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/*
* Copyright © 2018 Samuel Holland <samuel@sholland.org>
* Copyright © 2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
* SPDX-License-Identifier: Apache-2.0
*/
package com.wireguard.android.util;
import android.support.annotation.NonNull;
import com.wireguard.util.Keyed;
import com.wireguard.util.SortedKeyedList;
import java.util.AbstractList;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.Set;
import java.util.Spliterator;
/**
* KeyedArrayList that enforces uniqueness and sorted order across the set of keys. This class uses
* binary search to improve lookup and replacement times to O(log(n)). However, due to the
* array-based nature of this class, insertion and removal of elements with anything but the largest
* key still require O(n) time.
*/
public class ObservableSortedKeyedArrayList<K, E extends Keyed<? extends K>>
extends ObservableKeyedArrayList<K, E> implements ObservableSortedKeyedList<K, E> {
private final Comparator<? super K> comparator;
private final transient KeyList<K, E> keyList = new KeyList<>(this);
@SuppressWarnings("WeakerAccess")
public ObservableSortedKeyedArrayList() {
comparator = null;
}
public ObservableSortedKeyedArrayList(final Comparator<? super K> comparator) {
this.comparator = comparator;
}
public ObservableSortedKeyedArrayList(final Collection<? extends E> c) {
this();
addAll(c);
}
public ObservableSortedKeyedArrayList(final SortedKeyedList<K, E> other) {
this(other.comparator());
addAll(other);
}
@Override
public boolean add(final E e) {
final int insertionPoint = getInsertionPoint(e);
if (insertionPoint < 0) {
// Skipping insertion is non-destructive if the new and existing objects are the same.
if (e == get(-insertionPoint - 1))
return false;
throw new IllegalArgumentException("Element with same key already exists in list");
}
super.add(insertionPoint, e);
return true;
}
@Override
public void add(final int index, final E e) {
final int insertionPoint = getInsertionPoint(e);
if (insertionPoint < 0)
throw new IllegalArgumentException("Element with same key already exists in list");
if (insertionPoint != index)
throw new IndexOutOfBoundsException("Wrong index given for element");
super.add(index, e);
}
@Override
public boolean addAll(@NonNull final Collection<? extends E> c) {
boolean didChange = false;
for (final E e : c)
if (add(e))
didChange = true;
return didChange;
}
@Override
public boolean addAll(int index, @NonNull final Collection<? extends E> c) {
for (final E e : c)
add(index++, e);
return true;
}
@Override
public Comparator<? super K> comparator() {
return comparator;
}
@Override
public K firstKey() {
if (isEmpty())
// The parameter in the exception is only to shut
// lint up, we never care for the exception message.
throw new NoSuchElementException("Empty set");
return get(0).getKey();
}
private int getInsertionPoint(final E e) {
if (comparator != null) {
return -Collections.binarySearch(keyList, e.getKey(), comparator) - 1;
} else {
@SuppressWarnings("unchecked") final List<Comparable<? super K>> list =
(List<Comparable<? super K>>) keyList;
return -Collections.binarySearch(list, e.getKey()) - 1;
}
}
@Override
public int indexOfKey(final K key) {
final int index;
if (comparator != null) {
index = Collections.binarySearch(keyList, key, comparator);
} else {
@SuppressWarnings("unchecked") final List<Comparable<? super K>> list =
(List<Comparable<? super K>>) keyList;
index = Collections.binarySearch(list, key);
}
return index >= 0 ? index : -1;
}
@Override
@NonNull
public Set<K> keySet() {
return keyList;
}
@Override
public int lastIndexOfKey(final K key) {
// There can never be more than one element with the same key in the list.
return indexOfKey(key);
}
@Override
public K lastKey() {
if (isEmpty())
// The parameter in the exception is only to shut
// lint up, we never care for the exception message.
throw new NoSuchElementException("Empty set");
return get(size() - 1).getKey();
}
@Override
public E set(final int index, final E e) {
final int order;
if (comparator != null) {
order = comparator.compare(e.getKey(), get(index).getKey());
} else {
@SuppressWarnings("unchecked") final Comparable<? super K> key =
(Comparable<? super K>) e.getKey();
order = key.compareTo(get(index).getKey());
}
if (order != 0) {
// Allow replacement if the new key would be inserted adjacent to the replaced element.
final int insertionPoint = getInsertionPoint(e);
if (insertionPoint < index || insertionPoint > index + 1)
throw new IndexOutOfBoundsException("Wrong index given for element");
}
return super.set(index, e);
}
@Override
@NonNull
public Collection<E> values() {
return this;
}
private static final class KeyList<K, E extends Keyed<? extends K>>
extends AbstractList<K> implements Set<K> {
private final ObservableSortedKeyedArrayList<K, E> list;
private KeyList(final ObservableSortedKeyedArrayList<K, E> list) {
this.list = list;
}
@Override
public K get(final int index) {
return list.get(index).getKey();
}
@Override
public int size() {
return list.size();
}
@Override
@SuppressWarnings("EmptyMethod")
public Spliterator<K> spliterator() {
return super.spliterator();
}
}
}
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