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

10 Jan 2019

      On Thu, Jan 10, 2019 at 4:22 PM Michael Powell  wrote:
...
On Thu, Jan 10, 2019 at 4:21 PM Michael Powell  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::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 {
    using iterator_type = It;
    using skipper_type = Skipper;
    using char_rule_type = qi::rule;
    json_grammar() : json_grammar::base_type(value_) {
        // ...
     }
private:
    struct escapes_t : qi::symbols {
        escapes_t() {
            this->add("\\b", '\b')
                ("\\f", '\f')
                ("\\n", '\n')
                ("\\r", '\r')
                ("\\t", '\t')
                ("\\v", '\v')
                ("\\\\", '\\')
                ("\\/", '/')
                ("\\'", '\'')
                ("\\\"", '"')
                ;
        }
    } char_esc;
//qi::rule line_cont;
    char_rule_type hex_esc, unicode_esc;
    qi::rule quot_str, tick_str, str_lit;
qi::rule(), skipper_type> array_;
    qi::rule(),
skipper_type> member;
    qi::rule>(), skipper_type> object_;
qi::rule member_key;
    qi::rule value_;
qi::rule numeric_sign;
    qi::rule float_lit;
    qi::rule
floating_point;
    qi::rule hex_int, oct_int,
dec_int, int_lit;
    qi::rule integer;
qi::rule bool_lit;
    qi::rule null_lit;
};
Best regards,
Michael Powell