org.hypergraphdb.type

Class RecordType

java.lang.Object

org.hypergraphdb.type.RecordType

All Implemented Interfaces:

HGGraphHolder, HGAtomType, HGCompositeType

public class RecordType
extends Object
implements HGCompositeType

A RecordType represents a particular combination of slots that can be used to construct records. The latter are instances of Record.

It is important that the slots in a record type are maintained in an order matching the HG store layout of record values.

A null record is represented with a null handle HGHandleFactory.nullHandle(), while and empty record is represented with a newly created handle that doesn't point to anything.

Author:

Borislav Iordanov

Field Summary

Fields

Modifier and Type	Field and Description
protected HyperGraph	graph
protected ArrayList<HGHandle>	slots
protected HGHandle	thisHandle

Constructor Summary

Constructors

Constructor and Description
RecordType()

Method Summary

Methods

Modifier and Type	Method and Description
void	addSlot(HGHandle slot)
boolean	equals(Object other)
HGHandle	getAt(int i)
Iterator<String>	getDimensionNames() Return an Iterator listing the names of all dimensions of this composite type.
HGProjection	getProjection(String dimensionName) Get the projection function for a particular dimension.
HGAtomRef.Mode	getReferenceMode(HGHandle slot)
List<HGHandle>	getSlots()
int	hashCode()
Object	make(HGPersistentHandle handle, LazyRef<HGHandle[]> targetSet, IncidenceSetRef incidenceSet) Construct a new run-time instance of a hypergraph atom.
void	release(HGPersistentHandle handle) Release a hypergraph value instance from the persistent store.
void	remove(HGHandle slot)
void	removeAt(int i)
void	setHyperGraph(HyperGraph hg) During load time, set the HyperGraph instance to which this atom belongs.
void	setThisHandle(HGHandle thisHandle)
int	slotCount()
HGPersistentHandle	store(Object instance) Store a run-time instance of a hypergraph atom into the hypergraph HGStore as a new atom.
boolean	subsumes(Object general, Object specific) A generic semantic predicate that returns true if the first argument is more general than the second.
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

slots

protected ArrayList<HGHandle> slots

graph

protected HyperGraph graph

thisHandle

protected HGHandle thisHandle

Constructor Detail

RecordType

public RecordType()

Method Detail

getReferenceMode

public HGAtomRef.Mode getReferenceMode(HGHandle slot)

setThisHandle

public void setThisHandle(HGHandle thisHandle)

getDimensionNames

public Iterator<String> getDimensionNames()

Description copied from interface: HGCompositeType

Return an Iterator listing the names of all dimensions of this composite type. A projection function can be obtained through the getProjection method.

Specified by:

getDimensionNames in interface HGCompositeType

getProjection

public HGProjection getProjection(String dimensionName)

Description copied from interface: HGCompositeType

Get the projection function for a particular dimension.

Specified by:

getProjection in interface HGCompositeType

Parameters:

dimensionName - The name of the dimension.

Returns:

The HGProjection instance.

getSlots

public List<HGHandle> getSlots()

addSlot

public void addSlot(HGHandle slot)

remove

public void remove(HGHandle slot)

removeAt

public void removeAt(int i)

getAt

public HGHandle getAt(int i)

slotCount

public int slotCount()

setHyperGraph

public void setHyperGraph(HyperGraph hg)

Description copied from interface: HGGraphHolder

During load time, set the HyperGraph instance to which this atom belongs.

Specified by:

setHyperGraph in interface HGGraphHolder

make

public Object make(HGPersistentHandle handle,
          LazyRef<HGHandle[]> targetSet,
          IncidenceSetRef incidenceSet)

Description copied from interface: HGAtomType

Construct a new run-time instance of a hypergraph atom. A plain node must be constructed whenever the targetSet parameter is null or of length 0. Otherwise, a HGLink instance must be constructed.

It is not required that all atom types be able to construct both plain (node) atoms and HGLinks. It is up to an HGAtomType implementation to support either or both. When a HGLink counterpart is not available for a particular run-time type, an implementation may choose to create an instance of the default link value holder implementation HGValuedLink, provided by HyperGraph.

Specified by:

make in interface HGAtomType

Parameters:

handle - The HGPersistentHandle of the atom value.

targetSet - When the atom is a link, this parameter holds the target set of the link. When the atom is a node, the parameter is an array of 0 length.

incidenceSet - A lazy reference to the set of links pointing to this atom. This is null if we are constructing an internal/nested value of some complex type.

Returns:

The run-time atom instance. The return value should never be null. In case the handle points to an invalid instance (inexisting or with a erronous layout), the method should throw a HGException.

store

public HGPersistentHandle store(Object instance)

Description copied from interface: HGAtomType

Store a run-time instance of a hypergraph atom into the hypergraph HGStore as a new atom.

Specified by:

store in interface HGAtomType

Parameters:

instance - The atom instance.

Returns:

The persistent handle of the stored value.

release

public void release(HGPersistentHandle handle)

Description copied from interface: HGAtomType

Release a hypergraph value instance from the persistent store.

This method should be called when a HGPersistentHandle returned from the store is no longer in use.

Specified by:

release in interface HGAtomType

Parameters:

handle - The persistent handle of the value to release.

subsumes

public boolean subsumes(Object general,
               Object specific)

Description copied from interface: HGAtomType

A generic semantic predicate that returns true if the first argument is more general than the second. Atom types must implement this notion of specialization whenever meaningful in the context of the entities being constructed.

The notion of subsumption can be seen as partial equivalence, or equivalence in one direction only.

As a relation, subsumtion is transitive and reflexive. The latter implies that, at a minimum, the subsumes method must return true if general.equals(specific).

Specified by:

subsumes in interface HGAtomType

Parameters:

general - The object which might be more general. Cannot be null.

specific - The object which might be more specific. Cannot be null.

Returns:

true if specific can be used whenever general is required and false otherwise.

equals

public boolean equals(Object other)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object