Re: [Boost-users] Spirit : Is possible to build rule step by step?

Subject: Re: [Boost-users] Spirit : Is possible to build rule step by step?
From: Andrea Fontana (info_at_[hidden])
Date: 2011-01-17 11:48:42

Thank you Hartmut, really helpful.

On 17 January 2011 17:24, Hartmut Kaiser <hartmut.kaiser_at_[hidden]> wrote:

> > I'm trying to write a small example using spirit.
> >
> > I can write a rule in this way:
> >
> > my_rule = lit("example") | lit("example2");
> >
> > Also in this way:
> >
> > std::string ex("example")
> > std::string ex2("example2");
> > my_rule = lit(ex) | lit(ex2))
> >
> > Is there a way to do this:
> > std::string ex("example")
> > std::string ex2("example2");
> > my_rule = lit(ex);
> > my_rule = my_rule | lit(ex2));
>
> Make that:
>
>   my_rule = my_rule.copy() | lit(ex2));
>
> and it will work. The explicit copy is needed, as in this context rules are
> always held by reference.
>
> > I need to append strings from an array...
> > Maybe I miss something from docs.
>
> But since you seem to have only a bunch of strings to match, why don't you
> use a symbol table (see qi::symbols). This is not only easier to set up
> iteratively, it's more efficient at runtime as well.
>
> Regards Hartmut
> ---------------
> http://boost-spirit.com
>
>
>
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