hash_index
A fast hash table template for array indexes that keeps the hash keys separated from the mapped values.
hash_index is based on a similar data structure used by the DOOM 3 game from id Software.
I have adapted it to be usable as a standalone template class and also added a few
extra customization options and additional helper methods. You can find the original
idHashIndex class in here.
Basic usage example:
#include "hash_index.hpp"
#include <cassert>
#include <string>
#include <vector>
struct Player
{
std::string name;
int level;
int health;
// ...
};
class PlayerRegistry
{
public:
const Player * findPlayerByName(const std::string & name) const
{
const auto p_index = hash_idx.find(name_hasher(name), name, player_list,
[](const std::string & name, const Player & player)
{
return name == player.name;
});
if (p_index == hash_idx.null_index)
{
return nullptr;
}
return &player_list[p_index];
}
void addPlayer(std::string name, const int lvl, const int hp)
{
hash_idx.insert(name_hasher(name), player_list.size());
player_list.push_back({ std::move(name), lvl, hp });
}
private:
hash_index<> hash_idx;
std::vector<Player> player_list;
std::hash<std::string> name_hasher;
};
int main()
{
PlayerRegistry player_reg;
player_reg.addPlayer("Timmy", 10, 100);
player_reg.addPlayer("K1ll3r", 63, 97 );
player_reg.addPlayer("1337john", 82, 100);
assert(player_reg.findPlayerByName("Timmy") != nullptr);
assert(player_reg.findPlayerByName("K1ll3r") != nullptr);
assert(player_reg.findPlayerByName("1337john") != nullptr);
assert(player_reg.findPlayerByName("bobby") == nullptr);
assert(player_reg.findPlayerByName("johnny") == nullptr);
}You can find more documentation in the hash_index.hpp header file.
License
hash_index is released under the terms of the GPL version 3
to comply with the original license used by the code this was based on.