<boost/url/grammar/ci_string.hpp>
using ci_hash = /* implementation-defined */;
The hash function is non-cryptographic and not hardened against algorithmic complexity attacks. This is a suitable hash function for unordered containers. The function is defined only for strings containing low-ASCII characters.
boost::unordered_map< std::string, std::string, ci_hash, ci_equal > m1;
std::unordered_map < std::string, std::string, ci_hash, ci_equal > m2; // (since C++20)