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/* Gets the bit-th bit from key */
#define GET_BIT(key, bit) (key[bit / 8] & (1 << (bit & 7)))
/* Checks if the bit-th bit from key1 and key2 differ, returns 1 if they do */
#define GET_BIT_XOR(key1, key2, bit) ((key1[bit / 8] ^ key2[bit / 8]) & (1 << (bit & 7)))
template<typename Data> struct patricia_elem
{
unsigned int bit;
patricia_elem<Data> *up, *one, *zero;
typename std::list<Data>::iterator node;
Anope::string key;
Data data;
};
template<typename Data, typename char_traits = std::std_char_traits>
class patricia_tree
{
typedef std::basic_string<char, char_traits, std::allocator<char> > String;
patricia_elem<Data> *root;
std::list<Data> list;
public:
patricia_tree()
{
this->root = NULL;
}
virtual ~patricia_tree()
{
while (this->root)
this->erase(this->root->key);
}
typedef typename std::list<Data>::iterator iterator;
typedef typename std::list<Data>::const_iterator const_iterator;
inline iterator begin() { return this->list.begin(); }
inline iterator end() { return this->list.end(); }
inline const const_iterator begin() const { return this->list.begin(); }
inline const const_iterator end() const { return this->list.end(); }
inline Data front() { return this->list.front(); }
inline Data back() { return this->list.back(); }
inline size_t size() const { return this->list.size(); }
inline bool empty() const { return this->list.empty(); }
Data find(const Anope::string &ukey)
{
Anope::string key;
for (size_t i = 0, j = ukey.length(); i < j; ++i)
key.push_back(char_traits::chartolower(ukey[i]));
size_t keylen = key.length();
patricia_elem<Data> *prev = NULL, *cur = this->root;
bool bitval;
while (cur && (!prev || prev->bit < cur->bit))
{
prev = cur;
if (cur->bit / 8 < keylen)
bitval = GET_BIT(key, cur->bit);
else
bitval = false;
cur = bitval ? cur->one : cur->zero;
}
if (cur && String(cur->key.c_str()).compare(key.c_str()) == 0)
return cur->data;
return NULL;
}
void insert(const Anope::string &ukey, Data data)
{
Anope::string key;
for (size_t i = 0, j = ukey.length(); i < j; ++i)
key.push_back(char_traits::chartolower(ukey[i]));
size_t keylen = key.length();
patricia_elem<Data> *prev = NULL, *cur = this->root;
bool bitval;
while (cur && (!prev || prev->bit < cur->bit))
{
prev = cur;
if (cur->bit / 8 < keylen)
bitval = GET_BIT(key, cur->bit);
else
bitval = false;
cur = bitval ? cur->one : cur->zero;
}
if (cur && String(cur->key.c_str()).compare(key.c_str()) == 0)
return;
patricia_elem<Data> *newelem = new patricia_elem<Data>();
newelem->up = prev;
newelem->key = key;
newelem->data = data;
if (!cur)
newelem->bit = prev ? prev->bit + 1 : 0;
else
for (newelem->bit = 0; GET_BIT_XOR(key, cur->key, newelem->bit) == 0; ++newelem->bit);
patricia_elem<Data> *place = prev;
while (place && newelem->bit < place->bit)
{
prev = place;
place = place->up;
}
if (GET_BIT(key, newelem->bit))
{
newelem->one = newelem;
newelem->zero = place == prev ? cur : prev;
}
else
{
newelem->zero = newelem;
newelem->one = place == prev ? cur : prev;
}
if (place != prev)
{
prev->up = newelem;
newelem->up = place;
}
if (place)
{
bitval = GET_BIT(key, place->bit);
if (bitval)
place->one = newelem;
else
place->zero = newelem;
}
else
this->root = newelem;
this->list.push_front(data);
newelem->node = this->list.begin();
}
Data erase(const Anope::string &ukey)
{
Anope::string key;
for (size_t i = 0, j = ukey.length(); i < j; ++i)
key.push_back(char_traits::chartolower(ukey[i]));
size_t keylen = key.length();
patricia_elem<Data> *prev = NULL, *cur = this->root;
bool bitval;
while (cur && (!prev || prev->bit < cur->bit))
{
prev = cur;
if (cur->bit / 8 < keylen)
bitval = GET_BIT(key, cur->bit);
else
bitval = false;
cur = bitval ? cur->one : cur->zero;
}
if (!cur || String(cur->key.c_str()).compare(key.c_str()))
return NULL;
patricia_elem<Data> *other = (bitval ? prev->zero : prev->one);
if (!prev->up)
this->root = other;
else if (prev->up->zero == prev)
prev->up->zero = other;
else
prev->up->one = other;
if (prev->zero && prev->zero->up == prev)
prev->zero->up = prev->up;
if (prev->one && prev->one->up == prev)
prev->one->up = prev->up;
if (cur != prev)
{
if (!cur->up)
this->root = prev;
else if (cur->up->zero == cur)
cur->up->zero = prev;
else
cur->up->one = prev;
if (cur->zero && cur->zero->up == cur)
cur->zero->up = prev;
if (cur->one && cur->one->up == cur)
cur->one->up = prev;
prev->one = cur->one;
prev->zero = cur->zero;
prev->up = cur->up;
prev->bit = cur->bit;
}
this->list.erase(cur->node);
Data data = cur->data;
delete cur;
return data;
}
};
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