/*
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* Copyright (C) 2010 The Android Open Source Project
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* Copyright (C) 2012 Google Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package cn.emay.sdk.util.json.gson.internal;
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import java.io.ObjectStreamException;
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import java.io.Serializable;
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import java.util.AbstractMap;
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import java.util.AbstractSet;
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import java.util.Comparator;
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import java.util.ConcurrentModificationException;
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import java.util.Iterator;
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import java.util.LinkedHashMap;
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import java.util.NoSuchElementException;
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import java.util.Set;
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/**
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* A map of comparable keys to values. Unlike {@code TreeMap}, this class uses
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* insertion order for iteration order. Comparison order is only used as an
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* optimization for efficient insertion and removal.
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*
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* <p>
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* This implementation was derived from Android 4.1's TreeMap class.
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*/
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public final class LinkedTreeMap<K, V> extends AbstractMap<K, V> implements Serializable {
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@SuppressWarnings({ "unchecked", "rawtypes" }) // to avoid Comparable<Comparable<Comparable<...>>>
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private static final Comparator<Comparable> NATURAL_ORDER = new Comparator<Comparable>() {
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public int compare(Comparable a, Comparable b) {
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return a.compareTo(b);
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}
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};
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Comparator<? super K> comparator;
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Node<K, V> root;
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int size = 0;
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int modCount = 0;
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// Used to preserve iteration order
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final Node<K, V> header = new Node<K, V>();
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/**
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* Create a natural order, empty tree map whose keys must be mutually comparable
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* and non-null.
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*/
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@SuppressWarnings("unchecked") // unsafe! this assumes K is comparable
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public LinkedTreeMap() {
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this((Comparator<? super K>) NATURAL_ORDER);
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}
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/**
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* Create a tree map ordered by {@code comparator}. This map's keys may only be
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* null if {@code comparator} permits.
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*
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* @param comparator
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* the comparator to order elements with, or {@code null} to use the
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* natural ordering.
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*/
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@SuppressWarnings({ "unchecked", "rawtypes" }) // unsafe! if comparator is null, this assumes K is comparable
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public LinkedTreeMap(Comparator<? super K> comparator) {
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this.comparator = comparator != null ? comparator : (Comparator) NATURAL_ORDER;
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}
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@Override
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public int size() {
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return size;
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}
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@Override
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public V get(Object key) {
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Node<K, V> node = findByObject(key);
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return node != null ? node.value : null;
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}
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@Override
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public boolean containsKey(Object key) {
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return findByObject(key) != null;
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}
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@Override
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public V put(K key, V value) {
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if (key == null) {
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throw new NullPointerException("key == null");
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}
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Node<K, V> created = find(key, true);
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V result = created.value;
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created.value = value;
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return result;
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}
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@Override
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public void clear() {
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root = null;
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size = 0;
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modCount++;
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// Clear iteration order
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Node<K, V> header = this.header;
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header.next = header.prev = header;
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}
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@Override
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public V remove(Object key) {
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Node<K, V> node = removeInternalByKey(key);
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return node != null ? node.value : null;
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}
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/**
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* Returns the node at or adjacent to the given key, creating it if requested.
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*
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* @throws ClassCastException
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* if {@code key} and the tree's keys aren't mutually comparable.
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*/
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Node<K, V> find(K key, boolean create) {
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Comparator<? super K> comparator = this.comparator;
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Node<K, V> nearest = root;
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int comparison = 0;
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if (nearest != null) {
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// Micro-optimization: avoid polymorphic calls to Comparator.compare().
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@SuppressWarnings("unchecked") // Throws a ClassCastException below if there's trouble.
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Comparable<Object> comparableKey = (comparator == NATURAL_ORDER) ? (Comparable<Object>) key : null;
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while (true) {
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comparison = (comparableKey != null) ? comparableKey.compareTo(nearest.key) : comparator.compare(key, nearest.key);
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// We found the requested key.
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if (comparison == 0) {
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return nearest;
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}
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// If it exists, the key is in a subtree. Go deeper.
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Node<K, V> child = (comparison < 0) ? nearest.left : nearest.right;
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if (child == null) {
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break;
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}
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nearest = child;
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}
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}
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// The key doesn't exist in this tree.
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if (!create) {
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return null;
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}
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// Create the node and add it to the tree or the table.
