1 /*

     2  * Copyright (c) 2003, 2012, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Oracle designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Oracle in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 

    26 package java.util;

    27 

    28 /**

    29  * Private implementation class for EnumSet, for "regular sized" enum types

    30  * (i.e., those with 64 or fewer enum constants).

    31  *

    32  * @author Josh Bloch

    33  * @since 1.5

    34  * @serial exclude

    35  */

    36 class RegularEnumSet<E extends Enum<E>> extends EnumSet<E> {

    37     private static final long serialVersionUID = 3411599620347842686L;

    38     /**

    39      * Bit vector representation of this set.  The 2^k bit indicates the

    40      * presence of universe[k] in this set.

    41      */

    42     private long elements = 0L;

    43 

    44     RegularEnumSet(Class<E>elementType, Enum<?>[] universe) {

    45         super(elementType, universe);

    46     }

    47 

    48     void addRange(E from, E to) {

    49         elements = (-1L >>>  (from.ordinal() - to.ordinal() - 1)) << from.ordinal();

    50     }

    51 

    52     void addAll() {

    53         if (universe.length != 0)

    54             elements = -1L >>> -universe.length;

    55     }

    56 

    57     void complement() {

    58         if (universe.length != 0) {

    59             elements = ~elements;

    60             elements &= -1L >>> -universe.length;  // Mask unused bits

    61         }

    62     }

    63 

    64     /**

    65      * Returns an iterator over the elements contained in this set.  The

    66      * iterator traverses the elements in their <i>natural order</i> (which is

    67      * the order in which the enum constants are declared). The returned

    68      * Iterator is a "snapshot" iterator that will never throw {@link

    69      * ConcurrentModificationException}; the elements are traversed as they

    70      * existed when this call was invoked.

    71      *

    72      * @return an iterator over the elements contained in this set

    73      */

    74     public Iterator<E> iterator() {

    75         return new EnumSetIterator<>();

    76     }

    77 

    78     private class EnumSetIterator<E extends Enum<E>> implements Iterator<E> {

    79         /**

    80          * A bit vector representing the elements in the set not yet

    81          * returned by this iterator.

    82          */

    83         long unseen;

    84 

    85         /**

    86          * The bit representing the last element returned by this iterator

    87          * but not removed, or zero if no such element exists.

    88          */

    89         long lastReturned = 0;

    90 

    91         EnumSetIterator() {

    92             unseen = elements;

    93         }

    94 

    95         public boolean hasNext() {

    96             return unseen != 0;

    97         }

    98 

    99         @SuppressWarnings("unchecked")

   100         public E next() {

   101             if (unseen == 0)

   102                 throw new NoSuchElementException();

   103             lastReturned = unseen & -unseen;

   104             unseen -= lastReturned;

   105             return (E) universe[Long.numberOfTrailingZeros(lastReturned)];

   106         }

   107 

   108         public void remove() {

   109             if (lastReturned == 0)

   110                 throw new IllegalStateException();

   111             elements &= ~lastReturned;

   112             lastReturned = 0;

   113         }

   114     }

   115 

   116     /**

   117      * Returns the number of elements in this set.

   118      *

   119      * @return the number of elements in this set

   120      */

   121     public int size() {

   122         return Long.bitCount(elements);

   123     }

   124 

   125     /**

   126      * Returns <tt>true</tt> if this set contains no elements.

   127      *

   128      * @return <tt>true</tt> if this set contains no elements

   129      */

   130     public boolean isEmpty() {

   131         return elements == 0;

   132     }

   133 

   134     /**

   135      * Returns <tt>true</tt> if this set contains the specified element.

   136      *

   137      * @param e element to be checked for containment in this collection

   138      * @return <tt>true</tt> if this set contains the specified element

   139      */

   140     public boolean contains(Object e) {

   141         if (e == null)

   142             return false;

   143         Class<?> eClass = e.getClass();

   144         if (eClass != elementType && eClass.getSuperclass() != elementType)

   145             return false;

   146 

   147         return (elements & (1L << ((Enum<?>)e).ordinal())) != 0;

   148     }

   149 

   150     // Modification Operations

   151 

   152     /**

   153      * Adds the specified element to this set if it is not already present.

   154      *

   155      * @param e element to be added to this set

   156      * @return <tt>true</tt> if the set changed as a result of the call

   157      *

   158      * @throws NullPointerException if <tt>e</tt> is null

   159      */

   160     public boolean add(E e) {

   161         typeCheck(e);

   162 

   163         long oldElements = elements;

   164         elements |= (1L << ((Enum<?>)e).ordinal());

   165         return elements != oldElements;

   166     }

   167 

   168     /**

   169      * Removes the specified element from this set if it is present.

