Modernes C++ programmieren

//#(execute) c++; compiler:g132; options:-O3 -std=c++23; libs:-
// https://godbolt.org/z/ob9voovMx 
#include <string>
#include <string_view>
#include <vector>
#include <map> // multimap
namespace qw::impl_multimap {
using std::vector; using std::multimap; 
using std::string; using std::string_view;
class index_impl {
    vector<string> entries;
    multimap<string, size_t> qindex;
public:
    void add(string_view normalized, string_view original);
    string getBestMatch(string_view normalized) const;
    size_t size() const {
        return entries.size();
    }
private:
    vector<string> qgramify(string_view normalized) const;
    static constexpr size_t Q = 3;
    static const std::string PREFIX;
    static const std::string SUFFIX;
public: // test interface
    vector<string> _qgramify(string_view n) const { return qgramify(n); }
    static size_t _q() { return Q; }
    static std::string _prefix() { return PREFIX; }
    static std::string _suffix() { return SUFFIX; }
};
} // namespace qw::impl_multimap