Boost Spirit调试枚举类（c ++ 11）编译错误

Question

我正在尝试调试一个包含带有BOOST_SPIRIT_DEBUG_NODE的枚举类的简单结构，但我总是得到编译错误“C：\\ boost \\ boost \\ spirit \\ home \\ support \\ attributes.hpp：1226：错误：无法绑定'std： ：basic_ostream'左值'到'std :: basic_ostream &&'靠近'out << val;'“

我不知道为什么我会得到这样的右值错误，我试图为运算符<<为枚举类添加一个手动重载，但这也不起作用。

我正在使用boost 1.55并尝试使用gcc 4.8与Windows 8.1 x64上的MinGW 32位进行编译。

当我将枚举类更改为默认的c ++枚举时，它可以工作，但我想使用新的枚举类来进行正确的命名空间处理。

Answer 1

我不知道为什么我会得到这样的右值错误，我试图为运算符<<为枚举类添加一个手动重载，但这也不起作用。

我认为这是必需的代码，因为它确实有效：

1. 首先，使用经典的Enum Live on Coliru

    #define BOOST_SPIRIT_DEBUG #include <boost/spirit/include/qi.hpp> #include <iostream> namespace qi = boost::spirit::qi; struct data_t { std::string label; enum Choice { left, right, up, down } choice; data_t(std::string label="default", Choice choice=left): label(std::move(label)), choice(choice) {} friend std::ostream& operator<<(std::ostream& os, Choice const& v) { switch(v) { case left: return os << "left"; case right:return os << "right"; case up: return os << "up"; case down: return os << "down"; default: return os << "?"; } } friend std::ostream& operator<<(std::ostream& os, data_t const& v) { return os << "{label:" << v.label << ";choice:" << v.choice << "}"; } }; template <typename It, typename Skipper = qi::space_type> struct parser : qi::grammar<It, data_t(), Skipper> { parser() : parser::base_type(start) { using namespace qi; choice_.add ("left", data_t::left) ("right", data_t::right) ("up", data_t::up) ("down", data_t::down); start %= as_string[ lexeme[+graph] ] >> lexeme [choice_]; BOOST_SPIRIT_DEBUG_NODE(start); } private: qi::symbols<char, data_t::Choice> choice_; qi::rule<It, data_t(), Skipper> start; }; bool doParse(const std::string& input) { typedef std::string::const_iterator It; auto f(begin(input)), l(end(input)); parser<It, qi::space_type> p; data_t data; try { bool ok = qi::phrase_parse(f,l,p,qi::space,data); if (ok) { std::cout << "parse success\\n"; std::cout << "data: " << data << "\\n"; } else std::cerr << "parse failed: '" << std::string(f,l) << "'\\n"; if (f!=l) std::cerr << "trailing unparsed: '" << std::string(f,l) << "'\\n"; return ok; } catch(const qi::expectation_failure<It>& e) { std::string frag(e.first, e.last); std::cerr << e.what() << "'" << frag << "'\\n"; } return false; } int main() { bool ok = doParse("label1 up"); return ok? 0 : 255; } 

2. 第二部分是关于Coliru的Enum课程

    #define BOOST_SPIRIT_DEBUG #include <boost/spirit/include/qi.hpp> #include <iostream> namespace qi = boost::spirit::qi; struct data_t { std::string label; enum class Choice { left, right, up, down } choice; data_t(std::string label="default", Choice choice=Choice::left): label(std::move(label)), choice(choice) {} friend std::ostream& operator<<(std::ostream& os, Choice const& v) { switch(v) { case Choice::left: return os << "left"; case Choice::right:return os << "right"; case Choice::up: return os << "up"; case Choice::down: return os << "down"; default: return os << "?"; } } friend std::ostream& operator<<(std::ostream& os, data_t const& v) { return os << "{label:" << v.label << ";choice:" << v.choice << "}"; } }; template <typename It, typename Skipper = qi::space_type> struct parser : qi::grammar<It, data_t(), Skipper> { parser() : parser::base_type(start) { using namespace qi; choice_.add ("left", data_t::Choice::left) ("right", data_t::Choice::right) ("up", data_t::Choice::up) ("down", data_t::Choice::down); start %= as_string[ lexeme[+graph] ] >> lexeme [choice_]; BOOST_SPIRIT_DEBUG_NODE(start); } private: qi::symbols<char, data_t::Choice> choice_; qi::rule<It, data_t(), Skipper> start; }; bool doParse(const std::string& input) { typedef std::string::const_iterator It; auto f(begin(input)), l(end(input)); parser<It, qi::space_type> p; data_t data; try { bool ok = qi::phrase_parse(f,l,p,qi::space,data); if (ok) { std::cout << "parse success\\n"; std::cout << "data: " << data << "\\n"; } else std::cerr << "parse failed: '" << std::string(f,l) << "'\\n"; if (f!=l) std::cerr << "trailing unparsed: '" << std::string(f,l) << "'\\n"; return ok; } catch(const qi::expectation_failure<It>& e) { std::string frag(e.first, e.last); std::cerr << e.what() << "'" << frag << "'\\n"; } return false; } int main() { bool ok = doParse("label1 up"); return ok? 0 : 255; } 

我的猜测是你忘了将序列化添加到你的枚举或结构中。