/*
 * Copyright (c) 2003, 2012, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */

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

 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 <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);

 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 <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;
 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 <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 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 <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 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 <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 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 <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 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
 * <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 o 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 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;
 }
}