Extracting Values from string using spirit parser - c++

Question

i have following line
/90pv-RKSJ-UCS2C usecmap
std::string const line = "/90pv-RKSJ-UCS2C usecmap";
auto first = line.begin(), last = line.end();
std::string label, token;
bool ok = qi::phrase_parse(
first, last,
qi::lexeme [ "/" >> +~qi::char_(" ") ] >> ' ' >> qi::lexeme[+~qi::char_(' ')] , qi::space, label, token);
if (ok)
std::cout << "Parse success: label='" << label << "', token='" << token << "'\n";
else
std::cout << "Parse failed\n";
if (first!=last)
std::cout << "Remaining unparsed input: '" << std::string(first, last) << "'\n";
I want to 90pv-RKSJ-UCS2C in label and usecmap in token variable.
I extract 90pv-RKSJ-UCS2C value but not usecmap

Answer 1

With space the skipper, you cannot ever match ' ' (it is skipped!). See also: Boost spirit skipper issues
So, either don't use a skipper, or allow the skipper to eat it:
bool ok = qi::phrase_parse(
first, last,
qi::lexeme [ "/" >> +qi::graph ] >> qi::lexeme[+qi::graph], qi::blank, label, token);
Notes:
I used qi::graph instead of the ~qi::char_(" ") formulation
I used blank_type because you said
i have following line
Which implies that line-ends should not be skipped
Demo
Live On Coliru
#include <boost/spirit/include/qi.hpp>
namespace qi = boost::spirit::qi;
int main()
{
std::string const line = "/90pv-rksj-ucs2c usecmap";
auto first = line.begin(), last = line.end();
std::string label, token;
bool ok = qi::phrase_parse(
first, last,
qi::lexeme [ "/" >> +qi::graph ] >> qi::lexeme[+qi::graph], qi::blank, label, token);
if (ok)
std::cout << "parse success: label='" << label << "', token='" << token << "'\n";
else
std::cout << "parse failed\n";
if (first!=last)
std::cout << "remaining unparsed input: '" << std::string(first, last) << "'\n";
}
Prints:
parse success: label='90pv-rksj-ucs2c', token='usecmap'

Answer 2

If you are using C++11, I suggest using regular expression.
#include <iostream>
#include <regex>
using namespace std;
int main() {
regex re("^/([^\\s]*)\\s([^\\s]*)"); // 1st () captures
// 90pv-RKSJ-UCS2C and 2nd () captures usecmap
smatch sm;
string s="/90pv-RKSJ-UCS2C usecmap";
regex_match(s,sm,re);
for(int i=0;i<sm.size();i++) {
cout<<sm[i]<<endl;
}
string label=sm[1],token=sm[2];
system("pause");
}