使用Boost：：Spirit解析具有未知键的"键=值"列表

我有一个像下面这样的字符串：

[GENERAL]
FMax Antenna = 3000
FMin Antenna = 2000
Invalid key  = Invalid value
EMin Antenna = -50
EMax Antenna = 80

我想解析它，以便将FMin Antenna、FMax Antenna、EMin Antenna、EMax Antenna的值保存在结构中。我创建了一个精神解析器，但它部分工作。 由于该文件可以有很多key = value行，因此我只需要解析我需要的内容(我必须读取的键值)，而忽略其他对。

key和value都可以是带有空格和制表符的字母数字字符串。

我已经在解析器中定义了我要读取的键，但是当我遇到未知键时，我无法读取它后面的键(在示例示例中，我无法读取EMin Antenna和EMax Antenna因为在未知键之后定义)。

我已经尝试了下面的代码： 如果我解析file1，它只包含我想读取的键，它可以工作，但是如果我在文件中间添加未知的key = value对，就像在file2中一样，它会停止读取所有后续行。

如何修复它并在未知键值对后继续解析文件？

#include <boost/optional/optional_io.hpp>
#include <boost/date_time/posix_time/posix_time.hpp>
#include <boost/date_time/posix_time/posix_time_io.hpp>
#include <boost/fusion/adapted/struct.hpp>
#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/include/phoenix.hpp>
namespace qi = boost::spirit::qi;
const std::string file1 = R"xx(
[GENERAL]
FMax Antenna = 3000
FMin Antenna = 2000
EMin Antenna = -50
EMax Antenna = 80
)xx";
const std::string file2 = R"xx(
[GENERAL]
FMax Antenna = 3000
FMin Antenna = 2000
EMin Antenna = -50
pappa pio = po po
EMax Antenna = 80
Ciao = 55
)xx";
struct Data {
double minFrequency = 0.0;
double maxFrequency = 0.0;
double minElevation = 0.0;
double maxElevation = 0.0;
};
BOOST_FUSION_ADAPT_STRUCT(
Data,
(double, minFrequency)
(double, maxFrequency)
(double, minElevation)
(double, maxElevation)
)
template <typename It, typename Skipper = qi::space_type>
struct grammar : qi::grammar<It, Data(), Skipper> {
grammar() : grammar::base_type(start) {
auto minFrequency = bind(&Data::minFrequency, qi::_val);
auto maxFrequency = bind(&Data::maxFrequency, qi::_val);
auto minElevation = bind(&Data::minElevation, qi::_val);
auto maxElevation = bind(&Data::maxElevation, qi::_val);
start = qi::no_case["[GENERAL]"] >> *(
("FMin Antenna" >> qi::lit('=') >> qi::int_)[minFrequency = qi::_1] |
("FMax Antenna" >> qi::lit('=') >> qi::int_)[maxFrequency = qi::_1] |
("EMin Antenna" >> qi::lit('=') >> qi::int_)[minElevation = qi::_1] |
("EMax Antenna" >> qi::lit('=') >> qi::int_)[maxElevation = qi::_1] |
(+(qi::alnum | qi::blank) >> qi::lit('=') >> +(qi::alnum | qi::blank)) // Issue here?
);
}
private:
qi::rule<It, Data(), Skipper> start;
};
int main() {
using It = std::string::const_iterator;
Data parsed1, parsed2;
bool ok = qi::phrase_parse(file1.begin(), file1.end(), grammar<It>(), qi::space, parsed1);
std::cout << "--- File 1 ---" << std::endl;
std::cout << "parsed   = " << std::boolalpha << ok << std::endl;
std::cout << "min freq = " << parsed1.minFrequency << std::endl;
std::cout << "max freq = " << parsed1.maxFrequency << std::endl;
std::cout << "min elev = " << parsed1.minElevation << std::endl;
std::cout << "max elev = " << parsed1.maxElevation << std::endl;
std::cout << "--- File 2 ---" << std::endl;
ok = qi::phrase_parse(file2.begin(), file2.end(), grammar<It>(), qi::space, parsed2);
std::cout << "parsed   = " << std::boolalpha << ok << std::endl;
std::cout << "min freq = " << parsed2.minFrequency << std::endl;
std::cout << "max freq = " << parsed2.maxFrequency << std::endl;
std::cout << "min elev = " << parsed2.minElevation << std::endl;
std::cout << "max elev = " << parsed2.maxElevation << std::endl;
return 0;
}

输出：

--- File 1 ---
parsed   = true
min freq = 2000
max freq = 3000
min elev = -50
max elev = 80
--- File 2 ---
parsed   = true
min freq = 2000
max freq = 3000
min elev = -50
max elev = 0  <-- This should be 80 like in the first parsing