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/* |
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* Written by Doug Lea with assistance from members of JCP JSR-166 |
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* Expert Group and released to the public domain, as explained at |
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* http://creativecommons.org/licenses/publicdomain |
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* http://creativecommons.org/publicdomain/zero/1.0/ |
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*/ |
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package jsr166x; |
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package jsr166x; |
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import java.util.*; |
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import java.util.concurrent.*; |
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/** |
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* A scalable concurrent {@link SortedSet} and (priority) {@link |
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* Queue} implementation based on a {@link ConcurrentSkipListMap}. |
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* This class maintains a set in ascending order, sorted according to |
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* the <i>natural order</i> for the element's class (see {@link |
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* Comparable}), or by the comparator provided at creation time, |
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* depending on which constructor is used.<p> |
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* A scalable concurrent {@link NavigableSet} implementation based on |
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* a {@link ConcurrentSkipListMap}. This class maintains a set in |
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* ascending order, sorted according to the <i>natural order</i> for |
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* the element's class (see {@link Comparable}), or by the comparator |
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* provided at creation time, depending on which constructor is |
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* used. |
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* |
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* This implementation provides expected average <i>log(n)</i> time |
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* cost for the <tt>contains</tt>, <tt>add</tt>, and <tt>remove</tt> |
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* <p>This implementation provides expected average <i>log(n)</i> time |
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* cost for the {@code contains}, {@code add}, and {@code remove} |
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* operations and their variants. Insertion, removal, and access |
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* operations safely execute concurrently by multiple |
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* threads. Iterators are <i>weakly consistent</i>, returning elements |
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* reflecting the state of the set at some point at or since the |
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* creation of the iterator. They do <em>not</em> throw {@link |
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* ConcurrentModificationException}, and may procede concurrently with |
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* ConcurrentModificationException}, and may proceed concurrently with |
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* other operations. |
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* |
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* <p>This class provides extended <tt>SortedSet</tt> methods |
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* searching for closest matches. Methods <tt>lower</tt>, |
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* <tt>floor</tt>, <tt>ceiling</tt>, and <tt>higher</tt> return |
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* elements respectively less, less than or equal, greater than or |
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* equal, and greater than a given value, returning null if there is |
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* no such element. These methods are designed for locating, not |
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* traversing entries. To traverse, use iterators and/or |
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* <tt>subset</tt>. |
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* |
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* <p>The class additionally supports {@link Queue} methods such as |
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* <tt>poll</tt> that atomically returns and removes the first |
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* element, if one exists. Thus, this class can serve as a priority |
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* queue in which there are no duplicate elements. |
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* |
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* <p>The {@link ConcurrentSkipListSubSet} objects returned by methods |
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* <tt>subset</tt>, <tt>headSet</tt>, and <tt>tailSet</tt> support the |
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* same extended set of operations as this class, but operate on their |
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* designated subrange of elements. |
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* |
