xml_assemble: Putting together SOAP responses

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(September 9, 2003): OK, it's probably not very logical to include xml_assemble at this level, but what the hey, it's not that complex. The idea is this: when a complex structure is passed via SOAP, it is flattened out, and references are passed as "href" attributes within the document. So this: 
<item>
<rec>
<order>1</order>
</rec>
</item>
is instead passed as this: 
<item>
<rec href="#i1"/>
</item>
<rec id="1">
<order>1</order>
</rec>
And of course this can go as many levels as necessary. The benefit is ... well, frankly I'm not sure what the benefit is, but it sure as heck is necessary to be able to reassemble those structures. So let's do so.

The function takes a starting structure and a source XML. It begins by copying the starting structure, then checking it for "href" attributes. If there are any, they're recursively fixed up and copied into the structure we're checking. In order to avoid repetition of searching effort, though, we want to keep a list of locations we know need fixup. Since the fixups won't affect loc locations, we're safe in doing a search-all first, then going through that list to find things to fix.

To make that work, I first needed to implement xml_search_all for C (I'd formerly only really thought it made sense in higher-level languages, but it sure does insinuate itself into your consciousness once it exists.) Once that worked, the assembly itself is really straightforward.
  
XMLAPI XML * xml_assemble (XML * start, XML * src)
{
   XML * copy;
   XML * hrefs;
   XML * href;
   const char * ref;
   XML * assembled;
   XML * repl;

   if (*xml_attrval (start, "href") == '#') {
      assembled = xml_assemble (xml_search (src, xml_name (start), "id", xml_attrval (start, "href") + 1), src);
      xml_unset (assembled, "id");
      xml_unset (assembled, "SOAP-ENC:root");
      return (assembled);
   }

   copy = xml_copy (start);
   hrefs = xml_search_all (copy, NULL, "href", NULL);
   href = xml_firstelem (hrefs);
   while (href) {
      repl = xml_loc (copy, xml_attrval (href, "loc"));
      ref = xml_attrval (repl, "href");
      if (*ref == '#') {
         assembled = xml_assemble (xml_search (src, NULL, "id", ref + 1), src);
         xml_rename (assembled, xml_name (repl));
         xml_unset (assembled, "id");
         xml_unset (assembled, "SOAP-ENC:root");
         xml_replace (repl, assembled);
      }
      href = xml_nextelem (href);
   }

   xml_free (hrefs);
   return copy;
}
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