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fix review comments rebase on master fix checkstyle error use single class imports
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src/main/java/org/apache/commons/collections4/PairedIterable.java
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| /* | ||
| * Licensed to the Apache Software Foundation (ASF) under one or more | ||
| * contributor license agreements. See the NOTICE file distributed with | ||
| * this work for additional information regarding copyright ownership. | ||
| * The ASF 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.apache.commons.collections4; | ||
|
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| import org.apache.commons.collections4.iterators.PairedIterator; | ||
| import org.apache.commons.collections4.iterators.PairedIterator.PairedItem; | ||
|
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| import java.util.Iterator; | ||
| import java.util.stream.Stream; | ||
| import java.util.stream.StreamSupport; | ||
|
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| import static java.util.Objects.requireNonNull; | ||
|
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| /** | ||
| * Provides iteration over the elements contained in a pair of Iterables in-tandem. | ||
| * | ||
| * <p> | ||
| * Given two {@link Iterable} instances {@code A} and {@code B}, the {@link #iterator} method on this | ||
| * iterator provide a Pair of {@code A.next()} and {@code B.next()} until one of the iterators is | ||
| * exhausted. | ||
| * </p> | ||
| * This can simplify zipping over two iterables using the for-each construct. | ||
| * Example usage: | ||
| * <pre>{@code | ||
| * List<Integer> studentIds = ... | ||
| * List<String> studentNames = ... | ||
| * | ||
| * for (PairedItem<Integer, String> items : PairedIterable.of(studentIds, studentNames) { | ||
| * Integer studentId = item.getLeft(); | ||
| * String studentName = item.getRight(); | ||
| * ... | ||
| * } | ||
| * }</pre> | ||
| * | ||
| * @param <L> the left elements' type | ||
| * @param <R> the right elements' type | ||
| * @since 4.5 | ||
| */ | ||
| public class PairedIterable<L, R> implements Iterable<PairedItem<L, R>> { | ||
|
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| /** | ||
| * The left {@link Iterable}s to evaluate. | ||
| */ | ||
| private final Iterable<L> leftIterable; | ||
|
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| /** | ||
| * The right {@link Iterable}s to evaluate. | ||
| */ | ||
| private final Iterable<R> rightIterable; | ||
|
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| /** | ||
| * Constructs a new {@code PairedIterable} that will provide iteration over two given iterables. | ||
| * | ||
| * @param leftIterable the iterable for the left side element. | ||
| * @param rightIterable the iterable for the right side element. | ||
| * @throws NullPointerException if either iterator is null | ||
| * @since 4.5 | ||
| */ | ||
| public PairedIterable(Iterable<L> leftIterable, Iterable<R> rightIterable) { | ||
| this.leftIterable = requireNonNull(leftIterable); | ||
| this.rightIterable = requireNonNull(rightIterable); | ||
| } | ||
|
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| /** | ||
| * Convenience static factory to construct the PairedIterable from provided | ||
| * {@link Iterable} sources. | ||
| * | ||
| * @param leftIterable the iterable for the left side element. | ||
| * @param rightIterable the iterable for the right side element. | ||
| * @return the Iterable to iterate over the elements derived from the provided iterables. | ||
| * @throws NullPointerException if either iterables is null | ||
| * @since 4.5 | ||
| */ | ||
| public static <L, R> PairedIterable<L, R> of(Iterable<L> leftIterable, Iterable<R> rightIterable) { | ||
| return new PairedIterable<>(leftIterable, rightIterable); | ||
| } | ||
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| @Override | ||
| public Iterator<PairedItem<L, R>> iterator() { | ||
| return PairedIterator.ofIterables(leftIterable, rightIterable); | ||
| } | ||
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| public Stream<PairedItem<L, R>> stream() { | ||
| return StreamSupport.stream(spliterator(), false); | ||
| } | ||
| } |
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src/main/java/org/apache/commons/collections4/iterators/PairedIterator.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,169 @@ | ||
| /* | ||
| * Licensed to the Apache Software Foundation (ASF) under one or more | ||
| * contributor license agreements. See the NOTICE file distributed with | ||
| * this work for additional information regarding copyright ownership. | ||
| * The ASF 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.apache.commons.collections4.iterators; | ||
|
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| import static java.util.Objects.requireNonNull; | ||
|
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| import java.util.Iterator; | ||
| import java.util.NoSuchElementException; | ||
| import org.apache.commons.collections4.iterators.PairedIterator.PairedItem; | ||
|
|
||
| /** | ||
| * Provides a iteration over the elements contained in a pair of Iterators. | ||
| * | ||
| * <p> | ||
| * Given two {@link Iterator} instances {@code A} and {@code B}, the {@link #next} method on this | ||
| * iterator provide a Pair of {@code A.next()} and {@code B.next()} until one of the iterators is | ||
