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/*******************************************************************************
* Copyright (c) 2008, 2015 Matthew Hall and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Matthew Hall - initial API and implementation (bug 215531)
* Matthew Hall - bug 124684
* (through ViewerElementSet.java)
* Matthew Hall - bugs 262269, 303847
* Stefan Xenos <sxenos@gmail.com> - Bug 335792
******************************************************************************/
package org.eclipse.core.internal.databinding.identity;
import java.lang.reflect.Array;
import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
/**
* A {@link Set} of elements where elements are added, removed and compared by
* identity. Elements of the set are compared using <code>==</code> instead of
* {@link #equals(Object)}.
* <p>
* This class is <i>not</i> a strict implementation the {@link Set} interface.
* It intentionally violates the {@link Set} contract, which requires the use of
* {@link #equals(Object)} when comparing elements.
*
* @param <E>
* the type of the elements in this collection
* @since 1.2
*/
public class IdentitySet<E> implements Set<E> {
private final Set<IdentityWrapper<E>> wrappedSet;
/**
* Constructs an IdentitySet.
*/
public IdentitySet() {
this.wrappedSet = new HashSet<>();
}
/**
* Constructs an IdentitySet containing all the unique instances in the
* specified collection.
*
* @param collection
* the collection whose elements are to be added to this set.
*/
public IdentitySet(Collection<? extends E> collection) {
this();
addAll(collection);
}
@Override
public boolean add(E o) {
return wrappedSet.add(IdentityWrapper.wrap(o));
}
@Override
public boolean addAll(Collection<? extends E> c) {
boolean changed = false;
for (E element : c) {
changed |= wrappedSet.add(IdentityWrapper.wrap(element));
}
return changed;
}
@Override
public void clear() {
wrappedSet.clear();
}
@Override
public boolean contains(Object o) {
return wrappedSet.contains(IdentityWrapper.wrap(o));
}
@Override
public boolean containsAll(Collection<?> c) {
for (Object element : c)
if (!wrappedSet.contains(IdentityWrapper.wrap(element)))
return false;
return true;
}
@Override
public boolean isEmpty() {
return wrappedSet.isEmpty();
}
@Override
public Iterator<E> iterator() {
final Iterator<IdentityWrapper<E>> wrappedIterator = wrappedSet
.iterator();
return new Iterator<E>() {
@Override
public boolean hasNext() {
return wrappedIterator.hasNext();
}
@Override
public E next() {
return wrappedIterator.next().unwrap();
}
@Override
public void remove() {
wrappedIterator.remove();
}
};
}
@Override
public boolean remove(Object o) {
return wrappedSet.remove(IdentityWrapper.wrap(o));
}
@Override
public boolean removeAll(Collection<?> c) {
boolean changed = false;
for (Object element : c)
changed |= remove(element);
return changed;
}
@Override
public boolean retainAll(Collection<?> c) {
// Have to do this the slow way to ensure correct comparisons. i.e.
// cannot delegate to c.contains(it) since we can't be sure will
// compare elements the way we want.
boolean changed = false;
Object[] retainAll = c.toArray();
outer: for (Iterator<E> iterator = iterator(); iterator.hasNext();) {
E element = iterator.next();
for (int i = 0; i < retainAll.length; i++) {
if (element == retainAll[i]) {
continue outer;
}
}
iterator.remove();
changed = true;
}
return changed;
}
@Override
public int size() {
return wrappedSet.size();
}
@Override
public Object[] toArray() {
return toArray(new Object[wrappedSet.size()]);
}
@SuppressWarnings("unchecked")
@Override
public <T> T[] toArray(T[] a) {
int size = wrappedSet.size();
T[] result = a;
if (a.length < size) {
result = (T[]) Array.newInstance(a.getClass().getComponentType(), size);
}
int i = 0;
for (IdentityWrapper<? extends E> wrapper : wrappedSet) {
result[i++] = (T) wrapper.unwrap();
}
return result;
}
@Override
public boolean equals(Object obj) {
if (obj == this)
return true;
if (!(obj instanceof Set))
return false;
Set<?> that = (Set<?>) obj;
return size() == that.size() && containsAll(that);
}
@Override
public int hashCode() {
int hash = 0;
for (E element : this) {
hash += element == null ? 0 : element.hashCode();
}
return hash;
}
}
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