src/main/decaf/util/LRUCache.h

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.
 */

#ifndef _DECAF_UTIL_LRUCACHE_H_
#define _DECAF_UTIL_LRUCACHE_H_

#include <decaf/util/Config.h>

#include <decaf/util/LinkedHashMap.h>
#include <decaf/lang/exceptions/IllegalArgumentException.h>

namespace decaf {
namespace util {

    template<typename K, typename V, typename HASHCODE = HashCode<K> >
    class LRUCache : public LinkedHashMap<K, V, HASHCODE> {
    protected:

        int maxCacheSize;

    public:


        LRUCache() : LinkedHashMap<K, V, HASHCODE>(0, 0.75f, true), maxCacheSize(10000) {}

        LRUCache(int maximumCacheSize) :
            LinkedHashMap<K, V, HASHCODE>(0, 0.75f, true), maxCacheSize(maximumCacheSize) {

            if (maximumCacheSize <= 0) {
                throw decaf::lang::exceptions::IllegalArgumentException(
                        __FILE__, __LINE__, "Cache size must be greater than zero.");
            }
        }

        LRUCache(int initialCapacity, int maximumCacheSize, float loadFactor, bool accessOrder) :
            LinkedHashMap<K, V, HASHCODE>(initialCapacity, loadFactor, accessOrder), maxCacheSize(maximumCacheSize) {

            if (maximumCacheSize <= 0) {
                throw decaf::lang::exceptions::IllegalArgumentException(
                        __FILE__, __LINE__, "Cache size must be greater than zero.");
            }
        }

        virtual ~LRUCache() {}

        int getMaxCacheSize() const {
            return maxCacheSize;
        }

        void setMaxCacheSize(int size) {
            if (size <= 0) {
                throw decaf::lang::exceptions::IllegalArgumentException(
                        __FILE__, __LINE__, "Cache size must be greater than zero.");
            }

            this->maxCacheSize = size;
        }

    protected:

        virtual bool removeEldestEntry(const MapEntry<K, V>& eldest DECAF_UNUSED) {
            if (this->size() > maxCacheSize) {
                return true;
            }
            return false;
        }

    };

}}

#endif /* _DECAF_UTIL_LRUCACHE_H_ */

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