Re: [Boost-users] [Spirit 2] on_error to string

Subject: Re: [Boost-users] [Spirit 2] on_error to string
From: Vincent Agnus (vincent.agnus_at_[hidden])
Date: 2011-04-07 03:47:22

Le 06/04/2011 20:08, TONGARI a écrit :

>
> Does my first suggestion solve your first attempt?
>      i.e.   (ostream&)m_error << ...

I don't have see our answer in our previous mail. I have test it with
m_error as std::stringstream and phx::ref( (ostream&)m_error ). And it 
works fine !!!

Thanks a lot for our help

Note that there is a compilation error with *std::ostringstream* m_error 
and phx::ref( m_error )

>
>     for example if my start rule is
>     start = qi::char_("a-z") > qi::char_("!");
>
>     and I parse the string "a#" then I expect that _4 contain "!" ,
>     phx::bind(&boost::spirit::info::tag, qi::_4) return "literal-char"
>
>     2 questions :
>     a) I have a look in boost::spirit::info class is the
>     boost::spirit::info::value member is containing the data I want ( ie
>     "!")
>
>
> True here, but it's a more subtle thing than I can explain...
> Not every case can you get a utf8_string form boost::spirit::info::value.
>
> For example, "... > qi::char_('a', 'z')" you can get the value as a
> utf8_string "a-z";
> while "... > qi::char_("a-z")" you can only get a nil object from value.

OK

>
>     b) perhaps it exists an alternative like
>       phx::construct<>( phx::val("") << _4 )
>
>
> I don't know what you mean here.

With this kind of proposition I will hope to hack the string 
construction (m_error in this case is a std::string).
a) phx::construct<std::string>( phx::val("...") ) is a valid expression
b) phx::val("...") << _4 is a valid expression
c) phx::construct<std::string>( phx::val("...") << _4 ). The evaluation 
on this expression first compute (exp. b)  phx::val("...") << _4 then 
then apply (a) evaluation.

For my application I will use our workarond, thanks again

Vincent Agnus