I am trying to select specific elements from an XML document to make anthologies, and still retain the original numbering, by using \xmldoifelse; if the node matches, it is printed, and if it is not, the head number is incremented, to get something like this:

1 First Section (first match)

4 Fourth Section (second match, but fourth element in the XML file)

But the fail condition is not being triggered properly. Here are the files:

%
% anthologize.xml
%
\def\incrementheadnumber[#1]{\setupheadnumber[#1]
[\numexpr\namedheadnumber{#1}+1\relax]}

\startxmlsetups xml:selectivity:*
\xmlsetsetup{\xmldocument}{*}{-}
\xmlsetsetup{\xmldocument}{stuff|div|head}{xml:selectivity:*}
\stopxmlsetups

\xmlregisterdocumentsetup{selectivity}{xml:selectivity:*}

% Here is the difficulty.

\startxmlsetups{xml:selectivity:stuff}
    \xmldoifelse{#1}{/div[match()==1 or match()==4]/all()}
    {
      \xmlflush{#1}
    } {
      \incrementheadnumber[section]
    }
\stopxmlsetups

\startxmlsetups{xml:selectivity:div}
\xmlflush{#1}
\stopxmlsetups

\startxmlsetups{xml:selectivity:head}
\startsection[title={\xmlflush{#1}}]\stopsection
\stopxmlsetups

\starttext

\xmlprocessfile{selectivity}{bob.xml}{}

\stoptext

%
% bob.xml
%
<stuff>
<div>
    <head>First Section</head>
</div>
<div>
    <head>Second Section</head>
</div>
<div>
    <head>Third Section</head>
</div>
<div>
    <head>Fourth Section</head>
</div>
</stuff>

The result is that only the first and fourth heads are printed, as desired, but I end up with:

1 First Section

2 Fourth Section.

I have used the \incrementheadnumber function elsewhere, and it works fine. If I replace \incrementheadnumber[section] with \xmlflush{#1}, it prints:

1 First Section

2 Fourth Section

3 First Section

4 Second Section

5 Third Section

6 Fourth Section

So it seems to be properly triggering the true condition, but not the false condition, and I cannot figure out how to fix it. Using ConTeXt 2017.04.08 and LuaTeX 1.0.3. I do thank you for your help.

Sincerely,

Gerard Keiser