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/*
 * Copyright 2010 Google Inc. All Rights Reserved.
 *
 * 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 ml.karmaconfigs.shaded.maputil;

import java.io.Serializable;
import java.util.*;

import static ml.karmaconfigs.shaded.maputil.ConcurrentLinkedHashMap.checkNotNull;

/**
 * A common set of {@link Weigher} and {@link EntryWeigher} implementations.
 *
 * @author [email protected] (Ben Manes)
 * @see 
 * http://code.google.com/p/concurrentlinkedhashmap/
 */
public final class Weighers {

    private Weighers() {
        throw new AssertionError();
    }

    /**
     * A entry weigher backed by the specified weigher. The weight of the value
     * determines the weight of the entry.
     *
     * @param weigher the weigher to be "wrapped" in a entry weigher.
     * @return A entry weigher view of the specified weigher.
     */
    public static  EntryWeigher asEntryWeigher(
            final Weigher weigher) {
        return (weigher == singleton())
                ? Weighers.entrySingleton()
                : new EntryWeigherView(weigher);
    }

    /**
     * A weigher where an entry has a weight of 1. A map bounded with
     * this weigher will evict when the number of key-value pairs exceeds the
     * capacity.
     *
     * @return A weigher where a value takes one unit of capacity.
     */
    @SuppressWarnings({"cast", "unchecked"})
    public static  EntryWeigher entrySingleton() {
        return (EntryWeigher) SingletonEntryWeigher.INSTANCE;
    }

    /**
     * A weigher where a value has a weight of 1. A map bounded with
     * this weigher will evict when the number of key-value pairs exceeds the
     * capacity.
     *
     * @return A weigher where a value takes one unit of capacity.
     */
    @SuppressWarnings({"cast", "unchecked"})
    public static  Weigher singleton() {
        return (Weigher) SingletonWeigher.INSTANCE;
    }

    /**
     * A weigher where the value is a byte array and its weight is the number of
     * bytes. A map bounded with this weigher will evict when the number of bytes
     * exceeds the capacity rather than the number of key-value pairs in the map.
     * This allows for restricting the capacity based on the memory-consumption
     * and is primarily for usage by dedicated caching servers that hold the
     * serialized data.
     * 

     * A value with a weight of 0 will be rejected by the map. If a value
     * with this weight can occur then the caller should eagerly evaluate the
     * value and treat it as a removal operation. Alternatively, a custom weigher
     * may be specified on the map to assign an empty value a positive weight.
     *
     * @return A weigher where each byte takes one unit of capacity.
     */
    public static Weigher byteArray() {
        return ByteArrayWeigher.INSTANCE;
    }

    /**
     * A weigher where the value is a {@link Iterable} and its weight is the
     * number of elements. This weigher only should be used when the alternative
     * {@link #collection()} weigher cannot be, as evaluation takes O(n) time. A
     * map bounded with this weigher will evict when the total number of elements
     * exceeds the capacity rather than the number of key-value pairs in the map.
     * 

     * A value with a weight of 0 will be rejected by the map. If a value
     * with this weight can occur then the caller should eagerly evaluate the
     * value and treat it as a removal operation. Alternatively, a custom weigher
     * may be specified on the map to assign an empty value a positive weight.
     *
     * @return A weigher where each element takes one unit of capacity.
     */
    @SuppressWarnings({"cast", "unchecked"})
    public static  Weigher> iterable() {
        return IterableWeigher.INSTANCE;
    }

    /**
     * A weigher where the value is a {@link Collection} and its weight is the
     * number of elements. A map bounded with this weigher will evict when the
     * total number of elements exceeds the capacity rather than the number of
     * key-value pairs in the map.
     * 

     * A value with a weight of 0 will be rejected by the map. If a value
     * with this weight can occur then the caller should eagerly evaluate the
     * value and treat it as a removal operation. Alternatively, a custom weigher
     * may be specified on the map to assign an empty value a positive weight.
     *
     * @return A weigher where each element takes one unit of capacity.
     */
    @SuppressWarnings({"cast", "unchecked"})
    public static  Weigher> collection() {
        return CollectionWeigher.INSTANCE;
    }

