I am trying to parse the following messages with Spirit Qi:
"A/B AND C/D", "A/B", "A/B AND C/D AND E/F"
I am able to parse "A/B" but cannot get the correct results for the other strings.
I tried to following code:
qi::rule<It, AstNodeVector()> entries;
qi::rule<It, AstNodeVector()> lists;
qi::rule<It, std::string()> element;
this->entries= *(this->lists % " AND ");
this->lists= this->element >> '/' >> this->element;
this->element = qi::char_("A-Z");
What is wrong with my grammar?
It seems you're not skipping whitespace. Maybe that's a conceptual problem (see Boost spirit skipper issues).
Regardless, it does parse:
#include <boost/spirit/include/qi.hpp>
#include <iomanip>
namespace qi = boost::spirit::qi;
using AstNodeVector = std::vector<std::string>;
template <typename It>
struct P : qi::grammar<It, AstNodeVector()> {
P() : P::base_type(entries) {
entries = *(lists % " AND ");
lists = element >> '/' >> element;
element = qi::char_("A-Z");
}
private:
qi::rule<It, AstNodeVector()> entries;
qi::rule<It, AstNodeVector()> lists;
qi::rule<It, std::string()> element;
};
int main() {
using It = std::string::const_iterator;
P<It> const p {};
for (std::string const input: {
"A/B AND C/D",
"A/B",
"A/B AND C/D AND E/F",
})
{
It f = begin(input), l = end(input);
AstNodeVector results;
if (phrase_parse(f, l, p, qi::space, results)) {
std::cout << "Success: " << std::quoted(input) << "\n";
for (auto& el : results) {
std::cout << " -- " << std::quoted(el) << "\n";
}
} else {
std::cout << "FAIL: " << std::quoted(input) << "\n";
}
if (f != l) {
std::cout << "Remaining input: " << std::quoted(std::string(f,l)) << "\n";
}
}
}
Prints
Success: "A/B AND C/D"
-- "A"
-- "B"
-- "C"
-- "D"
Success: "A/B"
-- "A"
-- "B"
Success: "A/B AND C/D AND E/F"
-- "A"
-- "B"
-- "C"
-- "D"
-- "E"
-- "F"
Perhaps you should have included self-contained code, or elaborate on what exactly is the problem.