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Node<K, V> header = this.header;
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Node<K, V> created;
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if (nearest == null) {
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// Check that the value is comparable if we didn't do any comparisons.
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if (comparator == NATURAL_ORDER && !(key instanceof Comparable)) {
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throw new ClassCastException(key.getClass().getName() + " is not Comparable");
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}
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created = new Node<K, V>(nearest, key, header, header.prev);
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root = created;
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} else {
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created = new Node<K, V>(nearest, key, header, header.prev);
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if (comparison < 0) { // nearest.key is higher
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nearest.left = created;
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} else { // comparison > 0, nearest.key is lower
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nearest.right = created;
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}
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rebalance(nearest, true);
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}
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size++;
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modCount++;
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return created;
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}
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@SuppressWarnings("unchecked")
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Node<K, V> findByObject(Object key) {
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try {
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return key != null ? find((K) key, false) : null;
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} catch (ClassCastException e) {
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return null;
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}
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}
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/**
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* Returns this map's entry that has the same key and value as {@code
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* entry}, or null if this map has no such entry.
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*
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* <p>
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* This method uses the comparator for key equality rather than {@code
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* equals}. If this map's comparator isn't consistent with equals (such as
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* {@code String.CASE_INSENSITIVE_ORDER}), then {@code remove()} and {@code
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* contains()} will violate the collections API.
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*/
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Node<K, V> findByEntry(Entry<?, ?> entry) {
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Node<K, V> mine = findByObject(entry.getKey());
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boolean valuesEqual = mine != null && equal(mine.value, entry.getValue());
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return valuesEqual ? mine : null;
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}
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private boolean equal(Object a, Object b) {
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return a == b || (a != null && a.equals(b));
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}
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/**
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* Removes {@code node} from this tree, rearranging the tree's structure as
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* necessary.
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*
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* @param unlink
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* true to also unlink this node from the iteration linked list.
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*/
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void removeInternal(Node<K, V> node, boolean unlink) {
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if (unlink) {
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node.prev.next = node.next;
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node.next.prev = node.prev;
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}
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Node<K, V> left = node.left;
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Node<K, V> right = node.right;
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Node<K, V> originalParent = node.parent;
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if (left != null && right != null) {
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/*
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* To remove a node with both left and right subtrees, move an adjacent node
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* from one of those subtrees into this node's place.
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*
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* Removing the adjacent node may change this node's subtrees. This node may no
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* longer have two subtrees once the adjacent node is gone!
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*/
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Node<K, V> adjacent = (left.height > right.height) ? left.last() : right.first();
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removeInternal(adjacent, false); // takes care of rebalance and size--
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int leftHeight = 0;
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left = node.left;
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if (left != null) {
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leftHeight = left.height;
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adjacent.left = left;
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left.parent = adjacent;
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node.left = null;
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}
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int rightHeight = 0;
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right = node.right;
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if (right != null) {
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rightHeight = right.height;
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adjacent.right = right;
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right.parent = adjacent;
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node.right = null;
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}
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adjacent.height = Math.max(leftHeight, rightHeight) + 1;
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replaceInParent(node, adjacent);
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return;
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} else if (left != null) {
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replaceInParent(node, left);
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node.left = null;
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} else if (right != null) {
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replaceInParent(node, right);
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node.right = null;
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} else {
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replaceInParent(node, null);
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}
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rebalance(originalParent, false);
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size--;
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modCount++;
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}
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Node<K, V> removeInternalByKey(Object key) {
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Node<K, V> node = findByObject(key);
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if (node != null) {
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removeInternal(node, true);
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}
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return node;
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}
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private void replaceInParent(Node<K, V> node, Node<K, V> replacement) {
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Node<K, V> parent = node.parent;
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node.parent = null;
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if (replacement != null) {
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replacement.parent = parent;
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}
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if (parent != null) {
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if (parent.left == node) {
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parent.left = replacement;
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} else {
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assert (parent.right == node);
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parent.right = replacement;
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}
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} else {
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root = replacement;
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}
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}
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/**
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* Rebalances the tree by making any AVL rotations necessary between the
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* newly-unbalanced node and the tree's root.
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*
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* @param insert
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* true if the node was unbalanced by an insert; false if it was by a
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* removal.