| * exhausted. | ||
| * </p> | ||
| * Example usage: | ||
| * <pre>{@code | ||
| * List<Integer> studentIds = ... | ||
| * List<String> studentNames = ... | ||
| * | ||
| * PairedIterator<PairedItem<Integer, String>> pairedIterator = | ||
| * PairedIterator.ofIterables(studentIds, studentNames); | ||
| * | ||
| * while (pairedIterator.hasNext()) { | ||
| * PairedItem<Integer, String> item = pairedIterator.next(); | ||
| * ... | ||
| * } | ||
| * }</pre> | ||
| * | ||
| * @param <L> the left elements' type | ||
| * @param <R> the right elements' type | ||
| * @since 4.5 | ||
| */ | ||
| public class PairedIterator<L, R> implements Iterator<PairedItem<L, R>> { | ||
|
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| /** | ||
| * The left {@link Iterator}s to evaluate. | ||
| */ | ||
| private final Iterator<L> leftIterator; | ||
|
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| /** | ||
| * The right {@link Iterator}s to evaluate. | ||
| */ | ||
| private final Iterator<R> rightIterator; | ||
|
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| /** | ||
| * Constructs a new {@code ZipPairIterator} that will provide iteration over the two given | ||
| * iterators. | ||
| * | ||
| * @param leftIterator the iterator for the left side element. | ||
| * @param rightIterator the iterator for the right side element. | ||
| * @throws NullPointerException if either iterator is null | ||
| * @since 4.5 | ||
| */ | ||
| public PairedIterator(Iterator<L> leftIterator, Iterator<R> rightIterator) { | ||
| this.leftIterator = requireNonNull(leftIterator); | ||
| this.rightIterator = requireNonNull(rightIterator); | ||
| } | ||
|
|
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| /** | ||
| * Convenience static factory to construct the ZipPairIterator | ||
| * | ||
| * @param leftIterator the iterator for the left side element. | ||
| * @param rightIterator the iterator for the right side element. | ||
| * @return the iterator to iterate over the provided iterators. | ||
| * @throws NullPointerException if either iterator is null | ||
| * @since 4.5 | ||
| */ | ||
| public static <L, R> PairedIterator<L, R> of(Iterator<L> leftIterator, Iterator<R> rightIterator) { | ||
| return new PairedIterator<>(leftIterator, rightIterator); | ||
| } | ||
|
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| /** | ||
| * Convenience static factory to construct the ZipPairIterator from any {@link Iterable} sources. | ||
| * | ||
| * @param leftIterable the iterable for the left side element. | ||
| * @param rightIterable the iterable for the right side element. | ||
| * @return the iterator to iterate over the iterators derived from the provided iterables. | ||
| * @throws NullPointerException if either iterables is null | ||
| * @since 4.5 | ||
| */ | ||
| public static <L, R> PairedIterator<L, R> ofIterables(Iterable<L> leftIterable, Iterable<R> rightIterable) { | ||
| return of(requireNonNull(leftIterable).iterator(), requireNonNull(rightIterable).iterator()); | ||
| } | ||
|
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| /** | ||
| * Returns {@code true} if both the child iterators have remaining elements. | ||
| * | ||
| * @return true if both the child iterators have remaining elements | ||
| */ | ||
| @Override | ||
| public boolean hasNext() { | ||
| return leftIterator.hasNext() && rightIterator.hasNext(); | ||
| } | ||
|
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| /** | ||
| * Returns the next elements from both the child iterators. | ||
| * | ||
| * @return the next elements from both the iterators. | ||
| * @throws NoSuchElementException if any one child iterator is exhausted. | ||
| */ | ||
| @Override | ||
| public PairedItem<L, R> next() { | ||
| if (!hasNext()) { | ||
| throw new NoSuchElementException(); | ||
| } | ||
| return PairedItem.of(leftIterator.next(), rightIterator.next()); | ||
| } | ||
|
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| /** | ||
| * An immutable tuple class to represent elements from both the iterators. | ||
| * | ||
| * @param <L> the left elements' type | ||
| * @param <R> the right elements' type | ||
| * @since 4.5 | ||
| */ | ||
| public static final class PairedItem<L, R> { | ||
|
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| private final L leftItem; | ||
|
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| private final R rightItem; | ||
|
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| private PairedItem(L leftItem, R rightItem) { | ||
| this.leftItem = leftItem; | ||
| this.rightItem = rightItem; | ||
| } | ||
|
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| /** | ||
| * Convenience static factory method to construct the tuple pair. | ||
| * | ||
| * @param left the left element | ||
| * @param right the right element | ||
| * @return the Immutable tuple pair of two elements. | ||
| */ | ||
| private static <L, R> PairedItem<L, R> of(L left, R right) { | ||
| return new PairedItem<>(left, right); | ||
| } | ||
|
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| public L getLeftItem() { | ||
| return leftItem; | ||
| } | ||
|
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| public R getRightItem() { | ||
| return rightItem; | ||
| } | ||
|
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| @Override | ||
| public String toString() { | ||
| return String.format("{%s, %s}", leftItem, rightItem); | ||
| } | ||
| } | ||
| } |
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