/*
* 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.apache.flink.graph.pregel;
import java.util.Iterator;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.types.Either;
import org.apache.flink.types.NullValue;
/**
* An iterator that returns messages. The iterator is {@link java.lang.Iterable} at the same time to support
* the <i>foreach</i> syntax.
*/
public final class MessageIterator<Message> implements Iterator<Message>, Iterable<Message>, java.io.Serializable {
private static final long serialVersionUID = 1L;
private transient Iterator<Tuple2<?, Either<NullValue, Message>>> source;
private Message first = null;
final void setSource(Iterator<Tuple2<?, Either<NullValue, Message>>> source) {
this.source = source;
}
final void setFirst(Message msg) {
this.first = msg;
}
@Override
public final boolean hasNext() {
if (first != null) {
return true;
}
else {
return ((this.source != null) && (this.source.hasNext()));
}
}
@Override
public final Message next() {
if (first != null) {
Message toReturn = first;
first = null;
return toReturn;
}
return this.source.next().f1.right();
}
@Override
public final void remove() {
throw new UnsupportedOperationException();
}
@Override
public Iterator<Message> iterator() {
return this;
}
}