81 lines
2.2 KiB
Java
81 lines
2.2 KiB
Java
// SPDX-FileCopyrightText: 2021 Paul Schaub <vanitasvitae@fsfe.org>
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//
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// SPDX-License-Identifier: Apache-2.0
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package org.pgpainless.util;
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import javax.annotation.Nonnull;
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import java.lang.reflect.Array;
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import java.util.ArrayList;
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import java.util.Collection;
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import java.util.Iterator;
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import java.util.List;
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public final class CollectionUtils {
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private CollectionUtils() {
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}
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/**
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* Return all items returned by the {@link Iterator} as a {@link List}.
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*
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* @param iterator iterator
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* @param <I> type
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* @return list
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*/
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@Nonnull
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public static <I> List<I> iteratorToList(@Nonnull Iterator<I> iterator) {
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List<I> items = new ArrayList<>();
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while (iterator.hasNext()) {
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I item = iterator.next();
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items.add(item);
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}
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return items;
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}
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/**
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* Return a new array which contains <pre>t</pre> as first element, followed by the elements of <pre>ts</pre>.
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* @param t head
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* @param ts tail
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* @param <T> type
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* @return t and ts as array
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*/
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@Nonnull
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public static <T> T[] concat(@Nonnull T t, @Nonnull T[] ts) {
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T[] concat = (T[]) Array.newInstance(t.getClass(), ts.length + 1);
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concat[0] = t;
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System.arraycopy(ts, 0, concat, 1, ts.length);
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return concat;
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}
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/**
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* Return true, if the given array <pre>ts</pre> contains the element <pre>t</pre>.
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* @param ts elements
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* @param t searched element
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* @param <T> type
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* @return true if ts contains t, false otherwise
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*/
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public static <T> boolean contains(@Nonnull T[] ts, @Nonnull T t) {
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for (T i : ts) {
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if (i.equals(t)) {
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return true;
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}
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}
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return false;
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}
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/**
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* Add all items from the iterator to the collection.
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*
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* @param <T> type of item
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* @param iterator iterator to gather items from
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* @param collection collection to add items to
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*/
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public static <T> void addAll(@Nonnull Iterator<T> iterator, @Nonnull Collection<T> collection) {
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while (iterator.hasNext()) {
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collection.add(iterator.next());
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}
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}
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}
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