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* <p>Beware that, unlike in most collections, the <tt>size</tt> |
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* method is <em>NOT</em> a constant-time operation. Because of the |
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* <p>Beware that, unlike in most collections, the {@code size} |
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* method is <em>not</em> a constant-time operation. Because of the |
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* asynchronous nature of these sets, determining the current number |
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* of elements requires a traversal of the elements. |
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* of elements requires a traversal of the elements. Additionally, the |
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* bulk operations {@code addAll}, {@code removeAll}, |
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* {@code retainAll}, and {@code containsAll} are <em>not</em> |
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* guaranteed to be performed atomically. For example, an iterator |
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* operating concurrently with an {@code addAll} operation might view |
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* only some of the added elements. |
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* |
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* <p>This class and its iterators implement all of the |
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* <em>optional</em> methods of the {@link Set} and {@link Iterator} |
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* interfaces. Like most other concurrent collection implementations, |
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* this class does not permit the use of <tt>null</tt> elements. |
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* because null arguments and return values cannot be reliably |
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* this class does not permit the use of {@code null} elements. |
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* because {@code null} arguments and return values cannot be reliably |
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* distinguished from the absence of elements. |
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* |
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* @author Doug Lea |
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*/ |
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public class ConcurrentSkipListSet<E> |
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extends AbstractSet<E> |
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implements SortedSet<E>, Queue<E>, Cloneable, java.io.Serializable { |
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implements NavigableSet<E>, Cloneable, java.io.Serializable { |
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private static final long serialVersionUID = -2479143111061671589L; |
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* fields of underlying map, but enables this field to be declared |
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* final, which is necessary for thread safety. |
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*/ |
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private final ConcurrentSkipListMap<E,Object> m; |
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private final ConcurrentSkipListMap<E,Object> m; |
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/** |
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* Constructs a new, empty set, sorted according to the elements' natural |
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* order. |
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* order. |
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*/ |
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public ConcurrentSkipListSet() { |
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m = new ConcurrentSkipListMap<E,Object>(); |
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/** |
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* Constructs a new, empty set, sorted according to the specified |
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* comparator. |
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* comparator. |
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* |
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* @param c the comparator that will be used to sort this set. A |
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* <tt>null</tt> value indicates that the elements' <i>natural |
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* {@code null} value indicates that the elements' <i>natural |
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* ordering</i> should be used. |
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*/ |
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public ConcurrentSkipListSet(Comparator<? super E> c) { |
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* Constructs a new set containing the elements in the specified |
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* collection, sorted according to the elements' <i>natural order</i>. |
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* |
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* @param c The elements that will comprise the new set. |
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* @param c The elements that will comprise the new set |
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* |
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* @throws ClassCastException if the elements in the specified |
