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/* $Id$ */
/** @file hashtable.hpp Hash table support. */
#ifndef HASHTABLE_HPP
#define HASHTABLE_HPP
template <class Titem_>
struct CHashTableSlotT
{
typedef typename Titem_::Key Key; // make Titem_::Key a property of HashTable
Titem_ *m_pFirst;
FORCEINLINE CHashTableSlotT() : m_pFirst(NULL) {}
/** hash table slot helper - clears the slot by simple forgetting its items */
FORCEINLINE void Clear() {m_pFirst = NULL;}
/** hash table slot helper - linear search for item with given key through the given blob - const version */
FORCEINLINE const Titem_ *Find(const Key& key) const
{
for (const Titem_ *pItem = m_pFirst; pItem != NULL; pItem = pItem->GetHashNext()) {
if (pItem->GetKey() == key) {
/* we have found the item, return it */
return pItem;
}
}
return NULL;
}
/** hash table slot helper - linear search for item with given key through the given blob - non-const version */
FORCEINLINE Titem_ *Find(const Key& key)
{
for (Titem_ *pItem = m_pFirst; pItem != NULL; pItem = pItem->GetHashNext()) {
if (pItem->GetKey() == key) {
/* we have found the item, return it */
return pItem;
}
}
return NULL;
}
/** hash table slot helper - add new item to the slot */
FORCEINLINE void Attach(Titem_& new_item)
{
assert(new_item.GetHashNext() == NULL);
new_item.SetHashNext(m_pFirst);
m_pFirst = &new_item;
}
/** hash table slot helper - remove item from a slot */
FORCEINLINE bool Detach(Titem_& item_to_remove)
{
if (m_pFirst == &item_to_remove) {
m_pFirst = item_to_remove.GetHashNext();
item_to_remove.SetHashNext(NULL);
return true;
}
Titem_ *pItem = m_pFirst;
while (true) {
if (pItem == NULL) {
return false;
}
Titem_ *pNextItem = pItem->GetHashNext();
if (pNextItem == &item_to_remove) break;
pItem = pNextItem;
}
pItem->SetHashNext(item_to_remove.GetHashNext());
item_to_remove.SetHashNext(NULL);
return true;
}
/** hash table slot helper - remove and return item from a slot */
FORCEINLINE Titem_ *Detach(const Key& key)
{
/* do we have any items? */
if (m_pFirst == NULL) {
return NULL;
}
/* is it our first item? */
if (m_pFirst->GetKey() == key) {
Titem_& ret_item = *m_pFirst;
m_pFirst = m_pFirst->GetHashNext();
ret_item.SetHashNext(NULL);
return &ret_item;
}
/* find it in the following items */
Titem_ *pPrev = m_pFirst;
for (Titem_ *pItem = m_pFirst->GetHashNext(); pItem != NULL; pPrev = pItem, pItem = pItem->GetHashNext()) {
if (pItem->GetKey() == key) {
/* we have found the item, unlink and return it */
pPrev->SetHashNext(pItem->GetHashNext());
pItem->SetHashNext(NULL);
return pItem;
}
}
return NULL;
}
};
/** class CHashTableT<Titem, Thash_bits> - simple hash table
* of pointers allocated elsewhere.
*
* Supports: Add/Find/Remove of Titems.
*
* Your Titem must meet some extra requirements to be CHashTableT
* compliant:
* - its constructor/destructor (if any) must be public
* - if the copying of item requires an extra resource management,
* you must define also copy constructor
* - must support nested type (struct, class or typedef) Titem::Key
* that defines the type of key class for that item
* - must support public method:
* const Key& GetKey() const; // return the item's key object
*
* In addition, the Titem::Key class must support:
* - public method that calculates key's hash:
* int CalcHash() const;
* - public 'equality' operator to compare the key with another one
* bool operator == (const Key& other) const;
*/
template <class Titem_, int Thash_bits_>
class CHashTableT {
public:
typedef Titem_ Titem; // make Titem_ visible from outside of class
typedef typename Titem_::Key Tkey; // make Titem_::Key a property of HashTable
static const int Thash_bits = Thash_bits_; // publish num of hash bits
static const int Tcapacity = 1 << Thash_bits; // and num of slots 2^bits
protected:
/** each slot contains pointer to the first item in the list,
* Titem contains pointer to the next item - GetHashNext(), SetHashNext() */
typedef CHashTableSlotT<Titem_> Slot;
Slot m_slots[Tcapacity]; ///< here we store our data (array of blobs)
int m_num_items; ///< item counter
public:
/* default constructor */
FORCEINLINE CHashTableT() :
m_num_items(0)
{ }
FORCEINLINE ~CHashTableT() { }
protected:
/** static helper - return hash for the given key modulo number of slots */
FORCEINLINE static int CalcHash(const Tkey& key)
{
int32 hash = key.CalcHash();
if ((8 * Thash_bits) < 32) hash ^= hash >> (min(8 * Thash_bits, 31));
if ((4 * Thash_bits) < 32) hash ^= hash >> (min(4 * Thash_bits, 31));
if ((2 * Thash_bits) < 32) hash ^= hash >> (min(2 * Thash_bits, 31));
if ((1 * Thash_bits) < 32) hash ^= hash >> (min(1 * Thash_bits, 31));
hash &= (1 << Thash_bits) - 1;
return hash;
}
/** static helper - return hash for the given item modulo number of slots */
FORCEINLINE static int CalcHash(const Titem_& item) {return CalcHash(item.GetKey());}
public:
/** item count */
FORCEINLINE int Count() const {return m_num_items;}
/** simple clear - forget all items - used by CSegmentCostCacheT.Flush() */
FORCEINLINE void Clear()
{
for (size_t i = 0; i < lengthof(m_slots); i++) m_slots[i].Clear();
}
/** const item search */
const Titem_ *Find(const Tkey& key) const
{
int hash = CalcHash(key);
const Slot& slot = m_slots[hash];
const Titem_ *item = slot.Find(key);
return item;
}
/** non-const item search */
Titem_ *Find(const Tkey& key)
{
int hash = CalcHash(key);
Slot& slot = m_slots[hash];
Titem_ *item = slot.Find(key);
return item;
}
/** non-const item search & optional removal (if found) */
Titem_ *TryPop(const Tkey& key)
{
int hash = CalcHash(key);
Slot& slot = m_slots[hash];
Titem_ *item = slot.Detach(key);
if (item != NULL) {
m_num_items--;
}
return item;
}
/** non-const item search & removal */
Titem_& Pop(const Tkey& key)
{
Titem_ *item = TryPop(key);
assert(item != NULL);
return *item;
}
/** non-const item search & optional removal (if found) */
bool TryPop(Titem_& item)
{
const Tkey& key = item.GetKey();
int hash = CalcHash(key);
Slot& slot = m_slots[hash];
bool ret = slot.Detach(item);
if (ret) {
m_num_items--;
}
return ret;
}
/** non-const item search & removal */
void Pop(Titem_& item)
{
bool ret = TryPop(item);
assert(ret);
}
/** add one item - copy it from the given item */
void Push(Titem_& new_item)
{
int hash = CalcHash(new_item);
Slot& slot = m_slots[hash];
assert(slot.Find(new_item.GetKey()) == NULL);
slot.Attach(new_item);
m_num_items++;
}
};
#endif /* HASHTABLE_HPP */
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