/
LruHashSet.java
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/
LruHashSet.java
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/*
* Copyright 2012-2024 CodeLibs Project and the Others.
*
* 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 org.codelibs.core.collection;
import java.util.AbstractSet;
import java.util.ConcurrentModificationException;
import java.util.Iterator;
import java.util.Set;
/**
* @author shinsuke
*
*/
public class LruHashSet<E> extends AbstractSet<E> implements Set<E>, java.io.Serializable {
private static final long serialVersionUID = 1L;
private final LruHashMap<E, Object> map;
// Dummy value to associate with an Object in the backing Map
private static final Object PRESENT = new Object();
public LruHashSet(final int limitSize) {
map = new LruHashMap<>(limitSize);
}
/**
* Returns an iterator over the elements in this set. The elements are
* returned in no particular order.
*
* @return an Iterator over the elements in this set.
* @see ConcurrentModificationException
*/
@Override
public Iterator<E> iterator() {
return map.keySet().iterator();
}
/**
* Returns the number of elements in this set (its cardinality).
*
* @return the number of elements in this set (its cardinality).
*/
@Override
public int size() {
return map.size();
}
/**
* Returns true if this set contains no elements.
*
* @return true if this set contains no elements.
*/
@Override
public boolean isEmpty() {
return map.isEmpty();
}
/**
* Returns true if this set contains the specified element.
*
* @param o
* element whose presence in this set is to be tested.
* @return true if this set contains the specified element.
*/
@Override
public boolean contains(final Object o) {
return map.containsKey(o);
}
/**
* Adds the specified element to this set if it is not already present.
*
* @param o
* element to be added to this set.
* @return true if the set did not already contain the specified
* element.
*/
@Override
public boolean add(final E o) {
return map.put(o, PRESENT) == null;
}
/**
* Removes the specified element from this set if it is present.
*
* @param o
* object to be removed from this set, if present.
* @return true if the set contained the specified element.
*/
@Override
public boolean remove(final Object o) {
return map.remove(o) == PRESENT;
}
/**
* Removes all of the elements from this set.
*/
@Override
public void clear() {
map.clear();
}
}