3

私は boost::spirit::qi::grammar に取り組んでおり、元のテキストの一部を文法の合成出力構造 (より具体的には、ルールのコンポーネントの 1 つに一致した部分) にコピーしたいと考えています。 ）。文法は最終的に、より複雑な文法のサブ文法として使用されるため、元の入力に実際にアクセスすることはできません。

これはセマンティック アクションまたは文法コンテキストを介して実行できると推測していますが、元の parse() にアクセスせずにこれを実行する例を見つけることができません。

これが私がこれまでに持っているものです：

#include <iostream>
#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/include/phoenix.hpp>
#include <boost/fusion/include/adapt_struct.hpp>

namespace qi = boost::spirit::qi;

struct A
{
    std::string header;
    std::vector<int> ints;
    std::string inttext;
};

BOOST_FUSION_ADAPT_STRUCT(
    A,
    (std::string, header)
    (std::vector<int>, ints)
    //(std::string, inttext)
)

template <typename Iterator>
struct parser : qi::grammar< Iterator, A() >
{
    parser() : parser::base_type(start)
    {
        header %= qi::lexeme[ +qi::alpha ];
        ints %= qi::lexeme[ qi::int_ % qi::char_(",_") ]; // <---- capture the original text that matches this into inttext
        start %= header >> ' ' >> ints;
    }

    qi::rule<Iterator, std::string()> header;
    qi::rule<Iterator, std::vector<int>() > ints;
    qi::rule<Iterator, A()> start;
};

int main()
{
    A output;
    std::string input("out 1,2_3");
    auto iter = input.begin();
    parser<decltype(iter)> p;
    bool r = qi::parse(iter, input.end(), p, output);
    if( !r || iter != input.end() )
    {
        std::cout << "did not parse";
    }
    else
    {
        // would like output.inttext to be "1,2_3"
        std::cout << output.header << ": " << output.inttext << " -> [ ";
        for( auto & i: output.ints )
            std::cout << i << ' ';
        std::cout << ']' << std::endl;
    }
}
4

3 に答える 3

3

セマンティックアクションを使用せずにあなたが尋ねたことに似たもの：

#include <iostream>
#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/include/phoenix.hpp>
#include <boost/fusion/include/adapt_struct.hpp>
#include <boost/spirit/repository/include/qi_iter_pos.hpp>

namespace qi = boost::spirit::qi;
using boost::spirit::repository::qi::iter_pos;

struct ints_type
{
   std::vector<int> data;
   std::string::const_iterator begin;
   std::string::const_iterator end;   
};

struct A
{
    std::string header;
    ints_type ints;
};

BOOST_FUSION_ADAPT_STRUCT(
    ints_type,
    (std::string::const_iterator, begin)
    (std::vector<int>, data)
    (std::string::const_iterator, end)
)

BOOST_FUSION_ADAPT_STRUCT(
     A,
     (std::string, header)
     (ints_type, ints)
)

template <typename Iterator>
struct parser : qi::grammar< Iterator, A() >
{
    parser() : parser::base_type(start)
    {
        header %= qi::lexeme[ +qi::alpha ];
        ints %= qi::lexeme[ iter_pos >> qi::int_ % qi::char_(",_") >> iter_pos ]; // <---- capture the original text that matches this into inttext
        start %= header >> ' ' >> ints;
    }

    qi::rule<Iterator, std::string()> header;
    qi::rule<Iterator, ints_type() > ints;
    qi::rule<Iterator, A()> start;
};

int main()
{
    A output;
    std::string input("out 1,2_3");
    auto iter = input.begin();
    parser<decltype(iter)> p;
    bool r = qi::parse(iter, input.end(), p, output);
    if( !r || iter != input.end() )
    {
        std::cout << "did not parse";
    }
    else
    {
        // would like output.inttext to be "1,2_3"
        std::cout << output.header << ": " << std::string(output.ints.begin,output.ints.end) << " -> [ ";
        for( auto & i: output.ints.data )
            std::cout << i << ' ';
        std::cout << ']' << std::endl;
    }
}

セマンティック アクションの使用:

#include <iostream>
#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/include/phoenix.hpp>
#include <boost/fusion/include/adapt_struct.hpp>
#include <boost/spirit/repository/include/qi_iter_pos.hpp>

namespace qi = boost::spirit::qi;
namespace phx = boost::phoenix;
using boost::spirit::repository::qi::iter_pos;

struct ints_type
{
   std::vector<int> data;
   std::string inttext; 
};

struct A
{
    std::string header;
    ints_type ints;

};

BOOST_FUSION_ADAPT_STRUCT(
    ints_type,
    (std::vector<int>, data)
    (std::string, inttext)
)

BOOST_FUSION_ADAPT_STRUCT(
     A,
     (std::string, header)
     (ints_type, ints)
)

template <typename Iterator>
struct parser : qi::grammar< Iterator, A() >
{
    parser() : parser::base_type(start)
    {
        header %= qi::lexeme[ +qi::alpha ];
        ints = qi::lexeme[
                  (iter_pos >> qi::int_ % qi::char_(",_") >> iter_pos)
                     [phx::at_c<0>(qi::_val)=qi::_2,
                      phx::at_c<1>(qi::_val)=phx::construct<std::string>(qi::_1,qi::_3)] 
               ]; 
        start %= header >> ' ' >> ints;
    }

    qi::rule<Iterator, std::string()> header;
    qi::rule<Iterator, ints_type() > ints;
    qi::rule<Iterator, A()> start;
};

