RegularEnumSet.java 9.5 KB
Newer Older
D
duke 已提交
1
/*
2
 * Copyright (c) 2003, 2006, Oracle and/or its affiliates. All rights reserved.
D
duke 已提交
3 4 5 6
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
7
 * published by the Free Software Foundation.  Oracle designates this
D
duke 已提交
8
 * particular file as subject to the "Classpath" exception as provided
9
 * by Oracle in the LICENSE file that accompanied this code.
D
duke 已提交
10 11 12 13 14 15 16 17 18 19 20
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
21 22 23
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
D
duke 已提交
24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73
 */

package java.util;

/**
 * Private implementation class for EnumSet, for "regular sized" enum types
 * (i.e., those with 64 or fewer enum constants).
 *
 * @author Josh Bloch
 * @since 1.5
 * @serial exclude
 */
class RegularEnumSet<E extends Enum<E>> extends EnumSet<E> {
    /**
     * Bit vector representation of this set.  The 2^k bit indicates the
     * presence of universe[k] in this set.
     */
    private long elements = 0L;

    RegularEnumSet(Class<E>elementType, Enum[] universe) {
        super(elementType, universe);
    }

    void addRange(E from, E to) {
        elements = (-1L >>>  (from.ordinal() - to.ordinal() - 1)) << from.ordinal();
    }

    void addAll() {
        if (universe.length != 0)
            elements = -1L >>> -universe.length;
    }

    void complement() {
        if (universe.length != 0) {
            elements = ~elements;
            elements &= -1L >>> -universe.length;  // Mask unused bits
        }
    }

    /**
     * Returns an iterator over the elements contained in this set.  The
     * iterator traverses the elements in their <i>natural order</i> (which is
     * the order in which the enum constants are declared). The returned
     * Iterator is a "snapshot" iterator that will never throw {@link
     * ConcurrentModificationException}; the elements are traversed as they
     * existed when this call was invoked.
     *
     * @return an iterator over the elements contained in this set
     */
    public Iterator<E> iterator() {
74
        return new EnumSetIterator<>();
D
duke 已提交
75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302
    }

    private class EnumSetIterator<E extends Enum<E>> implements Iterator<E> {
        /**
         * A bit vector representing the elements in the set not yet
         * returned by this iterator.
         */
        long unseen;

        /**
         * The bit representing the last element returned by this iterator
         * but not removed, or zero if no such element exists.
         */
        long lastReturned = 0;

        EnumSetIterator() {
            unseen = elements;
        }

        public boolean hasNext() {
            return unseen != 0;
        }

        public E next() {
            if (unseen == 0)
                throw new NoSuchElementException();
            lastReturned = unseen & -unseen;
            unseen -= lastReturned;
            return (E) universe[Long.numberOfTrailingZeros(lastReturned)];
        }

        public void remove() {
            if (lastReturned == 0)
                throw new IllegalStateException();
            elements -= lastReturned;
            lastReturned = 0;
        }
    }

    /**
     * Returns the number of elements in this set.
     *
     * @return the number of elements in this set
     */
    public int size() {
        return Long.bitCount(elements);
    }

    /**
     * Returns <tt>true</tt> if this set contains no elements.
     *
     * @return <tt>true</tt> if this set contains no elements
     */
    public boolean isEmpty() {
        return elements == 0;
    }

    /**
     * Returns <tt>true</tt> if this set contains the specified element.
     *
     * @param e element to be checked for containment in this collection
     * @return <tt>true</tt> if this set contains the specified element
     */
    public boolean contains(Object e) {
        if (e == null)
            return false;
        Class eClass = e.getClass();
        if (eClass != elementType && eClass.getSuperclass() != elementType)
            return false;

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

    // Modification Operations

    /**
     * Adds the specified element to this set if it is not already present.
     *
     * @param e element to be added to this set
     * @return <tt>true</tt> if the set changed as a result of the call
     *
     * @throws NullPointerException if <tt>e</tt> is null
     */
    public boolean add(E e) {
        typeCheck(e);

        long oldElements = elements;
        elements |= (1L << ((Enum)e).ordinal());
        return elements != oldElements;
    }

