/*
* Copyright 2011-2013 HTTL Team.
*
* Licensed 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 httl.spi.interceptors;
import httl.Context;
import httl.spi.Interceptor;
import httl.spi.Listener;
import httl.util.Reqiured;
import java.io.IOException;
import java.text.ParseException;
/**
* MultiInterceptor. (SPI, Singleton, ThreadSafe)
*
* @see httl.spi.translators.CompiledTranslator#setInterceptor(Interceptor)
* @see httl.spi.translators.InterpretedTranslator#setInterceptor(Interceptor)
*
* @author Liang Fei (liangfei0201 AT gmail DOT com)
*/
public class MultiInterceptor implements Interceptor {
private static final String LISTENER_KEY = "__listener__";
private Listener chain;
/**
* httl.properties: interceptors=httl.spi.interceptors.ExtendsInterceptor
*/
@Reqiured
public void setInterceptors(Interceptor[] interceptors) {
Listener last = null;
for (int i = interceptors.length - 1; i >= 0; i--) {
final Interceptor current = interceptors[i];
final Listener next = last;
last = new Listener() {
public void render(Context context) throws IOException, ParseException {
if (next == null) {
Listener listener = (Listener) context.get(LISTENER_KEY);
if (listener != null) {
current.render(context, listener);
}
} else {
current.render(context, next);
}
}
};
}
this.chain = last;
}
public void render(Context context, Listener listener)
throws IOException, ParseException {
if (chain != null) {
Object old = context.put(LISTENER_KEY, listener);
try {
chain.render(context);
} finally {
if ( old != null) {
context.put(LISTENER_KEY, old);
} else {
context.remove(LISTENER_KEY);
}
}
} else {
listener.render(context);
}
}
}