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* collection are not comparable, or are not mutually comparable. |
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* @throws NullPointerException if the specified collection is null. |
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* collection are not comparable, or are not mutually comparable |
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* @throws NullPointerException if the specified collection is |
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* {@code null} |
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*/ |
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public ConcurrentSkipListSet(Collection<? extends E> c) { |
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m = new ConcurrentSkipListMap<E,Object>(); |
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* Constructs a new set containing the same elements as the specified |
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* sorted set, sorted according to the same ordering. |
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* |
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* @param s sorted set whose elements will comprise the new set. |
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* @throws NullPointerException if the specified sorted set is null. |
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* @param s sorted set whose elements will comprise the new set |
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* @throws NullPointerException if the specified sorted set is |
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* {@code null} |
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*/ |
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public ConcurrentSkipListSet(SortedSet<E> s) { |
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m = new ConcurrentSkipListMap<E,Object>(s.comparator()); |
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* Returns a shallow copy of this set. (The elements themselves |
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* are not cloned.) |
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* |
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* @return a shallow copy of this set. |
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* @return a shallow copy of this set |
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*/ |
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public Object clone() { |
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ConcurrentSkipListSet<E> clone = null; |
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try { |
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clone = (ConcurrentSkipListSet<E>) super.clone(); |
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} catch (CloneNotSupportedException e) { |
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throw new InternalError(); |
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} |
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try { |
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clone = (ConcurrentSkipListSet<E>) super.clone(); |
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} catch (CloneNotSupportedException e) { |
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throw new InternalError(); |
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} |
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clone.m.initialize(); |
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clone.addAll(this); |
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/** |
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* Returns the number of elements in this set. If this set |
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* contains more than <tt>Integer.MAX_VALUE</tt> elements, it |
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* returns <tt>Integer.MAX_VALUE</tt>. |
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* contains more than {@code Integer.MAX_VALUE} elements, it |
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* returns {@code Integer.MAX_VALUE}. |
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* |
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* <p>Beware that, unlike in most collections, this method is |
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* <em>NOT</em> a constant-time operation. Because of the |
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* will be inaccurate. Thus, this method is typically not very |
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* useful in concurrent applications. |
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* |
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* @return the number of elements in this set. |
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* @return the number of elements in this set |
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*/ |
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public int size() { |
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return m.size(); |
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return m.size(); |
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} |
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/** |
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* Returns <tt>true</tt> if this set contains no elements. |
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* @return <tt>true</tt> if this set contains no elements. |
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* Returns {@code true} if this set contains no elements. |
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* @return {@code true} if this set contains no elements |
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*/ |
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public boolean isEmpty() { |
