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 *
 * This file incorporates work covered by the following license notice:
 *
 *   Licensed to the Apache Software Foundation (ASF) under one or more
 *   contributor license agreements. See the NOTICE file distributed
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#ifndef INCLUDED_SOT_SOURCE_SDSTOR_STGAVL_HXX
#define INCLUDED_SOT_SOURCE_SDSTOR_STGAVL_HXX

// This is an abstract base class for nodes.
// Especially, the compare function must be implemented.

class StgAvlNode
{
    friend class StgAvlIterator;
private:
    short Locate( StgAvlNode*, StgAvlNode**, StgAvlNode**, StgAvlNode** );
    short Adjust( StgAvlNode**, StgAvlNode* );
    StgAvlNode* RotLL();
    StgAvlNode* RotLR();
    StgAvlNode* RotRR();
    StgAvlNode* RotRL();
    void   StgEnum( short& );
    static StgAvlNode* Rem( StgAvlNode**, StgAvlNode*, bool );
protected:
    short nId;                          // iterator ID
    short nBalance;                     // indicates tree balance
    StgAvlNode* pLeft, *pRight;         // leaves
    StgAvlNode();
public:
    virtual ~StgAvlNode();
    StgAvlNode* Find( StgAvlNode* );
    static bool Insert( StgAvlNode**, StgAvlNode* );
    static bool Remove( StgAvlNode**, StgAvlNode*, bool bDel = true );
    static bool Move( StgAvlNode**, StgAvlNode**, StgAvlNode* );
    virtual short Compare( const StgAvlNode* ) const = 0;
};

// The iterator class provides single stepping through an AVL tree.

class StgAvlIterator {
    StgAvlNode* pRoot;                  // root entry (parent)
    short       nCount;                 // tree size
    short       nCur;                   // current element
    StgAvlNode* Find( short );
public:
    StgAvlIterator( StgAvlNode* );
    StgAvlNode* First();
    StgAvlNode* Next();
};

#endif

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