org.hypergraphdb.indexing

Interface HGIndexer<KeyType,ValueType>

All Known Implementing Classes:

ByPartIndexer, ByTargetIndexer, CompositeIndexer, DirectValueIndexer, HGKeyIndexer, HGValueIndexer, LinkIndexer, TargetToTargetIndexer

public interface HGIndexer<KeyType,ValueType>

An HGIndexer represents an atom used internally by HyperGraphDB to manage indices. All indexers apply to a specific atom types.

Because indexers are stored as HyperGraphDB atoms, they must obey the Java Beans conventions of having a default constructor and getter/setter pair for each property that must be recorded into storage.

IMPORTANT:Instances of HGIndexer are frequently used to perform lookup on existing indices. For example, when trying to determine whether an atom of a complex type is being indexed by some projection, one constructs a ByPartIndexer and performs a lookup in the index manager. Thus, it is essential that implementation of HGIndexer provide proper hashCode and equals methods.

Author:

Borislav Iordanov

Method Summary

Methods

Modifier and Type	Method and Description
boolean	equals(Object other) Declared to enforce implementation.
Comparator<byte[]>	getComparator(HyperGraph graph) Return a comparator used to compare key values return by this indexer.
ByteArrayConverter<KeyType>	getConverter(HyperGraph graph) Return a ByteArrayConverter capable of translating keys returned by this indexer to/from a byte[].
HGHandle	getType() Return the handle of the atom type all of whose instances should be indexed by this indexer.
int	hashCode() Declared to enforce implementation.
void	index(HyperGraph graph, HGHandle atomHandle, Object atom, HGIndex<KeyType,ValueType> index) Add a particular atom the the index.
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,ValueType> index) Remove a particular from the index, assuming it is currently being indexed.

Method Detail

index

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

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

Parameters:

graph - The HyperGraph instance where the atom resides.

atomHandle -

atom -

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

unindex

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

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

Parameters:

graph - The HyperGraph instance where the atom resides.

atomHandle -

atom -

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

getConverter

ByteArrayConverter<KeyType> getConverter(HyperGraph graph)

Return a ByteArrayConverter capable of translating keys returned by this indexer to/from a byte[].

Parameters:

graph - The current HyperGraph instance.

Returns:

The ByteArrayConverter for type of index keys return by this indexer or null if keys are of type byte[].

getComparator

Comparator<byte[]> getComparator(HyperGraph graph)

Return a comparator used to compare key values return by this indexer. Note that the comparator's compare method will be invoked with byte[] parameters. It is the comparator's responsibility to convert them to the appropriate run-time type for performing the comparison if need be.

The method may return null if a default byte-by-byte comparator is to be used.

Parameters:

graph - The current HyperGraph instance.

Returns:

A comparator used to compare key values return by this indexer or null to use a default byte-by-byte comparison of keys.

getType

HGHandle getType()

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

setType

void setType(HGHandle type)

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

hashCode

int hashCode()

Declared to enforce implementation.

Overrides:

hashCode in class Object

equals

boolean equals(Object other)

Declared to enforce implementation.

Overrides:

equals in class Object