/*
 * Copyright Red Hat, Inc. and/or its affiliates
 * and other contributors as indicated by the @author tags and
 * the COPYRIGHT.txt file distributed with this work.
 *
 * 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 org.teiid.core.util;

import java.util.LinkedHashMap;
import java.util.Map.Entry;

/**
 * This class replaces a verbose legacy implementation of LRUCaching.
 */
public class LRUCache<K, V> extends LinkedHashMap<K, V> {

    /**
     * Default amount of space in the cache
     */
    protected static final int DEFAULT_SPACELIMIT = 100;

    protected int maxSize;

    /**
     * Creates a new cache.  Size of cache is defined by
     * <code>DEFAULT_SPACELIMIT</code>.
     */
    public LRUCache() {
        this(DEFAULT_SPACELIMIT);
    }

    public LRUCache(int maxSize) {
        super(16, .75f, true);
        this.maxSize = maxSize;
    }

    @Override
    protected boolean removeEldestEntry(Entry<K, V> eldest) {
        return size() > maxSize;
    }

    public int getSpaceLimit() {
        return maxSize;
    }

}
