我如何理解 boost 精神编译器错误
问题描述
我正在尝试使用 no_skip
指令来解析表单的输入:
这是我的代码
正如 llonesmiz 非常恰当地指出的:
- 寻找静态断言(
****** 像这样在错误 'novel' ******
中) 在失败"行上方直接(我的意思是直接)查找评论.这包括触发模板实例化的点.
<块引用>如果您在此处看到编译错误,指出无法将第四个参数转换为所需的目标类型,那么您可能正在尝试使用不兼容的船长类型的规则或语法.
在这种情况下,由于您想使用
trans_assign_expr
而没有船长,您必须声明它没有:
这使它编译.不过,输出表明它不/work/.
我不相信这是您想要做的.由于 lexeme
在这里似乎是更好的选择,无论如何.我会简化 id
规则:
lexeme
已经具有本地禁用正在使用的 Skipper 的属性.
这里的语法略有变化http://liveworkspace.org/code/70f3319342c5678504b16一>
如您所见,我将 with eol
包含在 no_skip 中(以避免船长吃掉标签).这样,船长在 trans_assign_expr
中仍然有效 - 这使它接受额外的空间.给定输入
现在输出
I am trying to use the no_skip
directive to parse input of the form:
I am using ascii::blank
as my skipper. I get an compile error when I wrap no_skip[ trans_assign_expr ]
to parse for the tab.
How do I fix this error, and in general, how do I understand these errors so that I can fix future ones? The boost spirit documentation never covers this aspect of using spirit :(
This is the error
In file included from /usr/include/boost/spirit/home/qi/nonterminal/grammar.hpp:18:0, from /usr/include/boost/spirit/include/qi_grammar.hpp:16, from ../src/RJstate.cpp:9: /usr/include/boost/spirit/home/qi/nonterminal/rule.hpp: In member function ‘bool boost::spirit::qi::rule::parse(Iterator&, const Iterator&, Context&, const Skipper&, Attribute&) const [with Context = boost::spirit::context, boost::fusion::vector0 >, Skipper = boost::spirit::qi::detail::unused_skipper > >, Attribute = const boost::spirit::unused_type, Iterator = __gnu_cxx::__normal_iterator >, T1 = boost::proto::exprns_::expr >, 0l>, T2 = boost::spirit::unused_type, T3 = boost::spirit::unused_type, T4 = boost::spirit::unused_type]’: /usr/include/boost/spirit/home/qi/reference.hpp:43:71: instantiated from ‘bool boost::spirit::qi::reference::parse(Iterator&, const Iterator&, Context&, const Skipper&, Attribute&) const [with Iterator = __gnu_cxx::__normal_iterator >, Context = boost::spirit::context, boost::fusion::vector0 >, Skipper = boost::spirit::qi::detail::unused_skipper > >, Attribute = const boost::spirit::unused_type, Subject = const boost::spirit::qi::rule >, boost::proto::exprns_::expr >, 0l>, boost::spirit::unused_type, boost::spirit::unused_type, boost::spirit::unused_type>]’ /usr/include/boost/spirit/home/qi/directive/no_skip.hpp:64:63: instantiated from ‘bool boost::spirit::qi::no_skip_directive::parse(Iterator&, const Iterator&, Context&, const Skipper&, Attribute&) const [with Iterator = __gnu_cxx::__normal_iterator >, Context = boost::spirit::context, boost::fusion::vector0 >, Skipper = boost::spirit::qi::char_class >, Attribute = const boost::spirit::unused_type, Subject = boost::spirit::qi::reference >, boost::proto::exprns_::expr >, 0l>, boost::spirit::unused_type, boost::spirit::unused_type, boost::spirit::unused_type> >]’ /usr/include/boost/spirit/home/qi/detail/fail_function.hpp:45:74: instantiated from ‘bool boost::spirit::qi::detail::fail_function::operator()(const Component&) const [with Component = boost::spirit::qi::no_skip_directive >, boost::proto::exprns_::expr >, 0l>, boost::spirit::unused_type, boost::spirit::unused_type, boost::spirit::unused_type> > >, Iterator = __gnu_cxx::__normal_iterator >, Context = boost::spirit::context, boost::fusion::vector0 >, Skipper = boost::spirit::qi::char_class >]’ /usr/include/boost/fusion/algorithm/query/detail/any.hpp:42:83: [ skipping 8 instantiation contexts ] /usr/include/boost/function/function_template.hpp:132:42: instantiated from ‘static R boost::detail::function::function_obj_invoker4::invoke(boost::detail::function::function_buffer&, T0, T1, T2, T3) [with FunctionObj = boost::spirit::qi::detail::parser_binder >, boost::proto::exprns_::expr >, 0l>, boost::spirit::unused_type, boost::spirit::unused_type, boost::spirit::unused_type> >, boost::fusion::cons >, boost::proto::exprns_::expr >, 0l>, boost::spirit::unused_type, boost::spirit::unused_type, boost::spirit::unused_type> > >, boost::fusion::nil> > > >, mpl_::bool_ >, R = bool, T0 = __gnu_cxx::__normal_iterator >&, T1 = const __gnu_cxx::__normal_iterator >&, T2 = boost::spirit::context, boost::fusion::vector0 >&, T3 = const boost::spirit::qi::char_class >&]’ /usr/include/boost/function/function_template.hpp:913:60: instantiated from ‘void boost::function4::assign_to(Functor) [with Functor = boost::spirit::qi::detail::parser_binder >, boost::proto::exprns_::expr >, 0l>, boost::spirit::unused_type, boost::spirit::unused_type, boost::spirit::unused_type> >, boost::fusion::cons >, boost::proto::exprns_::expr >, 0l>, boost::spirit::unused_type, boost::spirit::unused_type, boost::spirit::unused_type> > >, boost::fusion::nil> > > >, mpl_::bool_ >, R = bool, T0 = __gnu_cxx::__normal_iterator >&, T1 = const __gnu_cxx::__normal_iterator >&, T2 = boost::spirit::context, boost::fusion::vector0 >&, T3 = const boost::spirit::qi::char_class >&]’ /usr/include/boost/function/function_template.hpp:722:7: instantiated from ‘boost::function4::function4(Functor, typename boost::enable_if_c::value>::value, int>::type) [with Functor = boost::spirit::qi::detail::parser_binder >, boost::proto::exprns_::expr >, 0l>, boost::spirit::unused_type, boost::spirit::unused_type, boost::spirit::unused_type> >, boost::fusion::cons >, boost::proto::exprns_::expr >, 0l>, boost::spirit::unused_type, boost::spirit::unused_type, boost::spirit::unused_type> > >, boost::fusion::nil> > > >, mpl_::bool_ >, R = bool, T0 = __gnu_cxx::__normal_iterator >&, T1 = const __gnu_cxx::__normal_iterator >&, T2 = boost::spirit::context, boost::fusion::vector0 >&, T3 = const boost::spirit::qi::char_class >&, typename boost::enable_if_c::value>::value, int>::type = int]’ /usr/include/boost/function/function_template.hpp:1064:16: instantiated from ‘boost::function::function(Functor, typename boost::enable_if_c::value>::value, int>::type) [with Functor = boost::spirit::qi::detail::parser_binder >, boost::proto::exprns_::expr >, 0l>, boost::spirit::unused_type, boost::spirit::unused_type, boost::spirit::unused_type> >, boost::fusion::cons >, boost::proto::exprns_::expr >, 0l>, boost::spirit::unused_type, boost::spirit::unused_type, boost::spirit::unused_type> > >, boost::fusion::nil> > > >, mpl_::bool_ >, R = bool, T0 = __gnu_cxx::__normal_iterator >&, T1 = const __gnu_cxx::__normal_iterator >&, T2 = boost::spirit::context, boost::fusion::vector0 >&, T3 = const boost::spirit::qi::char_class >&, typename boost::enable_if_c::value>::value, int>::type = int]’ /usr/include/boost/function/function_template.hpp:1105:5: instantiated from ‘typename boost::enable_if_c::value>::value, boost::function&>::type boost::function::operator=(Functor) [with Functor = boost::spirit::qi::detail::parser_binder >, boost::proto::exprns_::expr >, 0l>, boost::spirit::unused_type, boost::spirit::unused_type, boost::spirit::unused_type> >, boost::fusion::cons >, boost::proto::exprns_::expr >, 0l>, boost::spirit::unused_type, boost::spirit::unused_type, boost::spirit::unused_type> > >, boost::fusion::nil> > > >, mpl_::bool_ >, R = bool, T0 = __gnu_cxx::__normal_iterator >&, T1 = const __gnu_cxx::__normal_iterator >&, T2 = boost::spirit::context, boost::fusion::vector0 >&, T3 = const boost::spirit::qi::char_class >&, typename boost::enable_if_c::value>::value, boost::function&>::type = boost::function >&, const __gnu_cxx::__normal_iterator >&, boost::spirit::context, boost::fusion::vector0 >&, const boost::spirit::qi::char_class >&)>&]’ /usr/include/boost/spirit/home/qi/nonterminal/rule.hpp:198:13: instantiated from ‘boost::spirit::qi::rule& boost::spirit::qi::rule::operator=(const Expr&) [with Expr = boost::proto::exprns_::expr >, boost::proto::exprns_::expr >, 0l>, boost::spirit::unused_type, boost::spirit::unused_type, boost::spirit::unused_type>&, const boost::proto::exprns_::expr, 0l>&>, 2l>&, const boost::proto::exprns_::expr, 0l>&, boost::spirit::qi::rule >, boost::proto::exprns_::expr >, 0l>, boost::spirit::unused_type, boost::spirit::unused_type, boost::spirit::unused_type>&>, 2l>&>, 2l>, Iterator = __gnu_cxx::__normal_iterator >, T1 = boost::proto::exprns_::expr >, 0l>, T2 = boost::spirit::unused_type, T3 = boost::spirit::unused_type, T4 = boost::spirit::unused_type, boost::spirit::qi::rule = boost::spirit::qi::rule >, boost::proto::exprns_::expr >, 0l>, boost::spirit::unused_type, boost::spirit::unused_type, boost::spirit::unused_type>]’ ../src/RJstate.cpp:49:7: instantiated from ‘fsm_grammar::fsm_grammar() [with Iterator = __gnu_cxx::__normal_iterator >, Skipper = boost::proto::exprns_::expr >, 0l>]’ ../src/RJstate.cpp:112:50: instantiated from here /usr/include/boost/spirit/home/qi/nonterminal/rule.hpp:277:17: error: no match for call to ‘(const function_type {aka const boost::function >&, const __gnu_cxx::__normal_iterator >&, boost::spirit::context, boost::fusion::vector0 >&, const boost::spirit::qi::char_class >&)>}) (__gnu_cxx::__normal_iterator >&, const __gnu_cxx::__normal_iterator >&, boost::spirit::qi::rule >, boost::proto::exprns_::expr >, 0l>, boost::spirit::unused_type, boost::spirit::unused_type, boost::spirit::unused_type>::context_type&, const boost::spirit::qi::detail::unused_skipper > >&)’ /usr/include/boost/function/function_template.hpp:1043:7: note: candidate is: /usr/include/boost/function/function_template.hpp:1006:1: note: boost::function4::result_type boost::function4::operator()(T0, T1, T2, T3) const [with R = bool, T0 = __gnu_cxx::__normal_iterator >&, T1 = const __gnu_cxx::__normal_iterator >&, T2 = boost::spirit::context, boost::fusion::vector0 >&, T3 = const boost::spirit::qi::char_class >&, boost::function4::result_type = bool] /usr/include/boost/function/function_template.hpp:1006:1: note: no known conversion for argument 4 from ‘const boost::spirit::qi::detail::unused_skipper > >’ to ‘const boost::spirit::qi::char_class >&’
This is my code
As llonesmiz very aptly pointed out:
- look for static asserts (
****** like this in the error 'novel' ******
) look for comments directly (I mean, directly) above a 'failing' line. This includes the points at which template instantiations were triggered.
If you are seeing a compilation error here stating that the forth 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.
In this case, since you want to use
trans_assign_expr
without a skipper, you must declare it without one:
This makes it compile. The output suggests it doesn't /work/, though.
I'm not convinced this is what you want to do. Since lexeme
seems to be a better option here, anyway. I'd simplify the id
rule:
lexeme
already has the property of locally disabling the Skipper in use.
Here is a slight change of the grammar http://liveworkspace.org/code/70f3319342c567854b9f785ac13508d6
As you can see, I include the with eol
in a no_skip (to avoid the skipper eating the tab). This way, the skipper is still in effect in trans_assign_expr
- which makes it accept the extra space. Given the input
The output is now
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