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+/*
+ * Copyright (C) 2010 The Guava Authors
+ *
+ * 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.
+ */
+
+package com.google.common.collect;
+
+import com.google.common.annotations.Beta;
+import com.google.common.annotations.GwtCompatible;
+
+import java.util.NoSuchElementException;
+
+import javax.annotation.Nullable;
+
+/**
+ * This class provides a skeletal implementation of the {@code Iterator}
+ * interface for sequences whose next element can always be derived from the
+ * previous element. Null elements are not supported, nor is the
+ * {@link #remove()} method.
+ *
+ * <p>Example: <pre> {@code
+ *
+ * Iterator<Integer> powersOfTwo = new AbstractLinkedIterator<Integer>(1) {
+ * protected Integer computeNext(Integer previous) {
+ * return (previous == 1 << 30) ? null : previous * 2;
+ * }
+ * };}</pre>
+ *
+ * @author Chris Povirk
+ * @since 8.0
+ * @deprecated This class has been renamed {@link AbstractSequentialIterator}.
+ * This class is scheduled to be removed in Guava release 13.0.
+ */
+@Beta
+@Deprecated
+@GwtCompatible
+public abstract class AbstractLinkedIterator<T>
+ extends UnmodifiableIterator<T> {
+ private T nextOrNull;
+
+ /**
+ * Creates a new iterator with the given first element, or, if {@code
+ * firstOrNull} is null, creates a new empty iterator.
+ */
+ protected AbstractLinkedIterator(@Nullable T firstOrNull) {
+ this.nextOrNull = firstOrNull;
+ }
+
+ /**
+ * Returns the element that follows {@code previous}, or returns {@code null}
+ * if no elements remain. This method is invoked during each call to
+ * {@link #next()} in order to compute the result of a <i>future</i> call to
+ * {@code next()}.
+ */
+ protected abstract T computeNext(T previous);
+
+ @Override
+ public final boolean hasNext() {
+ return nextOrNull != null;
+ }
+
+ @Override
+ public final T next() {
+ if (!hasNext()) {
+ throw new NoSuchElementException();
+ }
+ try {
+ return nextOrNull;
+ } finally {
+ nextOrNull = computeNext(nextOrNull);
+ }
+ }
+}