Re: [xml-dev] Beware of XPath expressions that produce false positives

[John Cowan <johnwcowan@gmail.com>]

On Sat, Sep 24, 2016 at 2:33 PM, Costello, Roger L. <costello@mitre.org> wrote:

[Definition] An element is empty if and only if the element consists of a text node containing a string of length zero and nothing else (no attribute, comment, processing instruction, child element, or non-string value).

In general, there are no text nodes of length zero.  <B/> and its equivalent <B></B> contain only an element node.  Furthermore, parsers may discard comments, so you can't be sure whether <B><!--foo--></B> will be treated the same as <B/> or not.

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John Cowan          http://vrici.lojban.org/~cowan        cowan@ccil.org

Cash registers don't really add and subtract;

        they only grind their gears.

But then they don't really grind their gears, either;

        they only obey the laws of physics.  --Unknown 

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