Re: How to synthesize std::map

On Fri, Jan 11, 2019 at 12:27 PM Michael Powell <[email protected]> wrote:
>
> At least from the forums I've read, this should be working, I'm not
> sure why it's not working now, current Boost 1.69 Spirit Qi.
>
> https://wandbox.org/permlink/HxB6Yg3r9ZpbHOxt

Even simplifying further, removing the key_t and grammar rule, for the
str_t, still does not work. Seems like a map/pair issue more than an
underlying key/str issue.

https://wandbox.org/permlink/fmffEazGRMTnl5w9

> On Fri, Jan 11, 2019 at 12:10 PM Michael Powell <[email protected]> wrote:
> >
> > Hello,
> >
> > Using Boost Spirit Qi, or std::unordered_map... I am receiving
> > assignment errors on build.
> >
> > Interestingly, I can map a Vector of Member Tuples without any compiler errors:
> >
> > std::vector<boost::tuple<key_t, value_t>> ...
> >
> > However attempting to map an Unordered Map does not seem to work as
> > well, or I need to do some additional work adapting it for Qi grammar
> > purposes:
> >
> > std::unordered_map<key_t, value_t> ...
> >
> > At least not without some help, perhaps... That or I need to do so in
> > one, swift rule.
> >
> > Assuming:
> >
> > using object_t = std::unordered_map<key_t, value_t>;
> > using member_t = object_t::node_type;
> >
> > For example, instead of:
> >
> > qi::rule<iterator_type, member_t(), skipper_type> member;
> > qi::rule<iterator_type, object_t(), skipper_type> object_;
> >
> > And which rules being defined as:
> >
> > member %= member_key >> ':' >> value_;
> >
> > object_ %= '{'
> >     >> (member % ',')
> >     >> '}';
> >
> > I wonder whether I need to just simplify and collapse the rules into one rule.
> >
> > object_ %= '{'
> >     >> ((member_key >> ':' >> value_) % ',')
> >     >> '}';
> >
> > With the compiler error being:
> >
> > 2>d:\dev\boost.org\boost_1_69_0\boost\spirit\home\qi\detail\assign_to.hpp(153):
> > error C2440: 'static_cast': cannot convert from 'const T_' to
> > 'Attribute'
> > 2>        with
> > 2>        [
> > 2>            T_=kingdom::json::key_t
> > 2>        ]
> > 2>        and
> > 2>        [
> > 2>            Attribute=std::_Node_handle<std::_List_node<std::pair<const
> > kingdom::json::key_t,kingdom::json::value_t>,std::_Default_allocator_traits<std::allocator<std::pair<const
> > kingdom::json::key_t,kingdom::json::value_t>>>::void_pointer>,std::allocator<std::pair<const
> > kingdom::json::key_t,kingdom::json::value_t>>,std::_Node_handle_map_base,kingdom::json::key_t,kingdom::json::value_t>
> > 2>        ]
> >
> > Thoughts? Suggestions?
> >
> > Cheers,
> >
> > Michael Powell