/*
* @(#)RegularEnumSet.java 1.8 06/01/27
*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
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() {
return new EnumSetIterator<E>();
}
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;
}
}
|
