Неоднозначный вариант и ударный дух x3

Пытаться подстроить ускорительный пример x3 calc для анализа функций, которые могут принимать функции в качестве аргументов. Однако он не компилируется.

namespace client{ namespace ast{
    struct ts;
    struct fnc;
    typedef boost::variant<
    ts,
    boost::recursive_wrapper<fnc>
    > node;
    struct ts{
        unsigned int id;
    };
    struct fnc{
        std::vector<char> id;
        std::vector<node> args;
    };
}}
BOOST_FUSION_ADAPT_STRUCT(
    client::ast::ts,
    (unsigned int, id)
)
BOOST_FUSION_ADAPT_STRUCT(
    client::ast::fnc,
    (std::vector<char>, id)
    (std::vector<client::ast::node>, args)
)
namespace client{
    namespace x3 = boost::spirit::x3;
    namespace calc_grammar{
        using x3::uint_;
        using x3::alpha;
        using x3::alnum;
        using x3::lit;
        using x3::char_;
        x3::rule<class funct, ast::fnc> const funct("function");
        x3::rule<class ts, ast::ts> const ts("timeseries");
        x3::rule<class funct_name, std::vector<char>> const funct_name("function_name");
        auto const funct_def = funct_name >> lit('(') >> -((ts|funct)%lit(',')) >> lit(')');
        auto const ts_def = lit('#') >> uint_ >> lit('#');
        auto const funct_name_def = lit('@') >> alpha >> *(alnum|char_('_'));
        auto const calc = x3::grammar(
            "calc", 
            funct = funct_def, 
            ts = ts_def,
            funct_name = funct_name_def
        );
    }
    using calc_grammar::calc;
}

ошибка C2665: 'boost:: detail:: variant:: make_initializer_node:: apply:: initializer_node:: initialize': ни одна из 5 перегрузок не могла преобразовать все типы аргументов

Там также примечание для пользователя в варианте .hpp

// NOTE TO USER :
// Compile error here indicates that the given type is not 
// unambiguously convertible to one of the variant types
// (or that no conversion exists).

Но я не мудрее...

namespace grammar_def { using namespace x3; rule<class funct, ast::fnc> const funct("function"); auto const ts = lexeme [ '#' >> uint_ >> '#' ]; auto const fname = lexeme [ '@' >> raw [ alpha >> *(alnum | '_') ] ]; auto const expr = ts|funct; auto const funct_def = fname >> '(' >> -expr % ',' >> ')'; BOOST_SPIRIT_DEFINE(funct) }

namespace client { namespace ast { static std::ostream& operator<<(std::ostream& os, ts const& v) { using namespace boost::fusion; return os << tuple_open("") << tuple_close("") << tuple_delimiter("") << as_vector(v); } static std::ostream& operator<<(std::ostream& os, fnc const& v) { using namespace boost::fusion; return os << tuple_open("") << tuple_close("") << tuple_delimiter("") << as_vector(v); } template<typename T> static std::ostream& operator<<(std::ostream& os, std::vector<T> const& v) { os << "("; for (auto& el : v) os << (&el==&v[0]?"":", ") << el; return os << ")"; } } }

Demo

У этого есть больше (опционально) сантехника, чтобы обеспечить более богатую информацию отладки:

//#define BOOST_SPIRIT_X3_DEBUG #include <iostream> #include <boost/fusion/include/adapt_struct.hpp> #include <boost/fusion/include/as_vector.hpp> #include <boost/fusion/include/io.hpp> #include <boost/spirit/home/x3.hpp> namespace client { namespace ast { struct ts; struct fnc; //using string = std::vector<char>; using string = std::string; // for easier printing/debugging struct ts { unsigned int id; ts(unsigned id=0):id(id) {} }; typedef boost::variant<ts, boost::recursive_wrapper<fnc> > node; struct fnc { string id; std::vector<node> args; }; } } BOOST_FUSION_ADAPT_STRUCT(client::ast::ts, id) BOOST_FUSION_ADAPT_STRUCT(client::ast::fnc, id, args) //namespace std { static ostream& operator<<(ostream&os, vector<char> const& v) { return os.write(&v[0], v.size()); } } namespace client { namespace ast { static std::ostream& operator<<(std::ostream& os, ts const& v) { using namespace boost::fusion; return os << tuple_open("") << tuple_close("") << tuple_delimiter("") << as_vector(v); } static std::ostream& operator<<(std::ostream& os, fnc const& v) { using namespace boost::fusion; return os << tuple_open("") << tuple_close("") << tuple_delimiter("") << as_vector(v); } template<typename T> static std::ostream& operator<<(std::ostream& os, std::vector<T> const& v) { os << "("; for (auto& el : v) os << (&el==&v[0]?"":", ") << el; return os << ")"; } } } namespace client { namespace x3 = boost::spirit::x3; namespace grammar_def { using namespace x3; x3::rule<class funct, ast::fnc> const funct("function"); auto const ts // = x3::rule<class ts, ast::ts> {"timeseries"} = lexeme [ '#' >> uint_ >> '#' ]; auto const fname // = x3::rule<class fname, ast::string> {"function_name"} = lexeme [ '@' >> raw [ alpha >> *(alnum | '_') ] ]; auto const expr // = rule<struct expr_, ast::node > {"expr"} = ts|funct; auto const funct_def = fname >> '(' >> -expr % ',' >> ')'; BOOST_SPIRIT_DEFINE(funct) } auto const& grammar = x3::skip(x3::space) [grammar_def::funct]; } #include <iostream> int main() { std::string const s { "@pow( #1#, \n" " @trunc(\n" " @pi ()\n" " ) )"}; std::cout << "Parsing '" << s << "'\n"; auto f = s.begin(); client::ast::fnc parsed; if (parse(f, s.end(), client::grammar, parsed)) { std::cout << "Parse succeeded: " << parsed << "\n"; } else { std::cout << "Parse failed\n"; } if (f != s.end()) std::cout << "Remaining unparsed input: '" << std::string(f, s.end()) << "'\n"; }

Печать

Parsing '@pow( #1#, @trunc( @pi () ) )' Parse succeeded: pow(1, trunc(pi()))

Ответ 1

Demo