isle/LEGO1/mxhashtable.h

#ifndef MXHASHTABLE_H
#define MXHASHTABLE_H

#include "mxtypes.h"
#include "mxcore.h"

#define HASH_TABLE_INIT_SIZE              128
#define HASH_TABLE_OPT_NO_EXPAND          0
#define HASH_TABLE_OPT_EXPAND_ADD         1
#define HASH_TABLE_OPT_EXPAND_MULTIPLY    2

template <class T>
class MxHashTableNode
{
public:
  MxHashTableNode<T>() {}
  MxHashTableNode<T>(T *p_obj, MxU32 p_hash)
  {
    m_obj = p_obj;
    m_hash = p_hash;
    m_prev = NULL;
    m_next = NULL;
  }

//private:
  T* m_obj;
  MxU32 m_hash;
  MxHashTableNode *m_prev;
  MxHashTableNode *m_next;
};

// See MxOmni::Create
// VTABLE 0x100dc1b0
template <class T>
class HashTableParent : public MxCore
{
public:
  HashTableParent() {
    m_numKeys = 0;
    m_customDestructor = Destroy;
  }

  // OFFSET: LEGO1 0x100afd30
  static void Destroy(T*) {};

  // OFFSET: LEGO1 0x100afcd0
  virtual MxS8 Compare(T*, T*) = 0;

protected:
  MxU32 m_numKeys; // +0x8
  void (*m_customDestructor)(T*); // +0xc
};

// VTABLE 0x100dc1e8
template <class T>
class MxHashTable : protected HashTableParent<T>
{
public:
  MxHashTable()
  {
    m_numSlots = HASH_TABLE_INIT_SIZE;
    m_slots = new MxHashTableNode<T>*[HASH_TABLE_INIT_SIZE];
    memset(m_slots, 0, sizeof(MxHashTableNode<T> *) * m_numSlots);
    m_resizeOption = HASH_TABLE_OPT_NO_EXPAND;
  }

  virtual ~MxHashTable();

  void Resize();
  void Add(T* );

  virtual MxS8 Compare(T*, T*) = 0;

  // OFFSET: LEGO1 0x100afdc0
  virtual MxU32 Hash(T*) = 0;

  // FIXME: use of friend here?
  friend class MxHashTableCursor<T>;

protected:
  void _NodeInsert(MxHashTableNode<T> *);

  MxHashTableNode<T> **m_slots; // +0x10
  MxU32 m_numSlots; // +0x14
  MxU32 m_autoResizeRatio;
  int m_resizeOption; // +0x1c
  // FIXME: or FIXME? This qword is used as an integer or double depending
  // on the value of m_resizeOption. Hard to say whether this is how the devs
  // did it, but a simple cast in either direction doesn't match.
  union {
    MxU32 m_increaseAmount;
    double m_increaseFactor;
  };
};

template <class T>
class MxHashTableCursor : public MxCore
{
public:
  MxHashTableCursor(MxHashTable<T> *p_hashTable)
  {
    m_table = p_hashTable;
    m_match = NULL;
  }

  MxBool Find(T *p_obj)
  {
    MxU32 hash = m_table->Hash(p_obj);
    int bucket = hash % m_table->m_numSlots;

    MxHashTableNode<T> *t = m_table->m_slots[bucket];

    while (t) {
      if (t->m_hash == hash && !m_table->Compare(t->m_obj, p_obj))
        m_match = t;
      t = t->m_next;
    }

    return m_match != NULL;
  }

  void GetMatch(T*& p_obj)
  {
    if (m_match) {
      p_obj = m_match->m_obj;
    }
  }

  void DeleteMatch()
  {
    // Cut the matching node out of the linked list
    // by updating pointer references.

    if (m_match->m_prev) {
      m_match->m_prev->m_next = m_match->m_next;
    } else {
      // No "prev" node, so move "next" to the head of the list.
      int bucket = m_match->m_hash % m_table->m_numSlots;
      m_table->m_slots[bucket] = m_match->m_next;
    }

    if (m_match->m_next)
      m_match->m_next->m_prev = m_match->m_prev;

    m_table->m_customDestructor(m_match->m_obj);
    delete m_match;
    m_table->m_numKeys--;
  }

private:
  MxHashTable<T> *m_table;
  MxHashTableNode<T> *m_match;
};


template <class T>
// OFFSET: LEGO1 0x100b0bd0
MxHashTable<T>::~MxHashTable()
{
  for (int i = 0; i < m_numSlots; i++) {
    MxHashTableNode<T> *t = m_slots[i];
    
    while (t) {
      MxHashTableNode<T> *next = t->m_next;
      m_customDestructor(t->m_obj);
      delete t;
      t = next;
    }
  }

  m_numKeys = 0;
  memset(m_slots, 0, sizeof(MxHashTableNode<T> *) * m_numSlots);

  delete[] m_slots;
}

template <class T>
// OFFSET: LEGO1 0x100b7ab0
inline void MxHashTable<T>::Resize()
{
  // Save a reference to the current table
  // so we can walk nodes and re-insert
  MxU32 old_size = m_numSlots;
  MxHashTableNode<T> **old_table = m_slots;

  switch (m_resizeOption) {
    case HASH_TABLE_OPT_EXPAND_ADD:
      m_numSlots = old_size + m_increaseAmount;
      break;
    case HASH_TABLE_OPT_EXPAND_MULTIPLY:
      m_numSlots = old_size * m_increaseFactor;
      break;
  }

  MxHashTableNode<T> **new_table = new MxHashTableNode<T>*[m_numSlots];
  // FIXME: order? m_numKeys set after `rep stosd`
  m_slots = new_table;
  memset(m_slots, 0, sizeof(MxHashTableNode<T> *) * m_numSlots);
  m_numKeys = 0;

  for (int i = 0; i != old_size; i++) {
    MxHashTableNode<T> *t = old_table[i];
    
    while (t) {
      MxHashTableNode<T> *next = t->m_next;
      _NodeInsert(t);
      t = next;
    }
  }

  delete[] old_table;
}

template <class T>
// OFFSET: LEGO1 0x100b7b80
inline void MxHashTable<T>::_NodeInsert(MxHashTableNode<T> *p_node)
{
  int bucket = p_node->m_hash % m_numSlots;
  
  p_node->m_next = m_slots[bucket];
  
  if (m_slots[bucket])
    m_slots[bucket]->m_prev = p_node;

  m_slots[bucket] = p_node;
  m_numKeys++;
}

template <class T>
inline void MxHashTable<T>::Add(T* p_newobj)
{
  if (m_resizeOption && ((m_numKeys + 1) / m_numSlots) > m_autoResizeRatio)
    MxHashTable<T>::Resize();

  MxU32 hash = Hash(p_newobj);
  MxHashTableNode<T> *node = new MxHashTableNode<T>(p_newobj, hash);

  MxHashTable<T>::_NodeInsert(node);
}

#endif // MXHASHTABLE_H