SF_Hash.h

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/*
* Copyright 2015 Autodesk, Inc. All rights reserved.
* Use of this software is subject to the terms of the Autodesk license agreement and any attachments or Appendices thereto provided at the time of installation or download,
* or which otherwise accompanies this software in either electronic or hard copy form, or which is signed by you and accepted by Autodesk.
*/

/**************************************************************************

PublicHeader:   None
Filename    :   KY_Hash.h
Content     :   Template hash-table/set implementation
Created     :   August 20, 2001
Authors     :   Michael Antonov, Sergey Sikorskiy

**************************************************************************/

#ifndef INC_KY_Kernel_Hash_H
#define INC_KY_Kernel_Hash_H

#include "gwnavruntime/kernel/SF_Allocator.h"
#include "gwnavruntime/kernel/SF_Alg.h"

#undef new

namespace Kaim {

// ***** Hash Table Implementation

// HastSet and Hash.
//
// Hash table, linear probing, internal chaining.  One  interesting/nice thing
// about this implementation is that the table itself is a flat chunk of memory
// containing no pointers, only relative indices. If the key and value types
// of the Hash contain no pointers, then the Hash can be serialized using raw IO.
//
// Never shrinks, unless you explicitly Clear() it.  Expands on
// demand, though.  For best results, if you know roughly how big your
// table will be, default it to that size when you create it.
//
// Key usability feature:
//
//   1. Allows node hash values to either be cached or not.
//
//   2. Allows for alternative keys with methods such as GetAlt(). Handy
//      if you need to search nodes by their components; no need to create
//      temporary nodes.
//


// *** Hash functors:
//
//  IdentityHash  - use when the key is already a good hash
//  HFixedSizeHash - general hash based on object's in-memory representation.


// Hash is just the input value; can use this for integer-indexed hash tables.
template<class C>
class IdentityHash
{
public:
    UPInt operator()(const C& data) const
    { return (UPInt) data; }
};

// Computes a hash of an object's representation.
template<class C>
class FixedSizeHash
{
public:
    // Alternative: "sdbm" hash function, suggested at same web page
    // above, http::/www.cs.yorku.ca/~oz/hash.html
    // This is somewhat slower then Bernstein, but it works way better than the above
    // hash function for hashing large numbers of 32-bit ints.
    static KY_INLINE UPInt SDBM_Hash(const void* data_in, UPInt size, UPInt seed = 5381)     
    {
        const UByte* data = (const UByte*) data_in;
        UPInt        h = seed;
        while (size > 0)
        {
            size--;
            h = (h << 16) + (h << 6) - h + (UPInt)data[size];
        }   
        return h;
    }

    UPInt operator()(const C& data) const
    {
        unsigned char*  p = (unsigned char*) &data;
        int size = sizeof(C);

        return SDBM_Hash(p, size);
    }
};



// *** HashsetEntry Entry types. 

// Compact hash table Entry type that re-computes hash keys during hash traversal.
// Good to use if the hash function is cheap or the hash value is already cached in C.
template<class C, class HashF>
class HashsetEntry
{
public:
    // Internal chaining for collisions.
    SPInt       NextInChain;
    C           Value;

    HashsetEntry()
        : NextInChain(-2) { }
    HashsetEntry(const HashsetEntry& e)
        : NextInChain(e.NextInChain), Value(e.Value) { }
    HashsetEntry(const C& key, SPInt next)
        : NextInChain(next), Value(key) { }

    bool    IsEmpty() const          { return NextInChain == -2;  }
    bool    IsEndOfChain() const     { return NextInChain == -1;  }

    // Cached hash value access - can be optimized bu storing hash locally.
    // Mask value only needs to be used if SetCachedHash is not implemented.
    UPInt   GetCachedHash(UPInt maskValue) const  { return HashF()(Value) & maskValue; }
    void    SetCachedHash(UPInt)                  {}

    void    Clear()
    {        
        Value.~C(); // placement delete
        NextInChain = -2;
    }
    // Free is only used from dtor of hash; Clear is used during regular operations:
    // assignment, hash reallocations, value reassignments, so on.
    void    Free() { Clear(); }
};

// Hash table Entry type that caches the Entry hash value for nodes, so that it
// does not need to be re-computed during access.
template<class C, class HashF>
class HashsetCachedEntry
{
public:
    // Internal chaining for collisions.
    SPInt       NextInChain;
    UPInt       HashValue;
    C           Value;

    HashsetCachedEntry()
        : NextInChain(-2) { }
    HashsetCachedEntry(const HashsetCachedEntry& e)
        : NextInChain(e.NextInChain), HashValue(e.HashValue), Value(e.Value) { }
    HashsetCachedEntry(const C& key, SPInt next)
        : NextInChain(next), Value(key) { }

    bool    IsEmpty() const          { return NextInChain == -2;  }
    bool    IsEndOfChain() const     { return NextInChain == -1;  }

    // Cached hash value access - can be optimized bu storing hash locally.
    // Mask value only needs to be used if SetCachedHash is not implemented.
    UPInt   GetCachedHash(UPInt maskValue) const  { KY_UNUSED(maskValue); return HashValue; }
    void    SetCachedHash(UPInt hashValue)        { HashValue = hashValue; }

    void    Clear()
    {
        Value.~C();
        NextInChain = -2;
    }
    // Free is only used from dtor of hash; Clear is used during regular operations:
    // assignment, hash reallocations, value reassignments, so on.
    void    Free() { Clear(); }
};



// *** HashSet implementation - relies on either cached or regular entries.
//
// Use: Entry = HashsetCachedEntry<C, HashF> if hashes are expensive to
//              compute and thus need caching in entries.
//      Entry = HashsetEntry<C, HashF> if hashes are already externally cached.
//
template<class C, class HashF = FixedSizeHash<C>,
         class AltHashF = HashF, 
         class Allocator = AllocatorGH<C>,         
         class Entry = HashsetCachedEntry<C, HashF> >
class HashSetBase
{
    enum { HashMinSize = 8 };

public:
    KY_MEMORY_REDEFINE_NEW(HashSetBase, Allocator::StatId)

    typedef HashSetBase<C, HashF, AltHashF, Allocator, Entry>    SelfType;

