package net.i2p.router.util;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collection;
import java.util.ConcurrentModificationException;
import java.util.Iterator;
import java.util.NoSuchElementException;
/**
* ArrayList that uses a single iterator. Useful to avoid object churn
* while keeping the conveniences of an iterator.
*
* @since 0.9.4 moved from net.i2p.util in 0.9.24
*
* @author zab
*/
public class CachedIteratorArrayList<E> extends ArrayList<E> {
private static final long serialVersionUID = 4863212596318574111L;
private final CachedIterator iterator = new CachedIterator();
public CachedIteratorArrayList() {
super();
}
public CachedIteratorArrayList(Collection<? extends E> c) {
super(c);
}
public CachedIteratorArrayList(int initialCapacity) {
super(initialCapacity);
}
@Override
public Iterator<E> iterator() {
iterator.reset();
return iterator;
}
private class CachedIterator implements Iterator<E>, Serializable {
/**
* Index of element to be returned by subsequent call to next.
*/
int cursor = 0;
/**
* Index of element returned by most recent call to next or
* previous. Reset to -1 if this element is deleted by a call
* to remove.
*/
int lastRet = -1;
/**
* The modCount value that the iterator believes that the backing
* List should have. If this expectation is violated, the iterator
* has detected concurrent modification.
*/
int expectedModCount = modCount;
void reset() {
cursor = 0;
lastRet = -1;
expectedModCount = modCount;
}
public boolean hasNext() {
return cursor != size();
}
public E next() {
checkForComodification();
try {
int i = cursor;
E next = get(i);
lastRet = i;
cursor = i + 1;
return next;
} catch (IndexOutOfBoundsException e) {
checkForComodification();
throw new NoSuchElementException();
}
}
public void remove() {
if (lastRet < 0)
throw new IllegalStateException();
checkForComodification();
try {
CachedIteratorArrayList.this.remove(lastRet);
if (lastRet < cursor)
cursor--;
lastRet = -1;
expectedModCount = modCount;
} catch (IndexOutOfBoundsException e) {
throw new ConcurrentModificationException();
}
}
final void checkForComodification() {
if (modCount != expectedModCount)
throw new ConcurrentModificationException();
}
}
}