/* |
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* Licensed to the Apache Software Foundation (ASF) under one or more |
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* contributor license agreements. See the NOTICE file distributed with |
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* this work for additional information regarding copyright ownership. |
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* The ASF licenses this file to You under the Apache License, Version 2.0 |
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* (the "License"); you may not use this file except in compliance with |
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* the License. You may obtain a copy of the License at |
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* |
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* http://www.apache.org/licenses/LICENSE-2.0 |
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* |
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* Unless required by applicable law or agreed to in writing, software |
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* distributed under the License is distributed on an "AS IS" BASIS, |
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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* See the License for the specific language governing permissions and |
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* limitations under the License. |
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*/ |
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package org.apache.commons.collections4.multimap; |
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import java.util.Collections; |
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import java.util.Map; |
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import java.util.Set; |
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import org.apache.commons.collections4.SetUtils; |
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import org.apache.commons.collections4.SetValuedMap; |
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/** |
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* Abstract implementation of the {@link SetValuedMap} interface to simplify the |
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* creation of subclass implementations. |
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* <p> |
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* Subclasses specify a Map implementation to use as the internal storage and |
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* the Set implementation to use as values. |
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* </p> |
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* |
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* @param <K> the type of the keys in this map |
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* @param <V> the type of the values in this map |
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* @since 4.1 |
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*/ |
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public abstract class AbstractSetValuedMap<K, V> extends AbstractMultiValuedMap<K, V> |
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implements SetValuedMap<K, V> { |
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/** |
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* Constructor needed for subclass serialisation. |
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*/ |
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protected AbstractSetValuedMap() { |
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super(); |
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} |
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/** |
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* A constructor that wraps, not copies |
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* |
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* @param map the map to wrap, must not be null |
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* @throws NullPointerException if the map is null |
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*/ |
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protected AbstractSetValuedMap(final Map<K, ? extends Set<V>> map) { |
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super(map); |
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} |
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// ----------------------------------------------------------------------- |
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@Override |
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@SuppressWarnings("unchecked") |
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protected Map<K, Set<V>> getMap() { |
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return (Map<K, Set<V>>) super.getMap(); |
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} |
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/** |
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* Creates a new value collection using the provided factory. |
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* @return a new list |
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*/ |
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@Override |
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protected abstract Set<V> createCollection(); |
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// ----------------------------------------------------------------------- |
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/** |
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* Gets the set of values associated with the specified key. This would |
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* return an empty set in case the mapping is not present |
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* |
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* @param key the key to retrieve |
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* @return the <code>Set</code> of values, will return an empty |
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* <code>Set</code> for no mapping |
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*/ |
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@Override |
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public Set<V> get(final K key) { |
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return wrappedCollection(key); |
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} |
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@Override |
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Set<V> wrappedCollection(final K key) { |
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return new WrappedSet(key); |
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} |
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/** |
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* Removes all values associated with the specified key. |
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* <p> |
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* A subsequent <code>get(Object)</code> would return an empty set. |
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* |
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* @param key the key to remove values from |
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* @return the <code>Set</code> of values removed, will return an empty, |
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* unmodifiable set for no mapping found. |
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*/ |
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@Override |
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public Set<V> remove(final Object key) { |
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return SetUtils.emptyIfNull(getMap().remove(key)); |
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} |
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// ----------------------------------------------------------------------- |
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/** |
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* Wrapped set to handle add and remove on the collection returned by |
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* {@code get(Object)}. |
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*/ |
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private class WrappedSet extends WrappedCollection implements Set<V> { |
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public WrappedSet(final K key) { |
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super(key); |
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} |
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@Override |
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public boolean equals(final Object other) { |
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final Set<V> set = (Set<V>) getMapping(); |
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if (set == null) { |
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return Collections.emptySet().equals(other); |
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} |
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if (!(other instanceof Set)) { |
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return false; |
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} |
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final Set<?> otherSet = (Set<?>) other; |
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return SetUtils.isEqualSet(set, otherSet); |
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} |
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@Override |
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public int hashCode() { |
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final Set<V> set = (Set<V>) getMapping(); |
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return SetUtils.hashCodeForSet(set); |
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} |
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} |
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} |