    HashSetBase() : pTable(NULL)                       {   }
    HashSetBase(int sizeHint) : pTable(NULL)           { SetCapacity(this, sizeHint);  }
    explicit HashSetBase(void* pmemAddr) : pTable(NULL){ KY_UNUSED(pmemAddr);  }
    HashSetBase(void* pmemAddr, int sizeHint) : pTable(NULL) { SetCapacity(pmemAddr, sizeHint);  }
    HashSetBase(const SelfType& src) : pTable(NULL)    { Assign(this, src); }
    ~HashSetBase()                                     
    { 
        if (pTable)
        {
            // Delete the entries.
            for (UPInt i = 0, n = pTable->SizeMask; i <= n; i++)
            {
                Entry*  e = &E(i);
                if (!e->IsEmpty())             
                    e->Free();
            }            

            Allocator::Free(pTable);
            pTable = NULL;
        }
    }


    void Assign(void* pmemAddr, const SelfType& src)
    {
        Clear();
        if (src.IsEmpty() == false)
        {
            SetCapacity(pmemAddr, src.GetSize());

            for (ConstIterator it = src.Begin(); it != src.End(); ++it)
            {
                Add(pmemAddr, *it);
            }
        }
    }


    // Remove all entries from the HashSet table.
    void Clear() 
    {
        if (pTable)
        {
            // Delete the entries.
            for (UPInt i = 0, n = pTable->SizeMask; i <= n; i++)
            {
                Entry*  e = &E(i);
                if (!e->IsEmpty())             
                    e->Clear();
            }            
                
            Allocator::Free(pTable);
            pTable = NULL;
        }
    }

    // Returns true if the HashSet is empty.
    bool IsEmpty() const
    {
        return pTable == NULL || pTable->EntryCount == 0;
    }


    // Set a new or existing value under the key, to the value.
    // Pass a different class of 'key' so that assignment reference object
    // can be passed instead of the actual object.
    template<class CRef>
    void Set(void* pmemAddr, const CRef& key)
    {
        UPInt  hashValue = HashF()(key);
        SPInt  index     = (SPInt)-1;

        if (pTable != NULL)
            index = findIndexCore(key, hashValue & pTable->SizeMask);

        if (index >= 0)
        {            
            E(index).Value = key;
        }
        else
        {
            // Entry under key doesn't exist.
            add(pmemAddr, key, hashValue);
        }
    }

    template<class CRef>
    inline void Add(void* pmemAddr, const CRef& key)
    {
        UPInt hashValue = HashF()(key);
        add(pmemAddr, key, hashValue);
    }

    // Remove by alternative key.
    template<class K>
    void RemoveAlt(const K& key)
    {   
        if (pTable == NULL)
            return;

        UPInt   hashValue = AltHashF()(key);
        SPInt   index     = hashValue & pTable->SizeMask;

        Entry*  e = &E(index);

        // If empty node or occupied by collider, we have nothing to remove.
        if (e->IsEmpty() || (e->GetCachedHash(pTable->SizeMask) != (UPInt)index))
            return;        

        // Save index
        SPInt   naturalIndex = index;
        SPInt   prevIndex    = -1;

        while ((e->GetCachedHash(pTable->SizeMask) != (UPInt)naturalIndex) || !(e->Value == key))
        {
            // Keep looking through the chain.
            prevIndex   = index;
            index       = e->NextInChain;
            if (index == -1)
                return; // End of chain, item not found
            e = &E(index);
        }

        // Found it - our item is at index
        if (naturalIndex == index)
        {
            // If we have a follower, move it to us
            if (!e->IsEndOfChain())
            {               
                Entry*  enext = &E(e->NextInChain);
                e->Clear();
                new (e) Entry(*enext);
                // Point us to the follower's cell that will be cleared
                e = enext;
            }
        }
        else
        {
            // We are not at natural index, so deal with the prev items next index
            E(prevIndex).NextInChain = e->NextInChain;
        }

        // Clear us, of the follower cell that was moved.
        e->Clear();
        pTable->EntryCount --;
        // Should we check the size to condense hash? ...
    }

    // Remove by main key.
    template<class CRef>
    void Remove(const CRef& key)
    {
        RemoveAlt(key);
    }

    // Retrieve the pointer to a value under the given key.
    //  - If there's no value under the key, then return NULL.    
    //  - If there is a value, return the pointer.    
    template<class K>
    C* Get(const K& key)
    {
        SPInt   index = findIndex(key);
        if (index >= 0)        
            return &E(index).Value;        
        return 0;
    }   

    template<class K>
    const C* Get(const K& key) const
    {
        SPInt   index = findIndex(key);
        if (index >= 0)        
            return &E(index).Value;        
        return 0;
    }

    // Alternative key versions of Get. Used by Hash.
    template<class K>
    const C* GetAlt(const K& key) const
    {
        SPInt   index = findIndexAlt(key);
        if (index >= 0)        
            return &E(index).Value;
        return 0;
    }

    template<class K>
    C* GetAlt(const K& key)
    {
        SPInt   index = findIndexAlt(key);
        if (index >= 0)        
            return &E(index).Value;
        return 0;
    }   

    template<class K>
    bool GetAlt(const K& key, C* pval) const
    {
        SPInt   index = findIndexAlt(key);
        if (index >= 0)
        {
            if (pval)
                *pval = E(index).Value;
            return true;
        }
        return false;
    }


    UPInt GetSize() const
    {
        return pTable == NULL ? 0 : (UPInt)pTable->EntryCount;
    }


    // Resize the HashSet table to fit one more Entry.  Often this
    // doesn't involve any action.
    void CheckExpand(void* pmemAddr)  
    {
        if (pTable == NULL)
        {
            // Initial creation of table.  Make a minimum-sized table.
            setRawCapacity(pmemAddr, HashMinSize);
        }
        else if (pTable->EntryCount * 5 > (pTable->SizeMask + 1) * 4)
        {
            // pTable is more than 4/5 ths full.  Expand.
            setRawCapacity(pmemAddr, (pTable->SizeMask + 1) * 2);
        }
    }

    // Hint the bucket count to >= n.
    void Resize(void* pmemAddr, UPInt n)    
    {
        // Not really sure what this means in relation to
        // STLport's hash_map... they say they "increase the
        // bucket count to at least n" -- but does that mean
        // their real capacity after Resize(n) is more like
        // n*2 (since they do linked-list chaining within
        // buckets?).
        SetCapacity(pmemAddr, n);
    }

