erl
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%%% Author : Alexey Shchepin <alexey@process-one.net>
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%%% Purpose : XML utils
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%%% Created : 20 Nov 2002 by Alexey Shchepin <alexey@process-one.net>
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%%%
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%%%
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%%% ejabberd, Copyright (C) 2002-2010 ProcessOne
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%%%
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%%% This program is free software; you can redistribute it and/or
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%%% modify it under the terms of the GNU General Public License as
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%%% published by the Free Software Foundation; either version 2 of the
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%%% License, or (at your option) any later version.
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%%%
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%%% This program is distributed in the hope that it will be useful,
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%%% but WITHOUT ANY WARRANTY; without even the implied warranty of
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%%% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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%%% General Public License for more details.
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%%%
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%%% You should have received a copy of the GNU General Public License
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%%% along with this program; if not, write to the Free Software
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%%% Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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%%% 02111-1307 USA
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%%%
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%%%----------------------------------------------------------------------
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-module(xml).
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-author('alexey@process-one.net').
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-export([element_to_string/1,
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crypt/1, make_text_node/1,
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remove_cdata/1,
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get_cdata/1, get_tag_cdata/1,
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get_attr/2, get_attr_s/2,
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get_tag_attr/2, get_tag_attr_s/2,
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get_subtag/2, get_subtag_cdata/2,
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append_subtags/2,
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get_path_s/2,
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replace_tag_attr/3]).
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%% Select at compile time how to escape characters in binary text
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%% nodes.
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%% Can be choosen with ./configure --enable-full-xml
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-ifdef(FULL_XML_SUPPORT).
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-define(ESCAPE_BINARY(CData), make_text_node(CData)).
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-else.
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-define(ESCAPE_BINARY(CData), crypt(CData)).
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-endif.
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element_to_string(El) ->
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case catch element_to_string_nocatch(El) of
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{'EXIT', Reason} ->
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erlang:error({badxml, El, Reason});
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Result ->
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Result
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end.
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element_to_string_nocatch(El) ->
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case El of
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{xmlelement, Name, Attrs, Els} ->
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if
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Els /= [] ->
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[$<, Name, attrs_to_list(Attrs), $>,
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[element_to_string_nocatch(E) || E <- Els],
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$<, $/, Name, $>];
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true ->
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[$<, Name, attrs_to_list(Attrs), $/, $>]
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end;
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%% We do not crypt CDATA binary, but we enclose it in XML CDATA
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{xmlcdata, CData} when is_binary(CData) ->
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?ESCAPE_BINARY(CData);
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%% We crypt list and possibly binaries if full XML usage is
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%% disabled unsupported (implies a conversion to list).
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{xmlcdata, CData} ->
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crypt(CData)
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end.
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attrs_to_list(Attrs) ->
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[attr_to_list(A) || A <- Attrs].
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attr_to_list({Name, Value}) ->
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[$\s, Name, $=, $', crypt(Value), $'].
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crypt(S) when is_list(S) ->
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[case C of
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$& -> "&";
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$< -> "<";
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$> -> ">";
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$" -> """;
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$' -> "'";
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_ -> C
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end || C <- S];
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crypt(S) when is_binary(S) ->
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crypt(binary_to_list(S)).
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%% Make a cdata_binary depending on what characters it contains
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make_text_node(CData) ->
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case cdata_need_escape(CData) of
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cdata ->
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CDATA1 = <<"<![CDATA[">>,
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CDATA2 = <<"]]>">>,
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list_to_binary([CDATA1, CData, CDATA2]);
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none ->
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CData;
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{cdata, EndTokens} ->
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EscapedCData = escape_cdata(CData, EndTokens),
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list_to_binary(EscapedCData)
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end.
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%% Returns escape type needed for the text node
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%% none, cdata, {cdata, [Positions]}
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%% Positions is a list a integer containing positions of CDATA end
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%% tokens, so that they can be escaped
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cdata_need_escape(CData) ->
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cdata_need_escape(CData, 0, false, []).
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cdata_need_escape(<<>>, _, false, _) ->
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none;
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cdata_need_escape(<<>>, _, true, []) ->
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cdata;
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cdata_need_escape(<<>>, _, true, CDataEndTokens) ->
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{cdata, lists:reverse(CDataEndTokens)};
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cdata_need_escape(<<$],$],$>,Rest/binary>>, CurrentPosition,
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_XMLEscape, CDataEndTokens) ->
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NewPosition = CurrentPosition + 3,
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cdata_need_escape(Rest, NewPosition, true,
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[CurrentPosition+1|CDataEndTokens]);
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%% Only <, & need to be escaped in XML text node
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%% See reference: http://www.w3.org/TR/xml11/#syntax
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cdata_need_escape(<<$<,Rest/binary>>, CurrentPosition,
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_XMLEscape, CDataEndTokens) ->
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cdata_need_escape(Rest, CurrentPosition+1, true, CDataEndTokens);
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cdata_need_escape(<<$&,Rest/binary>>, CurrentPosition,
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_XMLEscape, CDataEndTokens) ->
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cdata_need_escape(Rest, CurrentPosition+1, true, CDataEndTokens);
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cdata_need_escape(<<_:8,Rest/binary>>, CurrentPosition,
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XMLEscape, CDataEndTokens) ->
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cdata_need_escape(Rest, CurrentPosition+1, XMLEscape,
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CDataEndTokens).
