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/*
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 *
 * Copyright (c) 2007-2011 Oracle and/or its affiliates. All rights reserved.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License.  You can
 * obtain a copy of the License at
 * https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html
 * or packager/legal/LICENSE.txt.  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 and include the License file at packager/legal/LICENSE.txt.
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package org.jvnet.hk2.component;

import java.io.Serializable;
import java.util.Collection;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;

/**
 * Map from a key to multiple values.
 * Order is significant among values, and null values are allowed, although null keys are not.
 *
 * @author Kohsuke Kawaguchi
 * @author Jerome Dochez
 * @param  The key of the multi-map
 * @param  The types in the multi-map
 */
public class MultiMap implements Serializable, Cloneable {
    /**
     * For serialization
     */
    private static final long serialVersionUID = 893592003056170756L;
    
    private final Map> store = new LinkedHashMap>();

    /**
     * Creates an empty multi-map with default concurrency controls
     */
    public MultiMap() {
    }

    /**
     * Copy constructor.
     *
     * @param base map to copy
     */
    public MultiMap(MultiMap base) {
        this();
        for (Map.Entry> e : base.entrySet()) {
            List value = newList(e.getValue());
            if (!value.isEmpty()) {
                store.put(e.getKey(), newList(e.getValue()));
            }
        }
    }

    /**
     * Creates an optionally populated list to be used as an entry in the map.
     *
     * @param initialVal
     * @return
     */
    private List newList(Collection initialVals) {
        if (null == initialVals) {
            return new LinkedList();
         }
        
         return new LinkedList(initialVals);
    }
    
    /**
     * Returns the set of keys associated with this MultiMap
     * 
     * @return The set of keys currently available in this MultiMap.  Will not return null,
     * but may return a Set of lenght zero
     */
    public Set keySet() {
        return store.keySet();
    }

    /**
     * Adds one more key-value pair.
     *
     * @param k key to store the entry under
     * @param v value to store in the k's values.
     */
    public final void add(K k, V v) {
        List l = store.get(k);
        if (l == null) {
            l = newList(null);
            store.put(k, l);
        }
        l.add(v);
    }

    /**
     * Replaces all the existing values associated with the key
     * by the given value.  If v is empty the key k will
     * be removed from the MultiMap.
     *
     * @param k key for the values
     * @param v Can be null or empty.
     */
    public void set(K k, Collection v) {
        List addMe = newList(v);
        if (addMe.isEmpty()) {
            store.remove(k);
        }
        else {
            store.put(k, newList(v));
        }
    }

    /**
     * Replaces all the existing values associated with the key
     * by the given single value.
     *
     * @param k key for the values
     * @param v singleton value for k key
     *          

* This is short for set(k,Collections.singleton(v)) */ public void set(K k, V v) { List vlist = newList(null); vlist.add(v); store.put(k, vlist); } /** * Returns the elements indexed by the provided key * * @param k key for the values * @return Can be empty but never null. Read-only. */ public final List get(K k) { List l = store.get(k); if (l == null) { return Collections.emptyList(); } return Collections.unmodifiableList(l); } /** * This method merges all of the keys and values from another * MultiMap into this MultiMap. If a key/value pair is * found in both MultiMaps it is not re-added to this * MultiMap, but is instead discarded * * @param another The MultiMap from which to add values * to this MultiMap. If null this method does nothing */ public void mergeAll(MultiMap another) { if (another == null) return; for (Map.Entry> entry : another.entrySet()) { List ourList = store.get(entry.getKey()); if (null == ourList) { ourList = newList(entry.getValue()); if (!ourList.isEmpty()) { store.put(entry.getKey(), ourList); } } else { for (V v : entry.getValue()) { if (!ourList.contains(v)) { ourList.add(v); } } } } } /** * Package private (for getting the raw map for direct manipulation by the habitat) * * @param k the key * @return */ private final List _get(K k) { List l = store.get(k); if (l == null) { return Collections.emptyList(); } return l; } /** * Checks if the map contains the given key. * * @param k key to test * @return true if the map contains at least one element for this key */ public boolean containsKey(K k) { return !get(k).isEmpty(); } /** * Checks if the map contains the given key(s), also extending the search * to including the sub collection. * * @param k1 key from top collection * @param k2 key (value) from inner collection * @return true if the map contains at least one element for these keys */ public boolean contains(K k1, V k2) { List list = _get(k1); return list.contains(k2); } /** * Removes an key value from the map * * @param key key to be removed * @return the value stored under this key or null if there was none */ public List remove(K key) { return store.remove(key); } /** * Removes an key value pair from the map. If the list of * entries for that key is empty after the remove * it will be removed from the set of keys * * @param key key to be removed * @param entry the entry to be removed from the key'ed list * @return true if there was none that was deleted */ public boolean remove(K key, V entry) { List list = store.get(key); if (list == null) return false; boolean retVal = list.remove(entry); if (list.isEmpty()) { store.remove(key); } return retVal; } /** * Gets the first value if any, or null. *

* This is useful when you know the given key only has one value and you'd like * to get to that value. * * @param k key for the values * @return null if the key has no values or it has a value but the value is null. */ public V getOne(K k) { return getFirst(k); } private V getFirst(K k) { List lst = store.get(k); if (null == lst) { return null; } if (lst.isEmpty()) { return null; } return lst.get(0); } /** * Lists up all entries. * * @return a {@link java.util.Set} of {@link java.util.Map.Entry} of entries */ public Set>> entrySet() { return store.entrySet(); } /** * @return the map as "key=value1,key=value2,...." */ public String toCommaSeparatedString() { StringBuilder buf = new StringBuilder(); for (Map.Entry> e : entrySet()) { for (V v : e.getValue()) { if (buf.length() > 0) { buf.append(','); } buf.append(e.getKey()).append('=').append(v); } } return buf.toString(); } /** * Creates a copy of the map that contains the exact same key and value set. * Keys and values won't cloned. */ @Override public MultiMap clone() throws CloneNotSupportedException { super.clone(); return new MultiMap(this); } /** * Returns the size of the map. This returns the numbers * of keys in the map, not the number of values * * @return integer or 0 if the map is empty */ public int size() { return store.size(); } @Override public int hashCode() { return store.hashCode(); } @SuppressWarnings("unchecked") @Override public boolean equals(Object another) { if (another == null || !(another instanceof MultiMap)) return false; MultiMap other = (MultiMap) another; return store.equals(other.store); } @Override public String toString() { final StringBuilder builder = new StringBuilder(); final String newline = System.getProperty("line.separator"); builder.append("{"); for (final K key : store.keySet()) { builder.append(key).append(": "); builder.append(store.get(key)); builder.append(newline); } builder.append("}"); return builder.toString(); } }





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