boot 词汇分析器

这是一个简单的json语法分析器,也可以定义自己的分析器,先学习了

#include <boost/spirit.hpp> #include <string> #include <fstream> #include <sstream> #include <iostream> struct json_grammar   : public boost::spirit::grammar<json_grammar> {   struct print   {     void operator()(const char *begin, const char *end) const     {       std::cout << std::string(begin, end) << std::endl;     }   };   template <typename Scanner>   struct definition   {     boost::spirit::rule<Scanner> object, member, string, value, number, array;     definition(const json_grammar &self)     {       using namespace boost::spirit;       object = "{" >> member >> *("," >> member) >> "}";       member = string[print()] >> ":" >> value;       string = "\"" >> *~ch_p("\"") >> "\"";       value = string | number | object | array | "true" | "false" | "null";       number = real_p;       array = "[" >> value >> *("," >> value) >> "]";     }     const boost::spirit::rule<Scanner> &start()     {       return object;     }   }; }; int main(int argc, char *argv[]) {   std::ifstream fs(argv[1]);   std::ostringstream ss;   ss << fs.rdbuf();   std::string data = ss.str();   json_grammar g;   boost::spirit::parse_info<> pi = boost::spirit::parse(data.c_str(), g, boost::spirit::space_p);   if (pi.hit)   {     if (pi.full)       std::cout << "parsing all data successfully" << std::endl;     else       std::cout << "parsing data partially" << std::endl;     std::cout << pi.length << " characters parsed" << std::endl;   }   else     std::cout << "parsing failed; stopped at '" << pi.stop << "'" << std::endl; }