Re: [boost] spirit: Using actions on rules with more precision

From: John Ky (newhoggy_at_[hidden])
Date: 2006-01-23 22:19:23

Resolved.

I have to apologise - I just worked out that I needed to use
anychar - blank_p because blank_p was matching elsewhere in the grammar.

-John

On 1/24/06, John Ky <newhoggy_at_[hidden]> wrote:
> Hi Hartmut,
>
> Thanks for the help.
>
> I got it to work with an extra ::context_t in:
>
>    typedef rule<strlit_closure::context_t> rule_type;
>
> Is that the correct way to do it?
>
> Also, I have another problem:
>
> The rule:
>
>   rule_string mystringrule;
>   mystringrule =
>     * ( confix_p('"', (*c_escape_ch_p)[mystringrule.val +=
> construct_<string>(arg1, arg2)], "')
>       );
>
> Will match:
>
>   "hello""world"
>
> as:
>
>   helloworld
>
> But the rule:
>
>   rule_string mystringrule;
>   mystringrule =
>     * ( confix_p('"', (*c_escape_ch_p)[mystringrule.val +=
> construct_<string>(arg1, arg2)], "')
>       | (anychar_p - '"')      /* this line added */
>       );
>
> matched returning an empty string.
>
> -John
>
> On 1/24/06, Hartmut Kaiser <hartmut.kaiser_at_[hidden]> wrote:
> > John Ky wrote:
> >
> > > Is it possible to define a rule:
> > >
> > >     rule<> mystringrule = confix_p('"', *c_escape_ch_p, '"')
> > >
> > > differently such that I can use
> > >
> > >     std::string value;
> > >
> > >     bool result = parse("\"hello world\"",
> > > mystringrule[assign_a(value)]).full;
> > >
> > > and get the text = "hello world" assigned to value?
> > >
> > > Currently, I get text = "\"hello world\"" instead.  ie with
> > > double quotes at either end.
> >
> > I'ld suggest to use closures for that (not tested):
> >
> >     struct strlit_closure
> >     : public boost::spirit::closure<strlit_closure, std::string>
> >     {
> >         member1 val;
> >     };
> >
> >     typedef rule<strlit_closure> rule_type;
> >
> >     rule_type mystringrule
> >         = confix_p('"', *c_escape_ch_p[assign_a(mystringrule.val)], '"');
> >
> >     bool result = parse("\"hello world\"",
> >         mystringrule[assign_a(value)]).full;
> >
> > This is based on the fact, that the first closure member of a rule is used
> > as the rule's value.
> >
> > HTH
> > Regards Hartmut
>