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return m.isEmpty(); |
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return m.isEmpty(); |
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} |
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/** |
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* Returns <tt>true</tt> if this set contains the specified element. |
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* Returns {@code true} if this set contains the specified element. |
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* |
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* @param o the object to be checked for containment in this set. |
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* @return <tt>true</tt> if this set contains the specified element. |
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* @param o the object to be checked for containment in this set |
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* @return {@code true} if this set contains the specified element |
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* |
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* @throws ClassCastException if the specified object cannot be compared |
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* with the elements currently in the set. |
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* @throws NullPointerException if o is <tt>null</tt>. |
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* with the elements currently in the set |
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* @throws NullPointerException if o is {@code null} |
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*/ |
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public boolean contains(Object o) { |
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return m.containsKey(o); |
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return m.containsKey(o); |
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} |
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/** |
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* Adds the specified element to this set if it is not already present. |
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* |
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* @param o element to be added to this set. |
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* @return <tt>true</tt> if the set did not already contain the specified |
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* element. |
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* @param o element to be added to this set |
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* @return {@code true} if the set did not already contain the specified |
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* element |
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* |
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* @throws ClassCastException if the specified object cannot be compared |
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* with the elements currently in the set. |
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< |
* @throws NullPointerException if o is <tt>null</tt>. |
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* with the elements currently in the set |
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> |
* @throws NullPointerException if o is {@code null} |
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*/ |
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public boolean add(E o) { |
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return m.putIfAbsent(o, Boolean.TRUE) == null; |
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return m.putIfAbsent(o, Boolean.TRUE) == null; |
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} |
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|
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/** |
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* Removes the specified element from this set if it is present. |
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* |
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* @param o object to be removed from this set, if present. |
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< |
* @return <tt>true</tt> if the set contained the specified element. |
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> |
* @param o object to be removed from this set, if present |
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> |
* @return {@code true} if the set contained the specified element |
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* |
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* @throws ClassCastException if the specified object cannot be compared |
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< |
* with the elements currently in the set. |
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< |
* @throws NullPointerException if o is <tt>null</tt>. |
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> |
* with the elements currently in the set |
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> |
* @throws NullPointerException if o is {@code null} |
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*/ |
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public boolean remove(Object o) { |
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return m.removep(o); |
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> |
return m.removep(o); |
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} |
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|
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/** |
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* Removes all of the elements from this set. |
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*/ |
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public void clear() { |
