/**
* 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.waveprotocol.wave.model.conversation;
import org.waveprotocol.wave.model.util.CollectionUtils;
import org.waveprotocol.wave.model.util.Predicate;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Queue;
/**
* Iterators for conversations.
*
* @author anorth@google.com (Alex North)
*/
public final class BlipIterators {
/**
* A predicate that accepts all blips.
*/
private final static Predicate<ConversationBlip> ALL = new Predicate<ConversationBlip>() {
public boolean apply(ConversationBlip target) {
return true;
}
};
private static final class BlipIterator implements Iterator<ConversationBlip> {
private final Predicate<ConversationBlip> acceptsBlip;
private final Queue<ConversationThread> threads = CollectionUtils.newLinkedList();
private Iterator<? extends ConversationBlip> currentThreadItr;
private ConversationBlip nextBlip;
BlipIterator(ConversationThread thread, Predicate<ConversationBlip> acceptor) {
this.acceptsBlip = acceptor;
this.currentThreadItr = thread.getBlips().iterator();
this.nextBlip = findNextBlip();
}
@Override
public boolean hasNext() {
return nextBlip != null;
}
@Override
public ConversationBlip next() {
if (!hasNext()) {
throw new NoSuchElementException();
}
ConversationBlip result = nextBlip;
nextBlip = findNextBlip();
return result;
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
private ConversationBlip findNextBlip() {
ConversationBlip next = null;
while ((next == null) && currentThreadItr.hasNext()) {
ConversationBlip maybeNext;
maybeNext = currentThreadItr.next();
for (ConversationThread reply : maybeNext.getReplyThreads()) {
threads.add(reply);
}
if (acceptsBlip.apply(maybeNext)) {
next = maybeNext;
}
while (!currentThreadItr.hasNext() && (threads.peek() != null)) {
currentThreadItr = threads.remove().getBlips().iterator();
}
}
return next;
}
}
/**
* A breadth-first iterator over blips in a conversation. Deleted blips are
* skipped, but non-deleted descendant blips are included.
*/
public static Iterable<ConversationBlip> breadthFirst(Conversation conversation) {
return breadthFirst(conversation.getRootThread());
}
/**
* A breadth-first iterator over the non-deleted descendant blips of a thread.
*/
public static Iterable<ConversationBlip> breadthFirst(final ConversationThread thread) {
return new Iterable<ConversationBlip>() {
@Override
public Iterator<ConversationBlip> iterator() {
return new BlipIterator(thread, ALL);
}
};
}
private BlipIterators() {
}
}