    // Size the HashSet so that it can comfortably contain the given
    // number of elements.  If the HashSet already contains more
    // elements than newSize, then this may be a no-op.
    void SetCapacity(void* pmemAddr, UPInt newSize)
    {
        UPInt newRawSize = (newSize * 5) / 4;
        if (newRawSize <= GetSize())
            return;
        setRawCapacity(pmemAddr, newRawSize);
    }

    // Disable inappropriate 'operator ->' warning on MSVC6.
#ifdef KY_CC_MSVC
#if (KY_CC_MSVC < 1300)
# pragma warning(disable : 4284)
#endif
#endif

    // Iterator API, like STL.
    struct ConstIterator
    {   
        const C&    operator * () const
        {            
            KY_ASSERT(Index >= 0 && Index <= (SPInt)pHash->pTable->SizeMask);
            return pHash->E(Index).Value;
        }

        const C*    operator -> () const
        {
            KY_ASSERT(Index >= 0 && Index <= (SPInt)pHash->pTable->SizeMask);
            return &pHash->E(Index).Value;
        }

        void    operator ++ ()
        {
            // Find next non-empty Entry.
            if (Index <= (SPInt)pHash->pTable->SizeMask)
            {
                Index++;
                while ((UPInt)Index <= pHash->pTable->SizeMask &&
                    pHash->E(Index).IsEmpty())
                {
                    Index++;
                }
            }
        }

        bool    operator == (const ConstIterator& it) const
        {
            if (IsEnd() && it.IsEnd())
            {
                return true;
            }
            else
            {
                return (pHash == it.pHash) && (Index == it.Index);
            }
        }

        bool    operator != (const ConstIterator& it) const
        {
            return ! (*this == it);
        }


        bool    IsEnd() const
        {
            return (pHash == NULL) || 
                (pHash->pTable == NULL) || 
                (Index > (SPInt)pHash->pTable->SizeMask);
        }

        ConstIterator()
            : pHash(NULL), Index(0)
        { }

    public:
        // Constructor was intentionally made public to allow create
        // iterator with arbitrary index.
        ConstIterator(const SelfType* h, SPInt index)
            : pHash(h), Index(index)
        { }

        const SelfType* GetContainer() const
        {
            return pHash;
        }
        SPInt GetIndex() const
        {
            return Index;
        }

    protected:
        friend class HashSetBase<C, HashF, AltHashF, Allocator, Entry>;

        const SelfType* pHash;
        SPInt           Index;
    };

    friend struct ConstIterator;


    // Non-const Iterator; Get most of it from ConstIterator.
    struct Iterator : public ConstIterator
    {      
        // Allow non-const access to entries.
        C&  operator*() const
        {            
            KY_ASSERT(ConstIterator::Index >= 0 && ConstIterator::Index <= (SPInt)ConstIterator::pHash->pTable->SizeMask);
            return const_cast<SelfType*>(ConstIterator::pHash)->E(ConstIterator::Index).Value;
        }    

        C*  operator->() const 
        {
            return &(operator*());
        }

        Iterator()
            : ConstIterator(NULL, 0)
        { }

        // Removes current element from Hash
        void Remove()
        {
            RemoveAlt(operator*());
        }

        template <class K>
        void RemoveAlt(const K& key)
        {
            SelfType*   phash = const_cast<SelfType*>(ConstIterator::pHash);
            //Entry*      ee = &phash->E(ConstIterator::Index);
            //const C&    key = ee->Value;

            UPInt       hashValue = AltHashF()(key);
            SPInt       index     = hashValue & phash->pTable->SizeMask;

            Entry*      e = &phash->E(index);

            // If empty node or occupied by collider, we have nothing to remove.
            if (e->IsEmpty() || (e->GetCachedHash(phash->pTable->SizeMask) != (UPInt)index))
                return;        

            // Save index
            SPInt   naturalIndex = index;
            SPInt   prevIndex    = -1;

            while ((e->GetCachedHash(phash->pTable->SizeMask) != (UPInt)naturalIndex) || !(e->Value == key))
            {
                // Keep looking through the chain.
                prevIndex   = index;
                index       = e->NextInChain;
                if (index == -1)
                    return; // End of chain, item not found
                e = &phash->E(index);
            }

            if (index == (SPInt)ConstIterator::Index)
            {
                // Found it - our item is at index
                if (naturalIndex == index)
                {
                    // If we have a follower, move it to us
                    if (!e->IsEndOfChain())
                    {               
                        Entry*  enext = &phash->E(e->NextInChain);
                        e->Clear();
                        new (e) Entry(*enext);
                        // Point us to the follower's cell that will be cleared
                        e = enext;
                        --ConstIterator::Index;
                    }
                }
                else
                {
                    // We are not at natural index, so deal with the prev items next index
                    phash->E(prevIndex).NextInChain = e->NextInChain;
                }

                // Clear us, of the follower cell that was moved.
                e->Clear();
                phash->pTable->EntryCount --;
            }
            else 
                KY_ASSERT(0); //?
        }

    private:
        friend class HashSetBase<C, HashF, AltHashF, Allocator, Entry>;

        Iterator(SelfType* h, SPInt i0)
            : ConstIterator(h, i0)
        { }
    };

    friend struct Iterator;

    Iterator    Begin()
    {
        if (pTable == 0)
            return Iterator(NULL, 0);

        // Scan till we hit the First valid Entry.
        UPInt  i0 = 0;
        while (i0 <= pTable->SizeMask && E(i0).IsEmpty())
        {
            i0++;
        }
        return Iterator(this, i0);
    }
    Iterator        End()           { return Iterator(NULL, 0); }

    ConstIterator   Begin() const   { return const_cast<SelfType*>(this)->Begin();     }
    ConstIterator   End() const     { return const_cast<SelfType*>(this)->End();   }

    template<class K>
    Iterator Find(const K& key)
    {
        SPInt index = findIndex(key);
        if (index >= 0)        
            return Iterator(this, index);        
        return Iterator(NULL, 0);
    }

    template<class K>
    Iterator FindAlt(const K& key)
    {
        SPInt index = findIndexAlt(key);
        if (index >= 0)        
            return Iterator(this, index);        
        return Iterator(NULL, 0);
    }

    template<class K>
    ConstIterator Find(const K& key) const       { return const_cast<SelfType*>(this)->Find(key); }

    template<class K>
    ConstIterator FindAlt(const K& key) const    { return const_cast<SelfType*>(this)->FindAlt(key); }

private:
    // Find the index of the matching Entry.  If no match, then return -1.
    template<class K>
    SPInt findIndex(const K& key) const
    {
        if (pTable == NULL)
            return -1;
        UPInt hashValue = HashF()(key) & pTable->SizeMask;
        return findIndexCore(key, hashValue);
    }

    template<class K>
    SPInt findIndexAlt(const K& key) const
    {
        if (pTable == NULL)
            return -1;
        UPInt hashValue = AltHashF()(key) & pTable->SizeMask;
        return findIndexCore(key, hashValue);
    }

