Hi Bridger,

Questions like this are welcome!

A switch approach, as suggested by Liam, might look as follows:

  declare function local:dispatch(
    $nodes as node()*
  ) as item()* {
    for $node in $nodes
    return if (not($node instance of element())) then (
      $node
    ) else switch(name($node))
      case 'docs'   return local:passthru($node)
      case 'doc'    return local:docf($node)
      case 'title'  return local:title($node)
      case 'author' return local:author($node)
      case 'fields' return local:passthru($node)
      case 'field'  return (
        if($node/@name='first') then local:field-1($node) else
        if($node/@name='second') then local:field-2($node) else ()
      )
      default return ()
  };

The nested if conditions for the 'field' element could be rewritten to
a switch clause as well.

In most cases, I tend to use XQuery for transforming existing XML
nodes. The 'update' keyword gives you a concise syntax for updating
existing nodes [1]:

  declare %updating function local:rename($node, $name) {
    rename node $node as $name
  };
  $input/* update {
    local:rename(., 'new'),
    .//(title, author) ! (rename node . as 'new-' || name()),
    insert node element new-subject {
      .//field[@name = 'first']/text()
    } into .,
    insert node element new-section {
      element new-entry { .//field[@name = 'second']/text() }
    } into .,
    delete node .//fields
  }

In this little example, I have accommodated various different ways to
modify existing nodes (calling a function, using paths and the simple
map expression, …). As you can easily see, the approach is pretty
different to the identity transformation in XSLT: Instead of building
a new document, you are updating existing nodes. This can be both very
powerful and concise, because you can address and update descendant
nodes with a simple path expression, but it is mostly appropriate if
your old and new documents look similar.

If you want to stick with the official XQuery Update 1.0 syntax, you
can also use the more verbose copy/modiy/return statements (see the
same link).

Hope this helps, feel free to ask for more details,
Christian

[1] http://docs.basex.org/wiki/XQuery_Update#update