Re: [boost] [spirit] Support for one-pass iterators?

Subject: Re: [boost] [spirit] Support for one-pass iterators?
From: Hartmut Kaiser (hartmut.kaiser_at_[hidden])
Date: 2009-10-19 12:37:38

> >> The docs say that the grammar should pass a reference to the
> starting
> >> rule to the base class constructor (qi::grammar specialization). But
> >> at this point the rule's constructor has not yet been called. What's
> >> more, the base class calls a method on the passed reference.
> >
> > Where did you get that info? The base class does not call a method on
> > the passed reference. That is not correct. It only does so at parse
> > time and at that time, everything has already been constructed.
> 
> Hmm... I may be misinterpreting what I see at
> boost/spirit/home/qi/nonterminal/grammar.hpp:54, in the release branch:
> 
>      grammar(
>          start_type const& start
>        , std::string const& name_ = "unnamed-grammar")
> =>  : proto::extends<terminal,
> base_type>(terminal::make(start.alias()))
>      , name_(name_)
>      {}
> 
> Here "start" is a reference to a not yet constructed object.

All the construct is doing is to use the address of start (which is known
and well defined at this point). The address of an object doesn't change
during construction. Just look at the code, you'll see it. The code does not
refer to any member data items of 'start'. I see no problem with this. 

Do you have a real problem while using Spirit or is this discussion merely
'academic'?

Regards Hartmut

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