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package com.sun.faces.util;
import java.io.Serializable;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
/*
* Non-thread safe implementation of Set for use when most of the time there
* is only one element, but sometimes there are more than one.
*
*/
public class MostlySingletonSet<E> implements Set<E>, Serializable {
private static final long serialVersionUID = 2818326518724772145L;
private Set<E> inner;
public MostlySingletonSet() {
}
// <editor-fold defaultstate="collapsed" desc="Mutating methods">
@Override
public boolean add(E e) {
boolean result = true;
if (null == inner) {
inner = Collections.singleton(e);
} else {
// If we need to transition from one to more-than-one
if (1 == inner.size()) {
HashSet<E> newSet = new HashSet<>();
newSet.add(inner.iterator().next());
inner = newSet;
}
result = inner.add(e);
}
return result;
}
@Override
public boolean addAll(Collection<? extends E> c) {
boolean result = true;
if (null == inner && 1 == c.size()) {
inner = (Set<E>) Collections.singleton(c.iterator().next());
} else {
// If we need to transition from one to more-than-one
if (1 == inner.size()) {
HashSet<E> newSet = new HashSet<>();
newSet.add(inner.iterator().next());
inner = newSet;
}
result = inner.addAll(c);
}
return result;
}
@Override
public void clear() {
if (null != inner) {
// If we need to transition from more-than-one to zero
if (1 < inner.size()) {
inner.clear();
}
inner = null;
}
}
@Override
public boolean remove(Object o) {
boolean didRemove = false;
if (null != inner) {
if (1 == inner.size()) {
// If we need to transition from one to zero
E e = inner.iterator().next();
// If our element is not null, and the argument is not null
if (null != e && null != o) {
didRemove = e.equals(o);
} else {
didRemove = null == o;
}
if (didRemove) {
inner = null;
}
} else {
didRemove = inner.remove(o);
if (didRemove && 1 == inner.size()) {
Set<E> newInner = Collections.singleton(inner.iterator().next());
inner.clear();
inner = newInner;
}
}
}
return didRemove;
}
@Override
public boolean removeAll(Collection<?> c) {
boolean result = false;
if (null != inner) {
if (1 == inner.size()) {
// May throw NPE per spec for Collection.removeAll()
Iterator incomingIter = c.iterator();
E oneAndOnlyElement = inner.iterator().next();
// Iterate over the incoming collection
// looking for a member that is equal to our one and only
// element.
while (incomingIter.hasNext()) {
Object cur = incomingIter.next();
if (null != oneAndOnlyElement) {
// This handles null == cur.
if (result = oneAndOnlyElement.equals(cur)) {
break;
}
} else {
// oneAndOnlyElement is null
if (result = cur == null) {
break;
}
}
}
if (result) {
inner = null;
}
} else {
result = inner.removeAll(c);
if (result && 0 == inner.size()) {
inner = null;
}
}
}
return result;
}
@Override
public boolean retainAll(Collection<?> c) {
boolean didModify = false;
if (null != inner) {
if (1 == inner.size()) {
Iterator incomingIter = c.iterator();
E oneAndOnlyElement = inner.iterator().next();
// Iterate over the incoming collection
// looking for a member that is equal to our one and only
// element. If found, we take no action, otherwise
// we remove the oneAndOnlyElement.
boolean found = false;
while (incomingIter.hasNext()) {
Object cur = incomingIter.next();
if (null != oneAndOnlyElement) {
if (found = oneAndOnlyElement.equals(cur)) {
break;
}
} else {
if (found = cur == null) {
break;
}
}
}
if (didModify = !found) {
inner = null;
}
} else {
didModify = inner.retainAll(c);
}
}
return didModify;
}
// </editor-fold>
// <editor-fold defaultstate="collapsed" desc="Non-mutating methods">
@Override
public boolean contains(Object o) {
boolean result = false;
if (null != inner) {
result = inner.contains(o);
}
return result;
}
@Override
public boolean containsAll(Collection<?> c) {
boolean result = false;
if (null != inner) {
result = inner.containsAll(c);
}
return result;
}
@Override
public boolean isEmpty() {
boolean result = true;
if (null != inner) {
result = inner.isEmpty();
}
return result;
}
@Override
public int size() {
int size = 0;
if (null != inner) {
size = inner.size();
}
return size;
}
@Override
public boolean equals(Object obj) {
boolean result = false;
if (obj != null) {
if (obj instanceof MostlySingletonSet) {
final MostlySingletonSet<E> other = (MostlySingletonSet<E>) obj;
if (this.inner != other.inner && (this.inner == null || !this.inner.equals(other.inner))) {
result = false;
} else {
result = true;
}
} else if (obj instanceof Collection) {
Collection otherCollection = (Collection) obj;
if (null != inner) {
result = inner.equals(otherCollection);
} else {
result = otherCollection.isEmpty();
}
}
}
return result;
}
@Override
public int hashCode() {
int hash = 5;
hash = 83 * hash + (this.inner != null ? this.inner.hashCode() : 0);
return hash;
}
@Override
public String toString() {
String result = "empty";
if (null != inner) {
result = inner.toString();
}
return result;
}
// </editor-fold>
// <editor-fold defaultstate="collapsed" desc="Iteration and array">
@Override
public Iterator<E> iterator() {
Iterator<E> result;
if (null != inner) {
result = inner.iterator();
} else {
result = Collections.EMPTY_SET.iterator();
}
return result;
}
@Override
public Object[] toArray() {
Object [] result = null;
if (null != inner) {
result = inner.toArray();
}
return result;
}
@Override
public <T> T[] toArray(T[] a) {
T [] result = null;
if (null != inner) {
result = inner.toArray(a);
}
return result;
}
// </editor-fold>
}