com.sk89q.guavabackport.cache.AbstractSequentialIterator.java Source code

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Here is the source code for com.sk89q.guavabackport.cache.AbstractSequentialIterator.java

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/*
 * Copyright (C) 2008 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.sk89q.guavabackport.cache;

import java.util.NoSuchElementException;
import javax.annotation.Nullable;
import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.UnmodifiableIterator;

@GwtCompatible
abstract class AbstractSequentialIterator<T> extends UnmodifiableIterator<T> {
    private T nextOrNull;

    protected AbstractSequentialIterator(@Nullable final T firstOrNull) {
        this.nextOrNull = firstOrNull;
    }

    protected abstract T computeNext(final T p0);

    public final boolean hasNext() {
        return this.nextOrNull != null;
    }

    public final T next() {
        if (!this.hasNext()) {
            throw new NoSuchElementException();
        }
        try {
            return this.nextOrNull;
        } finally {
            this.nextOrNull = this.computeNext(this.nextOrNull);
        }
    }
}