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*/
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private void rebalance(Node<K, V> unbalanced, boolean insert) {
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for (Node<K, V> node = unbalanced; node != null; node = node.parent) {
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Node<K, V> left = node.left;
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Node<K, V> right = node.right;
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int leftHeight = left != null ? left.height : 0;
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int rightHeight = right != null ? right.height : 0;
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int delta = leftHeight - rightHeight;
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if (delta == -2) {
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Node<K, V> rightLeft = right.left;
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Node<K, V> rightRight = right.right;
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int rightRightHeight = rightRight != null ? rightRight.height : 0;
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int rightLeftHeight = rightLeft != null ? rightLeft.height : 0;
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int rightDelta = rightLeftHeight - rightRightHeight;
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if (rightDelta == -1 || (rightDelta == 0 && !insert)) {
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rotateLeft(node); // AVL right right
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} else {
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assert (rightDelta == 1);
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rotateRight(right); // AVL right left
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rotateLeft(node);
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}
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if (insert) {
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break; // no further rotations will be necessary
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}
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} else if (delta == 2) {
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Node<K, V> leftLeft = left.left;
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Node<K, V> leftRight = left.right;
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int leftRightHeight = leftRight != null ? leftRight.height : 0;
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int leftLeftHeight = leftLeft != null ? leftLeft.height : 0;
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int leftDelta = leftLeftHeight - leftRightHeight;
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if (leftDelta == 1 || (leftDelta == 0 && !insert)) {
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rotateRight(node); // AVL left left
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} else {
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assert (leftDelta == -1);
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rotateLeft(left); // AVL left right
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rotateRight(node);
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}
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if (insert) {
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break; // no further rotations will be necessary
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}
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} else if (delta == 0) {
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node.height = leftHeight + 1; // leftHeight == rightHeight
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if (insert) {
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break; // the insert caused balance, so rebalancing is done!
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}
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} else {
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assert (delta == -1 || delta == 1);
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node.height = Math.max(leftHeight, rightHeight) + 1;
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if (!insert) {
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break; // the height hasn't changed, so rebalancing is done!
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}
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}
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}
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}
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/**
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* Rotates the subtree so that its root's right child is the new root.
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*/
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private void rotateLeft(Node<K, V> root) {
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Node<K, V> left = root.left;
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Node<K, V> pivot = root.right;
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Node<K, V> pivotLeft = pivot.left;
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Node<K, V> pivotRight = pivot.right;
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// move the pivot's left child to the root's right
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root.right = pivotLeft;
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if (pivotLeft != null) {
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pivotLeft.parent = root;
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}
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replaceInParent(root, pivot);
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// move the root to the pivot's left
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pivot.left = root;
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root.parent = pivot;
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// fix heights
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root.height = Math.max(left != null ? left.height : 0, pivotLeft != null ? pivotLeft.height : 0) + 1;
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pivot.height = Math.max(root.height, pivotRight != null ? pivotRight.height : 0) + 1;
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}
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/**
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* Rotates the subtree so that its root's left child is the new root.
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*/
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private void rotateRight(Node<K, V> root) {
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Node<K, V> pivot = root.left;
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Node<K, V> right = root.right;
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Node<K, V> pivotLeft = pivot.left;
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Node<K, V> pivotRight = pivot.right;
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// move the pivot's right child to the root's left
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root.left = pivotRight;
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if (pivotRight != null) {
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pivotRight.parent = root;
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}
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replaceInParent(root, pivot);
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// move the root to the pivot's right
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pivot.right = root;
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root.parent = pivot;
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// fixup heights
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root.height = Math.max(right != null ? right.height : 0, pivotRight != null ? pivotRight.height : 0) + 1;
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pivot.height = Math.max(root.height, pivotLeft != null ? pivotLeft.height : 0) + 1;
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}
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private EntrySet entrySet;
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private KeySet keySet;
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@Override
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public Set<Entry<K, V>> entrySet() {
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EntrySet result = entrySet;
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return result != null ? result : (entrySet = new EntrySet());
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}
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@Override
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public Set<K> keySet() {
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KeySet result = keySet;
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return result != null ? result : (keySet = new KeySet());
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}
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static final class Node<K, V> implements Entry<K, V> {
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Node<K, V> parent;
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Node<K, V> left;
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Node<K, V> right;
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Node<K, V> next;
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Node<K, V> prev;
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final K key;
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V value;
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int height;
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/** Create the header entry */
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Node() {
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key = null;
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next = prev = this;
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}
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/** Create a regular entry */
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Node(Node<K, V> parent, K key, Node<K, V> next, Node<K, V> prev) {
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this.parent = parent;
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this.key = key;
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this.height = 1;
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this.next = next;
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this.prev = prev;
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prev.next = this;
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next.prev = this;
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}
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public K getKey() {
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return key;
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}
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public V getValue() {
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return value;
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}
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public V setValue(V value) {
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V oldValue = this.value;
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this.value = value;
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return oldValue;
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}
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@SuppressWarnings("rawtypes")
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@Override
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public boolean equals(Object o) {
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if (o instanceof Entry) {
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Entry other = (Entry) o;
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return (key == null ? other.getKey() == null : key.equals(other.getKey())) && (value == null ? other.getValue() == null : value.equals(other.getValue()));
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}
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return false;
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}
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@Override
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public int hashCode() {
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return (key == null ? 0 : key.hashCode()) ^ (value == null ? 0 : value.hashCode());
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}
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@Override
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public String toString() {
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return key + "=" + value;
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}
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/**
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* Returns the first node in this subtree.
