/*
* Copyright (c) 2011-2017 Pivotal Software Inc, All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package reactor.core.publisher;
import java.util.
Objects;
import org.reactivestreams.
Subscriber;
import reactor.core.
CoreSubscriber;
import reactor.core.
Fuseable;
import reactor.util.annotation.
Nullable;
/**
* A Stream that emits only one value and then complete.
* <p>
* Since the flux retains the value in a final field, any
* {@link this#subscribe(Subscriber)} will
* replay the value. This is a "Cold" fluxion.
* <p>
* Create such flux with the provided factory, E.g.:
* <pre>
* {@code
* Flux.just(1).subscribe(
* log::info,
* log::error,
* ()-> log.info("complete")
* )
* }
* </pre>
* Will log:
* <pre>
* {@code
* 1
* complete
* }
* </pre>
*
* @author Stephane Maldini
*/
final class
FluxJust<T> extends
Flux<T>
implements
Fuseable.
ScalarCallable<T>,
Fuseable,
SourceProducer<T> {
final T
value;
FluxJust(T
value) {
this.
value =
Objects.
requireNonNull(
value, "value");
}
@
Override
public T
call() throws
Exception {
return
value;
}
@
Override
public void
subscribe(final
CoreSubscriber<? super T>
actual) {
actual.
onSubscribe(new
WeakScalarSubscription<>(
value,
actual));
}
@
Override
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
BUFFERED) return 1;
return null;
}
static final class
WeakScalarSubscription<T> implements
QueueSubscription<T>,
InnerProducer<T>{
boolean
terminado;
final T
value;
final
CoreSubscriber<? super T>
actual;
WeakScalarSubscription(@
Nullable T
value,
CoreSubscriber<? super T>
actual) {
this.
value =
value;
this.
actual =
actual;
}
@
Override
public void
request(long
elements) {
if (
terminado) {
return;
}
terminado = true;
if (
value != null) {
actual.
onNext(
value);
}
actual.
onComplete();
}
@
Override
public void
cancel() {
terminado = true;
}
@
Override
public int
requestFusion(int
requestedMode) {
if ((
requestedMode &
Fuseable.
SYNC) != 0) {
return
Fuseable.
SYNC;
}
return 0;
}
@
Override
@
Nullable
public T
poll() {
if (!
terminado) {
terminado = true;
return
value;
}
return null;
}
@
Override
public boolean
isEmpty() {
return
terminado;
}
@
Override
public int
size() {
return
isEmpty() ? 0 : 1;
}
@
Override
public void
clear() {
terminado = true;
}
@
Override
public
CoreSubscriber<? super T>
actual() {
return
actual;
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
TERMINATED ||
key ==
Attr.
CANCELLED) return
terminado;
return
InnerProducer.super.scanUnsafe(
key);
}
}
}