reactor.rx.action.transformation.ScanAction Maven / Gradle / Ivy
/*
* Copyright (c) 2011-2014 Pivotal Software, Inc.
*
* 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.rx.action.transformation;
import reactor.fn.BiFunction;
import reactor.rx.action.Action;
/**
* @author Stephane Maldini
* @since 1.1, 2.0
*/
public class ScanAction extends Action {
private final BiFunction fn;
private final A initialValue;
private A acc;
private boolean initialized = false;
private static final Object NOVALUE_SENTINEL = new Object();
@SuppressWarnings("unchecked")
public ScanAction(A initial, BiFunction fn) {
this.initialValue = initial == null ? (A) NOVALUE_SENTINEL : initial;
this.acc = initialValue;
this.fn = fn;
}
/*final AtomicBoolean once = new AtomicBoolean();
final AtomicBoolean excessive = new AtomicBoolean();
@Override
public void requestMore(long n) {
if (once.compareAndSet(false, true)) {
if (acc == NOVALUE_SENTINEL || n == Long.MAX_VALUE) {
super.requestMore(n);
} else if (n == 1) {
excessive.set(true);
super.requestMore(1);
} else {
super.requestMore(n - 1);
}
} else {
if (excessive.compareAndSet(true, false) && n != Long.MAX_VALUE) {
super.requestMore(n - 1);
} else {
super.requestMore(n);
}
}
}*/
@Override
@SuppressWarnings("unchecked")
protected void doNext(T ev) {
checkInit();
if (this.acc == NOVALUE_SENTINEL) {
this.acc = (A) ev;
} else {
this.acc = fn.apply(acc, ev);
}
broadcastNext(acc);
}
@Override
protected void doComplete() {
checkInit();
super.doComplete();
}
private void checkInit() {
if (!initialized) {
initialized = true;
if (initialValue != NOVALUE_SENTINEL) {
broadcastNext(initialValue);
}
}
}
}