/*
* 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.ambari.view.hive2.client;
import com.google.common.collect.Lists;
import java.util.Iterator;
import java.util.List;
/**
* Wrapper over other iterables. Does not block and can be reset to start again from beginning.
*/
public class PersistentCursor<T, R> implements Cursor<T, R> {
private List<T> rows = Lists.newArrayList();
private List<R> columns = Lists.newArrayList();
private int offset = 0;
public PersistentCursor(List<T> rows, List<R> columns) {
this.rows = rows;
this.columns = columns;
}
@Override
public Iterator<T> iterator() {
return this;
}
@Override
public boolean hasNext() {
return rows.size() > 0 && offset < rows.size();
}
@Override
public T next() {
T row = rows.get(offset);
offset++;
return row;
}
@Override
public void remove() {
throw new RuntimeException("Read only cursor. Method not supported");
}
@Override
public boolean isResettable() {
return true;
}
@Override
public void reset() {
this.offset = 0;
}
@Override
public int getOffset() {
return offset;
}
@Override
public List<R> getDescriptions() {
return columns;
}
@Override
public void keepAlive() {
// Do Nothing as we are pre-fetching everything.
}
}