/*
* 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.
NoSuchElementException;
import java.util.
Objects;
import org.reactivestreams.
Subscription;
import reactor.core.
CoreSubscriber;
import reactor.core.
Fuseable;
import reactor.util.annotation.
Nullable;
/**
* Take the very last value from a Publisher source and and emit that one.
*
* @param <T> the value type
*/
final class
MonoTakeLastOne<T> extends
MonoFromFluxOperator<T, T>
implements
Fuseable {
final T
defaultValue;
MonoTakeLastOne(
Flux<? extends T>
source) {
super(
source);
this.
defaultValue = null;
}
MonoTakeLastOne(
Flux<? extends T>
source, T
defaultValue) {
super(
source);
this.
defaultValue =
Objects.
requireNonNull(
defaultValue, "defaultValue");
}
@
Override
public void
subscribe(
CoreSubscriber<? super T>
actual) {
source.
subscribe(new
TakeLastOneSubscriber<>(
actual,
defaultValue, true));
}
static final class
TakeLastOneSubscriber<T>
extends
Operators.
MonoSubscriber<T, T> {
final boolean
mustEmit;
final T
defaultValue;
Subscription s;
TakeLastOneSubscriber(
CoreSubscriber<? super T>
actual,
@
Nullable T
defaultValue,
boolean
mustEmit) {
super(
actual);
this.
defaultValue =
defaultValue;
this.
mustEmit =
mustEmit;
}
@
Override
public void
onSubscribe(
Subscription s) {
if (
Operators.
validate(this.
s,
s)) {
this.
s =
s;
actual.
onSubscribe(this);
s.
request(
Long.
MAX_VALUE);
}
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
PARENT) return
s;
return super.scanUnsafe(
key);
}
@
Override
public void
onNext(T
t) {
T
old =
value;
value =
t;
Operators.
onDiscard(
old,
actual.
currentContext()); //FIXME cache context
}
@
Override
public void
onComplete() {
T
v =
value;
if (
v == null) {
if (
mustEmit) {
if(
defaultValue != null){
complete(
defaultValue);
}
else {
actual.
onError(
Operators.
onOperatorError(new
NoSuchElementException(
"Flux#last() didn't observe any " + "onNext signal"),
actual.
currentContext()));
}
}
else {
actual.
onComplete();
}
return;
}
complete(
v);
}
@
Override
public void
cancel() {
super.cancel();
s.
cancel();
}
@
Override
public void
setValue(T
value) {
// value is always in a field
}
}
}