使用 boost spirit x3 分离解析器时出现链接错误

Question

我目前正在尝试使用 BOOST_SPIRIT_DEFINE/DECLARE/INSTANTIATE 将我的 boost spirit x3 解析器分成不同的 _def 和 .cpp 文件，但我一直收到链接错误。 HERE 是我的解析器，它是分开的。

链接器错误读取

<artificial>:(.text.startup+0xbb): undefined reference to `bool kyle::parser::impl::parse_rule<__gnu_cxx::__normal_iterator<char*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >, boost::spirit::x3::context<boost::spirit::x3::skipper_tag, boost::spirit::x3::char_class<boost::spirit::char_encoding::standard, boost::spirit::x3::space_tag> const, boost::spirit::x3::unused_type>, boost::spirit::x3::unused_type const>(boost::spirit::x3::rule<kyle::parser::impl::identifier_class, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, false>, __gnu_cxx::__normal_iterator<char*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >&, __gnu_cxx::__normal_iterator<char*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > const&, boost::spirit::x3::context<boost::spirit::x3::skipper_tag, boost::spirit::x3::char_class<boost::spirit::char_encoding::standard, boost::spirit::x3::space_tag> const, boost::spirit::x3::unused_type> const&, boost::spirit::x3::unused_type const&)'

我做错了什么？我怎样才能让我的例子发挥作用？

config.hpp:

#include <boost/spirit/home/x3.hpp>

namespace kyle{
namespace parser{

namespace x3 = boost::spirit::x3;

typedef std::string::const_iterator iterator_type;
typedef x3::phrase_parse_context<x3::ascii::space_type>::type context_type;

}
}

literals.cpp:

#include "literals_def.hpp"
#include "config.hpp"
#include <boost/spirit/home/x3.hpp>


namespace kyle {
namespace parser {
namespace impl {

BOOST_SPIRIT_INSTANTIATE(identifier_type, iterator_type, context_type);

}
}
}

literals_def.hpp:

#include <boost/spirit/home/x3.hpp>
#include "literals.hpp"

namespace kyle {
namespace parser {
namespace impl {

namespace x3 = boost::spirit::x3;


const identifier_type identifier = "identifier";



auto const identifier_def = x3::alpha >> *x3::alnum;

BOOST_SPIRIT_DEFINE(identifier)
}
impl::identifier_type identifier(){
    return impl::identifier;
}


}
}

literals.hpp:

#include <boost/spirit/home/x3.hpp>

namespace kyle{
namespace parser{
namespace impl {
namespace x3 = boost::spirit::x3;

struct identifier_class;

typedef x3::rule<identifier_class, std::string> identifier_type;

BOOST_SPIRIT_DECLARE(identifier_type)
}

impl::identifier_type identifier();


}
}

main.cpp:

#include "literals.hpp"
#include <iostream>

template<typename Parser>
bool test(std::string str, Parser&& p, bool full_match = true)
{
    auto in = str.begin();
    auto end = str.end();
    bool ret = boost::spirit::x3::phrase_parse(in, end, p, boost::spirit::x3::space);
    ret &= (!full_match || (in == end));
    return ret;

}

int main(){
    auto b = test("fobar", kyle::parser::identifier());
    std::cout << b << std::endl;

}

Answer 1

两点：

您将上下文定义为
```
typedef x3::phrase_parse_context<x3::space_type>::type context_type;
```
但是，您尝试使用 x3::space 而不是 x3::ascii::space 来调用它。

提示在您没有包含的错误消息中：

/home/sehe/custom/boost/boost/spirit/home/x3/nonterminal/rule.hpp:116: undefined reference to 'bool kyle::parser::impl::parse_rule<__gnu_cxx::__normal_iterator<char const*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >, boost::spirit::x3::context<boost::spirit::x3::skipper_tag, boost::spirit::x3::char_class<boost::spirit::char_encoding::standard, boost::spirit::x3::space_tag> const, boost::spirit::x3::unused_type>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >(boost::spirit::x3::rule<kyle::parser::impl::identifier_class, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, false>, __gnu_cxx::__normal_iterator<char const*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >&, __gnu_cxx::__normal_iterator<char const*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > const&, boost::spirit::x3::context<boost::spirit::x3::skipper_tag, boost::spirit::x3::char_class<boost::spirit::char_encoding::standard, boost::spirit::x3::space_tag> const, boost::spirit::x3::unused_type> const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >&)'
迭代器类型被推断为 std::string::iterator，而不是 std::string::const_iterator。修复它或者不要总是使用 auto：

Live On Melpon

完整代码

为了子孙后代

config.hpp:

#include <boost/spirit/home/x3.hpp>

namespace kyle{
    namespace parser{

        namespace x3 = boost::spirit::x3;

        typedef std::string::const_iterator iterator_type;
        typedef x3::phrase_parse_context<x3::space_type>::type context_type;

    }
}

literals.cpp:

#include "literals_def.hpp"
#include "config.hpp"
#include <boost/spirit/home/x3.hpp>

namespace kyle { namespace parser { namespace impl {
    BOOST_SPIRIT_INSTANTIATE(identifier_type, iterator_type, context_type);
} } }

literals_def.hpp:

#include <boost/spirit/home/x3.hpp>
#include "literals.hpp"

namespace kyle {
    namespace parser {
        namespace impl {

            namespace x3 = boost::spirit::x3;

            const identifier_type identifier = "identifier";
            auto const identifier_def = x3::alpha >> *x3::alnum;

            BOOST_SPIRIT_DEFINE(identifier)
        }
        impl::identifier_type identifier(){
            return impl::identifier;
        }
    }
}

literals.hpp:

#include <boost/spirit/home/x3.hpp>

namespace kyle{
    namespace parser{
        namespace impl {
            namespace x3 = boost::spirit::x3;

            struct identifier_class;

            typedef x3::rule<identifier_class, std::string> identifier_type;

            BOOST_SPIRIT_DECLARE(identifier_type)
        }

        impl::identifier_type identifier();
    }
}

main.cpp:

#include "literals.hpp"
#include <iostream>

template<typename Parser>
bool test(std::string const& str, Parser p, std::string& output, bool full_match = true)
{
    auto in = str.begin();
    auto end = str.end();
    bool ret = boost::spirit::x3::phrase_parse(in, end, p, boost::spirit::x3::space, output);
    ret &= (!full_match || (in == end));
    return ret;
}

int main(){
    std::string s;
    auto b = test("fobar", kyle::parser::identifier(), s);
    std::cout << b << ": " << s << std::endl;
}

CMakeLists.txt:

ADD_EXECUTABLE(sox3 main.cpp literals.cpp)

SET(CMAKE_CXX_COMPILER g++-5)
SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -isystem /home/sehe/custom/boost -std=c++14 -O3 -pthread -march=native -flto)

Answer 2

除了sehe的回答，补充一下：

您需要对声明的内容和实际使用的内容非常准确。 X3 允许任何可能的类型，但链接器不允许。

提示：当出现链接器错误时，在 BOOST_SPIRIT_INSTANTIATE 之后声明如下内容：

int x = context_type{};

会报错，是的，因为context_type不能转成int。但该错误也会为您提供上下文的确切类型。将它与链接器错误进行比较，您会发现您的错误。

使用 boost spirit x3 分离解析器时出现链接错误

linking errors while separate parser using boost spirit x3

c++

boost-spirit

linker-errors

boost-spirit-x3

完整代码