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/*
* Copyright 2013 the original author or authors.
*
* 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 org.springframework.yarn.listener;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import org.springframework.core.Ordered;
import org.springframework.core.annotation.AnnotationAwareOrderComparator;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.core.annotation.Order;
/**
* Composite item which can be used in other components which
* may want to allow automatic and annotation based ordering.
* Good use case is a list of listeners where user may want
* to place some of them to be processed before the others.
*
* @author Janne Valkealahti
*
* @param the type of the item
*/
public class OrderedComposite {
private List unordered = new ArrayList();
private List ordered = new ArrayList();
private Comparator comparator = new AnnotationAwareOrderComparator();
private List list = new ArrayList();
/**
* Public setter for the listeners.
*
* @param items items
*/
public void setItems(List items) {
unordered.clear();
ordered.clear();
for (S s : items) {
add(s);
}
}
/**
* Register additional item.
*
* @param item item
*/
public void add(S item) {
if (item instanceof Ordered) {
if (!ordered.contains(item)) {
ordered.add(item);
}
} else if (AnnotationUtils.isAnnotationDeclaredLocally(Order.class, item.getClass())) {
if (!ordered.contains(item)) {
ordered.add(item);
}
} else if (!unordered.contains(item)) {
unordered.add(item);
}
Collections.sort(ordered, comparator);
list.clear();
list.addAll(ordered);
list.addAll(unordered);
}
/**
* Public getter for the list of items. The {@link Ordered} items come
* first, followed by any unordered ones.
*
* @return an iterator over the list of items
*/
public Iterator iterator() {
return new ArrayList(list).iterator();
}
/**
* Public getter for the list of items in reverse. The {@link Ordered} items
* come last, after any unordered ones.
*
* @return an iterator over the list of items
*/
public Iterator reverse() {
ArrayList result = new ArrayList(list);
Collections.reverse(result);
return result.iterator();
}
}