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import java.io.Serializable;
import java.util.AbstractMap;
import java.util.AbstractSet;
import java.util.Collection;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Set;
/**
* @since 4.37
* @author Jaroslav Tulach
*/
public class Utils {
/**
* Create a typesafe filter of an unchecked enumeration.
* @param rawEnum an unchecked enumeration
* @param type the desired enumeration type
* @param strict if false, elements which are not null but not assignable to the requested type are omitted;
* if true, {@link ClassCastException} may be thrown from an enumeration operation
* @return an enumeration guaranteed to contain only objects of the requested type (or null)
*/
public static <E> Enumeration<E> checkedEnumerationByFilter(Enumeration rawEnum, final Class<E> type, final boolean strict) {
@SuppressWarnings("unchecked")
Enumeration<Object> _rawEnum = rawEnum;
return Enumerations.<Object,E>filter(_rawEnum, new Enumerations.Processor<Object,E>() {
public E process(Object o, Collection<Object> ignore) {
if (o == null) {
return null;
} else {
try {
return type.cast(o);
} catch (ClassCastException x) {
if (strict) {
throw x;
} else {
return null;
}
}
}
}
});
}
}
abstract class CheckedIterator<E> implements Iterator<E> {
static final Object WAITING = new Object();
private final Iterator it;
private Object next = WAITING;
public CheckedIterator(Iterator it) {
this.it = it;
}
protected abstract boolean accept(Object o);
public boolean hasNext() {
if (next != WAITING) {
return true;
}
while (it.hasNext()) {
next = it.next();
if (accept(next)) {
return true;
}
}
next = WAITING;
return false;
}
public E next() {
if (next == WAITING && !hasNext()) {
throw new NoSuchElementException();
}
assert next != WAITING;
@SuppressWarnings("unchecked")
// type-checking is done by accept()
E x = (E) next;
next = WAITING;
return x;
}
public void remove() {
it.remove();
}
}