    // Find the index of the matching Entry.  If no match, then return -1.
    template<class K>
    SPInt findIndexCore(const K& key, UPInt hashValue) const
    {
        // Table must exist.
        KY_ASSERT(pTable != 0);
        // Hash key must be 'and-ed' by the caller.
        KY_ASSERT((hashValue & ~pTable->SizeMask) == 0);

        UPInt           index = hashValue;
        const Entry*    e     = &E(index);

        // If empty or occupied by a collider, not found.
        if (e->IsEmpty() || (e->GetCachedHash(pTable->SizeMask) != index))
            return -1;

        while(1)
        {
            KY_ASSERT(e->GetCachedHash(pTable->SizeMask) == hashValue);

            if (e->GetCachedHash(pTable->SizeMask) == hashValue && e->Value == key)
            {
                // Found it.
                return index;
            }
            // Values can not be equal at this point.
            // That would mean that the hash key for the same value differs.
            KY_ASSERT(!(e->Value == key));

            // Keep looking through the chain.
            index = e->NextInChain;
            if (index == (UPInt)-1)
                break; // end of chain

            e = &E(index);
            KY_ASSERT(!e->IsEmpty());
        }
        return -1;
    }


    // Add a new value to the HashSet table, under the specified key.
    template<class CRef>
    void add(void* pmemAddr, const CRef& key, UPInt hashValue)
    {
        CheckExpand(pmemAddr);
        hashValue &= pTable->SizeMask;

        pTable->EntryCount++;

        SPInt   index        = hashValue;
        Entry*  naturalEntry = &(E(index));

        if (naturalEntry->IsEmpty())
        {
            // Put the new Entry in.
            new (naturalEntry) Entry(key, -1);
        }
        else
        {
            // Find a blank spot.
            SPInt blankIndex = index;
            do {
                blankIndex = (blankIndex + 1) & pTable->SizeMask;
            } while(!E(blankIndex).IsEmpty());

            Entry*  blankEntry = &E(blankIndex);

            if (naturalEntry->GetCachedHash(pTable->SizeMask) == (UPInt)index)
            {
                // Collision.  Link into this chain.

                // Move existing list head.
                new (blankEntry) Entry(*naturalEntry);    // placement new, copy ctor

                // Put the new info in the natural Entry.
                naturalEntry->Value       = key;
                naturalEntry->NextInChain = blankIndex;
            }
            else
            {
                // Existing Entry does not naturally
                // belong in this slot.  Existing
                // Entry must be moved.

                // Find natural location of collided element (i.e. root of chain)
                SPInt collidedIndex = naturalEntry->GetCachedHash(pTable->SizeMask);
                KY_ASSERT(collidedIndex >= 0 && collidedIndex <= (SPInt)pTable->SizeMask);
                for (;;)
                {
                    Entry*  e = &E(collidedIndex);
                    if (e->NextInChain == index)
                    {
                        // Here's where we need to splice.
                        new (blankEntry) Entry(*naturalEntry);
                        e->NextInChain = blankIndex;
                        break;
                    }
                    collidedIndex = e->NextInChain;
                    KY_ASSERT(collidedIndex >= 0 && collidedIndex <= (SPInt)pTable->SizeMask);
                }

                // Put the new data in the natural Entry.
                naturalEntry->Value       = key;
                naturalEntry->NextInChain = -1;                
            }            
        }

        // Record hash value: has effect only if cached node is used.
        naturalEntry->SetCachedHash(hashValue);
    }

    // Index access helpers.
    Entry& E(UPInt index)
    {
        // Must have pTable and access needs to be within bounds.
        KY_ASSERT(index <= pTable->SizeMask);
        return *(((Entry*) (pTable + 1)) + index);
    }
    const Entry& E(UPInt index) const
    {        
        KY_ASSERT(index <= pTable->SizeMask);
        return *(((Entry*) (pTable + 1)) + index);
    }


    // Resize the HashSet table to the given size (Rehash the
    // contents of the current table).  The arg is the number of
    // HashSet table entries, not the number of elements we should
    // actually contain (which will be less than this).
    void    setRawCapacity(void* pheapAddr, UPInt newSize)    
    {
        if (newSize == 0)
        {
            // Special case.
            Clear();
            return;
        }

        // Minimum size; don't incur rehashing cost when expanding
        // very small tables. Not that we perform this check before 
        // 'log2f' call to avoid fp exception with newSize == 1.
        if (newSize < HashMinSize)        
            newSize = HashMinSize;       
        else
        {
            // Force newSize to be a power of two.
            int bits = Alg::UpperBit(newSize-1) + 1; // Chop( Log2f((float)(newSize-1)) + 1);
            KY_ASSERT((UPInt(1) << bits) >= newSize);
            newSize = UPInt(1) << bits;
        }

        SelfType  newHash;
        newHash.pTable = (TableType*)
            Allocator::Alloc(
                pheapAddr, 
                sizeof(TableType) + sizeof(Entry) * newSize,
                __FILE__, __LINE__);
        // Need to do something on alloc failure!
        KY_ASSERT(newHash.pTable);

        newHash.pTable->EntryCount = 0;
        newHash.pTable->SizeMask = newSize - 1;
        UPInt i, n;

        // Mark all entries as empty.
        for (i = 0; i < newSize; i++)
            newHash.E(i).NextInChain = -2;

        // Copy stuff to newHash
        if (pTable)
        {            
            for (i = 0, n = pTable->SizeMask; i <= n; i++)
            {
                Entry*  e = &E(i);
                if (e->IsEmpty() == false)
                {
                    // Insert old Entry into new HashSet.
                    newHash.Add(pheapAddr, e->Value);
                    // placement delete of old element
                    e->Clear();
                }
            }

