Re: [Boost-users] [Spirit] Incompatible skipper type?

Subject: Re: [Boost-users] [Spirit] Incompatible skipper type?
From: Michael Powell (mwpowellhtx_at_[hidden])
Date: 2019-01-10 21:24:48

On Thu, Jan 10, 2019 at 4:22 PM Michael Powell <mwpowellhtx_at_[hidden]> wrote:
>
> On Thu, Jan 10, 2019 at 4:21 PM Michael Powell <mwpowellhtx_at_[hidden]> wrote:
> >
> > Hello,
>
> I should also mention, I am using the latest Boost 1.69.0.
>
> > I'm a bit confused here, not sure what this means:
> >
> > Severity Code Description Project File Line Suppression State
> > Error C2664 'bool boost::function4<R,T0,T1,T2,T3>::operator
> > ()(T0,T1,T2,T3) const': cannot convert argument 4 from 'const Skipper'
> > to 'T3' Kingdom.Json.Parser.Tests
> > d:\dev\boost.org\boost_1_69_0\boost\spirit\home\qi\nonterminal\rule.hpp
> > 304

It does not matter whether I call:

const auto parse_tried = qi::phrase_parse(begin, end,
json_grammar_type{}, json_grammar_type::skipper_type{}, actual);

Or this:

const auto parse_tried = qi::parse(begin, end, json_grammar_type{}, actual);

> > // If you are seeing a compilation error here stating that the
> > // fourth parameter can't be converted to a required target type
> > // then you are probably trying to use a rule or a grammar with
> > // an incompatible skipper type.
> > if (f(first, last, context, skipper)) {}
> >
> > Incompatible where? How? Requires clarification please. The default
> > Skipper type, which I am using at the moment, is
> > boost::spirit::qi::space_type. I aim to use the proven Comment Skipper
> > that I leveraged in a previous iteration eventually, but I expect that
> > compilation should work with the simple space type at least.
> >
> > Because as far as I can determine all of the rules in my Grammar have
> > the same Skipper type.
> >
> > struct json_grammar : qi::grammar<It, value_t(), Skipper> {
> >     using iterator_type = It;
> >     using skipper_type = Skipper;
> >     using char_rule_type = qi::rule<It, char()>;
> >     json_grammar() : json_grammar::base_type(value_) {
> >         // ...
> >      }
> > private:
> >     struct escapes_t : qi::symbols<char, char> {
> >         escapes_t() {
> >             this->add("\\b", '\b')
> >                 ("\\f", '\f')
> >                 ("\\n", '\n')
> >                 ("\\r", '\r')
> >                 ("\\t", '\t')
> >                 ("\\v", '\v')
> >                 ("\\\\", '\\')
> >                 ("\\/", '/')
> >                 ("\\'", '\'')
> >                 ("\\\"", '"')
> >                 ;
> >         }
> >     } char_esc;
> >
> >     //qi::rule<iterator_type> line_cont;
> >     char_rule_type hex_esc, unicode_esc;
> >     qi::rule<iterator_type, str_t()> quot_str, tick_str, str_lit;
> >
> >     qi::rule<iterator_type, std::vector<value_t>(), skipper_type> array_;
> >     qi::rule<iterator_type, boost::tuple<key_t, value_t>(),
> > skipper_type> member;
> >     qi::rule<iterator_type, std::vector<boost::tuple<key_t,
> > value_t>>(), skipper_type> object_;
> >
> >     qi::rule<iterator_type, key_t(), skipper_type> member_key;
> >     qi::rule<iterator_type, value_t(), skipper_type> value_;
> >
> >     qi::rule<iterator_type, numeric_sign_t(), skipper_type> numeric_sign;
> >     qi::rule<iterator_type, float_t(), skipper_type> float_lit;
> >     qi::rule<iterator_type, floating_point_number_t(), skipper_type>
> > floating_point;
> >     qi::rule<iterator_type, int_t(), skipper_type> hex_int, oct_int,
> > dec_int, int_lit;
> >     qi::rule<iterator_type, integer_number_t(), skipper_type> integer;
> >
> >     qi::rule<iterator_type, boolean_t(), skipper_type> bool_lit;
> >     qi::rule<iterator_type, null_t(), skipper_type> null_lit;
> > };
> >
> > Best regards,
> >
> > Michael Powell