CachingMap.java

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 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
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 * <p/>
 * http://www.apache.org/licenses/LICENSE-2.0
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package org.apache.sling.scripting.core.impl.helper;

import java.lang.ref.SoftReference;
import java.util.LinkedHashMap;
import java.util.Map;

/**
 * <p>
 * The {@code CachingMap} class offers an implementation of a {@link LinkedHashMap} that can be used for caches. The maps' values are
 * {@link SoftReference}s, such that garbage collection can be performed on the cache, if needed.
 * </p>
 * <p>
 * Read / write operations are <i>NOT</i> synchronised.
 * </p>
 *
 * @param <T> the type to which {@link SoftReference}s will be kept
 */
public class CachingMap<T> extends LinkedHashMap<String, SoftReference<T>> {

    private int capacity;

    /**
     * Creates a caching map with a maximum capacity equal to the {@code capacity} parameter.
     *
     * @param capacity the maximum capacity; if {@code capacity < 1} then this map will always remove the latest added element
     */
    public CachingMap(int capacity) {
        this.capacity = capacity;
    }

    @Override
    protected boolean removeEldestEntry(Map.Entry<String, SoftReference<T>> eldest) {
        return size() > capacity;
    }
}