dexlib2/src/main/java/org/jf/dexlib2/dexbacked/util/FixedSizeSet.java

/*
 * Copyright 2012, Google Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package org.jf.dexlib2.dexbacked.util;

import javax.annotation.Nonnull;
import java.util.AbstractSet;
import java.util.Iterator;
import java.util.NoSuchElementException;

/**
 * This provides a wrapper around AbstractSet to allow easy implementation when backed by a list that can be randomly
 * accessed.
 */
public abstract class FixedSizeSet<T> extends AbstractSet<T> {
    @Override
    public Iterator<T> iterator() {
        return new Iterator<T>() {
            int index = 0;

            @Override public boolean hasNext() { return index < size(); }
            @Override public void remove() { throw new UnsupportedOperationException(); }
            @Override
            public T next() {
                if (!hasNext()) {
                    throw new NoSuchElementException();
                }
                return readItem(index++);
            }
        };
    }

    /**
     * Reads the item at {@code index}
     * @param index The index of the item. This is guaranteed to be in [0, size)
     * @return The item at the given index
     */
    @Nonnull
    public abstract T readItem(int index);
}