[lxml-dev] special string subclasses for XPath string results

[Stefan Behnel]

Hi Ian,

I now implemented the basic behaviour on the trunk. It first crashed because
of a bug in Cython 0.9.6.10b, hope my patch will find its way into a release soon.

Attributes and text nodes are now handled. String results (such as returned by
the string() function) will remain plain strings - no way to recover here.


Ian Bicking wrote:
> For something like ::first-letter, I didn't really expect it to be
> possible to compile that to XPath.  Instead it would have to be
> something like:
> 
> def first_letter_selector(xpath_expr):
>     def selector(el):
>         result = xpath_expr(el)
>         return result.text_range(0, 1)
>     return selector

Something like that, yes. You could do

        for element in xpath_expr(el):
            for text in element.itertext()
                if text:
                    return text[0]
        return None # or raise or ...

or wouldn't we have to return a list here? As in

        return [ text[0] for element in xpath_expr(el)
                         for text in element.itertext()
                         if text ]


> For representing ranges I'd also like some text range (I don't have any
> immediate needs, so I'm personally in no rush here).  But it's not
> something that would have to replace the current text/tail attributes.
> It's just that in some code it can be nice to have something similar to
> the DOM TextNode, and this kind of provides that (except more nicely I
> think, as it would be more like a view).
> 
> Then the range might just be like:
> 
> class TextRange(object):

[...]

You could file this as a feature request in the bug tracker so that we won't
forget about it. It's definitely not clear enough for 2.0.

Stefan