Re: [boost] [Review] xpressive

From: Scott Woods (scottw_at_[hidden])
Date: 2005-09-18 17:23:07

----- Original Message -----
From: "Eric Niebler" <eric_at_[hidden]>
To: <boost_at_[hidden]>
Sent: Saturday, September 17, 2005 5:10 AM
Subject: Re: [boost] [Review] xpressive

> >>  2. In Filtering Nested Results, I wasn't clear what the purpose was.
Is
> >> it to show all the name matches before all the id matches? If so,
> >> choosing a less regular example string would help, e.g. with more names
> >> than ids, names following names some of the time, etc.
> >
> >
> >
> > I'm not at all sure of the utility of the nested results filter, and I
> > may just cut it. After matching a regex that contains nested regexes,
> > the match_results object contains nested results. Figuring out which
> > results correspond to which regex can be difficult. The filter lets
> > you see only those results corresponding to a particular nested regex.
> > But I've yet to need it in practice. *shrug*

I was assuming that nested results would be the way that complex
patterns (i..e. grammars) and semantic actions may be associated.
Having matched some deeply structured thing, nested results gives
you the ability to process the hierarchy in a clean fashion.

I'm not particularly championing this approach but its a workable
alternative. If you did the semantic actions another way then this point
wouldn't hold.