            // Delete our old data buffer.
            Allocator::Free(pTable);
        }

        // Steal newHash's data.
        pTable = newHash.pTable;
        newHash.pTable = NULL;
    }

    struct TableType
    {
        UPInt EntryCount;
        UPInt SizeMask;
        // Entry array follows this structure
        // in memory.
    };
    TableType*  pTable;
};




template<class C, class HashF = FixedSizeHash<C>,
         class AltHashF = HashF, 
         class Allocator = AllocatorGH<C>,         
         class Entry = HashsetCachedEntry<C, HashF> >
class HashSet : public HashSetBase<C, HashF, AltHashF, Allocator, Entry>
{
public:
    typedef HashSetBase<C, HashF, AltHashF, Allocator, Entry> BaseType;
    typedef HashSet<C, HashF, AltHashF, Allocator, Entry>     SelfType;

    HashSet()                                      {   }
    HashSet(int sizeHint) : BaseType(sizeHint)     {   }
    explicit HashSet(void* pheap) : BaseType(pheap)                {   }
    HashSet(void* pheap, int sizeHint) : BaseType(pheap, sizeHint) {   }
    HashSet(const SelfType& src) : BaseType(src)   {   }
    ~HashSet()                                     {   }

    void operator = (const SelfType& src)   { BaseType::Assign(this, src); }

    // Set a new or existing value under the key, to the value.
    // Pass a different class of 'key' so that assignment reference object
    // can be passed instead of the actual object.
    template<class CRef>
    void Set(const CRef& key)
    {
        BaseType::Set(this, key);
    }

    template<class CRef>
    inline void Add(const CRef& key)
    {
        BaseType::Add(this, key);
    }

    // Resize the HashSet table to fit one more Entry.  Often this
    // doesn't involve any action.
    void CheckExpand()  
    {
        BaseType::CheckExpand(this);
    }

    // Hint the bucket count to >= n.
    void Resize(UPInt n)    
    {
        BaseType::SetCapacity(this, n);
    }

    // Size the HashSet so that it can comfortably contain the given
    // number of elements.  If the HashSet already contains more
    // elements than newSize, then this may be a no-op.
    void SetCapacity(UPInt newSize)
    {
        BaseType::SetCapacity(this, newSize);
    }

};

// HashSet for local member only allocation (auto-heap).
template<class C, class HashF = FixedSizeHash<C>,
         class AltHashF = HashF, 
         int SID = Stat_Default_Mem,         
         class Entry = HashsetCachedEntry<C, HashF> >
class HashSetLH : public HashSet<C, HashF, AltHashF, AllocatorLH<C, SID>, Entry>
{
public:
    typedef HashSetLH<C, HashF, AltHashF, SID, Entry>                   SelfType;
    typedef HashSet<C, HashF, AltHashF, AllocatorLH<C, SID>, Entry >    BaseType;

    // Delegated constructors.
    HashSetLH()                                      { }
    HashSetLH(int sizeHint) : BaseType(sizeHint)     { }
    HashSetLH(const SelfType& src) : BaseType(src)   { }
    ~HashSetLH()                                     { }
    
    void    operator = (const SelfType& src)
    {
        BaseType::operator = (src);
    }
};

template<class C, class HashF = FixedSizeHash<C>,
         class AltHashF = HashF, 
         int SID = Stat_Default_Mem,         
         class Entry = HashsetCachedEntry<C, HashF> >
class HashSetDH : public HashSetBase<C, HashF, AltHashF, AllocatorDH<C, SID>, Entry>
{
    void* pHeap;
public:
    typedef HashSetDH<C, HashF, AltHashF, SID, Entry>                       SelfType;
    typedef HashSetBase<C, HashF, AltHashF, AllocatorDH<C, SID>, Entry>     BaseType;

    explicit HashSetDH(void* pheap) : pHeap(pheap)                                 {   }
    HashSetDH(void* pheap, int sizeHint) : BaseType(pheap, sizeHint), pHeap(pheap) {   }
    HashSetDH(const SelfType& src) : BaseType(src), pHeap(src.pHeap)               {   }
    ~HashSetDH()                                     {   }

    void operator = (const SelfType& src)
    { 
        BaseType::Assign(src.pHeap, src); 
        pHeap = src.pHeap;
    }

    // Set a new or existing value under the key, to the value.
    // Pass a different class of 'key' so that assignment reference object
    // can be passed instead of the actual object.
    template<class CRef>
    void Set(const CRef& key)
    {
        BaseType::Set(pHeap, key);
    }

    template<class CRef>
    inline void Add(const CRef& key)
    {
        BaseType::Add(pHeap, key);
    }

    // Resize the HashSet table to fit one more Entry.  Often this
    // doesn't involve any action.
    void CheckExpand()  
    {
        BaseType::CheckExpand(this);
    }

    // Hint the bucket count to >= n.
    void Resize(UPInt n)    
    {
        BaseType::SetCapacity(pHeap, n);
    }

    // Size the HashSet so that it can comfortably contain the given
    // number of elements.  If the HashSet already contains more
    // elements than newSize, then this may be a no-op.
    void SetCapacity(UPInt newSize)
    {
        BaseType::SetCapacity(pHeap, newSize);
    }

};

// HashSet with uncached hash code; declared for convenience.
template<class C, class HashF = FixedSizeHash<C>,
                  class AltHashF = HashF,
                  class Allocator = AllocatorGH<C> >
class HashSetUncached : public HashSet<C, HashF, AltHashF, Allocator, HashsetEntry<C, HashF> >
{
public:
    
    typedef HashSetUncached<C, HashF, AltHashF, Allocator>                  SelfType;
    typedef HashSet<C, HashF, AltHashF, Allocator, HashsetEntry<C, HashF> > BaseType;

    // Delegated constructors.
    HashSetUncached()                                        { }
    HashSetUncached(int sizeHint) : BaseType(sizeHint)       { }
    HashSetUncached(const SelfType& src) : BaseType(src)     { }
    ~HashSetUncached()                                       { }
    
    void    operator = (const SelfType& src)
    {
        BaseType::operator = (src);
    }
};

// HashSet with uncached hash code, for local-only use.
template<class C, class HashF = FixedSizeHash<C>,
                  class AltHashF = HashF,
                  int SID = Stat_Default_Mem >
class HashSetUncachedLH : public HashSet<C, HashF, AltHashF, AllocatorLH<C, SID>, HashsetEntry<C, HashF> >
{
public:
    
    typedef HashSetUncachedLH<C, HashF, AltHashF, SID>                                  SelfType;
    typedef HashSet<C, HashF, AltHashF, AllocatorLH<C, SID>, HashsetEntry<C, HashF> >   BaseType;