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m.clear(); |
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m.clear(); |
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} |
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|
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/** |
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* Returns an iterator over the elements in this set. The elements |
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* are returned in ascending order. |
| 216 |
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* |
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< |
* @return an iterator over the elements in this set. |
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> |
* @return an iterator over the elements in this set |
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*/ |
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public Iterator<E> iterator() { |
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< |
return m.keyIterator(); |
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< |
} |
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< |
|
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< |
/* ---------------- Queue operations -------------- */ |
| 236 |
< |
|
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< |
/** |
| 238 |
< |
* Adds the specified element, or fails if this element is already |
| 239 |
< |
* present. |
| 240 |
< |
* @param o the element to insert. |
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< |
* @return <tt>true</tt> if it was possible to add the element, |
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< |
* else <tt>false</tt> |
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< |
*/ |
| 244 |
< |
public boolean offer(E o) { |
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< |
return add(o); |
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> |
return m.keyIterator(); |
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} |
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|
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/** |
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< |
* Retrieves and removes the first (lowest) element. |
| 224 |
> |
* Returns an iterator over the elements in this set. The elements |
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> |
* are returned in descending order. |
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* |
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< |
* @return the least element, or <tt>null</tt> if empty. |
| 227 |
> |
* @return an iterator over the elements in this set |
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*/ |
| 229 |
< |
public E poll() { |
| 230 |
< |
return m.removeFirstKey(); |
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> |
public Iterator<E> descendingIterator() { |
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> |
return m.descendingKeyIterator(); |
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} |
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|
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< |
/** |
| 234 |
< |
* Retrieves and removes the first (lowest) element. This method |
| 235 |
< |
* differs from the <tt>poll</tt> method in that it throws an |
| 236 |
< |
* exception if empty. |
| 237 |
< |
* |
| 238 |
< |
* @return the first (lowest) element. |
| 239 |
< |
* @throws NoSuchElementException if empty. |
| 240 |
< |
*/ |
| 241 |
< |
public E remove() { |
| 242 |
< |
E x = m.removeFirstKey(); |
| 243 |
< |
if (x == null) |
| 244 |
< |
throw new NoSuchElementException(); |
| 245 |
< |
return x; |
| 233 |
> |
/* ---------------- AbstractSet Overrides -------------- */ |
| 234 |
> |
|
| 235 |
> |
/** |
| 236 |
> |
* Compares the specified object with this set for equality. Returns |
| 237 |
> |
* {@code true} if the specified object is also a set, the two sets |
| 238 |
> |
* have the same size, and every member of the specified set is |
| 239 |
> |
* contained in this set (or equivalently, every member of this set is |
| 240 |
> |
* contained in the specified set). This definition ensures that the |
| 241 |
> |
* equals method works properly across different implementations of the |
| 242 |
> |
* set interface. |
| 243 |
> |
* |
| 244 |
> |
* @param o Object to be compared for equality with this set |
| 245 |
> |
* @return {@code true} if the specified Object is equal to this set |
| 246 |
> |
*/ |
| 247 |
> |
public boolean equals(Object o) { |
| 248 |
> |
// Override AbstractSet version to avoid calling size() |
| 249 |
> |
if (o == this) |
| 250 |
> |
return true; |
| 251 |
> |
if (!(o instanceof Set)) |
| 252 |
> |
return false; |
| 253 |
> |
Collection c = (Collection) o; |
| 254 |
> |
try { |
| 255 |
> |
return containsAll(c) && c.containsAll(this); |
| 256 |
> |
} catch (ClassCastException unused) { |
| 257 |
> |
return false; |
| 258 |
> |
} catch (NullPointerException unused) { |
| 259 |
> |
return false; |
| 260 |
> |
} |
| 261 |
|
} |
| 262 |
|
|
| 263 |
|
/** |
| 264 |
< |
* Retrieves, but does not remove, the first (lowest) element, |
| 265 |
< |
* returning <tt>null</tt> if empty. |
| 266 |
< |
* |
| 267 |
< |
* @return the first (lowest) element, or <tt>null</tt> if empty. |
| 268 |
< |
*/ |
| 269 |
< |
public E peek() { |
| 270 |
< |
return m.lowestKey(); |
| 264 |
> |
* Removes from this set all of its elements that are contained in |
| 265 |
> |
* the specified collection. If the specified collection is also |
| 266 |
> |
* a set, this operation effectively modifies this set so that its |
| 267 |
> |
* value is the <i>asymmetric set difference</i> of the two sets. |
| 268 |
> |
* |
| 269 |
> |
* @param c collection that defines which elements will be removed from |
| 270 |
> |
* this set |
| 271 |
