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dsBtreeOnDisk.h

Go to the documentation of this file.

#ifndef dsBtreeOnDisk_h
#define dsBtreeOnDisk_h

#include <iostream>

#include <dsSmartException.h>
#include <dsutil.h>

DECLARE_EXCEPTION(dsBtreeOnDisk);

class dsBtreeOnDiskItem 
{
protected:
    char *key;
    void *val;
    size_t vsize;
    size_t ksize;

    int _deleted;

    long _left, _right, _parent, _dup;
    long _offs;

public:
    dsBtreeOnDiskItem()
    {
        key   = 0;
        val   = 0;
        vsize = 0;
        ksize = 0;
        
        _offs = 0; 
        _deleted = 0;
        _left = 0; _right = 0; _parent = 0; _dup = 0;
    }
    
    dsBtreeOnDiskItem(const char *xkey, void *xval, size_t size)
    {
         key   = ds_strdup(xkey);
         val   = xval;
         vsize = size;
         ksize = strlen(xkey)+1;

        _offs    = 0; 
        _deleted = 0;
        _left = 0; _right = 0; _parent = 0; _dup = 0;
    }

    ~dsBtreeOnDiskItem()
    {
        if (key)
                delete key;
    }

    friend class dsBtreeOnDisk;
};

class dsBtreeOnDiskRootItem : public dsBtreeOnDiskItem
{
    long _last_offs; // Actual for root item only

    dsBtreeOnDiskRootItem():
            dsBtreeOnDiskItem()
    {
        _last_offs = 0;
        key = ds_strdup("dsBtreeOnDiskOnDisk v1.002 (C) DMS 2003");
        ksize = strlen(key)+1;
    }


    friend class dsBtreeOnDisk;
};

class dsBtreeOnDisk
{
        std::iostream* _os;
        bool _allow_dup;

        void _walk(long offs);

    void rotate_right(dsBtreeOnDiskItem& item);
    void rotate_left(dsBtreeOnDiskItem& item);

protected:      
        virtual void visit(char *key, void *val, size_t vsize);
        
public:

        dsBtreeOnDiskRootItem _root;
        dsBtreeOnDiskItem _current;

        void IOWriteAt(long offs, dsBtreeOnDiskItem* item);
        void IOReadAt (long offs, dsBtreeOnDiskItem* item);
        void IOError  (long offs, dsBtreeOnDiskItem* item);

        int cf(dsBtreeOnDiskItem* a, dsBtreeOnDiskItem *b);

        dsBtreeOnDiskItem* seek(dsBtreeOnDiskItem* item);
        dsBtreeOnDiskItem* insert(dsBtreeOnDiskItem* item);

        void update(dsBtreeOnDiskItem* item, void *newval, size_t size);
        void remove(dsBtreeOnDiskItem* item);

        void walk();
    
        dsBtreeOnDisk(std::iostream* os, bool allow_duplicates = false);    
};




#endif

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