Re: [boost] xml?

Subject: Re: [boost] xml?
From: Phil Endecott (spam_from_boost_dev_at_[hidden])
Date: 2010-04-08 13:23:02

Maarten L. Hekkelman wrote:
> Op 08-04-10 17:22, Phil Endecott schreef:
>> Just one observation for now.  I see that you have a node class that 
>> points to its neighbours and parent.  I think this is quite a common 
>> pattern for XML, but it differs from e.g. the standard containers.  So 
>> it's not possible to use standard algorithms to iterate through your 
>> XML structure.
>>
> I started with containers, but ended up with the current structure since 
> it is so much more practical.
>
> You can still iterate in container style over children though. The 
> member 'children()' of a node returns a std::list of pointers to 
> children nodes. Therefore you can write code like:
>
> foreach (xml::element* e, node->children<xml::element>())
>      ;

Ah, I missed that.

> As I said, I started with simply nodes that had children in a member STL 
> list. This seemed the /right/ way to do it. But then I ran into problems 
> when I had to create processing instruction nodes, comment nodes and 
> even attribute nodes. These are needed for a correct (and 
> straightforward) xpath implementation. So I had to create a common base 
> class, node, and element now is a subclass of node.
>
> Fortunately, not all is lost. The children method above can be used for 
> traversal, but it is even more convenient to use xpath.evaluate() to 
> create a selection and iterate that:
>
> foreach (xml::element* e, xpath("//my-node").evaluate<xml::element*>(n))
>      ;

So could your XPath implementation be decoupled?  What interface does 
it use to traverse the XML tree?  Could it be used on top of a 
different XML tree implementation, such as a lazy one that stores the 
text of the XML document, if it provided a similar interface?

Regards,  Phil.