Class MBtreeKey

class MBtreeKey;

Description

Interface for ordering and creating keys for entries in a B-tree.

Derived classes implement this interface for particular types of key.

Members

Defined in MBtreeKey:

• Between(const TAny *,const TAny *,TBtreePivot &)constGets the midpoint between two keys.
• Compare(const TAny *,const TAny *)constOrders two keys.
• Key(const TAny *)constGets the key value for an entry.

IMPORT_C virtual const TAny* Key(const TAny *anEntry) const;

Description

Gets the key value for an entry.

Parameters

const TAny *anEntry Object for which to get the key value

Return value

const TAny * Pointer to the key value

virtual TInt Compare(const TAny *aLeft, const TAny *aRight) const=0;

Description

Orders two keys.

Parameters

const TAny *aLeft Pointer to first key const TAny *aRight Pointer to second key

Return value

TInt Positive, if the first key is after the second key; negative, if the first key is before the second key; zero, if the keys are equal

virtual void Between(const TAny *aLeft, const TAny *aRight, TBtreePivot &aPivot) const=0;

Description

Gets the midpoint between two keys.

The generated midpoint will be greater or equal to aLeft (by a comparison performed by the MBtreeKey::Compare(const TAny *,const TAny *)const function), and less than aRight.

Parameters

const TAny *aLeft First key const TAny *aRight Second key TBuf8 &aPivot On return, the midpoint between the two keys