/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.wicket.util.lang;
/**
*
* @author igor.vaynberg
*/
public class Exceptions
{
private Exceptions()
{
}
/**
* Gets root cause of the throwable
*
* @param throwable
* @return root cause
*/
public Throwable getRootCause(final Throwable throwable)
{
Throwable cursor = throwable;
while (cursor.getCause() != null)
{
cursor = cursor.getCause();
}
return cursor;
}
/**
* Looks for a cause of the specified type in throwable's chain
*
* @param <T>
* @param throwable
* @param causeType
* @return matched {@link Throwable} in the chain or {@code null} if none
*/
public static <T extends Throwable> T findCause(final Throwable throwable,
final Class<T> causeType)
{
return visit(throwable, new IThrowableVisitor<T>()
{
@Override
@SuppressWarnings("unchecked")
public void visit(final Throwable throwable, final Visit<T> visit)
{
if (causeType.isAssignableFrom(throwable.getClass()))
{
visit.stop((T)throwable);
}
}
});
}
/**
* Represents a visit
*
* @author igor
* @param <T>
*/
public static class Visit<T>
{
private T result;
private boolean stopped;
/**
* Stops visit with specified resut
*
* @param result
*/
public void stop(final T result)
{
this.result = result;
stop();
}
/**
* Stops visit
*/
public void stop()
{
stopped = true;
}
}
/**
* Visitor used to visit {@link Throwable} chains
*
* @param <T>
*/
public static interface IThrowableVisitor<T>
{
/**
* Visit a throwable
*
* @param throwable
* @param visit
*/
void visit(Throwable throwable, Visit<T> visit);
}
/**
* Visits the {@link Throwable}'s chain
*
* @param <T>
* @param throwable
* @param visitor
* @return result set on visitor or {@code null} if none
*/
public static <T> T visit(final Throwable throwable, final IThrowableVisitor<T> visitor)
{
Visit<T> visit = new Visit<>();
Throwable cursor = throwable;
while (cursor != null)
{
visitor.visit(cursor, visit);
if (visit.stopped)
{
return visit.result;
}
cursor = cursor.getCause();
}
return null;
}
}