Re: [boost] [Spirit-general] Spirit Questions

From: Hartmut Kaiser (hartmut.kaiser_at_[hidden])
Date: 2007-07-13 10:51:24

Jarrad, 

> Thanks, I saw this a long time ago at codeproject also. Is 
> there any real hope in the future that boost::any will take 
> advantage of this implementation?

Only, if somebody cares to push it through the review process (writes
documentation, etc.). Currently it's just an internal implementation detail
in Spirit2.

> This is related to my original question. While using 
> hold_any, I run into this problem when trying to use 
> BOOST_SPIRIT_DEBUG with a vector of hold_any.
> 
> binary '>>' : no operator found which takes a right-hand 
> operand of type 'std::vector<_Ty>' (or there is no acceptable 
> conversion)
> 1>        with
> 1>        [
> 1>            _Ty=boost::spirit::hold_any
> 1>        ]
> 
> The code I added was as follows
> 
> std::istream& operator>> (std::istream& i, vector<hold_any>& obj) {
>     return i;//obj.table->stream_in(i, &obj.object); }
> 
> std::ostream& operator<< (std::ostream& o, vector<hold_any> 
> const& obj) {
> 	o << "[";
> 	for(size_t i = 0; i < obj.size(); i++)
> 	{
> 		if(i > 0)
> 			o << ",";
> 		o << obj[i];
> 	}
> 	o << "]";
>     return o;
> }

Seems to be fine this way. Hold_any supports streaming only if the contained
datatype is streamable.

Regards Hartmut