/*
* 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.
ArrayDeque;
import org.reactivestreams.
Subscription;
import reactor.core.
CoreSubscriber;
import reactor.util.annotation.
Nullable;
/**
* Skips the last N elements from the source stream.
*
* @param <T> the value type
* @see <a href="https://github.com/reactor/reactive-streams-commons">Reactive-Streams-Commons</a>
*/
final class
FluxSkipLast<T> extends
FluxOperator<T, T> {
final int
n;
FluxSkipLast(
Flux<? extends T>
source, int
n) {
super(
source);
if (
n < 0) {
throw new
IllegalArgumentException("n >= 0 required but it was " +
n);
}
this.
n =
n;
}
@
Override
public void
subscribe(
CoreSubscriber<? super T>
actual) {
source.
subscribe(new
SkipLastSubscriber<>(
actual,
n));
}
//Fixme Does not implement ConditionalSubscriber until the full chain of operators
// supports fully conditional, requesting N onSubscribe cost is offset
static final class
SkipLastSubscriber<T>
extends
ArrayDeque<T>
implements
InnerOperator<T, T> {
final
CoreSubscriber<? super T>
actual;
final int
n;
Subscription s;
SkipLastSubscriber(
CoreSubscriber<? super T>
actual, int
n) {
this.
actual =
actual;
this.
n =
n;
}
@
Override
public void
onSubscribe(
Subscription s) {
if (
Operators.
validate(this.
s,
s)) {
this.
s =
s;
actual.
onSubscribe(this);
s.
request(
n);
}
}
@
Override
public void
onNext(T
t) {
if (
size() ==
n) {
actual.
onNext(
pollFirst());
}
offerLast(
t);
}
@
Override
public void
onError(
Throwable t) {
actual.
onError(
t);
Operators.
onDiscardQueueWithClear(this,
actual.
currentContext(), null);
}
@
Override
public void
onComplete() {
actual.
onComplete();
Operators.
onDiscardQueueWithClear(this,
actual.
currentContext(), null);
}
@
Override
@
Nullable
public
Object scanUnsafe(
Attr key) {
if (
key ==
Attr.
PARENT) return
s;
if (
key ==
Attr.
PREFETCH) return
n;
if (
key ==
Attr.
BUFFERED) return
size();
return
InnerOperator.super.scanUnsafe(
key);
}
@
Override
public
CoreSubscriber<? super T>
actual() {
return
actual;
}
@
Override
public void
request(long
n) {
s.
request(
n);
}
@
Override
public void
cancel() {
s.
cancel();
Operators.
onDiscardQueueWithClear(this,
actual.
currentContext(), null);
}
}
}