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/*-
* ============LICENSE_START=======================================================
* VID
* ================================================================================
* Copyright (C) 2017 - 2019 AT&T Intellectual Property. 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.
* ============LICENSE_END=========================================================
*/
package org.onap.vid.utils;
import java.util.Iterator;
import java.util.Spliterator;
import java.util.Spliterators;
import java.util.function.Consumer;
import java.util.function.Predicate;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;
public class Streams {
private Streams() {
// hide the implicit public constructor
}
public static <R> Predicate<R> not(Predicate<R> predicate) {
return predicate.negate();
}
public static <T> Stream<T> fromIterator(final Iterator<T> iterator) {
Iterable<T> iterable = () -> iterator;
return StreamSupport.stream(iterable.spliterator(), false);
}
public static <T> Stream<T> fromIterable(final Iterable<T> iterable) {
return StreamSupport.stream(iterable.spliterator(), false);
}
// https://stackoverflow.com/questions/20746429/limit-a-stream-by-a-predicate
private static <T> Spliterator<T> takeWhile(
Spliterator<T> splitr, Predicate<? super T> predicate) {
return new Spliterators.AbstractSpliterator<T>(splitr.estimateSize(), 0) {
boolean stillGoing = true;
@Override public boolean tryAdvance(Consumer<? super T> consumer) {
if (stillGoing) {
boolean hadNext = splitr.tryAdvance(elem -> {
if (predicate.test(elem)) {
consumer.accept(elem);
} else {
stillGoing = false;
}
});
return hadNext && stillGoing;
}
return false;
}
};
}
public static <T> Stream<T> takeWhile(Stream<T> stream, Predicate<? super T> predicate) {
return StreamSupport.stream(takeWhile(stream.spliterator(), predicate), false);
}
}
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