There is an XML selective parsing puzzle that I haven't been able to
figure out.

I've got some XML source that I'm reading using SAX (ie: SAXBuilder
builder = new SAXBuilder(); Document doc = builder.build(new
StringReader(bpSource));Element root = doc.getRootElement();)  I can
get everything I need out of the XML, that's not the problem.  It's a
logic problem with picking and choosing what to include and what to
discard based on a second input.

The inputs to the program are 1)an XML file, and 2) an array of
numbers.  Those numbers represent which choice statements will be
active.

So if I had array = {2}, and XML like this:
<choice>
 <select>
   <case activity="A"/> <!-- this is "1" -->
   <case activity="B"/> <!-- this is "2" -->
 </select>
 <sequence name = "A"><stuffA/></sequence>
 <sequence name = "B"><stuffB/></sequence>
</choice>

The result would be "<sequence name = "B"><stuffB/></sequence>" (the
case's activity matches up on the sequence name).

The problem comes when you have nested choices (besides just
"<stuffB>", you might have "<case><select>..." in that sequence as
well.  In other words, the solution needs to handle "n-level deep
choices".

There is an example input XML file at the bottom of this post.  For
that example, we might have a few different number array inputs:

if my input was {1}, my output would be:
<sequence name = "Run Option 1">
 <assign to="/Some1">run option 1 was chosen</assign>
</sequence>

if my input was {2, 1}, my output would be:
<sequence name = "Run Option 2">
 <assign to="/Some2">run option 2 was chosen</assign>
   <sequence name="Simple1">
     <assign to="/SomeVar1">simple 1 was chosen</assign>
   </sequence>
 <assign to="/Some2b">run option 2 ending</assign>
</sequence> <!-- end Run Option 2 -->

if my input was {2, 2, 1}, my output would be:
<sequence name = "Run Option 2">
 <assign to="/Some2">run option 2 was chosen</assign>
   <sequence name="Deep Nested">
       <sequence name="Run Deep 1">
         <assign to="/D1">d1</assign>
       </sequence>
   </sequence>
 <assign to="/Some2b">run option 2 ending</assign>
</sequence> <!-- end Run Option 2 -->

So, can anyone think of a smart way to assemble only the selected XML
out of the whole, based on the number array inputs?

--Dale--

Here is the sample XML file that goes with the example outputs above.
Some of you might recognize this a BPML (Business Process Modeling
Language), but that doesn't matter, that is, unless you know of a BPML
parser that does what I'm looking for!

<process name="aProcess">
 <sequence name="Main Sequence">

   <choice name="Outer Choice">
     <select>
       <case ref="option 1" activity="Run Option 1"/>
       <case ref="option 2" activity="Run Option 2"/>
     </select>
     <sequence name = "Run Option 1">
       <assign to="/Some1">run option 1 was chosen</assign>
     </sequence>
     <sequence name = "Run Option 2">
       <assign to="/Some2">run option 2 was chosen</assign>

       <choice name="Nested choice">
         <select>
           <case ref="option 1" activity="Simple1"/>
           <case ref="option 2" activity="Deep Nested"/>
           <case ref="option 3" activity="Simple2"/>
         </select>
         <sequence name="Simple1">
           <assign to="/SomeVar1">simple 1 was chosen</assign>
         </sequence>
         <sequence name="Deep Nested">

           <choice name="It's getting deep">
             <select>
               <case ref="deepoption 1" activity="Run Deep 1"/>
               <case ref="deepoption 2" activity="Run Deep 2"/>
             </select>
             <sequence name="Run Deep 1">
               <assign to="/D1">d1</assign>
             </sequence>
             <sequence name="Run Deep 2">
               <assign to="/D2">d2</assign>
             </sequence>
           </choice> <!-- end Deep Nested choice -->

         </sequence>
         <sequence name="Simple2">
           <assign to="/SomeVar2">simple 2 was chosen</assign>
         </sequence>
       </choice> <!-- end Nested choice -->

       <assign to="/Some2b">run option 2 ending</assign>
     </sequence> <!-- end Run Option 2 -->
   </choice> <!-- end Outer Choice -->
   
  </sequence> <!-- end Main Sequence -->
</process>