OW_NAMESPACE::Index Class Reference

The Index class is simply an interface class that helps facilitate a pluggable architecture for an indexing scheme on file. More...

#include <OW_Index.hpp>

Inheritance diagram for OW_NAMESPACE::Index:

[legend]Collaboration diagram for OW_NAMESPACE::Index:

[legend]List of all members.

Public Types
enum	EDuplicateKeysFlag { E_NO_DUPLICATES, E_ALLDUPLICATES }
Public Member Functions
virtual	~Index ()
	Destroy this Index object.
virtual void	open (const char *fileName, EDuplicateKeysFlag allowDuplicates=E_NO_DUPLICATES)=0
	Open the given index file.
virtual void	close ()=0
	Close the underlying index file if it is open.
virtual IndexEntry	findFirst (const char *key=0)=0
	Position the cursor on the 1st entry in the index or the first record with a given key.
virtual IndexEntry	findNext ()=0
	Position the cursor on the next entry in the index.
virtual IndexEntry	findPrev ()=0
	Position the cursor on the previous entry in the index.
virtual IndexEntry	find (const char *key)=0
	Position the cursor on the index entry associated a specified key.
virtual bool	add (const char *key, Int32 offset)=0
	Add an entry to the index.
virtual bool	remove (const char *key, Int32 offset=-1L)=0
	Remove an entry from the index.
virtual bool	update (const char *key, Int32 newOffset)=0
	Update an index entry.
virtual void	flush ()
	Flush all changes to the underlying index file.
Static Public Member Functions
static IndexRef	createIndexObject ()
	Create dynamically allocated instances of a sub-class of Indexer.

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Detailed Description

The Index class is simply an interface class that helps facilitate a pluggable architecture for an indexing scheme on file.

All Index objects will be used to maintain an index on some file. The only data ever associated with the key of the index will be a long value that will be used as an offset into a file. The implementor of the Index class must implement the createIndexObject class. This class will be called to get new Index objects that will later be deleted by the caller. The intention is for the implementor to create a sub-class of Index and have createIndexObject be the factory for those object.

Definition at line 61 of file OW_Index.hpp.

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Member Enumeration Documentation

enum OW_NAMESPACE::Index::EDuplicateKeysFlag

Enumerator: E_NO_DUPLICATES  E_ALLDUPLICATES  Definition at line 69 of file OW_Index.hpp.

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Constructor & Destructor Documentation

OW_NAMESPACE::Index::~Index (   )  [virtual]

Destroy this Index object. This will close the index file if it is open. Definition at line 43 of file OW_Index.cpp.

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Member Function Documentation

virtual bool OW_NAMESPACE::Index::add (  const char *  key, Int32  offset )  [pure virtual]

Add an entry to the index. Parameters: key  The key for the index entry to add. offset  The offset value for the index entry to add. Returns: true if an index entry was created in the index file. false if the index entry was already on file. Exceptions: IndexException  If the index file hasn't been opened. Implemented in OW_NAMESPACE::IndexImpl.

virtual void OW_NAMESPACE::Index::close (   )  [pure virtual]

Close the underlying index file if it is open. Implemented in OW_NAMESPACE::IndexImpl.

IndexRef OW_NAMESPACE::Index::createIndexObject (   )  [static]

Create dynamically allocated instances of a sub-class of Indexer. This method must be implemented by whomever desires to implement an Indexer sub-class. Returns: An instance of a sub-class of Indexer. Definition at line 91 of file OW_IndexImpl.cpp. Referenced by OW_NAMESPACE::HDB::checkFile(), OW_NAMESPACE::AssocDb::checkFile(), OW_NAMESPACE::HDB::createFile(), and OW_NAMESPACE::AssocDb::createFile().

virtual IndexEntry OW_NAMESPACE::Index::find (  const char *  key  )  [pure virtual]

Position the cursor on the index entry associated a specified key. Returns: An IndexEntry that contains information about the current entry in the index on success. On failure the returned IndexEntry will be null. Exceptions: IndexException  If the index file hasn't been opened. Implemented in OW_NAMESPACE::IndexImpl.

virtual IndexEntry OW_NAMESPACE::Index::findFirst (  const char *  key = 0  )  [pure virtual]

Position the cursor on the 1st entry in the index or the first record with a given key. Parameters: key  The key to find the first occurence of. If NULL is given, the 1st entry of the index is returned, otherwise the first entry that has a key that is greater than or equal to the key parameter. Returns: An IndexEntry that contains information about the 1st entry in the index on success. On failure the returned IndexEntry will be null. Exceptions: IndexException  If the index file hasn't been opened. Implemented in OW_NAMESPACE::IndexImpl.

virtual IndexEntry OW_NAMESPACE::Index::findNext (   )  [pure virtual]

Position the cursor on the next entry in the index. Returns: An IndexEntry that contains information about the current entry in the index on success. On failure the returned IndexEntry will be null. Exceptions: IndexException  If the index file hasn't been opened. Implemented in OW_NAMESPACE::IndexImpl.

virtual IndexEntry OW_NAMESPACE::Index::findPrev (   )  [pure virtual]

Position the cursor on the previous entry in the index. Returns: An IndexEntry that contains information about the current entry in the index on success. On failure the returned IndexEntry will be null. Exceptions: IndexException  If the index file hasn't been opened. Implemented in OW_NAMESPACE::IndexImpl.

void OW_NAMESPACE::Index::flush (   )  [virtual]

Flush all changes to the underlying index file. Reimplemented in OW_NAMESPACE::IndexImpl. Definition at line 48 of file OW_Index.cpp.

virtual void OW_NAMESPACE::Index::open (  const char *  fileName, EDuplicateKeysFlag  allowDuplicates = E_NO_DUPLICATES )  [pure virtual]

Open the given index file. Parameters: fileName  The file name for the index file. If the file name has an extension, it will be removed. The name of the index file will be the base of fileName with the extension ".ndx". Exceptions: IndexException  If the file cannot be created or opened.

virtual bool OW_NAMESPACE::Index::remove (  const char *  key, Int32  offset = -1L )  [pure virtual]

Remove an entry from the index. Parameters: key  The key of the index entry to remove. offset  The value for the offset field of the index entry to remove. This parm is meaningless unless the index allows duplicate keys. Returns: true if the index entry was removed from the index file. false if the index entry could not be found. Exceptions: IndexException  If the index file hasn't been opened. Implemented in OW_NAMESPACE::IndexImpl.

virtual bool OW_NAMESPACE::Index::update (  const char *  key, Int32  newOffset )  [pure virtual]

Update an index entry. Parameters: key  The key of the index entry to update. newOffset  The new value for the index entry. Returns: true if the record was updated. false if the record was not found. Exceptions: IndexException  If the index file hasn't been opened. Implemented in OW_NAMESPACE::IndexImpl.

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The documentation for this class was generated from the following files:

• OW_Index.hpp
• OW_Index.cpp
• OW_IndexImpl.cpp

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