org.hypergraphdb.handle

Class UUIDHandleFactory

java.lang.Object

org.hypergraphdb.handle.UUIDHandleFactory

All Implemented Interfaces:

HGHandleFactory

Direct Known Subclasses:

SequentialUUIDHandleFactory

public class UUIDHandleFactory
extends Object
implements HGHandleFactory

A persistent handle factory based on type IV (crypto-strong) UUIDs. This is the default handle factory. The handle produced by it a universally unique and play well in a distributed environment.

Author:

Borislav Iordanov

Field Summary

Fields

Modifier and Type	Field and Description
static UUIDHandleFactory	I

Constructor Summary

Constructors

Constructor and Description
UUIDHandleFactory()

Method Summary

Methods

Modifier and Type	Method and Description
HGPersistentHandle	anyHandle() The anyHandle is a persistent handle constant that represents a "don't care" handle during querying and comparison operations.
HGPersistentHandle	linkTypeHandle()
HGPersistentHandle	makeHandle() Construct and return a new, unique persistent handle.
HGPersistentHandle	makeHandle(byte[] buffer) Construct a persistent handle from its byte array representation.
HGPersistentHandle	makeHandle(byte[] buffer, int offset) Construct a persistent handle from its byte array representation where the byte array is part of a larger buffer and located at a particular offset.
HGPersistentHandle	makeHandle(String handleAsString) Construct a persistent handle from its string representation.
HGPersistentHandle	nullHandle() Return the representation of a null persistent handle.
HGPersistentHandle	nullTypeHandle()
HGPersistentHandle	subsumesTypeHandle()
HGPersistentHandle	topTypeHandle()

Methods inherited from class java.lang.Object

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

Field Detail

I

public static final UUIDHandleFactory I

Constructor Detail

UUIDHandleFactory

public UUIDHandleFactory()

Method Detail

anyHandle

public HGPersistentHandle anyHandle()

Description copied from interface: HGHandleFactory

The anyHandle is a persistent handle constant that represents a "don't care" handle during querying and comparison operations. It can be used, for instance, when defining an OrdererLinkCondition in a query.

For efficiency reasons, the equals method of the various implementations of the HGHandle interface ignore this constant, even though it would be more consistent to for anyHandle.equals(x) and x.equals(anyHandle) to always return true.

Specified by:

anyHandle in interface HGHandleFactory

makeHandle

public HGPersistentHandle makeHandle()

Description copied from interface: HGHandleFactory

Construct and return a new, unique persistent handle. The handle is permanently unique. It can be persistent (serialized) and restored without ever conflicting with another handle.

Specified by:

makeHandle in interface HGHandleFactory

makeHandle

public HGPersistentHandle makeHandle(String handleAsString)

Description copied from interface: HGHandleFactory

Construct a persistent handle from its string representation.

Specified by:

makeHandle in interface HGHandleFactory

makeHandle

public HGPersistentHandle makeHandle(byte[] buffer)

Description copied from interface: HGHandleFactory

Construct a persistent handle from its byte array representation.

Specified by:

makeHandle in interface HGHandleFactory

Parameters:

buffer - The byte array holding the handle value.

makeHandle

public HGPersistentHandle makeHandle(byte[] buffer,
                            int offset)

Description copied from interface: HGHandleFactory

Construct a persistent handle from its byte array representation where the byte array is part of a larger buffer and located at a particular offset.

Specified by:

makeHandle in interface HGHandleFactory

Parameters:

buffer - The byte array holding the handle value.

offset - The offset within buffer where the handle value starts.

nullHandle

public HGPersistentHandle nullHandle()

Description copied from interface: HGHandleFactory

Return the representation of a null persistent handle. A null handle is a single instance and therefore can be compared for equality by doing direct Java object reference comparison. A null handle can be recorded in storage as any other persistent handle - it refers to no value. Not that while HyperGraph's type system does not provide for null atom values or value projections, null references to values are permitted and supported through the null HGPersistentHandle

Specified by:

nullHandle in interface HGHandleFactory

topTypeHandle

public HGPersistentHandle topTypeHandle()

Specified by:

topTypeHandle in interface HGHandleFactory

nullTypeHandle

public HGPersistentHandle nullTypeHandle()

Specified by:

nullTypeHandle in interface HGHandleFactory

linkTypeHandle

public HGPersistentHandle linkTypeHandle()

Specified by:

linkTypeHandle in interface HGHandleFactory

subsumesTypeHandle

public HGPersistentHandle subsumesTypeHandle()

Specified by:

subsumesTypeHandle in interface HGHandleFactory