boost-sprit-lex 将多个标记统一为 lex 中由 id 区分的单个标记

boost-sprit-lex unifying multiple tokens into a single token in lex differentiated by the id(boost-sprit-lex 将多个标记统一为 lex 中由 id 区分的单个标记)

问题描述

edit :我已经删除了词法分析器，因为它没有与 Qi 完全集成并且只是混淆了语法(请参阅下面的答案).

edit : I have ripped out the lexer as it does not cleanly integrate with Qi and just obfuscates grammars (see answer below).

我的词法分析器如下所示:

My lexer looks as follows :

template <typename Lexer>
struct tokens : lex::lexer<Lexer>
{
tokens()
    : left_curly(""{""),
    right_curly(""}""),
    left_paren(""(""),
    right_paren("")""),
    colon(":"),
    scolon(";"),
    namespace_("(?i:namespace)"),
    event("(?i:event)"),
    optional("(?i:optional)"),
    required("(?i:required)"),
    repeated("(?i:repeated)"),
    t_int_4("(?i:int4)"),
    t_int_8("(?i:int8)"),
    t_string("(?i:string)"),
    ordinal("\d+"),
    identifier("\w+")

{
    using boost::spirit::lex::_val;

    this->self
        = 
        left_curly    
        | right_curly 
        | left_paren
        | right_paren
        | colon         
        | scolon
        | namespace_      
        | event             
        | optional           
        | required          
        | repeated
        | t_int_4
        | t_int_8
        | t_string
        | ordinal             
        | identifier         
        | lex::token_def<>("[ \t\n]+")   [lex::_pass = lex::pass_flags::pass_ignore];
}


lex::token_def<lex::omit> left_curly, right_curly, colon, scolon,repeated, left_paren, right_paren;
lex::token_def<lex::omit> namespace_, event, optional, required,t_int_4, t_int_8, t_string;
lex::token_def<boost::uint32_t> ordinal;
lex::token_def<std::string> identifier;

};

我希望 t_int_4、t_int_8 和 t_string 由由整数类型属性的单个标记类型表示.目前，我的 QI 语法必须为此进行提升，然后在 qi::rule 语义操作中设置标记:

I want t_int_4,t_int_8, and t_string to represented by a single token type attributed by an integral type. At the moment my QI grammar has to do the lifting for this and then set the token in a qi::rule semantic action :

 atomic_type = tok.t_int_4     [ _val = RBL_INT4]
                | tok.t_int_8             [ _val = RBL_INT8]
                | tok.t_string            [ _val = RBL_STRING];

推荐答案

来自最近几天关于将 lex 集成到 qi 语法中的问题.您似乎已经确定了多个集成问题.在这一点上，您应该问自己为什么要尝试将词法分析器集成到 PEG 语法中.PEG 语法可以巧妙地原位捕获标记化，因此您从引入词法分析器中并没有真正获得太多收益，尤其是考虑到 lex->qi 的情况，在这种情况下，引入词法分析器已向您表明，您不仅需要 hacks 来完成 qi 中整洁的事情在表达你的语法方面，还有一些技巧可以让错误处理和注释正常工作.所以我建议去掉Lex，坚持Qi.

From your questions relating to integrating lex into qi grammar, from the last few days. It seems you've identified multiple integration issues. At this point you should ask yourself why you are even trying to integrate a lexer into a PEG grammar. PEG grammars can neatly capture tokenization in situ, and so you don't really gain much from introducing lexer especially considering the lex->qi case where introducing a lexer has shown you that not only do you need hacks to do what is neat in qi in terms of expressing your grammar but also hacks for getting error handling and annotation working properly. Therefore I suggest removing Lex and sticking to Qi.

这是删除词法分析器后的语法.ast 位于它自己的文件中.

Here is your grammar with the lexer removed. The ast is in a file of it's own.

