use boost.spirit to parse url

url_parser.cpp

#include <boost/config/warning_disable.hpp>
#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/include/phoenix.hpp>

struct KV
{
	std::string k;
	std::string v;
};

struct URL
{
	std::string schema; // http/https
	std::string host;
	std::string username;
	std::string password;
	std::optional<int> port;
	std::string query_path = "/";
	std::vector<KV> query_params;
	std::string anchor;
};

namespace qi = boost::spirit::qi;

BOOST_FUSION_ADAPT_STRUCT(
	KV,
	(std::string, k)
	(std::string, v)
)

BOOST_FUSION_ADAPT_STRUCT(
	URL,
	(std::string, schema)
	(std::string, host)
	(std::string, username)
	(std::string, password)
	(std::optional<int>, port)
	(std::string, query_path)
	(std::vector<KV>, query_params)
	(std::string, anchor)
)

template <typename Iterator>
struct uri_grammer : qi::grammar<Iterator, URL()>
{
	typedef unsigned long ulong;
	uri_grammer() : uri_grammer::base_type(url)
	{

		url = schema [ boost::phoenix::at_c<0>(qi::_val) = qi::_1 ]
			  >> "://" -( username [ boost::phoenix::at_c<2>(qi::_val) = qi::_1 ] >> -( ':' >> password  [ boost::phoenix::at_c<3>(qi::_val) = qi::_1 ] ) >> '@' ) >> host [ boost::phoenix::at_c<1>(qi::_val) = qi::_1 ]
			  >> -(qi::lit(':') >> qi::int_ [ boost::phoenix::at_c<4>(qi::_val) = qi::_1 ] )
			  >> -(
				 query [ boost::phoenix::at_c<5>(qi::_val) = qi::_1 ] // >> -('?' >> params[ boost::phoenix::at_c<6>(qi::_val) = qi::_1 ] )
			  )
			  >> - (
				'#' >> anchor [ boost::phoenix::at_c<7>(qi::_val) = qi::_1 ]
			 );

		host = *(qi::char_ - '/' - ':');
		username = *(qi::char_ - ':' - '@');
		password = *(qi::char_ - '@');

		schema = *(qi::char_ - ':' - '/');

		query = *(qi::char_ - '#');

		params = param % '&';
		param = key >> '=' >> value;

		anchor = *(qi::char_);

		key = *(qi::char_ - '=' - '#');
		value = *(qi::char_ - '&' - '#');
	};

	qi::rule<Iterator, std::string()> key;
	qi::rule<Iterator, std::string()> value;

	qi::rule<Iterator, URL()> url;
	qi::rule<Iterator, std::string()> schema, host, username, password;

	qi::rule<Iterator, std::string()> query;
	qi::rule<Iterator, std::vector<KV>()> params;
	qi::rule<Iterator, KV()> param;
	qi::rule<Iterator, std::string()> anchor;
};

URL parse_url(const std::string& url)
{
	URL ast;

	uri_grammer<std::string::const_iterator> gramer;

	auto first = url.begin();

	bool r = boost::spirit::qi::parse(first, url.end(), gramer, ast);

	return ast;
}