    /**
     * A weigher where the value is a {@link List} and its weight is the number
     * of elements. A map bounded with this weigher will evict when the total
     * number of elements exceeds the capacity rather than the number of
     * key-value pairs in the map.
     * 

     * A value with a weight of 0 will be rejected by the map. If a value
     * with this weight can occur then the caller should eagerly evaluate the
     * value and treat it as a removal operation. Alternatively, a custom weigher
     * may be specified on the map to assign an empty value a positive weight.
     *
     * @return A weigher where each element takes one unit of capacity.
     */
    @SuppressWarnings({"cast", "unchecked"})
    public static  Weigher> list() {
        return ListWeigher.INSTANCE;
    }

    /**
     * A weigher where the value is a {@link Set} and its weight is the number
     * of elements. A map bounded with this weigher will evict when the total
     * number of elements exceeds the capacity rather than the number of
     * key-value pairs in the map.
     * 

     * A value with a weight of 0 will be rejected by the map. If a value
     * with this weight can occur then the caller should eagerly evaluate the
     * value and treat it as a removal operation. Alternatively, a custom weigher
     * may be specified on the map to assign an empty value a positive weight.
     *
     * @return A weigher where each element takes one unit of capacity.
     */
    @SuppressWarnings({"cast", "unchecked"})
    public static  Weigher> set() {
        return SetWeigher.INSTANCE;
    }

    /**
     * A weigher where the value is a {@link Map} and its weight is the number of
     * entries. A map bounded with this weigher will evict when the total number of
     * entries across all values exceeds the capacity rather than the number of
     * key-value pairs in the map.
     * 

     * A value with a weight of 0 will be rejected by the map. If a value
     * with this weight can occur then the caller should eagerly evaluate the
     * value and treat it as a removal operation. Alternatively, a custom weigher
     * may be specified on the map to assign an empty value a positive weight.
     *
     * @return A weigher where each entry takes one unit of capacity.
     */
    @SuppressWarnings({"cast", "unchecked"})
    public static  Weigher> map() {
        return MapWeigher.INSTANCE;
    }

    enum SingletonEntryWeigher implements EntryWeigher {
        INSTANCE;

        @Override
        public int weightOf(Object key, Object value) {
            return 1;
        }
    }

    enum SingletonWeigher implements Weigher {
        INSTANCE;

        @Override
        public int weightOf(Object value) {
            return 1;
        }
    }

    enum ByteArrayWeigher implements Weigher {
        INSTANCE;

        @Override
        public int weightOf(byte[] value) {
            return value.length;
        }
    }

    enum IterableWeigher implements Weigher> {
        INSTANCE;

        @Override
        public int weightOf(Iterable values) {
            if (values instanceof Collection) {
                return ((Collection) values).size();
            }
            int size = 0;
            for (Iterator i = values.iterator(); i.hasNext(); ) {
                i.next();
                size++;
            }
            return size;
        }
    }

    enum CollectionWeigher implements Weigher> {
        INSTANCE;

        @Override
        public int weightOf(Collection values) {
            return values.size();
        }
    }

    enum ListWeigher implements Weigher> {
        INSTANCE;

        @Override
        public int weightOf(List values) {
            return values.size();
        }
    }

    enum SetWeigher implements Weigher> {
        INSTANCE;

        @Override
        public int weightOf(Set values) {
            return values.size();
        }
    }

    enum MapWeigher implements Weigher> {
        INSTANCE;

        @Override
        public int weightOf(Map values) {
            return values.size();
        }
    }

    static final class EntryWeigherView implements EntryWeigher, Serializable {
        static final long serialVersionUID = 1;
        final Weigher weigher;

        EntryWeigherView(Weigher weigher) {
            checkNotNull(weigher);
            this.weigher = weigher;
        }

        @Override
        public int weightOf(K key, V value) {
            return weigher.weightOf(value);
        }
    }
}
    

    

    

            

    

            



    
    






    
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