Module org.apache.lucene.core

Package org.apache.lucene.util

Class AttributeFactory

java.lang.Object

org.apache.lucene.util.AttributeFactory

Direct Known Subclasses:

AttributeFactory.DefaultAttributeFactory, AttributeFactory.StaticImplementationAttributeFactory

public abstract class AttributeFactory
extends Object

An AttributeFactory creates instances of AttributeImpls.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static final class	AttributeFactory.DefaultAttributeFactory
static class	AttributeFactory.StaticImplementationAttributeFactory<A extends AttributeImpl>	Expert: AttributeFactory returning an instance of the given clazz for the attributes it implements.

Field Summary

Fields

Modifier and Type	Field	Description
static final AttributeFactory	DEFAULT_ATTRIBUTE_FACTORY	This is the default factory that creates AttributeImpls using the class name of the supplied Attribute interface class by appending Impl to it.
private static final MethodHandles.Lookup	lookup
private static final MethodType	NO_ARG_CTOR
private static final MethodType	NO_ARG_RETURNING_ATTRIBUTEIMPL

Constructor Summary

Constructors

Constructor	Description
AttributeFactory()

Method Summary

Modifier and Type	Method	Description
abstract AttributeImpl	createAttributeInstance(Class<? extends Attribute> attClass)	Returns an AttributeImpl for the supplied Attribute interface class.
(package private) static final MethodHandle	findAttributeImplCtor(Class<? extends AttributeImpl> clazz)	Returns a correctly typed MethodHandle for the no-arg ctor of the given class.
static <A extends AttributeImpl> AttributeFactory	getStaticImplementation(AttributeFactory delegate, Class<A> clazz)	Returns an AttributeFactory returning an instance of the given clazz for the attributes it implements.

Methods inherited from class java.lang.Object

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

Field Details

lookup

private static final MethodHandles.Lookup lookup

NO_ARG_CTOR

private static final MethodType NO_ARG_CTOR

NO_ARG_RETURNING_ATTRIBUTEIMPL

private static final MethodType NO_ARG_RETURNING_ATTRIBUTEIMPL

DEFAULT_ATTRIBUTE_FACTORY

public static final AttributeFactory DEFAULT_ATTRIBUTE_FACTORY

This is the default factory that creates AttributeImpls using the class name of the supplied Attribute interface class by appending Impl to it.

Constructor Details

AttributeFactory

public AttributeFactory()

Method Details

createAttributeInstance

public abstract AttributeImpl createAttributeInstance(Class<? extends Attribute> attClass)
                                               throws UndeclaredThrowableException

Returns an AttributeImpl for the supplied Attribute interface class.

Throws:

UndeclaredThrowableException - A wrapper runtime exception thrown if the constructor of the attribute class throws a checked exception. Note that attributes should not throw or declare checked exceptions; this may be verified and fail early in the future.

findAttributeImplCtor

static final MethodHandle findAttributeImplCtor(Class<? extends AttributeImpl> clazz)

Returns a correctly typed MethodHandle for the no-arg ctor of the given class.

getStaticImplementation

public static <A extends AttributeImpl>
AttributeFactory getStaticImplementation(AttributeFactory delegate,
 Class<A> clazz)

Returns an AttributeFactory returning an instance of the given clazz for the attributes it implements. The given clazz must have a public no-arg constructor. For all other attributes it calls the given delegate factory as fallback. This method can be used to prefer a specific AttributeImpl which combines multiple attributes over separate classes.

Please save instances created by this method in a static final field, because on each call, this does reflection for creating a MethodHandle.