org.elasticsearch.common.util.iterable.Iterables Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of elasticsearch Show documentation
Show all versions of elasticsearch Show documentation
Elasticsearch subproject :server
/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch licenses this file to you 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 org.elasticsearch.common.util.iterable;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Objects;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;
public class Iterables {
public Iterables() {
}
public static Iterable concat(Iterable... inputs) {
Objects.requireNonNull(inputs);
return new ConcatenatedIterable(inputs);
}
static class ConcatenatedIterable implements Iterable {
private final Iterable[] inputs;
ConcatenatedIterable(Iterable[] inputs) {
this.inputs = Arrays.copyOf(inputs, inputs.length);
}
@Override
public Iterator iterator() {
return Stream
.of(inputs)
.map(it -> StreamSupport.stream(it.spliterator(), false))
.reduce(Stream::concat)
.orElseGet(Stream::empty).iterator();
}
}
/** Flattens the two level {@code Iterable} into a single {@code Iterable}. Note that this pre-caches the values from the outer {@code
* Iterable}, but not the values from the inner one. */
public static Iterable flatten(Iterable> inputs) {
Objects.requireNonNull(inputs);
return new FlattenedIterables<>(inputs);
}
static class FlattenedIterables implements Iterable {
private final Iterable> inputs;
FlattenedIterables(Iterable> inputs) {
List> list = new ArrayList<>();
for (Iterable iterable : inputs) {
list.add(iterable);
}
this.inputs = list;
}
@Override
public Iterator iterator() {
return StreamSupport
.stream(inputs.spliterator(), false)
.flatMap(s -> StreamSupport.stream(s.spliterator(), false)).iterator();
}
}
public static boolean allElementsAreEqual(Iterable left, Iterable right) {
Objects.requireNonNull(left);
Objects.requireNonNull(right);
if (left instanceof Collection && right instanceof Collection) {
Collection collection1 = (Collection) left;
Collection collection2 = (Collection) right;
if (collection1.size() != collection2.size()) {
return false;
}
}
Iterator leftIt = left.iterator();
Iterator rightIt = right.iterator();
while (true) {
if (leftIt.hasNext()) {
if (!rightIt.hasNext()) {
return false;
}
Object o1 = leftIt.next();
Object o2 = rightIt.next();
if (Objects.equals(o1, o2)) {
continue;
}
return false;
}
return !rightIt.hasNext();
}
}
public static T getFirst(Iterable collection, T defaultValue) {
Objects.requireNonNull(collection);
Iterator iterator = collection.iterator();
return iterator.hasNext() ? iterator.next() : defaultValue;
}
public static T get(Iterable iterable, int position) {
Objects.requireNonNull(iterable);
if (position < 0) {
throw new IllegalArgumentException("position >= 0");
}
if (iterable instanceof List) {
List list = (List)iterable;
if (position >= list.size()) {
throw new IndexOutOfBoundsException(Integer.toString(position));
}
return list.get(position);
} else {
Iterator it = iterable.iterator();
for (int index = 0; index < position; index++) {
if (!it.hasNext()) {
throw new IndexOutOfBoundsException(Integer.toString(position));
}
it.next();
}
if (!it.hasNext()) {
throw new IndexOutOfBoundsException(Integer.toString(position));
}
return it.next();
}
}
}