zotmc.collect.FallbackingMap.java Source code

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Here is the source code for zotmc.collect.FallbackingMap.java

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/*
 * Copyright (c) 2014, Zothf, All rights reserved.
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3.0 of the License, or (at your option) any later version.
 * 
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 * 
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library.
 */

package zotmc.collect;

import java.util.Map;

import zotmc.collect.delegate.DelegateMap;

import com.google.common.base.Function;
import com.google.common.collect.Maps;

/**
 * A map which has default values according to the function provided.</br>
 * 
 * @author zot
 */
public abstract class FallbackingMap<K, V> extends DelegateMap<K, V> implements FunctionMap<K, V> {

    public static <K, V> FallbackingMap<K, V> create(final Function<K, V> function) {
        final Map<K, V> delegatee = Maps.newHashMap();

        return new FallbackingMap<K, V>() {
            @Override
            protected Map<K, V> delegatee() {
                return delegatee;
            }

            @Override
            public Function<K, V> function() {
                return function;
            }
        };
    }

    protected abstract Function<K, V> function();

    @Override
    public V put(K key, V value) {
        V ret = super.put(key, value);
        return ret != null ? ret : function().apply(key);
    }

    @Override
    public V remove(Object key) {
        V ret = super.remove(key);
        if (ret == null)
            try {
                ret = function().apply(castKey(key));
            } catch (ClassCastException ignored) {
            }
        return ret;
    }

    @Override
    public void set(K key, V value) {
        super.put(key, value);
    }

    @Override
    public void unset(K key) {
        super.remove(key);
    }

    @Override
    public V apply(K input) {
        V ret = super.get(input);
        return ret != null ? ret : function().apply(input);
    }

    @Override
    public V get(Object key) {
        V ret = super.get(key);
        if (ret == null)
            try {
                ret = function().apply(castKey(key));
            } catch (ClassCastException ignored) {
            }
        return ret;
    }

}