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/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
*
* Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
*
* The contents of this file are subject to the terms of either the GNU
* General Public License Version 2 only ("GPL") or the Common
* Development and Distribution License("CDDL") (collectively, the
* "License"). You may not use this file except in compliance with the
* License. You can obtain a copy of the License at
* http://www.netbeans.org/cddl-gplv2.html
* or nbbuild/licenses/CDDL-GPL-2-CP. See the License for the
* specific language governing permissions and limitations under the
* License. When distributing the software, include this License Header
* Notice in each file and include the License file at
* nbbuild/licenses/CDDL-GPL-2-CP. Sun designates this
* particular file as subject to the "Classpath" exception as provided
* by Sun in the GPL Version 2 section of the License file that
* accompanied this code. If applicable, add the following below the
* License Header, with the fields enclosed by brackets [] replaced by
* your own identifying information:
* "Portions Copyrighted [year] [name of copyright owner]"
*
* Contributor(s):
*
* The Original Software is NetBeans. The Initial Developer of the Original
* Software is Sun Microsystems, Inc. Portions Copyright 1997-2006 Sun
* Microsystems, Inc. All Rights Reserved.
*
* If you wish your version of this file to be governed by only the CDDL
* or only the GPL Version 2, indicate your decision by adding
* "[Contributor] elects to include this software in this distribution
* under the [CDDL or GPL Version 2] license." If you do not indicate a
* single choice of license, a recipient has the option to distribute
* your version of this file under either the CDDL, the GPL Version 2 or
* to extend the choice of license to its licensees as provided above.
* However, if you add GPL Version 2 code and therefore, elected the GPL
* Version 2 license, then the option applies only if the new code is
* made subject to such option by the copyright holder.
*/
import java.io.Serializable;
import java.util.AbstractSet;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Set;
/**
* @since 4.37
* @author Jaroslav Tulach
*/
public class Utils {
/**
* Create a typesafe view over an underlying raw set.
* Mutations affect the underlying set (this is not a copy).
* {@link Set#clear} will make the view empty but may not clear the underlying set.
* You may add elements only of the requested type.
* {@link Set#contains} also performs a type check and will throw {@link ClassCastException}
* for an illegal argument.
* The view is serializable if the underlying set is.
* @param rawSet an unchecked set
* @param type the desired element type
* @param strict if false, elements in the underlying set which are not null and which are not assignable
* to the requested type are omitted from the view;
* if true, a {@link ClassCastException} may arise during some set operation
* @return a view over the raw set guaranteed to match the specified type
*/
public static <E> Set<E> checkedSetByFilter(Set rawSet, Class<E> type, boolean strict) {
return new CheckedSet<E>(rawSet, type, strict);
}
private static final class CheckedSet<E> extends AbstractSet<E> implements Serializable {
private static final long serialVersionUID = 1L;
private final Set rawSet;
private final Class<E> type;
private final boolean strict;
public CheckedSet(Set rawSet, Class<E> type, boolean strict) {
this.rawSet = rawSet;
this.type = type;
this.strict = strict;
}
private boolean acceptEntry(Object o) {
if (o == null) {
return true;
} else if (type.isInstance(o)) {
return true;
} else if (strict) {
throw new ClassCastException(o + " was not a " + type.getName()); // NOI18N
} else {
return false;
}
}
@Override
public Iterator<E> iterator() {
return new CheckedIterator<E>(rawSet.iterator()) {
@Override
protected boolean accept(Object o) {
return acceptEntry(o);
}
};
}
@Override
public int size() {
int c = 0;
Iterator it = rawSet.iterator();
while (it.hasNext()) {
if (acceptEntry(it.next())) {
c++;
}
}
return c;
}
@Override
@SuppressWarnings("unchecked") // complains about usage of raw set
public boolean add(E o) {
return rawSet.add(type.cast(o));
}
@Override
public boolean contains(Object o) {
return rawSet.contains(type.cast(o));
}
}
}
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();
}
}
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