rx.internal.operators

Class NotificationLite<T>

java.lang.Object

rx.internal.operators.NotificationLite<T>

Type Parameters:

T -

public final class NotificationLite<T>
extends java.lang.Object

For use in internal operators that need something like materialize and dematerialize wholly within the implementation of the operator but don't want to incur the allocation cost of actually creating Notification objects for every onNext and onCompleted.

An object is allocated inside NotificationLite.error(Throwable) to wrap the Throwable but this shouldn't affect performance because exceptions should be exceptionally rare.

It's implemented as a singleton to maintain some semblance of type safety that is completely non-existent.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	accept(Observer<? super T> o, java.lang.Object n) Unwraps the lite notification and calls the appropriate method on the Observer.
java.lang.Object	completed() Creates a lite onCompleted notification without doing any allocation.
java.lang.Object	error(java.lang.Throwable e) Create a lite onError notification.
java.lang.Throwable	getError(java.lang.Object n) Returns the Throwable corresponding to this OnError lite notification.
T	getValue(java.lang.Object n) Returns the item corresponding to this OnNext lite notification.
static <T> NotificationLite<T>	instance() Gets the NotificationLite singleton.
boolean	isCompleted(java.lang.Object n) Indicates whether or not the lite notification represents an onCompleted event.
boolean	isError(java.lang.Object n) Indicates whether or not the lite notification represents an onError event.
Notification.Kind	kind(java.lang.Object n) Indicates which variety a particular lite notification is.
java.lang.Object	next(T t) Creates a lite onNext notification for the value passed in without doing any allocation.

Methods inherited from class java.lang.Object

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

Method Detail

instance

public static <T> NotificationLite<T> instance()

Gets the NotificationLite singleton.

Returns:

the sole NotificationLite object

next

public java.lang.Object next(T t)

Creates a lite onNext notification for the value passed in without doing any allocation. Can be unwrapped and sent with the NotificationLite.accept(rx.Observer<? super T>, java.lang.Object) method.

Parameters:

t - the item emitted to onNext

Returns:

the item, or a null token representing the item if the item is null

completed

public java.lang.Object completed()

Creates a lite onCompleted notification without doing any allocation. Can be unwrapped and sent with the NotificationLite.accept(rx.Observer<? super T>, java.lang.Object) method.

Returns:

a completion token

error

public java.lang.Object error(java.lang.Throwable e)

Create a lite onError notification. This call creates an object to wrap the Throwable, but since there should only be one of these, the performance impact should be small. Can be unwrapped and sent with the NotificationLite.accept(rx.Observer<? super T>, java.lang.Object) method.

Parameters:

e - the Throwable in the onError notification

Returns:

an object encapsulating the exception

accept

public boolean accept(Observer<? super T> o,
             java.lang.Object n)

Unwraps the lite notification and calls the appropriate method on the Observer.

Parameters:

o - the Observer to call onNext, onCompleted, or onError.

n - the lite notification

Returns:

true if n represents a termination event; false otherwise

Throws:

java.lang.IllegalArgumentException - if the notification is null.

java.lang.NullPointerException - if the Observer is null.

isCompleted

public boolean isCompleted(java.lang.Object n)

Indicates whether or not the lite notification represents an onCompleted event.

Parameters:

n - the lite notification

Returns:

true if n represents an onCompleted event; false otherwise

isError

public boolean isError(java.lang.Object n)

Indicates whether or not the lite notification represents an onError event.

Parameters:

n - the lite notification

Returns:

true if n represents an onError event; false otherwise

kind

public Notification.Kind kind(java.lang.Object n)

Indicates which variety a particular lite notification is. If you need something more complex than simply calling the right method on an Observer then you can use this method to get the Notification.Kind.

Parameters:

n - the lite notification

Returns:

the Notification.Kind of lite notification n is: either Kind.OnCompleted, Kind.OnError, or Kind.OnNext

Throws:

java.lang.IllegalArgumentException - if the notification is null.

getValue

public T getValue(java.lang.Object n)

Returns the item corresponding to this OnNext lite notification. Bad things happen if you pass this an OnComplete or OnError notification type. For performance reasons, this method does not check for this, so you are expected to prevent such a mishap.

Parameters:

n - the lite notification (of type Kind.OnNext)

Returns:

the unwrapped value, which can be null

getError

public java.lang.Throwable getError(java.lang.Object n)

Returns the Throwable corresponding to this OnError lite notification. Bad things happen if you pass this an OnComplete or OnNext notification type. For performance reasons, this method does not check for this, so you are expected to prevent such a mishap.

Parameters:

n - the lite notification (of type Kind.OnError)

Returns:

the Throwable wrapped inside n