    /**
     * Removes the specified element from this set if it is present.
     *
     * @param e element to be removed from this set, if present
     * @return <tt>true</tt> if the set contained the specified element
     */
    public boolean remove(Object e) {
        if (e == null)
            return false;
        Class eClass = e.getClass();
        if (eClass != elementType && eClass.getSuperclass() != elementType)
            return false;

        long oldElements = elements;
        elements &= ~(1L << ((Enum)e).ordinal());
        return elements != oldElements;
    }

    // Bulk Operations

    /**
     * Returns <tt>true</tt> if this set contains all of the elements
     * in the specified collection.
     *
     * @param c collection to be checked for containment in this set
     * @return <tt>true</tt> if this set contains all of the elements
     *        in the specified collection
     * @throws NullPointerException if the specified collection is null
     */
    public boolean containsAll(Collection<?> c) {
        if (!(c instanceof RegularEnumSet))
            return super.containsAll(c);

        RegularEnumSet es = (RegularEnumSet)c;
        if (es.elementType != elementType)
            return es.isEmpty();

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

    /**
     * Adds all of the elements in the specified collection to this set.
     *
     * @param c collection whose elements are to be added to this set
     * @return <tt>true</tt> if this set changed as a result of the call
     * @throws NullPointerException if the specified collection or any
     *     of its elements are null
     */
    public boolean addAll(Collection<? extends E> c) {
        if (!(c instanceof RegularEnumSet))
            return super.addAll(c);

        RegularEnumSet es = (RegularEnumSet)c;
        if (es.elementType != elementType) {
            if (es.isEmpty())
                return false;
            else
                throw new ClassCastException(
                    es.elementType + " != " + elementType);
        }

        long oldElements = elements;
        elements |= es.elements;
        return elements != oldElements;
    }

    /**
     * Removes from this set all of its elements that are contained in
     * the specified collection.
     *
     * @param c elements to be removed from this set
     * @return <tt>true</tt> if this set changed as a result of the call
     * @throws NullPointerException if the specified collection is null
     */
    public boolean removeAll(Collection<?> c) {
        if (!(c instanceof RegularEnumSet))
            return super.removeAll(c);

        RegularEnumSet es = (RegularEnumSet)c;
        if (es.elementType != elementType)
            return false;

        long oldElements = elements;
        elements &= ~es.elements;
        return elements != oldElements;
    }

    /**
     * Retains only the elements in this set that are contained in the
     * specified collection.
     *
     * @param c elements to be retained in this set
     * @return <tt>true</tt> if this set changed as a result of the call
     * @throws NullPointerException if the specified collection is null
     */
    public boolean retainAll(Collection<?> c) {
        if (!(c instanceof RegularEnumSet))
            return super.retainAll(c);

        RegularEnumSet<?> es = (RegularEnumSet<?>)c;
        if (es.elementType != elementType) {
            boolean changed = (elements != 0);
            elements = 0;
            return changed;
        }

        long oldElements = elements;
        elements &= es.elements;
        return elements != oldElements;
    }

    /**
     * Removes all of the elements from this set.
     */
    public void clear() {
        elements = 0;
    }

    /**
     * Compares the specified object with this set for equality.  Returns
     * <tt>true</tt> if the given object is also a set, the two sets have
     * the same size, and every member of the given set is contained in
     * this set.
     *
     * @param e object to be compared for equality with this set
     * @return <tt>true</tt> if the specified object is equal to this set
     */
    public boolean equals(Object o) {
        if (!(o instanceof RegularEnumSet))
            return super.equals(o);

        RegularEnumSet es = (RegularEnumSet)o;
        if (es.elementType != elementType)
            return elements == 0 && es.elements == 0;
        return es.elements == elements;
    }
}