modify regex to include comma - c++

Question

I have the following string:
arg1('value1') arg2('value '')2') arg3('user\'~!##$%^&*_~!##$%^&"*_-=+[{]}\|;:<.>?21')
The regex to extract the value looks like:
boost::regex re_arg_values("('[^']*(?:''[^']*)*'[^)]*)");
The above regex properly extracts the values. BUT when I include a comma , the code fails. For eg:
arg1('value1') arg2('value '')2') arg3('user\'~!##$%^&*_~!##$%^&"*_-=+[{]}\|;:<.>?21**,**')
How shall I modify this regex to include the comma?
FYI. The value can contain spaces, special characters, and also tabs. The code is in CPP.
Thanks in advance.

Answer 1

I'd not use a regex here.
The goal MUST be to parse values, and no doubt they will have useful values, that you need interpreted.
I'd devise a datastructure like:
#include <map>
namespace Config {
using Key = std::string;
using Value = boost::variant<int, std::string, bool>;
using Setting = std::pair<Key, Value>;
using Settings = std::map<Key, Value>;
}
For this you can write 1:1 a parser using Boost Spirit:
#include <boost/spirit/include/qi.hpp>
#include <boost/fusion/adapted/std_pair.hpp>
namespace Parser {
using It = std::string::const_iterator;
using namespace Config;
namespace qi = boost::spirit::qi;
using Skip = qi::blank_type;
qi::rule<It, std::string()> quoted_ = "'" >> *(
"'" >> qi::char_("'") // double ''
| '\\' >> qi::char_ // any character escaped
| ~qi::char_("'") // non-quotes
) >> "'";
qi::rule<It, Key()> key_ = +qi::char_("a-zA-Z0-9_"); // for example
qi::rule<It, Value()> value_ = qi::int_ | quoted_ | qi::bool_;
qi::rule<It, Setting(), Skip> setting_ = key_ >> '(' >> value_ >> ')';
qi::rule<It, Settings()> settings_ = qi::skip(qi::blank) [*setting_];
}
Note how this
interprets non-string values correctly
specifies what keys look like and parses them too
interprets string escapes, so the Value in the map contains the "real" string, after un-escaping
ignores whitespace outside values (use space_type if you want to ignore newlines as whitespace as well)
You can use it like:
int main() {
std::string const input = R"( arg1('value1') arg2('value '')2') arg3('user\'~!##$%^&*_~!##$%^&"*_-=+[{]}\|;:<.>?21**,**'))";
Config::Settings map;
if (parse(input.begin(), input.end(), Parser::settings_, map)) {
for(auto& entry : map)
std::cout << "config setting {" << entry.first << ", " << entry.second << "}\n";
}
}
Which prints
config setting {arg1, value1}
config setting {arg2, value ')2}
config setting {arg3, user'~!##$%^&*_~!##$%^&"*_-=+[{]}|;:<.>?21**,**}
Live Demo
Live On Coliru
#include <boost/spirit/include/qi.hpp>
#include <map>
#include <boost/fusion/adapted/std_pair.hpp>
namespace Config {
using Key = std::string;
using Value = boost::variant<int, std::string, bool>;
using Setting = std::pair<Key, Value>;
using Settings = std::map<Key, Value>;
}
namespace Parser {
using It = std::string::const_iterator;
using namespace Config;
namespace qi = boost::spirit::qi;
using Skip = qi::blank_type;
qi::rule<It, std::string()> quoted_ = "'" >> *(
"'" >> qi::char_("'") // double ''
| '\\' >> qi::char_ // any character escaped
| ~qi::char_("'") // non-quotes
) >> "'";
qi::rule<It, Key()> key_ = +qi::char_("a-zA-Z0-9_"); // for example
qi::rule<It, Value()> value_ = qi::int_ | quoted_ | qi::bool_;
qi::rule<It, Setting(), Skip> setting_ = key_ >> '(' >> value_ >> ')';
qi::rule<It, Settings()> settings_ = qi::skip(qi::blank) [*setting_];
}
int main() {
std::string const input = R"( arg1('value1') arg2('value '')2') arg3('user\'~!##$%^&*_~!##$%^&"*_-=+[{]}\|;:<.>?21**,**'))";
Config::Settings map;
if (parse(input.begin(), input.end(), Parser::settings_, map)) {
for(auto& entry : map)
std::cout << "config setting {" << entry.first << ", " << entry.second << "}\n";
}
}
BONUS
For comparison, here's the "same" but using regex:
Live On Coliru
#include <boost/regex.hpp>
#include <boost/range/iterator_range.hpp>
#include <iostream>
#include <map>
namespace Config {
using Key = std::string;
using RawValue = std::string;
using Settings = std::map<Key, RawValue>;
Settings parse(std::string const& input) {
Settings settings;
boost::regex re(R"((\w+)\(('.*?')\))");
auto f = boost::make_regex_iterator(input, re);
for (auto& match : boost::make_iterator_range(f, {}))
settings.emplace(match[1].str(), match[2].str());
return settings;
}
}
int main() {
std::string const input = R"( arg1('value1') arg2('value '')2') arg3('user\'~!##$%^&*_~!##$%^&"*_-=+[{]}\|;:<.>?21**,**'))";
Config::Settings map = Config::parse(input);
for(auto& entry : map)
std::cout << "config setting {" << entry.first << ", " << entry.second << "}\n";
}
Prints
config setting {arg1, 'value1'}
config setting {arg2, 'value ''}
config setting {arg3, 'user\'~!##$%^&*_~!##$%^&"*_-=+[{]}\|;:<.>?21**,**'}
Notes:
it no longer interprets and converts any values
it no longer processes escapes
it requires an additional runtime library dependency on boost_regex