/*
* 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.
Subscription;
import reactor.core.
CoreSubscriber;
import reactor.core.
Fuseable;
import reactor.util.annotation.
Nullable;
/**
* Emits only the element at the given index position or signals a
* default value if specified or IndexOutOfBoundsException if the sequence is shorter.
*
* @param <T> the value type
* @see <a href="https://github.com/reactor/reactive-streams-commons">Reactive-Streams-Commons</a>
*/
final class
MonoElementAt<T> extends
MonoFromFluxOperator<T, T>
implements
Fuseable {
final long
index;
final T
defaultValue;
MonoElementAt(
Flux<? extends T>
source, long
index) {
super(
source);
if (
index < 0) {
throw new
IndexOutOfBoundsException("index >= required but it was " +
index);
}
this.
index =
index;
this.
defaultValue = null;
}
MonoElementAt(
Flux<? extends T>
source, long
index, T
defaultValue) {
super(
source);
if (
index < 0) {
throw new
IndexOutOfBoundsException("index >= required but it was " +
index);
}
this.
index =
index;
this.
defaultValue =
Objects.
requireNonNull(
defaultValue, "defaultValue");
}
@
Override
public void
subscribe(
CoreSubscriber<? super T>
actual) {
source.
subscribe(new
ElementAtSubscriber<>(
actual,
index,
defaultValue));
}
static final class
ElementAtSubscriber<T>
extends
Operators.
MonoSubscriber<T, T> {
final T
defaultValue;
long
index;
Subscription s;
boolean
done;
ElementAtSubscriber(
CoreSubscriber<? super T>
actual, long
index,
T
defaultValue) {
super(
actual);
this.
index =
index;
this.
defaultValue =
defaultValue;
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
TERMINATED) return
done;
if (
key ==
Attr.
PARENT) return
s;
return super.scanUnsafe(
key);
}
@
Override
public void
request(long
n) {
super.request(
n);
if (
n > 0L) {
s.
request(
Long.
MAX_VALUE);
}
}
@
Override
public void
cancel() {
super.cancel();
s.
cancel();
}
@
Override
public void
onSubscribe(
Subscription s) {
if (
Operators.
validate(this.
s,
s)) {
this.
s =
s;
actual.
onSubscribe(this);
}
}
@
Override
public void
onNext(T
t) {
if (
done) {
Operators.
onNextDropped(
t,
actual.
currentContext());
return;
}
long
i =
index;
if (
i == 0) {
done = true;
s.
cancel();
actual.
onNext(
t);
actual.
onComplete();
return;
}
index =
i - 1;
Operators.
onDiscard(
t,
actual.
currentContext()); //FIXME cache currentcontext
}
@
Override
public void
onError(
Throwable t) {
if (
done) {
Operators.
onErrorDropped(
t,
actual.
currentContext());
return;
}
done = true;
actual.
onError(
t);
}
@
Override
public void
onComplete() {
if (
done) {
return;
}
done = true;
if(
defaultValue != null) {
complete(
defaultValue);
}
else{
actual.
onError(
Operators.
onOperatorError(new
IndexOutOfBoundsException(),
actual.
currentContext()));
}
}
}
}