/*******************************************************************************
* Copyright 2015 Analog Devices, Inc.
*
* 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 com.analog.lyric.collect;
import java.util.List;
import java.util.ListIterator;
import java.util.NoSuchElementException;
/**
* Iterable over the indices of non-null entries in a list.
* <p>
* @since 0.08
* @author Christopher Barber
*/
public class NonNullListIndices implements PrimitiveIterable.OfInt
{
private final List<?> _list;
/*--------------
* Construction
*/
public NonNullListIndices(List<?> list)
{
_list = list;
}
/*---------------------------
* PrimitiveIterable methods
*/
/**
* Returns iterator that will visit the indices of the {@linkplain #getList() contained list} that
* have non-null values. Indices are returned in increasing order.
*/
@Override
public PrimitiveIterator.OfInt iterator()
{
return new PrimitiveIterator.OfInt()
{
private final ListIterator<?> _iter = _list.listIterator();
private int _nextIndex = -1;
private void advance()
{
while (_nextIndex < 0 && _iter.hasNext())
{
if (_iter.next() != null)
{
_nextIndex = _iter.previousIndex();
}
}
}
@Override
public boolean hasNext()
{
advance();
return _nextIndex >= 0;
}
@Override
public void remove()
{
throw new UnsupportedOperationException("remove");
}
@Override
public Integer next()
{
return nextInt();
}
@Override
public int nextInt()
{
advance();
if (_nextIndex < 0)
{
throw new NoSuchElementException();
}
final int index = _nextIndex;
_nextIndex = -1;
return index;
}
};
}
/*--------------------
* NonNullListIndices
*/
/**
* The underlying list.
*/
public List<?> getList()
{
return _list;
}
}