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%% escape cdata that contain CDATA end tokens
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%% EndTokens is a list of position of end tokens (integer)
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%% This is supposed to be a very rare case: You need to generate several
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%% fields, splitting it in the middle of the end token.
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%% See example: http://en.wikipedia.org/wiki/CDATA#Uses_of_CDATA_sections
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escape_cdata(CData, EndTokens) ->
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escape_cdata(CData, 0, EndTokens, []).
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escape_cdata(<<>>, _CurrentPosition, [], Acc) ->
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lists:reverse(Acc);
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escape_cdata(Rest, CurrentPosition, [], Acc) ->
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CDATA1 = <<"<![CDATA[">>,
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CDATA2 = <<"]]>">>,
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escape_cdata(<<>>, CurrentPosition, [], [CDATA2, Rest, CDATA1|Acc]);
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escape_cdata(CData, Index, [Pos|Positions], Acc) ->
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CDATA1 = <<"<![CDATA[">>,
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CDATA2 = <<"]]>">>,
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Split = Pos-Index,
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{Part, Rest} = split_binary(CData, Split+1),
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%% Note: We build the list in reverse to optimize construction
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escape_cdata(Rest, Pos+1, Positions, [CDATA2, Part, CDATA1|Acc]).
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remove_cdata_p({xmlelement, _Name, _Attrs, _Els}) -> true;
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remove_cdata_p(_) -> false.
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remove_cdata(L) -> [E || E <- L, remove_cdata_p(E)].
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get_cdata(L) ->
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binary_to_list(list_to_binary(get_cdata(L, ""))).
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get_cdata([{xmlcdata, CData} | L], S) ->
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get_cdata(L, [S, CData]);
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get_cdata([_ | L], S) ->
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get_cdata(L, S);
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get_cdata([], S) ->
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S.
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get_tag_cdata({xmlelement, _Name, _Attrs, Els}) ->
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get_cdata(Els).
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get_attr(AttrName, Attrs) ->
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case lists:keysearch(AttrName, 1, Attrs) of
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{value, {_, Val}} ->
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{value, Val};
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_ ->
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false
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end.
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get_attr_s(AttrName, Attrs) ->
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case lists:keysearch(AttrName, 1, Attrs) of
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{value, {_, Val}} ->
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Val;
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_ ->
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""
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end.
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get_tag_attr(AttrName, {xmlelement, _Name, Attrs, _Els}) ->
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get_attr(AttrName, Attrs).
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get_tag_attr_s(AttrName, {xmlelement, _Name, Attrs, _Els}) ->
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get_attr_s(AttrName, Attrs).
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get_subtag({xmlelement, _, _, Els}, Name) ->
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get_subtag1(Els, Name).
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get_subtag1([El | Els], Name) ->
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case El of
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{xmlelement, Name, _, _} ->
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El;
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_ ->
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get_subtag1(Els, Name)
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end;
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get_subtag1([], _) ->
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false.
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get_subtag_cdata(Tag, Name) ->
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case get_subtag(Tag, Name) of
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false ->
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"";
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Subtag ->
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get_tag_cdata(Subtag)
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end.
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append_subtags({xmlelement, Name, Attrs, SubTags1}, SubTags2) ->
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{xmlelement, Name, Attrs, SubTags1 ++ SubTags2}.
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get_path_s(El, []) ->
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El;
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get_path_s(El, [{elem, Name} | Path]) ->
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case get_subtag(El, Name) of
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false ->
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"";
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SubEl ->
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get_path_s(SubEl, Path)
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end;
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get_path_s(El, [{attr, Name}]) ->
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get_tag_attr_s(Name, El);
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get_path_s(El, [cdata]) ->
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get_tag_cdata(El).
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replace_tag_attr(Attr, Value, {xmlelement, Name, Attrs, Els}) ->
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Attrs1 = lists:keydelete(Attr, 1, Attrs),
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Attrs2 = [{Attr, Value} | Attrs1],
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{xmlelement, Name, Attrs2, Els}.
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