int main()
{
    A output;
    std::string input("out 1,2_3");
    auto iter = input.begin();
    parser<decltype(iter)> p;
    bool r = qi::parse(iter, input.end(), p, output);
    if( !r || iter != input.end() )
    {
        std::cout << "did not parse";
    }
    else
    {
        // would like output.inttext to be "1,2_3"
        std::cout << output.header << ": " << output.ints.inttext << " -> [ ";
        for( auto & i: output.ints.data )
            std::cout << i << ' ';
        std::cout << ']' << std::endl;
    }
}
于 2013-04-04T17:46:37.117 に答える
1

dont_eatsubject 属性を返すが入力を消費しないカスタム ディレクティブを使用する別の方法。ルールが 2 回解析されるため、これはおそらく遅くなりintsますが、構文はより優れていると思います (また、独自のディレクティブを作成してみる良い口実になります) (これは、「boost/spirit/home/qi/directive/ lexeme.hpp")。

dont_eat.hpp

#if !defined(DONT_EAT_HPP)
#define DONT_EAT_HPP

#if defined(_MSC_VER)
#pragma once
#endif

#include <boost/spirit/home/qi/meta_compiler.hpp>
#include <boost/spirit/home/qi/skip_over.hpp>
#include <boost/spirit/home/qi/parser.hpp>
#include <boost/spirit/home/support/unused.hpp>
#include <boost/spirit/home/support/common_terminals.hpp>
#include <boost/spirit/home/qi/detail/attributes.hpp>
#include <boost/spirit/home/support/info.hpp>
#include <boost/spirit/home/support/handles_container.hpp>

namespace custom 
{ 
    BOOST_SPIRIT_TERMINAL(dont_eat); 
}

namespace boost { namespace spirit
{
    ///////////////////////////////////////////////////////////////////////////
    // Enablers
    ///////////////////////////////////////////////////////////////////////////
    template <>
    struct use_directive<qi::domain, custom::tag::dont_eat> // enables dont_eat
      : mpl::true_ {};
}}

namespace custom
{


    template <typename Subject>
    struct dont_eat_directive : boost::spirit::qi::unary_parser<dont_eat_directive<Subject> >
    {
        typedef Subject subject_type;
        dont_eat_directive(Subject const& subject)
          : subject(subject) {}

        template <typename Context, typename Iterator>
        struct attribute
        {
            typedef typename
                boost::spirit::traits::attribute_of<subject_type, Context, Iterator>::type
            type;
        };

        template <typename Iterator, typename Context
          , typename Skipper, typename Attribute>
        bool parse(Iterator& first, Iterator const& last
          , Context& context, Skipper const& skipper
          , Attribute& attr) const
        {
            Iterator temp = first;
            boost::spirit::qi::skip_over(temp, last, skipper);
            return subject.parse(temp, last, context, skipper, attr);
        }

        template <typename Context>
        boost::spirit::info what(Context& context) const
        {
            return info("dont_eat", subject.what(context));

        }

        Subject subject;
    };
}//custom
    ///////////////////////////////////////////////////////////////////////////
    // Parser generators: make_xxx function (objects)
    ///////////////////////////////////////////////////////////////////////////
namespace boost { namespace spirit { namespace qi
{
    template <typename Subject, typename Modifiers>
    struct make_directive<custom::tag::dont_eat, Subject, Modifiers>
    {
        typedef custom::dont_eat_directive<Subject> result_type;
        result_type operator()(unused_type, Subject const& subject, unused_type) const
        {
            return result_type(subject);
        }
    };
}}}

namespace boost { namespace spirit { namespace traits
{
    ///////////////////////////////////////////////////////////////////////////
    template <typename Subject>
    struct has_semantic_action<custom::dont_eat_directive<Subject> >
      : unary_has_semantic_action<Subject> {};

    ///////////////////////////////////////////////////////////////////////////
    template <typename Subject, typename Attribute, typename Context
        , typename Iterator>
    struct handles_container<custom::dont_eat_directive<Subject>, Attribute
        , Context, Iterator>
      : unary_handles_container<Subject, Attribute, Context, Iterator> {};
}}}

#endif

main.cpp

#include <iostream>
#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/include/phoenix.hpp>
#include <boost/fusion/include/adapt_struct.hpp>
#include "dont_eat.hpp"

namespace qi = boost::spirit::qi;
namespace phx = boost::phoenix;

struct ints_type
{
   std::vector<int> data;
   std::string inttext; 
};

struct A
{
    std::string header;
    ints_type ints;

};

BOOST_FUSION_ADAPT_STRUCT(
    ints_type,
    (std::vector<int>, data)
    (std::string, inttext)
)

BOOST_FUSION_ADAPT_STRUCT(
     A,
     (std::string, header)
     (ints_type, ints)
)

template <typename Iterator>
struct parser : qi::grammar< Iterator, A() >
{
    parser() : parser::base_type(start)
    {
        header %= qi::lexeme[ +qi::alpha ];
        ints = qi::lexeme[qi::int_ % qi::char_(",_")]; 
        ints_string = custom::dont_eat[ints] >> qi::as_string[qi::raw[ints]];
        start %= header >> ' ' >> ints_string;
    }

    qi::rule<Iterator, std::string()> header;
    qi::rule<Iterator, std::vector<int>() > ints;
    qi::rule<Iterator, ints_type() > ints_string;
    qi::rule<Iterator, A()> start;
};

int main()
{
    A output;
    std::string input("out 1,2_3");
    auto iter = input.begin();
    parser<decltype(iter)> p;
    bool r = qi::parse(iter, input.end(), p, output);
    if( !r || iter != input.end() )
    {
        std::cout << "did not parse";
    }
    else
    {
        // would like output.inttext to be "1,2_3"
        std::cout << output.header << ": " << output.ints.inttext << " -> [ ";
        for( auto & i: output.ints.data )
            std::cout << i << ' ';
        std::cout << ']' << std::endl;
    }
}
于 2013-04-05T15:12:55.370 に答える