/* (c) 2014 Open Source Geospatial Foundation - all rights reserved
* (c) 2001 - 2013 OpenPlans
* This code is licensed under the GPL 2.0 license, available at the root
* application directory.
*/
package org.geoserver.catalog;
/**
* Interface for classes which provide the ability to retrieve the delegate
* instance when the instance in question is in fact a proxy/decorator class.
* <p>
* Developers may wish to gain access to the resources that are wrapped (the
* delegates) as proxy class instances representing the the actual resources.
* <p>
* This interface aims to be compatible with the JDK 1.6 Wrapper class, which
* cannot be used in this release of GeoServer due to requirements of being
* JDK 1.5 compatible.
*/
public interface Wrapper {
/**
* Returns an object that implements the given interface to allow access to
* non-standard methods, or standard methods not exposed by the proxy.
*
* If the receiver implements the interface then the result is the receiver
* or a proxy for the receiver. If the receiver is a wrapper and the wrapped
* object implements the interface then the result is the wrapped object or
* a proxy for the wrapped object. Otherwise return the the result of
* calling <code>unwrap</code> recursively on the wrapped object or a
* proxy for that result. If the receiver is not a wrapper and does not
* implement the interface, then an <code>IllegalArgumentException</code> is thrown.
*
* @param iface
* A Class defining an interface that the result must implement.
* @return an object that implements the interface. May be a proxy for the
* actual implementing object.
* @throws java.sql.IllegalArgumentException
* If no object found that implements the interface
*/
<T> T unwrap(java.lang.Class<T> iface) throws IllegalArgumentException;
/**
* Returns true if this either implements the interface argument or is
* directly or indirectly a wrapper for an object that does. Returns false
* otherwise. If this implements the interface then return true, else if
* this is a wrapper then return the result of recursively calling
* <code>isWrapperFor</code> on the wrapped object. If this does not
* implement the interface and is not a wrapper, return false. This method
* should be implemented as a low-cost operation compared to
* <code>unwrap</code> so that callers can use this method to avoid
* expensive <code>unwrap</code> calls that may fail. If this method
* returns true then calling <code>unwrap</code> with the same argument
* should succeed.
*
* @param iface
* a Class defining an interface.
* @return true if this implements the interface or directly or indirectly
* wraps an object that does.
*/
boolean isWrapperFor(java.lang.Class<?> iface);
}