c++ - ¿Cómo capturo la entrada original en la salida sintetizada de una gramática espiritual?

boost boost-spirit

Question

Estoy trabajando en un boost :: spirit :: qi :: grammar y me gustaría copiar una parte del texto original en la estructura de salida sintetizada de la gramática (más específicamente, la parte que coincide con uno de los componentes de la regla) ) La gramática finalmente se usaría como una subgramática para una gramática más complicada, por lo que realmente no tengo acceso a la entrada original.

Supongo que esto puede hacerse a través de acciones semánticas o el contexto de la gramática, pero no puedo encontrar un ejemplo que lo haga sin acceso al análisis original ().

Esto es lo que tengo hasta ahora:

#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;
    }
}

Answer 1

Algo similar a lo que preguntaste sin usar acciones semánticas:

#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;
    }
}

Usando acciones semánticas:

#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;
    }
}

Answer 2

Otra alternativa que usa una directiva personalizada dont_eat que devuelve el atributo subject pero no consume ninguna entrada. Esto es posiblemente más lento ya que la regla es analizada dos veces, pero creo que la sintaxis es más agradable (y es una buena excusa para intentar crear su propia directiva) (Es una versión ligeramente modificada de "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;
    }
}

Answer 3

Esta directiva devuelve una fusion::vector2<> con el atributo del sujeto como su primer miembro y la cadena correspondiente al atributo sintetizado como su segundo. Creo que este es el método más fácil de reutilizar siempre y cuando adaptes tus estructuras adecuadamente. No estoy seguro de que esta fusion::vector2<> sea ​​la mejor manera de manejar los atributos, pero en las pruebas limitadas que he hecho, ha funcionado bien. Con esta directiva, la regla ints_string sería simplemente:

ints_string=custom::annotate[ints];
//or ints_string=custom::annotate[qi::lexeme[qi::int_ % qi::char_(",_")]];

Ejemplo en LWS.

anotar.hpp

#if !defined(ANNOTATE_HPP)
#define ANNOTATE_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(annotate); 
}

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

namespace custom
{


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

        template <typename Context, typename Iterator>
        struct attribute
        {
            typedef 
                boost::fusion::vector2<
                    typename boost::spirit::traits::attribute_of<subject_type, Context, Iterator>::type
                    ,std::string
                >
            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
        {
            boost::spirit::qi::skip_over(first, last, skipper);
            Iterator save = first;
            typename boost::spirit::traits::attribute_of<subject_type, Context, Iterator>::type attr_;
            if(subject.parse(first, last, context, skipper, attr_))
            {
                boost::spirit::traits::assign_to(attr_,boost::fusion::at_c<0>(attr));
                boost::spirit::traits::assign_to(std::string(save,first),boost::fusion::at_c<1>(attr));
                return true;
            }
            first = save;
            return false;
        }

        template <typename Context>
        boost::spirit::info what(Context& context) const
        {
            return info("annotate", 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::annotate, Subject, Modifiers>
    {
        typedef custom::annotate_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::annotate_directive<Subject> >
      : unary_has_semantic_action<Subject> {};

    ///////////////////////////////////////////////////////////////////////////
    template <typename Subject, typename Attribute, typename Context
        , typename Iterator>
    struct handles_container<custom::annotate_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 "annotate.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::annotate[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;
    std::string annotation;
    bool r = qi::parse(iter, input.end(), custom::annotate[p], output, annotation);
    if( !r || iter != input.end() )
    {
        std::cout << "did not parse";
    }
    else
    {
        // would like output.inttext to be "1,2_3"
        std::cout << "annotation: " << annotation << std::endl;
        std::cout << output.header << ": " << output.ints.inttext << " -> [ ";
        for( auto & i: output.ints.data )
            std::cout << i << '' '';
        std::cout << '']'' << std::endl;
    }
}