> |
* @return {@code true} if this set changed as a result of the call |
| 272 |
> |
* |
| 273 |
> |
* @throws ClassCastException if the types of one or more elements in this |
| 274 |
> |
* set are incompatible with the specified collection |
| 275 |
> |
* @throws NullPointerException if the specified collection, or any |
| 276 |
> |
* of its elements are {@code null} |
| 277 |
> |
*/ |
| 278 |
> |
public boolean removeAll(Collection<?> c) { |
| 279 |
> |
// Override AbstractSet version to avoid unnecessary call to size() |
| 280 |
> |
boolean modified = false; |
| 281 |
> |
for (Iterator<?> i = c.iterator(); i.hasNext(); ) |
| 282 |
> |
if (remove(i.next())) |
| 283 |
> |
modified = true; |
| 284 |
> |
return modified; |
| 285 |
|
} |
| 286 |
|
|
| 282 |
– |
/** |
| 283 |
– |
* Retrieves, but does not remove, the first (lowest) element. |
| 284 |
– |
* This method differs from the <tt>peek</tt> method only in that |
| 285 |
– |
* it throws an exception if empty. |
| 286 |
– |
* |
| 287 |
– |
* @return the first (lowest) element. |
| 288 |
– |
* @throws NoSuchElementException if empty. |
| 289 |
– |
*/ |
| 290 |
– |
public E element() { |
| 291 |
– |
return m.firstKey(); |
| 292 |
– |
} |
| 293 |
– |
|
| 287 |
|
/* ---------------- Relational operations -------------- */ |
| 288 |
|
|
| 289 |
|
/** |
| 290 |
|
* Returns an element greater than or equal to the given element, or |
| 291 |
< |
* null if there is no such element. |
| 292 |
< |
* |
| 291 |
> |
* {@code null} if there is no such element. |
| 292 |
> |
* |
| 293 |
|
* @param o the value to match |
| 294 |
< |
* @return an element greater than or equal to given element, or null |
| 295 |
< |
* if there is no such element. |
| 294 |
> |
* @return an element greater than or equal to given element, or |
| 295 |
> |
* {@code null} if there is no such element |
| 296 |
|
* @throws ClassCastException if o cannot be compared with the elements |
| 297 |
< |
* currently in the set. |
| 298 |
< |
* @throws NullPointerException if o is <tt>null</tt> |
| 297 |
> |
* currently in the set |
| 298 |
> |
* @throws NullPointerException if o is {@code null} |
| 299 |
|
*/ |
| 300 |
|
public E ceiling(E o) { |
| 301 |
|
return m.ceilingKey(o); |
| 302 |
|
} |
| 303 |
|
|
| 304 |
|
/** |
| 305 |
< |
* Returns an element strictly less than the given element, or null if |
| 306 |
< |
* there is no such element. |
| 307 |
< |
* |
| 305 |
> |
* Returns an element strictly less than the given element, or |
| 306 |
> |
* {@code null} if there is no such element. |
| 307 |
> |
* |
| 308 |
|
* @param o the value to match |
| 309 |
|
* @return the greatest element less than the given element, or |
| 310 |
< |
* null if there is no such element. |
| 310 |
> |
* {@code null} if there is no such element |
| 311 |
|
* @throws ClassCastException if o cannot be compared with the elements |
| 312 |
< |
* currently in the set. |
| 313 |
< |
* @throws NullPointerException if o is <tt>null</tt>. |
| 312 |
> |
* currently in the set |
| 313 |
> |
* @throws NullPointerException if o is {@code null} |
| 314 |
|
*/ |
| 315 |
|
public E lower(E o) { |
| 316 |
|
return m.lowerKey(o); |
| 317 |
|
} |
| 318 |
|
|
| 319 |
|
/** |
| 320 |
< |
* Returns an element less than or equal to the given element, or null |
| 321 |
< |
* if there is no such element. |
| 322 |
< |
* |
| 320 |
> |
* Returns an element less than or equal to the given element, or |
| 321 |
> |
* {@code null} if there is no such element. |
| 322 |
> |
* |
| 323 |
|
* @param o the value to match |
| 324 |
|
* @return the greatest element less than or equal to given |
| 325 |
< |
* element, or null if there is no such element. |
| 325 |
> |
* element, or {@code null} if there is no such element |
| 326 |
|
* @throws ClassCastException if o cannot be compared with the elements |
| 327 |
< |
* currently in the set. |
| 328 |
< |
* @throws NullPointerException if o is <tt>null</tt>. |
| 327 |
> |
* currently in the set |
| 328 |
> |
* @throws NullPointerException if o is {@code null} |
| 329 |
|
*/ |
| 330 |
|
public E floor(E o) { |
| 331 |
|
return m.floorKey(o); |
| 332 |
|
} |
| 333 |
|
|
| 334 |
|
/** |
| 335 |
< |
* Returns an element strictly greater than the given element, or null |
| 336 |
< |
* if there is no such element. |
| 337 |
< |
* |
| 335 |
> |
* Returns an element strictly greater than the given element, or |
| 336 |
> |
* {@code null} if there is no such element. |
| 337 |
> |
* |
| 338 |
|
* @param o the value to match |
| 339 |
|
* @return the least element greater than the given element, or |
| 340 |
< |
* null if there is no such element. |
| 340 |
> |
* {@code null} if there is no such element |
| 341 |
|
* @throws ClassCastException if o cannot be compared with the elements |
| 342 |
< |
* currently in the set. |
| 343 |
< |
* @throws NullPointerException if o is <tt>null</tt>. |
| 342 |
> |
* currently in the set |
| 343 |
> |
* @throws NullPointerException if o is {@code null} |
| 344 |
|
*/ |
| 345 |
|
public E higher(E o) { |
| 346 |
|
return m.higherKey(o); |
| 347 |
|
} |
| 348 |
|
|
| 349 |
+ |
/** |
| 350 |
+ |
* Retrieves and removes the first (lowest) element. |
| 351 |
+ |
* |
| 352 |
+ |
* @return the least element, or {@code null} if empty |
| 353 |
+ |
*/ |
| 354 |
+ |
public E pollFirst() { |
| 355 |
+ |
return m.pollFirstKey(); |
| 356 |
+ |
} |
| 357 |
+ |
|
| 358 |
+ |
/** |
| 359 |
+ |
* Retrieves and removes the last (highest) element. |
| 360 |
+ |
* |
| 361 |
+ |
* @return the last element, or {@code null} if empty |
| 362 |
+ |
*/ |
| 363 |
+ |
public E pollLast() { |
| 364 |
+ |
return m.pollLastKey(); |
| 365 |
+ |
} |
| 366 |
+ |
|
| 367 |
+ |
|
| 368 |
|
/* ---------------- SortedSet operations -------------- */ |
| 369 |
|
|
| 370 |
|
|
| 371 |
|
/** |
| 372 |
< |
* Returns the comparator used to order this set, or <tt>null</tt> |
