c++ - Boost::Spirit::Qi - 将规则拆分为单独的类

Question

我想将我的规则(作品)拆分成单独的类。我在 Boost::Spirit::Qi 中找不到任何这样做的例子。

Boost 示例都显示了一个语法类中的规则。

这是我的语法:

<start> ::= @ ( <event_bool_no_param> )
<event_bool_no_param> ::= RAMPING_COMPLETED | STATE_TIMEOUT  

这是我的语法课:

template <typename Iterator, typename Skipper>
struct Event_Grammar
    : boost::spirit::qi::grammar<Iterator, Skipper>
{
    Event_Grammar() : Event_Grammar::base_type(start)
        {
            using boost::spirit::ascii::char_;
            using boost::spirit::qi::eps;

            start = 
                (
                    char_('@') >> char_('(') >> Event_Bool_No_Param<Iterator>() >> char_(')')
                )
                ;

        }
    boost::spirit::qi::rule<Iterator, Skipper> start;
};

这是我的另一门语法课:

template <typename Iterator>
struct Event_Bool_No_Param
    : qi::grammar<Iterator>
{
    Event_Bool_No_Param () 
        : Event_Bool_No_Param::base_type(start)
        {
            using qi::lexeme;
            using qi::lit;

            start =
                lit("STATE_TIMEOUT") | lit("RAMPING_COMPLETED") | lit("PASSIVE_MEAS_COMPLETED")
                ;
        }
    qi::rule<Iterator> start;
};

我收到一个未处理的异常错误，文本为“@ ( STATE_TIMEOUT )”。

这是顶部(最近)堆栈跟踪:

Event_Grammar.exe!boost::spirit::qi::sequence_base<boost::spirit::qi::sequence<boost::fusion::cons<boost::spirit::qi::literal_char<boost::spirit::char_encoding::ascii,0,0>,boost::fusion::cons<boost::spirit::qi::literal_char<boost::spirit::char_encoding::ascii,0,0>,boost::fusion::cons<boost::spirit::qi::reference<boost::spirit::qi::rule<std::_String_const_iterator<char,std::char_traits<char>,std::allocator<char> >,boost::spirit::unused_type,boost::spirit::unused_type,boost::spirit::unused_type,boost::spirit::unused_type> const >,boost::fusion::cons<boost::spirit::qi::literal_char<boost::spirit::char_encoding::ascii,0,0>,boost::fusion::nil_> > > > >,boost::fusion::cons<boost::spirit::qi::literal_char<boost::spirit::char_encoding::ascii,0,0>,boost::fusion::cons<boost::spirit::qi::literal_char<boost::spirit::char_encoding::ascii,0,0>,boost::fusion::cons<boost::spirit::qi::reference<boost::spirit::qi::rule<std::_String_const_iterator<char,std::char_traits<char>,std::allocator<char> >,boost::spirit::unused_type,boost::spirit::unused_type,boost::spirit::unused_type,boost::spirit::unused_type> const >,boost::fusion::cons<boost::spirit::qi::literal_char<boost::spirit::char_encoding::ascii,0,0>,boost::fusion::nil_> > > > >::parse_impl<std::_String_const_iterator<char,std::char_traits<char>,std::allocator<char> >,boost::spirit::context<boost::fusion::cons<boost::spirit::unused_type &,boost::fusion::nil_>,boost::fusion::vector0<void> >,boost::spirit::qi::char_class<boost::spirit::tag::char_code<boost::spirit::tag::space,boost::spirit::char_encoding::ascii> >,boost::spirit::unused_type>(std::_String_const_iterator<char,std::char_traits<char>,std::allocator<char> > & first, const std::_String_const_iterator<char,std::char_traits<char>,std::allocator<char> > & last, boost::spirit::context<boost::fusion::cons<boost::spirit::unused_type &,boost::fusion::nil_>,boost::fusion::vector0<void> > & context, const boost::spirit::qi::char_class<boost::spirit::tag::char_code<boost::spirit::tag::space,boost::spirit::char_encoding::ascii> > & skipper, boost::spirit::unused_type & attr_, boost::mpl::bool_<0> __formal)  Line 88 + 0x55 bytes C++
    Event_Grammar.exe!boost::spirit::qi::sequence_base<boost::spirit::qi::sequence<boost::fusion::cons<boost::spirit::qi::literal_char<boost::spirit::char_encoding::ascii,0,0>,boost::fusion::cons<boost::spirit::qi::literal_char<boost::spirit::char_encoding::ascii,0,0>,boost::fusion::cons<boost::spirit::qi::reference<boost::spirit::qi::rule<std::_String_const_iterator<char,std::char_traits<char>,std::allocator<char> >,boost::spirit::unused_type,boost::spirit::unused_type,boost::spirit::unused_type,boost::spirit::unused_type> const >,boost::fusion::cons<boost::spirit::qi::literal_char<boost::spirit::char_encoding::ascii,0,0>,boost::fusion::nil_> > > > >,boost::fusion::cons<boost::spirit::qi::literal_char<boost::spirit::char_encoding::ascii,0,0>,boost::fusion::cons<boost::spirit::qi::literal_char<boost::spirit::char_encoding::ascii,0,0>,boost::fusion::cons<boost::spirit::qi::reference<boost::spirit::qi::rule<std::_String_const_iterator<char,std::char_traits<char>,std::allocator<char> >,boost::spirit::unused_type,boost::spirit::unused_type,boost::spirit::unused_type,boost::spirit::unused_type> const >,boost::fusion::cons<boost::spirit::qi::literal_char<boost::spirit::char_encoding::ascii,0,0>,boost::fusion::nil_> > > > >::parse<std::_String_const_iterator<char,std::char_traits<char>,std::allocator<char> >,boost::spirit::context<boost::fusion::cons<boost::spirit::unused_type &,boost::fusion::nil_>,boost::fusion::vector0<void> >,boost::spirit::qi::char_class<boost::spirit::tag::char_code<boost::spirit::tag::space,boost::spirit::char_encoding::ascii> >,boost::spirit::unused_type>(std::_String_const_iterator<char,std::char_traits<char>,std::allocator<char> > & first, const std::_String_const_iterator<char,std::char_traits<char>,std::allocator<char> > & last, boost::spirit::context<boost::fusion::cons<boost::spirit::unused_type &,boost::fusion::nil_>,boost::fusion::vector0<void> > & context, const boost::spirit::qi::char_class<boost::spirit::tag::char_code<boost::spirit::tag::space,boost::spirit::char_encoding::ascii> > & skipper, boost::spirit::unused_type & attr_)  Line 125 C++
    Event_Grammar.exe!boost::spirit::qi::detail::parser_binder<boost::spirit::qi::sequence<boost::fusion::cons<boost::spirit::qi::literal_char<boost::spirit::char_encoding::ascii,0,0>,boost::fusion::cons<boost::spirit::qi::literal_char<boost::spirit::char_encoding::ascii,0,0>,boost::fusion::cons<boost::spirit::qi::reference<boost::spirit::qi::rule<std::_String_const_iterator<char,std::char_traits<char>,std::allocator<char> >,boost::spirit::unused_type,boost::spirit::unused_type,boost::spirit::unused_type,boost::spirit::unused_type> const >,boost::fusion::cons<boost::spirit::qi::literal_char<boost::spirit::char_encoding::ascii,0,0>,boost::fusion::nil_> > > > >,boost::mpl::bool_<0> >::call<std::_String_const_iterator<char,std::char_traits<char>,std::allocator<char> >,boost::spirit::qi::char_class<boost::spirit::tag::char_code<boost::spirit::tag::space,boost::spirit::char_encoding::ascii> >,boost::spirit::context<boost::fusion::cons<boost::spirit::unused_type &,boost::fusion::nil_>,boost::fusion::vector0<void> > >(std::_String_const_iterator<char,std::char_traits<char>,std::allocator<char> > & first, const std::_String_const_iterator<char,std::char_traits<char>,std::allocator<char> > & last, boost::spirit::context<boost::fusion::cons<boost::spirit::unused_type &,boost::fusion::nil_>,boost::fusion::vector0<void> > & context, const boost::spirit::qi::char_class<boost::spirit::tag::char_code<boost::spirit::tag::space,boost::spirit::char_encoding::ascii> > & skipper, boost::mpl::bool_<0> __formal)  Line 44    C++

