Dépôt officiel du code source de l'ERP OpenConcerto

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 * 
 * Copyright 2011 OpenConcerto, by ILM Informatique. All rights reserved.
 * 
 * The contents of this file are subject to the terms of the GNU General Public License Version 3
 * only ("GPL"). You may not use this file except in compliance with the License. You can obtain a
 * copy of the License at http://www.gnu.org/licenses/gpl-3.0.html See the License for the specific
 * language governing permissions and limitations under the License.
 * 
 * When distributing the software, include this License Header Notice in each file.
 */
 
 package org.openconcerto.utils.cc;

import org.openconcerto.utils.CollectionUtils;
import org.openconcerto.utils.cache.LRUMap;
import org.openconcerto.utils.cache.Memoizer;

import java.util.Map;

import net.jcip.annotations.NotThreadSafe;

/**
 * Allow to cache the result of a function.
 * 
 * @author sylvain
 *
 * @param <K> the type of the function parameter.
 * @param <V> the type of the function result.
 * @param <X> the type of the function exception.
 * @see LRUMap to limit cache size.
 * @see Memoizer for a thread-safe class with concurrent creation of entries.
 */
@NotThreadSafe
public class CachedTransformer<K, V, X extends Exception> implements ITransformerExn<K, V, X> {

    private final Map<K, V> map;
    private final boolean allowNullValue;
    private final ITransformerExn<K, V, X> function;

    public CachedTransformer(final Map<K, V> map, final ITransformerExn<K, V, X> function) {
        this(map, function, false);
    }

    public CachedTransformer(final Map<K, V> map, final ITransformerExn<K, V, X> function, final boolean allowNullValue) {
        this.map = map;
        this.function = function;
        this.allowNullValue = allowNullValue;
    }

    @Override
    public final V transformChecked(K key) throws X {
        return this.get(key);
    }

    public V get(K key) throws X {
        return CollectionUtils.computeIfAbsent(this.map, key, this.function, this.allowNullValue);
    }
}