[英]boost spirit parsing identifier
I would like to create parser that will parse identifiers that start with alpha or _ and it might have alpha, num or _ in the body 我想创建一个解析器,该解析器将解析以alpha或_开头的标识符,并且主体中可能包含alpha,num或_
This is what I have so far: 这是我到目前为止的内容:
#include <boost/config/warning_disable.hpp>
#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/include/phoenix.hpp>
#include <boost/spirit/home/support/iterators/line_pos_iterator.hpp>
#include <boost/spirit/repository/include/qi_confix.hpp>
#include <boost/spirit/include/phoenix_fusion.hpp>
#include <boost/spirit/include/phoenix_stl.hpp>
using namespace boost::spirit;
#include <boost/fusion/include/adapt_struct.hpp>
////////////////////////////////
// extra facilities
struct get_line_f
{
template <typename> struct result { typedef size_t type; };
template <typename It> size_t operator()(It const& pos_iter) const
{
return get_line(pos_iter);
}
};
struct Position
{
Position()
: line(-1)
{
}
size_t line;
};
struct Identifier : public Position
{
Identifier()
: Position()
, name()
{
}
std::string name;
};
BOOST_FUSION_ADAPT_STRUCT(Identifier,
(std::string, name)
(size_t, line)
)
//
////////////////////////////////
template <typename Iterator>
struct source_identifier: qi::grammar<Iterator, Identifier(), qi::space_type>
{
source_identifier() : source_identifier::base_type(start)
{
using qi::alpha;
using qi::alnum;
using qi::raw;
using qi::_val;
using qi::_1;
namespace phx = boost::phoenix;
using phx::at_c;
using phx::begin;
name %= (qi::alpha | "_")
>> *(qi::alnum | "_");
start = raw [ name[at_c<0>(_val) = _1] ]
[
at_c<1>(_val) = get_line_(begin(_1))
]
;
}
boost::phoenix::function<get_line_f> get_line_;
qi::rule<Iterator, Identifier(), qi::space_type> start;
qi::rule<Iterator, std::string()> name;
};
why this returns an empty name if there is '_' in the identifier, it works in case there isn't 为什么如果标识符中有“ _”,则返回一个空名称,如果没有
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