org.lenskit.data.store

Class EntityCollection

java.lang.Object

java.util.AbstractCollection<Entity>

org.lenskit.data.store.EntityCollection

All Implemented Interfaces:

java.lang.Iterable<Entity>, java.util.Collection<Entity>

public abstract class EntityCollection
extends java.util.AbstractCollection<Entity>

A collection of entities of a single type. This collection augments the Collection interface with logic for different kinds of (possibly optimized) entity searches.

Method Summary

Modifier and Type	Method and Description
abstract <T> java.util.List<Entity>	find(Attribute<T> attr) Find entities with an attribute.
abstract java.util.List<Entity>	find(java.lang.String name, java.lang.Object value) Find entities by attribute.
abstract <T> java.util.List<Entity>	find(TypedName<T> name, T value) Find entities by attribute.
java.util.List<SortKey>	getSortKeys() Get the sort keys, if this collection stores attributes in sorted order.
abstract EntityType	getType() Get the type of entity stored in this collection.
abstract java.util.Map<java.lang.Long,java.util.List<Entity>>	grouped(TypedName<java.lang.Long> attr) Get a grouped view of the data.
abstract LongSet	idSet()
abstract Entity	lookup(long id) Look up an entity by ID.
static EntityCollectionBuilder	newBareBuilder(EntityType type) Create a new builder for colletions of bare entitites (only storing IDs).
static EntityCollectionBuilder	newBuilder(EntityType type) Create a new entity collection builder.
static EntityCollectionBuilder	newBuilder(EntityType type, AttributeSet attrs) Create a new packed entity collection builder.
static EntityCollectionBuilder	newBuilder(EntityType type, AttributeSet attrs, java.lang.Class<? extends EntityBuilder> eb) Create a new packed entity collection builder.

Methods inherited from class java.util.AbstractCollection

add, addAll, clear, contains, containsAll, isEmpty, iterator, remove, removeAll, retainAll, size, toArray, toArray, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Collection

equals, hashCode, parallelStream, removeIf, spliterator, stream

Methods inherited from interface java.lang.Iterable

forEach

Method Detail

newBuilder

public static EntityCollectionBuilder newBuilder(EntityType type)

Create a new entity collection builder.

Returns:

The builder.

newBuilder

public static EntityCollectionBuilder newBuilder(EntityType type,
                                                 AttributeSet attrs)

Create a new packed entity collection builder.

Parameters:

type - The entity type.

attrs - The attributes to store.

Returns:

An entity collection builder.

newBuilder

public static EntityCollectionBuilder newBuilder(EntityType type,
                                                 AttributeSet attrs,
                                                 java.lang.Class<? extends EntityBuilder> eb)

Create a new packed entity collection builder.

Parameters:

type - The entity type.

attrs - The attributes to store.

eb - An entity builder to use when reconstituting entities.

Returns:

An entity collection builder.

newBareBuilder

public static EntityCollectionBuilder newBareBuilder(EntityType type)

Create a new builder for colletions of bare entitites (only storing IDs).

Parameters:

type - The entity type.

Returns:

The builder.

getType

public abstract EntityType getType()

Get the type of entity stored in this collection.

Returns:

The entity type this collection stores.

idSet

public abstract LongSet idSet()

lookup

@Nullable
public abstract Entity lookup(long id)

Look up an entity by ID.

Parameters:

id - The entity ID.

Returns:

The entity, or null if no such entity exists.

find

@Nonnull
public abstract <T> java.util.List<Entity> find(TypedName<T> name,
                                                         T value)

Find entities by attribute.

Parameters:

name - The attribute name.

value - The attribute value.

Returns:

A list of entities for which attribute name has value value.

find

@Nonnull
public abstract <T> java.util.List<Entity> find(Attribute<T> attr)

Find entities with an attribute.

Parameters:

attr - The attribute to look for.

T - The attribute type.

Returns:

A list of entities with the specified attribute.

find

@Nonnull
public abstract java.util.List<Entity> find(java.lang.String name,
                                                     java.lang.Object value)

Find entities by attribute.

Parameters:

name - The attribute name.

value - The attribute value.

Returns:

A list of entities for which attribute name has value value.

grouped

public abstract java.util.Map<java.lang.Long,java.util.List<Entity>> grouped(TypedName<java.lang.Long> attr)

Get a grouped view of the data.

Parameters:

attr - The grouping attribute.

Returns:

A map of values to entities with that value in the specified attribute.

getSortKeys

public java.util.List<SortKey> getSortKeys()

Get the sort keys, if this collection stores attributes in sorted order.

Returns:

The sort keys.