Re: [xml-dev] Entities contain XML tags?

[Michael Kay <mike@saxonica.com>]

On 04/08/2012 07:42, Dan Shelton wrote:
> Can entities themselves contain XML tags? I'm trying to write my own
> XML parser (for fun) and try to understand when entity expansion
> should be done - before tag parsing, after tag parsing or do entities
> only apply to text data?
>
Unfortunately the logical layer of XML (the element hierarchy) and the 
physical layer (the entity hierarchy) are deeply intertwined (read, not 
properly layered). Entities can contain elements, but they can't contain 
unmatched tags. So you can't simply expand the entity references to 
create a concatenated character stream and then parse the character 
stream: the parsing needs to be aware of entity boundaries.

With parameter entities it gets even worse, but it's so long since I did 
anything serious with DTDs that I have thankfully forgotten the details.

Michael Kay
Saxonica