org.apache.cassandra.utils.InsertionOrderedNavigableSet Maven / Gradle / Ivy
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/*
* 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.cassandra.utils;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.NavigableSet;
import java.util.NoSuchElementException;
import java.util.Objects;
import java.util.SortedSet;
import com.google.common.base.Preconditions;
/**
* A {@link NavigableSet} that enforces in-order insertion of elements. This is helpful when we
* have an already-ordered collection with no duplicates and want constant time insertion.
*
* Note: Not all methods of {@link NavigableSet} are implemented.
*
* @param the type of elements maintained by this set
*/
public class InsertionOrderedNavigableSet implements NavigableSet
{
private final ArrayList elements;
private final Comparator comparator;
public InsertionOrderedNavigableSet(Comparator comparator)
{
this.elements = new ArrayList<>();
this.comparator = comparator;
}
@Override
public E lower(E e)
{
throw new UnsupportedOperationException();
}
@Override
public E floor(E e)
{
throw new UnsupportedOperationException();
}
@Override
public E ceiling(E e)
{
throw new UnsupportedOperationException();
}
@Override
public E higher(E e)
{
throw new UnsupportedOperationException();
}
@Override
public E pollFirst()
{
if (isEmpty())
return null;
return elements.remove(0);
}
@Override
public E pollLast()
{
if (isEmpty())
return null;
return elements.remove(size() - 1);
}
@Override
public int size()
{
return elements.size();
}
@Override
public boolean isEmpty()
{
return elements.isEmpty();
}
@Override
public boolean contains(Object o)
{
return elements.contains(o);
}
@Override
public Iterator iterator()
{
return elements.iterator();
}
@Override
public Object[] toArray()
{
return elements.toArray();
}
@Override
public T[] toArray(T[] a)
{
return elements.toArray(a);
}
@Override
public boolean add(E e)
{
if (!isEmpty() && comparator.compare(e, last()) <= 0)
throw new IllegalStateException("Cannot add element " + e + " as it is not greater than the current last element " + last());
return elements.add(e);
}
@Override
public boolean remove(Object o)
{
return elements.remove(o);
}
@Override
public boolean containsAll(Collection c)
{
return elements.containsAll(c);
}
@Override
public boolean addAll(Collection c)
{
boolean modified = false;
for (E element : c)
if (add(element))
modified = true;
return modified;
}
@Override
public boolean retainAll(Collection c)
{
return elements.retainAll(c);
}
@Override
public boolean removeAll(Collection c)
{
return elements.removeAll(c);
}
@Override
public void clear()
{
elements.clear();
}
@Override
public NavigableSet descendingSet()
{
throw new UnsupportedOperationException();
}
@Override
public Iterator descendingIterator()
{
throw new UnsupportedOperationException();
}
@Override
public NavigableSet subSet(E fromElement, boolean fromInclusive, E toElement, boolean toInclusive)
{
throw new UnsupportedOperationException();
}
@Override
public NavigableSet headSet(E toElement, boolean inclusive)
{
Preconditions.checkNotNull(toElement);
if (isEmpty())
return Collections.emptyNavigableSet();
NavigableSet head = new InsertionOrderedNavigableSet<>(comparator);
for (E element : elements)
{
int comparison = comparator.compare(element, toElement);
if (comparison > 0 || comparison == 0 && !inclusive)
break;
head.add(element);
}
return head;
}
@Override
public NavigableSet tailSet(E fromElement, boolean inclusive)
{
Preconditions.checkNotNull(fromElement);
if (isEmpty())
return Collections.emptyNavigableSet();
NavigableSet tail = new InsertionOrderedNavigableSet<>(comparator);
for (E element : elements)
{
int comparison = comparator.compare(element, fromElement);
if (comparison < 0 || comparison == 0 && !inclusive)
continue;
tail.add(element);
}
return tail;
}
@Override
public Comparator comparator()
{
return comparator;
}
@Override
public SortedSet subSet(E fromElement, E toElement)
{
throw new UnsupportedOperationException();
}
@Override
public SortedSet headSet(E toElement)
{
return headSet(toElement, false);
}
@Override
public SortedSet tailSet(E fromElement)
{
return tailSet(fromElement, true);
}
@Override
public E first()
{
if (isEmpty())
throw new NoSuchElementException();
return elements.get(0);
}
@Override
public E last()
{
if (isEmpty())
throw new NoSuchElementException();
return elements.get(size() - 1);
}
@Override
public boolean equals(Object o)
{
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
InsertionOrderedNavigableSet that = (InsertionOrderedNavigableSet) o;
return Objects.equals(elements, that.elements) && Objects.equals(comparator, that.comparator);
}
@Override
public int hashCode()
{
return Objects.hash(elements, comparator);
}
}