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*/
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public Node<K, V> first() {
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Node<K, V> node = this;
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Node<K, V> child = node.left;
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while (child != null) {
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node = child;
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child = node.left;
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}
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return node;
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}
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/**
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* Returns the last node in this subtree.
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*/
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public Node<K, V> last() {
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Node<K, V> node = this;
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Node<K, V> child = node.right;
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while (child != null) {
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node = child;
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child = node.right;
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}
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return node;
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}
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}
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private abstract class LinkedTreeMapIterator<T> implements Iterator<T> {
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Node<K, V> next = header.next;
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Node<K, V> lastReturned = null;
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int expectedModCount = modCount;
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LinkedTreeMapIterator() {
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}
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public final boolean hasNext() {
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return next != header;
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}
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final Node<K, V> nextNode() {
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Node<K, V> e = next;
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if (e == header) {
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throw new NoSuchElementException();
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}
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if (modCount != expectedModCount) {
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throw new ConcurrentModificationException();
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}
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next = e.next;
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return lastReturned = e;
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}
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public final void remove() {
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if (lastReturned == null) {
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throw new IllegalStateException();
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}
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removeInternal(lastReturned, true);
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lastReturned = null;
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expectedModCount = modCount;
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}
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}
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class EntrySet extends AbstractSet<Entry<K, V>> {
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@Override
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public int size() {
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return size;
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}
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@Override
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public Iterator<Entry<K, V>> iterator() {
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return new LinkedTreeMapIterator<Entry<K, V>>() {
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public Entry<K, V> next() {
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return nextNode();
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}
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};
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}
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@Override
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public boolean contains(Object o) {
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return o instanceof Entry && findByEntry((Entry<?, ?>) o) != null;
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}
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@Override
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public boolean remove(Object o) {
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if (!(o instanceof Entry)) {
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return false;
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}
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Node<K, V> node = findByEntry((Entry<?, ?>) o);
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if (node == null) {
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return false;
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}
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removeInternal(node, true);
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return true;
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}
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@Override
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public void clear() {
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LinkedTreeMap.this.clear();
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}
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}
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final class KeySet extends AbstractSet<K> {
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@Override
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public int size() {
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return size;
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}
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@Override
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public Iterator<K> iterator() {
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return new LinkedTreeMapIterator<K>() {
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public K next() {
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return nextNode().key;
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}
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};
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}
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@Override
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public boolean contains(Object o) {
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return containsKey(o);
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}
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@Override
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public boolean remove(Object key) {
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return removeInternalByKey(key) != null;
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}
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@Override
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public void clear() {
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LinkedTreeMap.this.clear();
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}
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}
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/**
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* If somebody is unlucky enough to have to serialize one of these, serialize it
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* as a LinkedHashMap so that they won't need Gson on the other side to
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* deserialize it. Using serialization defeats our DoS defence, so most apps
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* shouldn't use it.
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*/
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private Object writeReplace() throws ObjectStreamException {
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return new LinkedHashMap<K, V>(this);
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}
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}
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