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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.jdisc.handler;
import java.util.Optional;
public interface DelegatedRequestHandler extends RequestHandler {
RequestHandler getDelegate();
default RequestHandler getDelegateRecursive() {
RequestHandler delegate = getDelegate();
while(delegate instanceof DelegatedRequestHandler) {
delegate = ((DelegatedRequestHandler) delegate).getDelegate();
}
return delegate;
}
/** Find delegated request handler recursively */
static RequestHandler resolve(RequestHandler h) {
if (h instanceof DelegatedRequestHandler dh) return dh.getDelegateRecursive();
return h;
}
/**
* Find delegated request handler of specified type recursively
* Note that the returned handler may not be the innermost handler.
*/
static <T extends RequestHandler> Optional<T> resolve(Class<T> type, RequestHandler h) {
T candidate = type.isInstance(h) ? type.cast(h) : null;
while (h instanceof DelegatedRequestHandler) {
h = ((DelegatedRequestHandler) h).getDelegate();
if (type.isInstance(h)) candidate = type.cast(h);
}
return Optional.ofNullable(candidate);
}
}
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