[j-nsp] understaning the copy-node in SLAX

[Phil Shafer]

Martin T writes:
>When I run this with traceoptions enabled, then I can see that "<abc
>a="12" b="34" c="56"/>" is present in the output document. I guess
>that this inner for-each loop, based on my example, expands to this:
>
>copy-node {
>    attribute "a" {
>        expr 12;
>    }
>    attribute "b" {
>        expr 34;
>    }
>    attribute "c" {
>        expr 56;
>    }
>}
>
>Now "copy-node" does its shallow copy and copies "abc" element node
>and specified three attribute nodes to result tree. Am I correct?

copy-node create a node with the target (default .) name which you
can then populate with contents:

https://www.w3.org/TR/1999/REC-xslt-19991116#copying

    The xsl:copy element provides an easy way of copying the current
    node. Instantiating the xsl:copy element creates a copy of the
    current node. The namespace nodes of the current node are
    automatically copied as well, but the attributes and children
    of the node are not automatically copied. The content of the
    xsl:copy element is a template for the attributes and children
    of the created node; the content is instantiated only for nodes
    of types that can have attributes or children (i.e. root nodes
    and element nodes).

It's rather like:

    element name() {
        ...
    }

>In
>addition, why does copy-node run only once despite the fact that it is
>in the for-each loop? Is it because copy-node discards all the child
>elements of its current node and thus there are no more element
>nodes(<klm>, <name>, <name> based on my example) to loop through?

It's simpler than that; it's copying the current node, so there's
only one of them.  The nested "for-each" hits all the current node's
attributes, so you end up with:

% cat /tmp/foo.slax
version 1.2;

var $results := {
    <abc a="12" b="34" c="56"> {
        <klm k="78"> {
            <name n="9"> "foo";
        }
    }
}

main <top> {
    for-each ($results/abc) {
        copy-node {
            for-each (@*) {
                attribute name(.) {
                    expr .;
                }
            }
        }
    }
}
% slaxproc -E -g /tmp/foo.slax
<?xml version="1.0"?>
<top>
  <abc a="12" b="34" c="56"/>
</top>
Bock %

Thanks,
 Phil