The BOOST_SPIRIT_INSTANTIATE
marco 相当于做
namespace client { namespace parser
{
template bool parse_rule<iterator_type, context_type, statement_type::attribute_type>(
statement_type rule_, iterator_type &first, iterator_type const &last,
context_type const &context,
statement_type ::attribute_type &attr);
;
}}
所以关键的一点是iterator_type
and context_type
match exactly呼叫站点所需的那些。现在,未解析的符号是(已分解):
bool client::parser::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::error_handler_tag,
std::reference_wrapper<boost::spirit::x3::error_handler<__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::ascii, boost::spirit::x3::space_tag> const,
boost::spirit::x3::unused_type> >,
std::__cxx11::list<client::ast::statement, std::allocator<client::ast::statement> >
>
(boost::spirit::x3::rule<client::parser::statement_class, std::__cxx11::list<client::ast::statement, std::allocator<client::ast::statement> >, 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::error_handler_tag,
std::reference_wrapper<boost::spirit::x3::error_handler<__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::ascii, boost::spirit::x3::space_tag> const,
boost::spirit::x3::unused_type> > const &,
std::__cxx11::list<client::ast::statement, std::allocator<client::ast::statement> >&)
这意味着 iterator_type 应该是:
__gnu_cxx::__normal_iterator<char const*, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >,
这确实是什么std::string::const_iterator
扩展到我的系统上。因此,上下文类型可能不匹配。通过在上面添加强制类型错误BOOST_SPIRIT_INSTANTIATE
像这样调用:
struct {} _ = *static_cast<client::parser::context_type*>(nullptr);
我能够强制编译器输出扩展类型context_type
在实例化点:
statement.cpp:12 error: conversion from ‘client::parser::context_type {aka boost::spirit::x3::context<boost::spirit::x3::error_handler_tag, const std::reference_wrapper<boost::spirit::x3::error_handler<__gnu_cxx::__normal_iterator<const char*, std::__cxx11::basic_string<char> > > >, boost::spirit::x3::context<boost::spirit::x3::skipper_tag, const boost::spirit::x3::char_class<boost::spirit::char_encoding::ascii, boost::spirit::x3::space_tag>, boost::spirit::x3::unused_type> >}’ to non-scalar type ‘client::parser::<anonymous struct>’ requested
这告诉我们上下文类型是(为了易读而格式化):
boost::spirit::x3::context<
boost::spirit::x3::error_handler_tag,
const std::reference_wrapper<boost::spirit::x3::error_handler<
__gnu_cxx::__normal_iterator<const char *, std::__cxx11::basic_string<char> > > >,
boost::spirit::x3::context<
boost::spirit::x3::skipper_tag,
boost::spirit::x3::char_class<boost::spirit::char_encoding::ascii, boost::spirit::x3::space_tag> const,
boost::spirit::x3::unused_type> >,
但是:链接器将其作为
boost::spirit::x3::context<
boost::spirit::x3::error_handler_tag,
std::reference_wrapper<boost::spirit::x3::error_handler<
__gnu_cxx::__normal_iterator<const 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::ascii, boost::spirit::x3::space_tag> const,
boost::spirit::x3::unused_type> >
最明显的区别在于默认模板参数的拼写std::basic_string
(char_traits
和allocator
),但这实际上没有区别。然而,真正重要的区别是缺乏const
与reference_wrapper<>
type.
修复它
我想这可能是X3历史上曾经的一次改变。在这种情况下,最简单的解决方法是删除const
在config.hpp中:
typedef x3::context<
error_handler_tag
, std::reference_wrapper<error_handler_type>
, phrase_context_type>
context_type;
事实上,它现在可以编译了