How do I capture the original input into the synthesized output from a spirit grammar?

Question

I\'m working on a boost::spirit::qi::grammar and would like to copy a portion of the original text into the synthesized output structure of the grammar (more specifically, t

Answer 1

Something similar to what you asked without using semantic actions:

#include 
#include 
#include 
#include 
#include 

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

struct ints_type
{
   std::vector 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, data)
    (std::string::const_iterator, end)
)

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

template 
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 header;
    qi::rule ints;
    qi::rule start;
};

int main()
{
    A output;
    std::string input("out 1,2_3");
    auto iter = input.begin();
    parser 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;
    }
}

Using semantic actions:

#include 
#include 
#include 
#include 
#include 

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

struct ints_type
{
   std::vector data;
   std::string inttext; 
};

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

};

BOOST_FUSION_ADAPT_STRUCT(
    ints_type,
    (std::vector, data)
    (std::string, inttext)
)

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

template 
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(qi::_1,qi::_3)] 
               ]; 
        start %= header >> ' ' >> ints;
    }

    qi::rule header;
    qi::rule ints;
    qi::rule start;
};

int main()
{
    A output;
    std::string input("out 1,2_3");
    auto iter = input.begin();
    parser 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;
    }
}