oauth/access_token response parser

nyan.cc

#include <iostream>
#include <unordered_map>
#include <boost/fusion/include/std_pair.hpp>
#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/include/qi_grammar.hpp>

namespace qi = boost::spirit::qi;

template <class String, class Iterator = typename String::const_iterator>
struct query_string : qi::grammar<Iterator, std::unordered_map<String, String>()> {
  query_string() : query_string::base_type(map_) {
    map_ = pair_ % qi::lit('&');
    pair_ = string_ >> qi::lit('=') >> string_;
    string_ = +qi::char_("0-9a-zA-Z_");
  }
  qi::rule<Iterator, std::unordered_map<String, String>()> map_;
  qi::rule<Iterator, std::pair<String, String>()> pair_;
  qi::rule<Iterator, String()> string_;
};

auto main() -> int {
  {
    std::cout << "- std::string --------------------\n";

    const std::string str(
        "oauth_token=hogehogehogehogehogehogehogehogehogehoge&"
        "oauth_token_secret=fugafugafugafugafugafugafugafugafugafuga&"
        "user_id=12345&"
        "screen_name=nyan");
    std::unordered_map<std::string, std::string> res{};

    if (qi::parse(str.begin(), str.end(), query_string<std::string>(), res)) {
      for (auto&& v : res) {
        std::cout << v.first << " => " << v.second << '\n';
      }
    }
  }

  {
    std::wcout << L"- std::wstring -------------------\n";

    const std::wstring str(
        L"oauth_token=hogehogehogehogehogehogehogehogehogehoge&"
        "oauth_token_secret=fugafugafugafugafugafugafugafugafugafuga&"
        "user_id=12345&"
        "screen_name=nyan");
    std::unordered_map<std::wstring, std::wstring> res{};

    if (qi::parse(str.begin(), str.end(), query_string<std::wstring>(), res)) {
      for (auto&& v : res) {
        std::wcout << v.first << L" => " << v.second << L'\n';
      }
    }
  }
}