   170      *

   171      * @param e element to be removed from this set, if present

   172      * @return <tt>true</tt> if the set contained the specified element

   173      */

   174     public boolean remove(Object e) {

   175         if (e == null)

   176             return false;

   177         Class<?> eClass = e.getClass();

   178         if (eClass != elementType && eClass.getSuperclass() != elementType)

   179             return false;

   180 

   181         long oldElements = elements;

   182         elements &= ~(1L << ((Enum<?>)e).ordinal());

   183         return elements != oldElements;

   184     }

   185 

   186     // Bulk Operations

   187 

   188     /**

   189      * Returns <tt>true</tt> if this set contains all of the elements

   190      * in the specified collection.

   191      *

   192      * @param c collection to be checked for containment in this set

   193      * @return <tt>true</tt> if this set contains all of the elements

   194      *        in the specified collection

   195      * @throws NullPointerException if the specified collection is null

   196      */

   197     public boolean containsAll(Collection<?> c) {

   198         if (!(c instanceof RegularEnumSet))

   199             return super.containsAll(c);

   200 

   201         RegularEnumSet<?> es = (RegularEnumSet<?>)c;

   202         if (es.elementType != elementType)

   203             return es.isEmpty();

   204 

   205         return (es.elements & ~elements) == 0;

   206     }

   207 

   208     /**

   209      * Adds all of the elements in the specified collection to this set.

   210      *

   211      * @param c collection whose elements are to be added to this set

   212      * @return <tt>true</tt> if this set changed as a result of the call

   213      * @throws NullPointerException if the specified collection or any

   214      *     of its elements are null

   215      */

   216     public boolean addAll(Collection<? extends E> c) {

   217         if (!(c instanceof RegularEnumSet))

   218             return super.addAll(c);

   219 

   220         RegularEnumSet<?> es = (RegularEnumSet<?>)c;

   221         if (es.elementType != elementType) {

   222             if (es.isEmpty())

   223                 return false;

   224             else

   225                 throw new ClassCastException(

   226                     es.elementType + " != " + elementType);

   227         }

   228 

   229         long oldElements = elements;

   230         elements |= es.elements;

   231         return elements != oldElements;

   232     }

   233 

   234     /**

   235      * Removes from this set all of its elements that are contained in

   236      * the specified collection.

   237      *

   238      * @param c elements to be removed from this set

   239      * @return <tt>true</tt> if this set changed as a result of the call

   240      * @throws NullPointerException if the specified collection is null

   241      */

   242     public boolean removeAll(Collection<?> c) {

   243         if (!(c instanceof RegularEnumSet))

   244             return super.removeAll(c);

   245 

   246         RegularEnumSet<?> es = (RegularEnumSet<?>)c;

   247         if (es.elementType != elementType)

   248             return false;

   249 

   250         long oldElements = elements;

   251         elements &= ~es.elements;

   252         return elements != oldElements;

   253     }

   254 

   255     /**

   256      * Retains only the elements in this set that are contained in the

   257      * specified collection.

   258      *

   259      * @param c elements to be retained in this set

   260      * @return <tt>true</tt> if this set changed as a result of the call

   261      * @throws NullPointerException if the specified collection is null

   262      */

   263     public boolean retainAll(Collection<?> c) {

   264         if (!(c instanceof RegularEnumSet))

   265             return super.retainAll(c);

   266 

   267         RegularEnumSet<?> es = (RegularEnumSet<?>)c;

   268         if (es.elementType != elementType) {

   269             boolean changed = (elements != 0);

   270             elements = 0;

   271             return changed;

   272         }

   273 

   274         long oldElements = elements;

   275         elements &= es.elements;

   276         return elements != oldElements;

   277     }

   278 

   279     /**

   280      * Removes all of the elements from this set.

   281      */

   282     public void clear() {

   283         elements = 0;

   284     }

   285 

   286     /**

   287      * Compares the specified object with this set for equality.  Returns

   288      * <tt>true</tt> if the given object is also a set, the two sets have

   289      * the same size, and every member of the given set is contained in

   290      * this set.

   291      *

   292      * @param o object to be compared for equality with this set

   293      * @return <tt>true</tt> if the specified object is equal to this set

   294      */

   295     public boolean equals(Object o) {

   296         if (!(o instanceof RegularEnumSet))

   297             return super.equals(o);

   298 

   299         RegularEnumSet<?> es = (RegularEnumSet<?>)o;

   300         if (es.elementType != elementType)

   301             return elements == 0 && es.elements == 0;

   302         return es.elements == elements;

   303     }

   304 }