#include "ast.hpp"
#define BOOST_SPIRIT_USE_PHOENIX_V3
#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/include/phoenix_core.hpp>
#include <boost/range/iterator_range.hpp>
#include <vector>

namespace qi = boost::spirit::qi;
namespace ascii = boost::spirit::ascii;
namespace px = boost::phoenix;

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

        start = ascii::space | qi::lit("//") >> *(ascii::char_ - qi::eol) >> qi::eol;
    }

    qi::rule<Iterator> start;
};

struct error_handler_
{
    typedef void result_type;
    template<typename First, typename Last, typename ErrorPos, typename What>
    void operator()(First f, Last l, ErrorPos e, What w) const
    {
        std::cout << "Expected : " << w << std::endl;
        std::cout << std::string(f,l) << std::endl;
        int i = std::distance(f,e);
        std::cout << std::string(i+1,' ') <<  "^---- here"  << std::endl;
    }
};

px::function<error_handler_> error_handler;

template<typename Iterator>
struct annotation_state
{
  typedef boost::iterator_range<Iterator> annotation_iterator;
  typedef std::vector<annotation_iterator> annotation_iterators;

  annotation_iterators annotations;
};

template<typename Iterator>
struct annotate_
{
    typedef void result_type;

    annotation_state<Iterator> & as;
    annotate_(annotation_state<Iterator> & as) : as(as) {}

    template<typename Val, typename First, typename Last>
    void operator()(Val v, First f, Last l) const
    {
      v.id = as.annotations.size();
      as.annotations.push_back(boost::make_iterator_range(f,l));
      std::cout << std::string(f,l) << std::endl;
    }
};



template <typename Iterator, typename Skipper>
struct grammar : qi::grammar<Iterator,namespace_descriptor(),Skipper>
{
    grammar(annotation_state<Iterator> & as) 
        : grammar::base_type(namespace_descriptor_),
          annotation_state_(as),
          annotate(as)

    {
        using namespace qi;

        atomic_type.add
            ("int4", RBL_INT4)
            ("int8", RBL_INT8)
            ("string", RBL_STRING);

        event_entry_qualifier.add
            ("optional", ENTRY_OPTIONAL)
            ("required", ENTRY_REQUIRED)
            ("repeated", ENTRY_REPEATED);

        oid_ = ordinal  > ':' > identifier;
        ordinal = uint_parser<boost::uint32_t>();
        identifier = +(char_("a","z") | char_("A","Z") | char_('_'));
        type_descriptor_ = atomic_type_ | compound_type_;
        atomic_type_ = no_case[atomic_type] > attr("");

        compound_type_ = 
            no_case[lit("event")] 
            > attr(RBL_EVENT) 
            > '(' 
            > identifier  
            > ')';

        event_entry_ = 
            no_case[event_entry_qualifier] 
            > oid_ 
            > type_descriptor_ 
            > ';';

        event_descriptor_ = 
            no_case[lit("event")] 
            > oid_ 
            > '{' 
            > *(event_entry_) 
            > '}'; 

        namespace_descriptor_ = 
            no_case[lit("namespace")] 
            > identifier 
            > '{' 
            > * (event_descriptor_) 
            > '}'; 

        identifier.name("identifier");
        oid_.name("ordinal-identifier pair");
        ordinal.name("ordinal");

        on_error<fail>(namespace_descriptor_, ::error_handler(_1,_2,_3,_4));
        on_success(oid_, annotate(_val,_1,_3));
        on_success(type_descriptor_, annotate(_val,_1,_3));
        on_success(event_entry_, annotate(_val,_1,_3));
        on_success(event_descriptor_, annotate(_val,_1,_3));
    }

    annotation_state<Iterator> & annotation_state_;
    px::function<annotate_<Iterator> > annotate;

    qi::rule< Iterator, oid()> oid_;
    qi::rule< Iterator, boost::uint32_t()> ordinal;
    qi::rule< Iterator, std::string()> identifier;
    qi::rule< Iterator, type_descriptor()> type_descriptor_;
    qi::rule< Iterator, type_descriptor()> atomic_type_;
    qi::rule< Iterator, type_descriptor()> compound_type_; 

    qi::rule< Iterator, event_entry(), Skipper> event_entry_;
    qi::rule< Iterator, event_descriptor(), Skipper> event_descriptor_;
    qi::rule< Iterator, namespace_descriptor(), Skipper> namespace_descriptor_;

    qi::symbols<char, int> atomic_type;
    qi::symbols<char, int> event_entry_qualifier;
};

int main()
{
    std::string test = "namespace ns { event 1:sihan { OpTIONAL 1:hassan event(haSsan);} }";
    typedef std::string::iterator it;

    it beg = test.begin();
    it end = test.end();

    annotation_state<it> as;
    skipper<it> skip;
    grammar<it, skipper<it> > g(as);


    bool r = qi::phrase_parse(beg,end,g,skip);
    if(r)
        ;
    else
    {
        std::cout << "parsing failed" << std::endl;
    }
}

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