/*

 * Copyright (c) 2003, 2019, Oracle and/or its affiliates. All rights reserved.

 * 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

 * published by the Free Software Foundation.  Oracle designates this

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

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

 *

 * 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.

 *

 * 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.

 */

package java.util;

/**

 * Private implementation class for EnumSet, for "jumbo" enum types

 * (i.e., those with more than 64 elements).

 *

 * @author Josh Bloch

 * @since 1.5

 * @serial exclude

 */

class JumboEnumSet<E extends Enum<E>> extends EnumSet<E> {

    @java.io.Serial

    private static final long serialVersionUID = 334349849919042784L;

    /**

     * Bit vector representation of this set.  The ith bit of the jth

     * element of this array represents the  presence of universe[64*j +i]

     * in this set.

     */

    private long elements[];

    // Redundant - maintained for performance

    private int size = 0;

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

        super(elementType, universe);

        elements = new long[(universe.length + 63) >>> 6];

    }

    void addRange(E from, E to) {

        int fromIndex = from.ordinal() >>> 6;

        int toIndex = to.ordinal() >>> 6;

        if (fromIndex == toIndex) {

            elements[fromIndex] = (-1L >>>  (from.ordinal() - to.ordinal() - 1))

                            << from.ordinal();

        } else {

            elements[fromIndex] = (-1L << from.ordinal());

            for (int i = fromIndex + 1; i < toIndex; i++)

                elements[i] = -1;

            elements[toIndex] = -1L >>> (63 - to.ordinal());

        }

        size = to.ordinal() - from.ordinal() + 1;

    }

    void addAll() {

        for (int i = 0; i < elements.length; i++)

            elements[i] = -1;

        elements[elements.length - 1] >>>= -universe.length;

        size = universe.length;

    }

    void complement() {

        for (int i = 0; i < elements.length; i++)

            elements[i] = ~elements[i];

        elements[elements.length - 1] &= (-1L >>> -universe.length);

        size = universe.length - size;

    }

    /**

     * 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 "weakly consistent" iterator that will never throw {@link

     * ConcurrentModificationException}.

     *

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

     */

    public Iterator<E> iterator() {

        return new EnumSetIterator<>();

    }

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

        /**

         * A bit vector representing the elements in the current "word"

         * of the set not yet returned by this iterator.

         */

        long unseen;

        /**

         * The index corresponding to unseen in the elements array.

         */

        int unseenIndex = 0;

        /**

         * The bit representing the last element returned by this iterator

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

         */

        long lastReturned = 0;

        /**

         * The index corresponding to lastReturned in the elements array.

         */

        int lastReturnedIndex = 0;

        EnumSetIterator() {

            unseen = elements[0];

        }

        @Override

        public boolean hasNext() {

            while (unseen == 0 && unseenIndex < elements.length - 1)

                unseen = elements[++unseenIndex];

            return unseen != 0;

        }

        @Override

        @SuppressWarnings("unchecked")

        public E next() {

            if (!hasNext())

                throw new NoSuchElementException();

            lastReturned = unseen & -unseen;

            lastReturnedIndex = unseenIndex;

            unseen -= lastReturned;

            return (E) universe[(lastReturnedIndex << 6)

                                + Long.numberOfTrailingZeros(lastReturned)];

        }

        @Override

        public void remove() {

            if (lastReturned == 0)

                throw new IllegalStateException();

            final long oldElements = elements[lastReturnedIndex];

            elements[lastReturnedIndex] &= ~lastReturned;

            if (oldElements != elements[lastReturnedIndex]) {

                size--;

            }

            lastReturned = 0;

        }

    }

    /**

     * Returns the number of elements in this set.

     *

     * @return the number of elements in this set

     */

    public int size() {

        return size;

    }

    /**

     * Returns {@code true} if this set contains no elements.

     *

     * @return {@code true} if this set contains no elements

     */

    public boolean isEmpty() {

        return size == 0;

    }

    /**

     * Returns {@code true} if this set contains the specified element.

