org.lenskit.data.entities

Class AttributeSet

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractSet<TypedName<?>>

org.lenskit.data.entities.AttributeSet

All Implemented Interfaces:

java.io.Serializable, java.lang.Iterable<TypedName<?>>, java.util.Collection<TypedName<?>>, java.util.Set<TypedName<?>>

@Immutable
public class AttributeSet
extends java.util.AbstractSet<TypedName<?>>
implements java.io.Serializable

A set of attributes. Attributes are mapped to positions. If CommonAttributes.ENTITY_ID is in the set, it is always at position 0. Iteration is in order.

This class exists for two reasons:

• To share space for storing attribute names - including the list of attribute names - between multiple entities with the same set of attributes.
• To speed up lookups; microbenchmarks have found that linear search with object identity is faster than hashtable lookups for small maps, and entities do not tend to have very many attributes.

See Also:

Serialized Form

Method Summary

Modifier and Type	Method and Description
boolean	contains(java.lang.Object o)
static AttributeSet	create(java.util.List<? extends TypedName<?>> names) Create a new attribute set.
static AttributeSet	create(TypedName<?>... names) Create a new attribute set.
TypedName<?>	getAttribute(int idx) Get the type name for an attribute by index.
java.util.Iterator<TypedName<?>>	iterator()
int	lookup(java.lang.String name) Look up an attribute.
int	lookup(TypedName<?> name) Look up an attribute.
int	lookup(TypedName<?> name, boolean matchSubclasses) Look up an attribute.
java.util.Set<java.lang.String>	nameSet() Get a set-of-strings view of this attribute set.
int	size() Get the number of attributes in this set.

Methods inherited from class java.util.AbstractSet

equals, hashCode, removeAll

Methods inherited from class java.util.AbstractCollection

add, addAll, clear, containsAll, isEmpty, remove, retainAll, toArray, toArray, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Set

add, addAll, clear, containsAll, isEmpty, remove, retainAll, spliterator, toArray, toArray

Methods inherited from interface java.util.Collection

parallelStream, removeIf, stream

Methods inherited from interface java.lang.Iterable

forEach

Method Detail

create

public static AttributeSet create(TypedName<?>... names)

Create a new attribute set.

Parameters:

names - The list of attributes.

Returns:

The attribute set.

create

public static AttributeSet create(java.util.List<? extends TypedName<?>> names)

Create a new attribute set.

Parameters:

names - The list of attributes.

Returns:

The attribute set.

lookup

public int lookup(TypedName<?> name)

Look up an attribute.

Parameters:

name - The attribute.

Returns:

The attribute’s index, or a negative value if it does not exist. Nonexistence is further differentiated with -1 for no attribute, -2 for type mismatch.

lookup

public int lookup(TypedName<?> name,
                  boolean matchSubclasses)

Look up an attribute.

Parameters:

name - The attribute.

matchSubclasses - If true, then attributes whose types are subclasses of name’s type will also match.

Returns:

The attribute’s index, or a negative value if it does not exist. Nonexistence is further differentiated with -1 for no attribute, -2 for type mismatch.

lookup

public int lookup(java.lang.String name)

Look up an attribute.

Parameters:

name - The attribute name.

Returns:

The attribute’s index, or a negative value if it does not exist.

getAttribute

public TypedName<?> getAttribute(int idx)

Get the type name for an attribute by index.

Parameters:

idx - The attribute index.

Returns:

The type name.

iterator

public java.util.Iterator<TypedName<?>> iterator()

Specified by:

iterator in interface java.lang.Iterable<TypedName<?>>

Specified by:

iterator in interface java.util.Collection<TypedName<?>>

Specified by:

iterator in interface java.util.Set<TypedName<?>>

Specified by:

iterator in class java.util.AbstractCollection<TypedName<?>>

contains

public boolean contains(java.lang.Object o)

Specified by:

contains in interface java.util.Collection<TypedName<?>>

Specified by:

contains in interface java.util.Set<TypedName<?>>

Overrides:

contains in class java.util.AbstractCollection<TypedName<?>>

size

public int size()

Get the number of attributes in this set.

Specified by:

size in interface java.util.Collection<TypedName<?>>

Specified by:

size in interface java.util.Set<TypedName<?>>

Specified by:

size in class java.util.AbstractCollection<TypedName<?>>

Returns:

The number of attributes in this set.

nameSet

public java.util.Set<java.lang.String> nameSet()

Get a set-of-strings view of this attribute set.

Returns:

The A set-of-strings view of the attribute set.