    // Delegated constructors.
    HashSetUncachedLH()                                    { }
    HashSetUncachedLH(int sizeHint) : BaseType(sizeHint)   { }
    HashSetUncachedLH(const SelfType& src) : BaseType(src) { }
    ~HashSetUncachedLH()                                   { }
    
    void    operator = (const SelfType& src)
    {
        BaseType::operator = (src);
    }
};

// HashSet with uncached hash code, for using with custom heap.
template<class C, 
         class HashF = FixedSizeHash<C>,
         class AltHashF = HashF,
         int SID = Stat_Default_Mem >
class HashSetUncachedDH : public HashSetDH<C, HashF, AltHashF, SID, HashsetEntry<C, HashF> >
{
public:

    typedef HashSetUncachedDH<C, HashF, AltHashF, SID>                  SelfType;
    typedef HashSetDH<C, HashF, AltHashF, SID, HashsetEntry<C, HashF> > BaseType;

    // Delegated constructors.
    explicit HashSetUncachedDH(void* pheap) : BaseType(pheap)                  { }
    HashSetUncachedDH(void* pheap, int sizeHint) : BaseType(pheap, sizeHint)   { }
    HashSetUncachedDH(const SelfType& src) : BaseType(src) { }
    ~HashSetUncachedDH()                                   { }

    void    operator = (const SelfType& src)
    {
        BaseType::operator = (src);
    }
};



// ***** Hash hash table implementation

// Node for Hash - necessary so that Hash can delegate its implementation
// to HashSet.
template<class C, class U, class HashF>
struct HashNode
{
    typedef HashNode<C, U, HashF>   SelfType;
    typedef C                       FirstType;
    typedef U                       SecondType;

    C   First;
    U   Second;

    // NodeRef is used to allow passing of elements into HashSet
    // without using a temporary object.
    struct NodeRef
    {
        const C*   pFirst;
        const U*   pSecond;

        NodeRef(const C& f, const U& s) : pFirst(&f), pSecond(&s) { }
        NodeRef(const NodeRef& src)     : pFirst(src.pFirst), pSecond(src.pSecond) { }

        // Enable computation of ghash_node_hashf.
        inline UPInt GetHash() const            { return HashF()(*pFirst); } 
        // Necessary conversion to allow HashNode::operator == to work.
        operator const C& () const              { return *pFirst; }
    };

    // Note: No default constructor is necessary.
     HashNode(const HashNode& src) : First(src.First), Second(src.Second)    { }
     HashNode(const NodeRef& src) : First(*src.pFirst), Second(*src.pSecond)  { }
    void operator = (const NodeRef& src)  { First  = *src.pFirst; Second = *src.pSecond; }

#ifdef KY_CC_RENESAS
    bool operator == (const NodeRef& src) const { return (First == *src.pFirst); }
#endif

    template<class K>
    bool operator == (const K& src) const   { return (First == src); }

    template<class K>
    static UPInt CalcHash(const K& data)   { return HashF()(data); }
    inline UPInt GetHash() const           { return HashF()(First); }

    // Hash functors used with this node. A separate functor is used for alternative
    // key lookup so that it does not need to access the '.First' element.    
    struct NodeHashF
    {    
        template<class K>
        UPInt operator()(const K& data) const { return data.GetHash(); } 
    };    
    struct NodeAltHashF
    {
        template<class K>
        UPInt operator()(const K& data) const { return HashNode<C,U,HashF>::CalcHash(data); }
    };
};



// **** Extra hashset_entry types to allow NodeRef construction.

// The big difference between the below types and the ones used in hash_set is that
// these allow initializing the node with 'typename C::NodeRef& keyRef', which
// is critical to avoid temporary node allocation on stack when using placement new.

// Compact hash table Entry type that re-computes hash keys during hash traversal.
// Good to use if the hash function is cheap or the hash value is already cached in C.
template<class C, class HashF>
class HashsetNodeEntry
{
public:
    // Internal chaining for collisions.
    SPInt NextInChain;
    C     Value;

    HashsetNodeEntry()
        : NextInChain(-2) { }
    HashsetNodeEntry(const HashsetNodeEntry& e)
        : NextInChain(e.NextInChain), Value(e.Value) { }
    HashsetNodeEntry(const C& key, SPInt next)
        : NextInChain(next), Value(key) { }    
    HashsetNodeEntry(const typename C::NodeRef& keyRef, SPInt next)
        : NextInChain(next), Value(keyRef) { }

    bool    IsEmpty() const             { return NextInChain == -2;  }
    bool    IsEndOfChain() const        { return NextInChain == -1;  }
    UPInt   GetCachedHash(UPInt maskValue) const  { return HashF()(Value) & maskValue; }
    void    SetCachedHash(UPInt hashValue)        { KY_UNUSED(hashValue); }

    void    Clear()
    {        
        Value.~C(); // placement delete
        NextInChain = -2;
    }
    // Free is only used from dtor of hash; Clear is used during regular operations:
    // assignment, hash reallocations, value reassignments, so on.
    void    Free() { Clear(); }
};

// Hash table Entry type that caches the Entry hash value for nodes, so that it
// does not need to be re-computed during access.
template<class C, class HashF>
class HashsetCachedNodeEntry
{
public:
    // Internal chaining for collisions.
    SPInt NextInChain;
    UPInt HashValue;
    C     Value;

    HashsetCachedNodeEntry()
        : NextInChain(-2) { }
    HashsetCachedNodeEntry(const HashsetCachedNodeEntry& e)
        : NextInChain(e.NextInChain), HashValue(e.HashValue), Value(e.Value) { }
    HashsetCachedNodeEntry(const C& key, SPInt next)
        : NextInChain(next), Value(key) { }
    HashsetCachedNodeEntry(const typename C::NodeRef& keyRef, SPInt next)
        : NextInChain(next), Value(keyRef) { }

    bool    IsEmpty() const            { return NextInChain == -2;  }
    bool    IsEndOfChain() const       { return NextInChain == -1;  }
    UPInt   GetCachedHash(UPInt maskValue) const  { KY_UNUSED(maskValue); return HashValue; }
    void    SetCachedHash(UPInt hashValue)        { HashValue = hashValue; }

    void    Clear()
    {
        Value.~C();
        NextInChain = -2;
    }
    // Free is only used from dtor of hash; Clear is used during regular operations:
    // assignment, hash reallocations, value reassignments, so on.
    void    Free() { Clear(); }
};


template<class C, class U,
         class HashF = FixedSizeHash<C>,
         class Allocator = AllocatorGH<C>,
         class HashNode = Kaim::HashNode<C,U,HashF>,
         class Entry = HashsetCachedNodeEntry<HashNode, typename HashNode::NodeHashF>,
         class Container =  HashSet<HashNode, typename HashNode::NodeHashF,
             typename HashNode::NodeAltHashF, Allocator,
             Entry> >
class Hash
{
public:
    KY_MEMORY_REDEFINE_NEW(Hash, Allocator::StatId)

