subconverter/src/string_hash.h

#ifndef STRING_HASH_H_INCLUDED
#define STRING_HASH_H_INCLUDED

#include <string>

typedef uint64_t hash_t;

constexpr hash_t prime = 0x100000001B3ull;
constexpr hash_t basis = 0xCBF29CE484222325ull;

inline hash_t hash_(char const* str)
{
    hash_t ret{basis};
    while(*str)
    {
        ret ^= *str;
        ret *= prime;
        str++;
    }
    return ret;
}

inline hash_t hash_(const std::string &str)
{
    return hash_(str.data());
}

constexpr hash_t hash_compile_time(char const* str, hash_t last_value = basis)
{
    return *str ? hash_compile_time(str + 1, (*str ^ last_value) * prime) : last_value;
}

constexpr unsigned long long operator "" _hash(char const* p, size_t)
{
    return hash_compile_time(p);
}

#endif // STRING_HASH_H_INCLUDED