     *

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

     * @return {@code true} 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;

        int eOrdinal = ((Enum<?>)e).ordinal();

        return (elements[eOrdinal >>> 6] & (1L << eOrdinal)) != 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 {@code true} if the set changed as a result of the call

     *

     * @throws NullPointerException if {@code e} is null

     */

    public boolean add(E e) {

        typeCheck(e);

        int eOrdinal = e.ordinal();

        int eWordNum = eOrdinal >>> 6;

        long oldElements = elements[eWordNum];

        elements[eWordNum] |= (1L << eOrdinal);

        boolean result = (elements[eWordNum] != oldElements);

        if (result)

            size++;

        return result;

    }

    /**

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

     *

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

     * @return {@code true} 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;

        int eOrdinal = ((Enum<?>)e).ordinal();

        int eWordNum = eOrdinal >>> 6;

        long oldElements = elements[eWordNum];

        elements[eWordNum] &= ~(1L << eOrdinal);

        boolean result = (elements[eWordNum] != oldElements);

        if (result)

            size--;

        return result;

    }

    // Bulk Operations

    /**

     * Returns {@code true} if this set contains all of the elements

     * in the specified collection.

     *

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

     * @return {@code true} 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 JumboEnumSet))

            return super.containsAll(c);

        JumboEnumSet<?> es = (JumboEnumSet<?>)c;

        if (es.elementType != elementType)

            return es.isEmpty();

        for (int i = 0; i < elements.length; i++)

            if ((es.elements[i] & ~elements[i]) != 0)

                return false;

        return true;

    }

    /**

     * 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 {@code true} 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 JumboEnumSet))

            return super.addAll(c);

        JumboEnumSet<?> es = (JumboEnumSet<?>)c;

        if (es.elementType != elementType) {

            if (es.isEmpty())

                return false;

            else

                throw new ClassCastException(

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

        }

        for (int i = 0; i < elements.length; i++)

            elements[i] |= es.elements[i];

        return recalculateSize();

    }

    /**

     * 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 {@code true} 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 JumboEnumSet))

            return super.removeAll(c);

        JumboEnumSet<?> es = (JumboEnumSet<?>)c;

        if (es.elementType != elementType)

            return false;

        for (int i = 0; i < elements.length; i++)

            elements[i] &= ~es.elements[i];

        return recalculateSize();

    }

    /**

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

     * specified collection.

     *

     * @param c elements to be retained in this set

     * @return {@code true} 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 JumboEnumSet))

            return super.retainAll(c);

        JumboEnumSet<?> es = (JumboEnumSet<?>)c;

        if (es.elementType != elementType) {

            boolean changed = (size != 0);

            clear();

            return changed;

        }

        for (int i = 0; i < elements.length; i++)

            elements[i] &= es.elements[i];

        return recalculateSize();

    }

    /**

     * Removes all of the elements from this set.

     */

    public void clear() {

        Arrays.fill(elements, 0);

        size = 0;

    }

    /**

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

     * {@code true} 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 o object to be compared for equality with this set

     * @return {@code true} if the specified object is equal to this set

     */

    public boolean equals(Object o) {

        if (!(o instanceof JumboEnumSet))

            return super.equals(o);

        JumboEnumSet<?> es = (JumboEnumSet<?>)o;

        if (es.elementType != elementType)

            return size == 0 && es.size == 0;

        return Arrays.equals(es.elements, elements);

    }

    /**

     * Recalculates the size of the set.  Returns true if it's changed.

     */

    private boolean recalculateSize() {

        int oldSize = size;

        size = 0;

        for (long elt : elements)

            size += Long.bitCount(elt);

        return size != oldSize;

    }

    public EnumSet<E> clone() {

        JumboEnumSet<E> result = (JumboEnumSet<E>) super.clone();

        result.elements = result.elements.clone();

        return result;

    }

}