boost之program_options库，解析命令行参数、读取配置文件config.conf的方法

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#include <fstream>
#include <map>
#include <boost/tokenizer.hpp>
#include <boost/token_functions.hpp>
#include <vector>

using namespace std;

#include <boost/program_options.hpp>
using namespace boost;
namespace po = boost::program_options;

std::pair<std::string, std::string> at_option_parser(std::string const& s)
{
if ('@' == s[0])
{
return make_pair(std::string("config"), s.substr(1));
}
else
{
return std::pair<std::string, std::string>();
}
}

int main(int argc, char*argv[])
{
//
string host_ip;
short host_port;

string server_ip;
short server_port;

//
po::options_description hostoptions("host options");
hostoptions.add_options()
("host_ip,H", po::value<string>(&host_ip), "set db_host")
("host_port,P", po::value<short>(&host_port)->default_value(3306), "set db_port");

po::options_description general("general options");
general.add_options()
("help,h", "produce help message")
("server_ip,s", po::value<string>(&server_ip), "set the http_server's ip. e.g. '202.106.0.20'")
("server_port,p", po::value<short>(&server_port)->default_value(80), "set the http_server's port. default:80");

string config_file;
po::options_description config("config options");
config.add_options()
("config", po::value<string>(&config_file)->default_value("config.conf"),
"set config file, specified with '@name' too");

po::options_description all("All options");
all.add(hostoptions).add(general).add(config);

po::variables_map vm;
po::store(po::command_line_parser(argc, argv).options(all).extra_parser(::at_option_parser).run(), vm);

if (vm.count("help"))
{
cout << hostoptions <<endl;
cout << general << endl;
cout << config << endl;
return false;
}

if (vm.count("config"))
{
string conf_name = vm["config"].as<string>();
ifstream ifs_config(conf_name.c_str());

if (! ifs_config)
{
cerr << "could not open the configure file" << endl;
return false;
}

std::stringstream ss;
ss<< ifs_config.rdbuf();

boost::char_separator<char> sep(" \n\r");
std::string sstr=ss.str();
boost::tokenizer<boost::char_separator<char>> tok(sstr,sep);
std::vector<std::string> args;
std::copy(tok.begin(),tok.end(),back_inserter(args));
po::store(po::command_line_parser(args).options(all).run(), vm);
}
po::notify(vm);
//
cout<<"host_ip: "<<host_ip<<endl;
cout<<"host_port: "<<host_port<<endl;

cout<<"server_ip: "<<server_ip<<endl;
cout<<"server_port: "<<server_port<<endl;

return 0;
}
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