    // Types used for hash_set.
    typedef U                                                           ValueType;
    typedef Hash<C, U, HashF, Allocator, HashNode, Entry, Container>    SelfType;

    // Actual hash table itself, implemented as hash_set.
    Container   mHash;

public:
    Hash()     {  }
    Hash(int sizeHint) : mHash(sizeHint)                        { }
    explicit Hash(void* pheap) : mHash(pheap)                   { }
    Hash(void* pheap, int sizeHint) : mHash(pheap, sizeHint)    { }
    Hash(const SelfType& src) : mHash(src.mHash)                { }
    ~Hash()                                                     { }

    void    operator = (const SelfType& src)    { mHash = src.mHash; }

    // Remove all entries from the Hash table.
    inline void    Clear() { mHash.Clear(); }
    // Returns true if the Hash is empty.
    inline bool    IsEmpty() const { return mHash.IsEmpty(); }

    // Access (set).
    inline void    Set(const C& key, const U& value)
    {
        typename HashNode::NodeRef e(key, value);
        mHash.Set(e);
    }
    inline void    Add(const C& key, const U& value)
    {
        typename HashNode::NodeRef e(key, value);
        mHash.Add(e);
    }

    // Removes an element by clearing its Entry.
    inline void     Remove(const C& key)
    {   
        mHash.RemoveAlt(key);
    }
    template<class K>
    inline void     RemoveAlt(const K& key)
    {   
        mHash.RemoveAlt(key);
    }

    // Retrieve the value under the given key.    
    //  - If there's no value under the key, then return false and leave *pvalue alone.
    //  - If there is a value, return true, and Set *Pvalue to the Entry's value.
    //  - If value == NULL, return true or false according to the presence of the key.    
    bool    Get(const C& key, U* pvalue) const   
    {
        const HashNode* p = mHash.GetAlt(key);
        if (p)
        {
            if (pvalue)
                *pvalue = p->Second;
            return true;
        }
        return false;
    }

    template<class K>
    bool    GetAlt(const K& key, U* pvalue) const   
    {
        const HashNode* p = mHash.GetAlt(key);
        if (p)
        {
            if (pvalue)
                *pvalue = p->Second;
            return true;
        }
        return false;
    }

    // Retrieve the pointer to a value under the given key.    
    //  - If there's no value under the key, then return NULL.    
    //  - If there is a value, return the pointer.    
    inline U*  Get(const C& key)
    {
        HashNode* p = mHash.GetAlt(key);
        return p ? &p->Second : 0;
    }
    inline const U* Get(const C& key) const
    {
        const HashNode* p = mHash.GetAlt(key);
        return p ? &p->Second : 0;
    }

    template<class K>
    inline U*  GetAlt(const K& key)
    {
        HashNode* p = mHash.GetAlt(key);
        return p ? &p->Second : 0;
    }
    template<class K>
    inline const U* GetAlt(const K& key) const
    {
        const HashNode* p = mHash.GetAlt(key);
        return p ? &p->Second : 0;
    }

    // Sizing methods - delegate to Hash.
    inline UPInt   GetSize() const              { return mHash.GetSize(); }    
    inline void    Resize(UPInt n)              { mHash.Resize(n); }
    inline void    SetCapacity(UPInt newSize)   { mHash.SetCapacity(newSize); }

    // Iterator API, like STL.
    typedef typename Container::ConstIterator   ConstIterator;
    typedef typename Container::Iterator        Iterator;

    inline Iterator        Begin()              { return mHash.Begin(); }
    inline Iterator        End()                { return mHash.End(); }
    inline ConstIterator   Begin() const        { return mHash.Begin(); }
    inline ConstIterator   End() const          { return mHash.End();   }

    Iterator        Find(const C& key)          { return mHash.FindAlt(key);  }
    ConstIterator   Find(const C& key) const    { return mHash.FindAlt(key);  }

    template<class K>
    Iterator        FindAlt(const K& key)       { return mHash.FindAlt(key);  }
    template<class K>
    ConstIterator   FindAlt(const K& key) const { return mHash.FindAlt(key);  }
};



// Local-only version of Hash
template<class C, class U,         
         class HashF = FixedSizeHash<C>,
         int SID = Stat_Default_Mem,        
         class HashNode = Kaim::HashNode<C,U,HashF>,
         class Entry = HashsetCachedNodeEntry<HashNode, typename HashNode::NodeHashF> >
class HashLH
    : public Hash<C, U, HashF, AllocatorLH<C, SID>, HashNode, Entry>
{
public:
    typedef HashLH<C, U, HashF, SID, HashNode, Entry>               SelfType;
    typedef Hash<C, U, HashF, AllocatorLH<C, SID>, HashNode, Entry> BaseType;

    // Delegated constructors.
    HashLH()                                        { }
    HashLH(int sizeHint) : BaseType(sizeHint)       { }
    HashLH(const SelfType& src) : BaseType(src)     { }
    ~HashLH()                                       { }
    void operator = (const SelfType& src)            { BaseType::operator = (src); }
};


// Custom-heap version of Hash
template<class C, class U,         
         class HashF = FixedSizeHash<C>,
         int SID = Stat_Default_Mem,        
         class HashNode = Kaim::HashNode<C,U,HashF>,
         class Entry = HashsetCachedNodeEntry<HashNode, typename HashNode::NodeHashF> >
class HashDH
    : public Hash<C, U, HashF, AllocatorDH<C, SID>, HashNode, Entry, 
                HashSetDH<HashNode, typename HashNode::NodeHashF,
                    typename HashNode::NodeAltHashF, SID, Entry> >
{
public:
    typedef HashDH<C, U, HashF, SID, HashNode, Entry>                  SelfType;
    typedef Hash<C, U, HashF, AllocatorDH<C, SID>, HashNode, Entry, 
        HashSetDH<HashNode, typename HashNode::NodeHashF,
            typename HashNode::NodeAltHashF, SID, Entry> >              BaseType;

