/*
* Copyright 2014, The OpenNMS Group
*
* 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.opennms.newts.aggregate;
import static com.google.common.base.Preconditions.checkNotNull;
import java.util.Iterator;
import java.util.NoSuchElementException;
import org.opennms.newts.api.Duration;
import org.opennms.newts.api.Timestamp;
/**
* Aligned, fixed-interval iterator of {@link Timestamp}s.
*
* @author eevans
*/
public class IntervalGenerator implements Iterator<Timestamp>, Iterable<Timestamp> {
private final Duration m_interval;
private final Timestamp m_final;
private final boolean m_reversed;
private Timestamp m_current;
public IntervalGenerator(Timestamp start, Timestamp finish, Duration interval) {
this(start, finish, interval, false);
}
public IntervalGenerator(Timestamp start, Timestamp finish, Duration interval, boolean reversed) {
m_interval = checkNotNull(interval, "interval argument");
checkNotNull(start, "start argument");
checkNotNull(finish, "finish argument");
m_current = reversed ? finish : start;
m_final = reversed ? start : finish;
m_reversed = reversed;
}
@Override
public boolean hasNext() {
return m_reversed ? m_current.gte(m_final) : m_current.lte(m_final);
}
@Override
public Timestamp next() {
if (!hasNext()) {
throw new NoSuchElementException();
}
try {
return m_current;
}
finally {
m_current = m_reversed ? m_current.minus(m_interval) : m_current.plus(m_interval);
}
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
@Override
public Iterator<Timestamp> iterator() {
return this;
}
}