hu.akarnokd.asyncenum.AsyncRepeatCallable Maven / Gradle / Ivy
/*
* Copyright 2017 David Karnok
*
* 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 hu.akarnokd.asyncenum;
import java.util.concurrent.*;
final class AsyncRepeatCallable implements AsyncEnumerable {
final Callable extends T> callable;
AsyncRepeatCallable(Callable extends T> callable) {
this.callable = callable;
}
@Override
public AsyncEnumerator enumerator() {
return new RepeatCallableEnumerator<>(callable);
}
static final class RepeatCallableEnumerator implements AsyncEnumerator {
final Callable extends T> callable;
T result;
RepeatCallableEnumerator(Callable extends T> callable) {
this.callable = callable;
}
@Override
public CompletionStage moveNext() {
result = null;
try {
result = callable.call();
} catch (Exception ex) {
return CompletableFuture.failedStage(ex);
}
return TRUE;
}
@Override
public T current() {
return result;
}
@Override
public void cancel() {
// No action, consumer should stop calling moveNext().
}
}
}