Re: Delaying activation of actions

[Hans Aberg]

On 13 Feb 2007, at 14:32, Frans Englich wrote:

> I have a design problem that I don't know how to solve, so any  
> pointer would
> be highly appreciated!
>
> The problem is that is that in a parser for pseudo-XML, ...

If it is a known problem, perhaps you might check the USenet  
newsgroup comp.compilers, or some XML list.

> I need to delay the
> lookup of certain names, to after all namespace declarations has  
> been parsed.
> Here's an example:
>
> <e attribute="{p:herePrefixPisUsed}"
> xmlns:p="http://example.com/HerePrefixPisDeclared"/>
>
> As can be seen, "xmlns:p" appears after "p:herePrefixPisUsed".
>
> The problem is that the parser operates sequentially, and attempts  
> to resolve
> "p" inside "p:herePrefixPisUsed", but since "xmlns:p" hasn't been  
> encountered
> yet, it doesn't know about it, and hence fails.

Unless you can save "{p:herePrefixPisUsed}", and resolve in the  
actions, when he 'xmlns:p=', I think you will have a hard parsing  
problem. You might cause delays in the parsing by the use of %glr,  
and letting the grammar be ambiguous until being resolved.

  Hans Aberg