| 372 |
> |
* Returns the comparator used to order this set, or {@code null} |
| 373 |
|
* if this set uses its elements natural ordering. |
| 374 |
|
* |
| 375 |
< |
* @return the comparator used to order this set, or <tt>null</tt> |
| 376 |
< |
* if this set uses its elements natural ordering. |
| 375 |
> |
* @return the comparator used to order this set, or {@code null} |
| 376 |
> |
* if this set uses its elements natural ordering |
| 377 |
|
*/ |
| 378 |
|
public Comparator<? super E> comparator() { |
| 379 |
|
return m.comparator(); |
| 382 |
|
/** |
| 383 |
|
* Returns the first (lowest) element currently in this set. |
| 384 |
|
* |
| 385 |
< |
* @return the first (lowest) element currently in this set. |
| 386 |
< |
* @throws NoSuchElementException sorted set is empty. |
| 385 |
> |
* @return the first (lowest) element currently in this set |
| 386 |
> |
* @throws NoSuchElementException sorted set is empty |
| 387 |
|
*/ |
| 388 |
|
public E first() { |
| 389 |
|
return m.firstKey(); |
| 392 |
|
/** |
| 393 |
|
* Returns the last (highest) element currently in this set. |
| 394 |
|
* |
| 395 |
< |
* @return the last (highest) element currently in this set. |
| 396 |
< |
* @throws NoSuchElementException sorted set is empty. |
| 395 |
> |
* @return the last (highest) element currently in this set |
| 396 |
> |
* @throws NoSuchElementException sorted set is empty |
| 397 |
|
*/ |
| 398 |
|
public E last() { |
| 399 |
|
return m.lastKey(); |
| 400 |
|
} |
| 401 |
|
|
| 402 |
+ |
|
| 403 |
+ |
|
| 404 |
|
/** |
| 405 |
|
* Returns a view of the portion of this set whose elements range from |
| 406 |
< |
* <tt>fromElement</tt>, inclusive, to <tt>toElement</tt>, exclusive. (If |
| 407 |
< |
* <tt>fromElement</tt> and <tt>toElement</tt> are equal, the returned |
| 406 |
> |
* {@code fromElement}, inclusive, to {@code toElement}, exclusive. (If |
| 407 |
> |
* {@code fromElement} and {@code toElement} are equal, the returned |
| 408 |
|
* sorted set is empty.) The returned sorted set is backed by this set, |
| 409 |
|
* so changes in the returned sorted set are reflected in this set, and |
| 410 |
< |
* vice-versa. |
| 411 |
< |
* @param fromElement low endpoint (inclusive) of the subSet. |
| 412 |
< |
* @param toElement high endpoint (exclusive) of the subSet. |
| 410 |
> |
* vice-versa. |
| 411 |
> |
* @param fromElement low endpoint (inclusive) of the subSet |
| 412 |
> |
* @param toElement high endpoint (exclusive) of the subSet |
| 413 |
|
* @return a view of the portion of this set whose elements range from |
| 414 |
< |
* <tt>fromElement</tt>, inclusive, to <tt>toElement</tt>, |
| 415 |
< |
* exclusive. |
| 416 |
< |
* @throws ClassCastException if <tt>fromElement</tt> and |
| 417 |
< |
* <tt>toElement</tt> cannot be compared to one another using |
| 414 |
> |
* {@code fromElement}, inclusive, to {@code toElement}, |
| 415 |
> |
* exclusive |
| 416 |
> |
* @throws ClassCastException if {@code fromElement} and |
| 417 |
> |
* {@code toElement} cannot be compared to one another using |
| 418 |
|
* this set's comparator (or, if the set has no comparator, |
| 419 |
< |
* using natural ordering). |
| 420 |
< |
* @throws IllegalArgumentException if <tt>fromElement</tt> is |
| 421 |
< |
* greater than <tt>toElement</tt>. |
| 422 |
< |
* @throws NullPointerException if <tt>fromElement</tt> or |
| 423 |
< |
* <tt>toElement</tt> is <tt>null</tt>. |
| 419 |
> |
* using natural ordering) |
| 420 |
> |
* @throws IllegalArgumentException if {@code fromElement} is |
| 421 |
> |
* greater than {@code toElement} |
| 422 |
> |
* @throws NullPointerException if {@code fromElement} or |
| 423 |
> |
* {@code toElement} is {@code null} |
| 424 |
|
*/ |
| 425 |
< |
public ConcurrentSkipListSubSet<E> subSet(E fromElement, E toElement) { |
| 426 |
< |
return new ConcurrentSkipListSubSet<E>(m, fromElement, toElement); |
| 425 |
> |
public NavigableSet<E> subSet(E fromElement, E toElement) { |
| 426 |
> |
return new ConcurrentSkipListSubSet<E>(m, fromElement, toElement); |
| 427 |
|
} |
| 428 |
|
|
| 429 |
|
/** |
| 430 |
|
* Returns a view of the portion of this set whose elements are strictly |
| 431 |
< |
* less than <tt>toElement</tt>. The returned sorted set is backed by |
| 431 |
> |
* less than {@code toElement}. The returned sorted set is backed by |
| 432 |
|
* this set, so changes in the returned sorted set are reflected in this |
| 433 |
< |
* set, and vice-versa. |
| 434 |
< |
* @param toElement high endpoint (exclusive) of the headSet. |
| 433 |
> |
* set, and vice-versa. |
| 434 |
> |
* @param toElement high endpoint (exclusive) of the headSet |
| 435 |
|
* @return a view of the portion of this set whose elements are strictly |
| 436 |
< |
* less than toElement. |
| 437 |
< |
* @throws ClassCastException if <tt>toElement</tt> is not compatible |
| 436 |
> |
* less than toElement |
| 437 |
> |
* @throws ClassCastException if {@code toElement} is not compatible |
| 438 |
|
* with this set's comparator (or, if the set has no comparator, |
| 439 |
< |
* if <tt>toElement</tt> does not implement <tt>Comparable</tt>). |
| 440 |
< |
* @throws NullPointerException if <tt>toElement</tt> is <tt>null</tt>. |
| 439 |
> |
* if {@code toElement} does not implement {@code Comparable}) |
| 440 |
> |
* @throws NullPointerException if {@code toElement} is {@code null} |
| 441 |
|
*/ |
| 442 |
< |
public ConcurrentSkipListSubSet<E> headSet(E toElement) { |
| 443 |
< |
return new ConcurrentSkipListSubSet<E>(m, null, toElement); |
| 442 |
> |
public NavigableSet<E> headSet(E toElement) { |
| 443 |
> |
return new ConcurrentSkipListSubSet<E>(m, null, toElement); |
| 444 |
|
} |
| 445 |
|
|
| 446 |
|
|
| 447 |
|
/** |
| 448 |
|
* Returns a view of the portion of this set whose elements are |
| 449 |
< |
* greater than or equal to <tt>fromElement</tt>. The returned |