这里是异常发生的代码位置，function_template.hpp#761:

result_type operator()(BOOST_FUNCTION_PARMS) const
{
  if (this->empty())
    boost::throw_exception(bad_function_call());

  return get_vtable()->invoker
           (this->functor BOOST_FUNCTION_COMMA BOOST_FUNCTION_ARGS);
}

所以，我的问题是:

1. 是否所有规则都需要在单个语法类中？
2. 如何在规则中引用语法类？
3. 我在上面的类(class)中哪里出错了？

我正在使用:

• boost 1.57.0
• Visual Studio 2010
• Windows 7

Answer 1

首先是问题:

1. 是否所有规则都需要在单个语法类中？

   绝对不是。语法只是一种将规则组合在一起并在需要时提供额外状态的机制。语法只是一个类/结构，因此它是封装语法概念的非常方便的工具。

2. 如何在规则中引用语法类？

   您需要一个语法实例。临时会引起悲伤。

3. 我在上面的类(class)中哪里出错了？

   错误在于您在构建规则时创建了临时对象。您需要一个语法(或规则)的实例，它将组合成其他语法和规则。

例如，以下内容:

Live On Coliru

#include <boost/spirit/home/qi.hpp>
namespace qi    = boost::spirit::qi;
namespace ascii = boost::spirit::qi::ascii;

template <typename Iterator>
struct Event_Bool_No_Param : qi::grammar<Iterator>
{
    Event_Bool_No_Param () 
        : Event_Bool_No_Param::base_type(start)
    {
        using qi::lit;

        start =
            lit("STATE_TIMEOUT") | lit("RAMPING_COMPLETED") | lit("PASSIVE_MEAS_COMPLETED")
            ;
    }
    qi::rule<Iterator> start;
};


template <typename Iterator, typename Skipper>
struct Event_Grammar : boost::spirit::qi::grammar<Iterator, Skipper>
{
    Event_Grammar() : Event_Grammar::base_type(start)
    {
        using boost::spirit::ascii::char_;

        start = 
            char_('@') >> char_('(') >> event_no_param >> char_(')')
            ;

    }
    qi::rule<Iterator, Skipper> start;
    Event_Bool_No_Param<Iterator> event_no_param;
};

int main()
{
    using iterator_t = std::string::const_iterator;
    std::string input = "@ ( STATE_TIMEOUT )";
    iterator_t iter = input.begin();
    iterator_t end = input.end();

    Event_Grammar<iterator_t,ascii::space_type> grammar;   

    bool ok = qi::phrase_parse( iter, end
            , grammar
            , ascii::space
            );

    return ok? 0 : 255;
}

---

哪个或？

至于用哪个OR符号，|和||不是一回事。你很可能想要 | 。

| - 是另一种选择。

A | B | C

• parse an A or a B or a C

|| - 是顺序或运算符 ( sequential or )

A || B * parse A followed by an optional B or parse B

    A >> -B | B