    // Delegated constructors.
    explicit HashDH(void* pheap) : BaseType(pheap)                        { }
    HashDH(void* pheap, int sizeHint) : BaseType(pheap, sizeHint)         { }
    HashDH(const SelfType& src) : BaseType(src)     { }
    ~HashDH()                                       { }
    void operator = (const SelfType& src) { BaseType::operator = (src); }
};


// Hash with uncached hash code; declared for convenience.
template<class C, class U, class HashF = FixedSizeHash<C>, class Allocator = AllocatorGH<C> >
class HashUncached
    : public Hash<C, U, HashF, Allocator, HashNode<C,U,HashF>,
                   HashsetNodeEntry<HashNode<C,U,HashF>, typename HashNode<C,U,HashF>::NodeHashF> >
{
public:
    typedef HashUncached<C, U, HashF, Allocator>                                                   SelfType;
    typedef Hash<C, U, HashF, Allocator, HashNode<C,U,HashF>,
                  HashsetNodeEntry<HashNode<C,U,HashF>, typename HashNode<C,U,HashF>::NodeHashF> > BaseType;

    // Delegated constructors.
    HashUncached()                                        { }
    HashUncached(int sizeHint) : BaseType(sizeHint)       { }
    HashUncached(const SelfType& src) : BaseType(src)     { }
    ~HashUncached()                                       { }
    void operator = (const SelfType& src)                  { BaseType::operator = (src); }
};


// Local heap member-only hash
template<class C, class U, class HashF = FixedSizeHash<C>, int StatId = Stat_Default_Mem>
class HashUncachedLH
    : public HashLH<C, U, HashF, StatId, HashNode<C,U,HashF>,
                   HashsetNodeEntry<HashNode<C,U,HashF>, typename HashNode<C,U,HashF>::NodeHashF> >
{
public:
    typedef HashUncachedLH<C, U, HashF, StatId>                                          SelfType;
    typedef HashLH<C, U, HashF, StatId, HashNode<C,U,HashF>,
        HashsetNodeEntry<HashNode<C,U,HashF>, typename HashNode<C,U,HashF>::NodeHashF> > BaseType;

    // Delegated constructors.
    HashUncachedLH()                                        { }
    HashUncachedLH(int sizeHint) : BaseType(sizeHint)       { }
    HashUncachedLH(const SelfType& src) : BaseType(src)     { }
    ~HashUncachedLH()                                       { }
    void operator = (const SelfType& src)                    { BaseType::operator = (src); }
};

// Custom-heap hash
template<class C, class U, class HashF = FixedSizeHash<C>, int StatId = Stat_Default_Mem>
class HashUncachedDH
    : public HashDH<C, U, HashF, StatId, HashNode<C,U,HashF>,
    HashsetNodeEntry<HashNode<C,U,HashF>, typename HashNode<C,U,HashF>::NodeHashF> >
{
public:
    typedef HashUncachedDH<C, U, HashF, StatId>                                          SelfType;
    typedef HashDH<C, U, HashF, StatId, HashNode<C,U,HashF>,
        HashsetNodeEntry<HashNode<C,U,HashF>, typename HashNode<C,U,HashF>::NodeHashF> > BaseType;

    // Delegated constructors.
    explicit HashUncachedDH(void* pheap) : BaseType(pheap)  { }
    HashUncachedDH(void* pheap, int sizeHint) : BaseType(pheap, sizeHint) { }
    HashUncachedDH(const SelfType& src) : BaseType(src)     { }
    ~HashUncachedDH()                                       { }
    void operator = (const SelfType& src)                   { BaseType::operator = (src); }
};

// And identity hash in which keys serve as hash value. Can be uncached,
// since hash computation is assumed cheap.
template<class C, class U, class Allocator = AllocatorGH<C>, class HashF = IdentityHash<C> >
class HashIdentity
    : public HashUncached<C, U, HashF, Allocator>
{
public:
    typedef HashIdentity<C, U, Allocator, HashF> SelfType;
    typedef HashUncached<C, U, HashF, Allocator> BaseType;

    // Delegated constructors.
    HashIdentity()                                        { }
    HashIdentity(int sizeHint) : BaseType(sizeHint)       { }
    HashIdentity(const SelfType& src) : BaseType(src)     { }
    ~HashIdentity()                                       { }
    void operator = (const SelfType& src)                 { BaseType::operator = (src); }
};



// Local member-only heap hash identity
template<class C, class U, int SID = Stat_Default_Mem, class HashF = IdentityHash<C> >
class HashIdentityLH
    : public HashUncachedLH<C, U, HashF, SID>
{
public:
    typedef HashIdentityLH<C, U, SID, HashF>               SelfType;
    typedef HashUncachedLH<C, U, HashF, SID>               BaseType;

    // Delegated constructors.
    HashIdentityLH()                                       { }
    HashIdentityLH(int sizeHint) : BaseType(sizeHint)      { }
    HashIdentityLH(const SelfType& src) : BaseType(src)    { }
    ~HashIdentityLH()                                      { }
    void operator = (const SelfType& src)                  { BaseType::operator = (src); }
};

// Hash identity with specified heap
template<class C, class U, int SID = Stat_Default_Mem, class HashF = IdentityHash<C> >
class HashIdentityDH
    : public HashUncachedDH<C, U, HashF, SID>
{
public:
    typedef HashIdentityDH<C, U, SID, HashF>               SelfType;
    typedef HashUncachedDH<C, U, HashF, SID>               BaseType;

    // Delegated constructors.
    explicit HashIdentityDH(void* pheap) : BaseType(pheap) { }
    HashIdentityDH(void* pheap, int sizeHint) : BaseType(pheap, sizeHint)      { }
    HashIdentityDH(const SelfType& src) : BaseType(src)    { }
    ~HashIdentityDH()                                      { }
    void operator = (const SelfType& src)                  { BaseType::operator = (src); }
};

} // Scaleform

// Redefine operator 'new' if necessary.
#if defined(KY_DEFINE_NEW)
#define new KY_DEFINE_NEW
#endif

#endif