| 449 |
> |
* greater than or equal to {@code fromElement}. The returned |
| 450 |
|
* sorted set is backed by this set, so changes in the returned |
| 451 |
|
* sorted set are reflected in this set, and vice-versa. |
| 452 |
< |
* @param fromElement low endpoint (inclusive) of the tailSet. |
| 452 |
> |
* @param fromElement low endpoint (inclusive) of the tailSet |
| 453 |
|
* @return a view of the portion of this set whose elements are |
| 454 |
< |
* greater than or equal to <tt>fromElement</tt>. |
| 455 |
< |
* @throws ClassCastException if <tt>fromElement</tt> is not |
| 454 |
> |
* greater than or equal to {@code fromElement} |
| 455 |
> |
* @throws ClassCastException if {@code fromElement} is not |
| 456 |
|
* compatible with this set's comparator (or, if the set has no |
| 457 |
< |
* comparator, if <tt>fromElement</tt> does not implement |
| 458 |
< |
* <tt>Comparable</tt>). |
| 459 |
< |
* @throws NullPointerException if <tt>fromElement</tt> is <tt>null</tt>. |
| 460 |
< |
*/ |
| 461 |
< |
public ConcurrentSkipListSubSet<E> tailSet(E fromElement) { |
| 462 |
< |
return new ConcurrentSkipListSubSet<E>(m, fromElement, null); |
| 457 |
> |
* comparator, if {@code fromElement} does not implement |
| 458 |
> |
* {@code Comparable}) |
| 459 |
> |
* @throws NullPointerException if {@code fromElement} is {@code null} |
| 460 |
> |
*/ |
| 461 |
> |
public NavigableSet<E> tailSet(E fromElement) { |
| 462 |
> |
return new ConcurrentSkipListSubSet<E>(m, fromElement, null); |
| 463 |
> |
} |
| 464 |
> |
|
| 465 |
> |
/** |
| 466 |
> |
* Subsets returned by {@link ConcurrentSkipListSet} subset operations |
| 467 |
> |
* represent a subrange of elements of their underlying |
| 468 |
> |
* sets. Instances of this class support all methods of their |
| 469 |
> |
* underlying sets, differing in that elements outside their range are |
| 470 |
> |
* ignored, and attempts to add elements outside their ranges result |
| 471 |
> |
* in {@link IllegalArgumentException}. Instances of this class are |
| 472 |
> |
* constructed only using the {@code subSet}, {@code headSet}, and |
| 473 |
> |
* {@code tailSet} methods of their underlying sets. |
| 474 |
> |
*/ |
| 475 |
> |
static class ConcurrentSkipListSubSet<E> |
| 476 |
> |
extends AbstractSet<E> |
| 477 |
> |
implements NavigableSet<E>, java.io.Serializable { |
| 478 |
> |
|
| 479 |
> |
private static final long serialVersionUID = -7647078645896651609L; |
| 480 |
> |
|
| 481 |
> |
/** The underlying submap */ |
| 482 |
> |
private final ConcurrentSkipListMap.ConcurrentSkipListSubMap<E,Object> s; |
| 483 |
> |
|
| 484 |
> |
/** |
| 485 |
> |
* Creates a new submap. |
| 486 |
> |
* @param fromElement inclusive least value, or {@code null} if from start |
| 487 |
> |
* @param toElement exclusive upper bound or {@code null} if to end |
| 488 |
> |
* @throws IllegalArgumentException if fromElement and toElement |
| 489 |
> |
* non-null and fromElement greater than toElement |
| 490 |
> |
*/ |
| 491 |
> |
ConcurrentSkipListSubSet(ConcurrentSkipListMap<E,Object> map, |
| 492 |
> |
E fromElement, E toElement) { |
| 493 |
> |
s = new ConcurrentSkipListMap.ConcurrentSkipListSubMap<E,Object> |
| 494 |
> |
(map, fromElement, toElement); |
| 495 |
> |
} |
| 496 |
> |
|
| 497 |
> |
// subsubset construction |
| 498 |
> |
|
| 499 |
> |
public NavigableSet<E> subSet(E fromElement, E toElement) { |
| 500 |
> |
if (!s.inOpenRange(fromElement) || !s.inOpenRange(toElement)) |
| 501 |
> |
throw new IllegalArgumentException("element out of range"); |
| 502 |
> |
return new ConcurrentSkipListSubSet<E>(s.getMap(), |
| 503 |
> |
fromElement, toElement); |
| 504 |
> |
} |
| 505 |
> |
|
| 506 |
> |
public NavigableSet<E> headSet(E toElement) { |
| 507 |
> |
E least = s.getLeast(); |
| 508 |
> |
if (!s.inOpenRange(toElement)) |
| 509 |
> |
throw new IllegalArgumentException("element out of range"); |
| 510 |
> |
return new ConcurrentSkipListSubSet<E>(s.getMap(), |
| 511 |
> |
least, toElement); |
| 512 |
> |
} |
| 513 |
> |
|
| 514 |
> |
public NavigableSet<E> tailSet(E fromElement) { |
| 515 |
> |
E fence = s.getFence(); |
| 516 |
> |
if (!s.inOpenRange(fromElement)) |
| 517 |
> |
throw new IllegalArgumentException("element out of range"); |
| 518 |
> |
return new ConcurrentSkipListSubSet<E>(s.getMap(), |
| 519 |
> |
fromElement, fence); |
| 520 |
> |
} |
| 521 |
> |
|
| 522 |
> |
// relays to submap methods |
| 523 |
> |
|
| 524 |
> |
public int size() { return s.size(); } |
| 525 |
> |
public boolean isEmpty() { return s.isEmpty(); } |
| 526 |
> |
public boolean contains(Object o) { return s.containsKey(o); } |
| 527 |
> |
public void clear() { s.clear(); } |
| 528 |
> |
public E first() { return s.firstKey(); } |
| 529 |
> |
public E last() { return s.lastKey(); } |
| 530 |
> |
public E ceiling(E o) { return s.ceilingKey(o); } |
| 531 |
> |
public E lower(E o) { return s.lowerKey(o); } |
| 532 |
> |
public E floor(E o) { return s.floorKey(o); } |
| 533 |
> |
public E higher(E o) { return s.higherKey(o); } |
| 534 |
> |
public boolean remove(Object o) { return s.remove(o)==Boolean.TRUE; } |
| 535 |
> |
public boolean add(E o) { return s.put(o, Boolean.TRUE)==null; } |
| 536 |
> |
public Comparator<? super E> comparator() { return s.comparator(); } |
| 537 |
> |
public Iterator<E> iterator() { return s.keySet().iterator(); } |
| 538 |
> |
public Iterator<E> descendingIterator() { |
| 539 |
> |
return s.descendingKeySet().iterator(); |
| 540 |
> |
} |
| 541 |
> |
public E pollFirst() { |
| 542 |
> |
Map.Entry<E,?> e = s.pollFirstEntry(); |
| 543 |
> |
return (e == null) ? null : e.getKey(); |
| 544 |
> |
} |
| 545 |
> |
public E pollLast() { |
| 546 |
> |
Map.Entry<E,?> e = s.pollLastEntry(); |
| 547 |
> |
return (e == null) ? null : e.getKey(); |
| 548 |
> |
} |
| 549 |
> |
|
| 550 |
|
} |
| 551 |
< |
} |
| 551 |
> |
} |
