从提升::元组::元组检索字符串

Question

在阅读了 https://www.boost.org/doc/libs/1_67_0/libs/tuple/doc/html/tuple_users_guide.html 的文章后 以下注释对我来说是一个问题。 请注意，使用 std：：string 或 C 样式字符串元素提取元组通常不起作用，因为流式元组表示形式可能无法明确解析。 我应该使用什么类型来明确地将字符串从流解析为元组？

从元组中检索 std：：string 时，字符串由空格分隔。这是不希望的！设置分隔符例如数字符号(#(无济于事。

// typedef tuple
typedef std::string td_current_gmt, td_remote_endpoint, 
td_request, td_response, td_elapsed_time;
typedef boost::tuples::tuple<td_current_gmt, td_remote_endpoint, 
td_request, td_response, td_elapsed_time> tuple_logging;
// store in tuple
tuple_logging tl{ current_gmt, remote_endpoint, 
request, response, elapsed_time };
// write tuple to file
tl = boost::tuples::make_tuple(current_gmt, remote_endpoint,
request, response, elapsed_time);
boost::filesystem::path p = { "logging" };
boost::filesystem::ofstream ofs{ p };
ofs << /*boost::tuples::set_delimiter('#') <<*/ tl;
ofs.close();
// read tuple from file
tuple_logging tlin{ current_gmt, remote_endpoint,
request, response, elapsed_time };
boost::filesystem::ifstream ifs{ p };
//ifs >> boost::tuples::set_delimiter('#');
ifs >> tlin;

输出为 (星期五， 16 八月 2019 06：28：05( 但实际上它必须是(周五，16 Aug 2019 06：28：05 GMT 192.168.178.14：52832 TRACE/HTTP/1.1 HTTP/1.1 200 OK 8.936800(

Answer 1

这是代码。

void parse_logfile(
boost::filesystem::ifstream& ifs,
const boost::filesystem::path& p,
std::vector<tuple_logging>& vector_with_tuples

( { typedef std：：string one_line_from_logging;

one_line_from_logging str;
tuple_logging tlin;
// clear vector
vector_with_tuples.clear();
// open log file for reading
ifs.open(p);
// read one line from log file, until eof
while (std::getline(ifs, str))
{
size_t sBegin = 0, sEnd = 0;
// 1
// first character on a line is '(',
// start at sBegin = 1
sBegin = sEnd + 1;
sEnd = str.find('#', sBegin);
std::string current_gmt_ = str.substr(sBegin, sEnd - sBegin);
// 2
sBegin = sEnd + 1;
sEnd = str.find('#', sBegin);
std::string remote_endpoint_ = str.substr(sBegin, sEnd - sBegin);
// 3
sBegin = sEnd + 1;
sEnd = str.find('#', sBegin);
std::string request_ = str.substr(sBegin, sEnd - sBegin);
// 4
sBegin = sEnd + 1;
sEnd = str.find('#', sBegin);
std::string response_ = str.substr(sBegin, sEnd - sBegin);
// 5
sBegin = sEnd + 1;
// last character on a line is ')'
sEnd = str.find(')', sBegin);
std::string elapsed_time_ = str.substr(sBegin, sEnd - sBegin);
// create tuple from parsed log data out of file
tlin = boost::tuples::make_tuple(
current_gmt_,
remote_endpoint_,
request_,
response_,
elapsed_time_
);
// set tuple into vector
vector_with_tuples.push_back(tlin);
}
// close log file
ifs.close();

}