org.hypergraphdb.indexing

Class HGKeyIndexer<KeyType>

java.lang.Object

org.hypergraphdb.indexing.HGKeyIndexer<KeyType>

All Implemented Interfaces:

HGIndexer<KeyType,HGPersistentHandle>

Direct Known Subclasses:

ByPartIndexer, ByTargetIndexer, CompositeIndexer, DirectValueIndexer, LinkIndexer

public abstract class HGKeyIndexer<KeyType>
extends Object
implements HGIndexer<KeyType,HGPersistentHandle>

An HGKeyIndexer represents an atom used internally by HyperGraphDB to manage key-based indices. All such indexers are responsible for producing a key for the given atom instance being indexed. In addition, when the keys produced are NOT of type byte[], a key indexer must provide a ByteArrayConverter capable of translating a key to/from a byte[].

Implementations may also provide a Comparator for keys for sorted indices and when the default byte[] comparator is not suitable.

Author:

Borislav Iordanov

Constructor Summary

Constructors

Constructor and Description
HGKeyIndexer()
HGKeyIndexer(HGHandle type)
HGKeyIndexer(String name, HGHandle type)

Method Summary

Methods

Modifier and Type	Method and Description
abstract KeyType	getKey(HyperGraph graph, Object atom) Returns an index key for the given atom.
String	getName()
HGHandle	getType() Return the handle of the atom type all of whose instances should be indexed by this indexer.
void	index(HyperGraph graph, HGHandle atomHandle, Object atom, HGIndex<KeyType,HGPersistentHandle> index) Add a particular atom the the index.
void	setName(String name)
void	setType(HGHandle type) Set the handle of the atom type all of whose instances should be indexed by this indexer.
void	unindex(HyperGraph graph, HGHandle atomHandle, Object atom, HGIndex<KeyType,HGPersistentHandle> index) Remove a particular from the index, assuming it is currently being indexed.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.hypergraphdb.indexing.HGIndexer

equals, getComparator, getConverter, hashCode

Constructor Detail

HGKeyIndexer

public HGKeyIndexer()

HGKeyIndexer

public HGKeyIndexer(String name,
            HGHandle type)

HGKeyIndexer

public HGKeyIndexer(HGHandle type)

Method Detail

getName

public String getName()

setName

public void setName(String name)

getType

public HGHandle getType()

Description copied from interface: HGIndexer

Return the handle of the atom type all of whose instances should be indexed by this indexer.

Specified by:

getType in interface HGIndexer<KeyType,HGPersistentHandle>

setType

public void setType(HGHandle type)

Description copied from interface: HGIndexer

Set the handle of the atom type all of whose instances should be indexed by this indexer.

Specified by:

setType in interface HGIndexer<KeyType,HGPersistentHandle>

index

public void index(HyperGraph graph,
         HGHandle atomHandle,
         Object atom,
         HGIndex<KeyType,HGPersistentHandle> index)

Description copied from interface: HGIndexer

Add a particular atom the the index. This method can safely assume that the atom hasn't been previously added to the index.

Specified by:

index in interface HGIndexer<KeyType,HGPersistentHandle>

Parameters:

graph - The HyperGraph instance where the atom resides.

index - The storage index where the atom should be added.

unindex

public void unindex(HyperGraph graph,
           HGHandle atomHandle,
           Object atom,
           HGIndex<KeyType,HGPersistentHandle> index)

Description copied from interface: HGIndexer

Remove a particular from the index, assuming it is currently being indexed.

Specified by:

unindex in interface HGIndexer<KeyType,HGPersistentHandle>

Parameters:

graph - The HyperGraph instance where the atom resides.

index - The storage index from the atom should be removed.

getKey

public abstract KeyType getKey(HyperGraph graph,
             Object atom)

Returns an index key for the given atom.

Parameters:

graph - The current HyperGraph instance.

atom - The atom being indexed.

Returns:

The index key. If the return value is not a byte[], a non-null ByteArrayConverter must be provided by the getConverter method.