64 lines
1.7 KiB
Java
64 lines
1.7 KiB
Java
package fr.pandacube.lib.core.util;
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import java.util.ArrayList;
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import java.util.Arrays;
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import java.util.Collection;
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import java.util.Iterator;
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import java.util.NoSuchElementException;
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public class IteratorIterator<T> implements Iterator<T> {
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public static <T> IteratorIterator<T> ofCollectionOfIterable(Collection<Iterable<T>> coll) {
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return new IteratorIterator<>(coll.stream().map(i -> i.iterator()).iterator());
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}
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public static <T> IteratorIterator<T> ofCollectionOfIterator(Collection<Iterator<T>> coll) {
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return new IteratorIterator<>(new ArrayList<>(coll).iterator());
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}
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@SafeVarargs
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public static <T> IteratorIterator<T> ofArrayOfIterable(Iterable<T>... arr) {
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return new IteratorIterator<>(Arrays.stream(arr).map(i -> i.iterator()).iterator());
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}
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@SafeVarargs
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public static <T> IteratorIterator<T> ofArrayOfIterator(Iterator<T>... arr) {
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return new IteratorIterator<>(Arrays.asList(arr).iterator());
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}
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private Iterator<Iterator<T>> iterators;
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private Iterator<T> currentIterator = null;
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private IteratorIterator(Iterator<Iterator<T>> iterators) {
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this.iterators = iterators;
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}
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private void fixCurrentIterator() {
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if (currentIterator != null && !currentIterator.hasNext()) {
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currentIterator = null;
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}
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}
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private void fixState() {
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fixCurrentIterator();
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while (currentIterator == null && iterators.hasNext()) {
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currentIterator = iterators.next();
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fixCurrentIterator();
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}
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}
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@Override
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public boolean hasNext() {
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fixState();
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return currentIterator != null && currentIterator.hasNext();
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}
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@Override
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public T next() {
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if (!hasNext())
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throw new NoSuchElementException("No next value found in iterator.");
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return currentIterator.next();
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}
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}
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