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Convert LinkedHashTreeMap to Kotlin (#1508)

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* Initial pass at converting LinkedHashTreeMap to Kotlin

* Update tests as needed

* Remove Arrays use

* Separate find nullability

* Clean up a few expression bodies

* Various little cleanups and warnings

* Sprinkle in some knownNotNulls where useful

* add() is not implemented

* clean up some visibility and properties that can be fields

* Some minor formatting

* Some minor formatting
This commit is contained in:
Zac Sweers
2022-01-23 18:03:25 -05:00
committed by GitHub
parent b2a67760d4
commit 2c9e3d036a
3 changed files with 780 additions and 861 deletions
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855
moshi/src/main/java/com/squareup/moshi/LinkedHashTreeMap.java
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/*
* Copyright (C) 2010-2012 Square, 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
*
* https://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.squareup.moshi;
import java.io.ObjectStreamException;
import java.io.Serializable;
import java.util.AbstractMap;
import java.util.AbstractSet;
import java.util.Arrays;
import java.util.Comparator;
import java.util.ConcurrentModificationException;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.NoSuchElementException;
import java.util.Set;
import javax.annotation.Nullable;
/**
* A map of comparable keys to values. Unlike {@code TreeMap}, this class uses insertion order for
* iteration order. Comparison order is only used as an optimization for efficient insertion and
* removal.
*
* <p>This implementation was derived from Android 4.1's TreeMap and LinkedHashMap classes.
*/
final class LinkedHashTreeMap<K, V> extends AbstractMap<K, V> implements Serializable {
@SuppressWarnings({"unchecked", "rawtypes"}) // to avoid Comparable<Comparable<Comparable<...>>>
private static final Comparator<Comparable> NATURAL_ORDER =
new Comparator<Comparable>() {
public int compare(Comparable a, Comparable b) {
return a.compareTo(b);
}
};
final Comparator<? super K> comparator;
Node<K, V>[] table;
final Node<K, V> header;
int size = 0;
int modCount = 0;
int threshold;
/** Create a natural order, empty tree map whose keys must be mutually comparable and non-null. */
LinkedHashTreeMap() {
this(null);
}
/**
* Create a tree map ordered by {@code comparator}. This map's keys may only be null if {@code
* comparator} permits.
*
* @param comparator the comparator to order elements with, or {@code null} to use the natural
* ordering.
*/
@SuppressWarnings({
"unchecked",
"rawtypes" // Unsafe! if comparator is null, this assumes K is comparable.
})
LinkedHashTreeMap(Comparator<? super K> comparator) {
this.comparator = comparator != null ? comparator : (Comparator) NATURAL_ORDER;
this.header = new Node<>();
this.table = new Node[16]; // TODO: sizing/resizing policies
this.threshold = (table.length / 2) + (table.length / 4); // 3/4 capacity
}
@Override
public int size() {
return size;
}
@Override
public V get(Object key) {
Node<K, V> node = findByObject(key);
return node != null ? node.value : null;
}
@Override
public boolean containsKey(Object key) {
return findByObject(key) != null;
}
@Override
public V put(K key, @Nullable V value) {
if (key == null) {
throw new NullPointerException("key == null");
}
Node<K, V> created = find(key, true);
V result = created.value;
created.value = value;
return result;
}
@Override
public void clear() {
Arrays.fill(table, null);
size = 0;
modCount++;
// Clear all links to help GC
Node<K, V> header = this.header;
for (Node<K, V> e = header.next; e != header; ) {
Node<K, V> next = e.next;
e.next = e.prev = null;
e = next;
}
header.next = header.prev = header;
}
@Override
public V remove(Object key) {
Node<K, V> node = removeInternalByKey(key);
return node != null ? node.value : null;
}
/**
* Returns the node at or adjacent to the given key, creating it if requested.
*
* @throws ClassCastException if {@code key} and the tree's keys aren't mutually comparable.
*/
Node<K, V> find(K key, boolean create) {
Comparator<? super K> comparator = this.comparator;
Node<K, V>[] table = this.table;
int hash = secondaryHash(key.hashCode());
int index = hash & (table.length - 1);
Node<K, V> nearest = table[index];
int comparison = 0;
if (nearest != null) {
// Micro-optimization: avoid polymorphic calls to Comparator.compare().
@SuppressWarnings("unchecked") // Throws a ClassCastException below if there's trouble.
Comparable<Object> comparableKey =
(comparator == NATURAL_ORDER) ? (Comparable<Object>) key : null;
while (true) {
comparison =
(comparableKey != null)
? comparableKey.compareTo(nearest.key)
: comparator.compare(key, nearest.key);
// We found the requested key.
if (comparison == 0) {
return nearest;
}
// If it exists, the key is in a subtree. Go deeper.
Node<K, V> child = (comparison < 0) ? nearest.left : nearest.right;
if (child == null) {
break;
}
nearest = child;
}
}
// The key doesn't exist in this tree.
if (!create) {
return null;
}
// Create the node and add it to the tree or the table.
Node<K, V> header = this.header;
Node<K, V> created;
if (nearest == null) {
// Check that the value is comparable if we didn't do any comparisons.
if (comparator == NATURAL_ORDER && !(key instanceof Comparable)) {
throw new ClassCastException(key.getClass().getName() + " is not Comparable");
}
created = new Node<>(nearest, key, hash, header, header.prev);
table[index] = created;
} else {
created = new Node<>(nearest, key, hash, header, header.prev);
if (comparison < 0) { // nearest.key is higher
nearest.left = created;
} else { // comparison > 0, nearest.key is lower
nearest.right = created;
}
rebalance(nearest, true);
}
if (size++ > threshold) {
doubleCapacity();
}
modCount++;
return created;
}
@SuppressWarnings("unchecked")
Node<K, V> findByObject(Object key) {
try {
return key != null ? find((K) key, false) : null;
} catch (ClassCastException e) {
return null;
}
}
/**
* Returns this map's entry that has the same key and value as {@code entry}, or null if this map
* has no such entry.
*
* <p>This method uses the comparator for key equality rather than {@code equals}. If this map's
* comparator isn't consistent with equals (such as {@code String.CASE_INSENSITIVE_ORDER}), then
* {@code remove()} and {@code contains()} will violate the collections API.
*/
Node<K, V> findByEntry(Entry<?, ?> entry) {
Node<K, V> mine = findByObject(entry.getKey());
boolean valuesEqual = mine != null && equal(mine.value, entry.getValue());
return valuesEqual ? mine : null;
}
private boolean equal(Object a, Object b) {
return a == b || (a != null && a.equals(b));
}
/**
* Applies a supplemental hash function to a given hashCode, which defends against poor quality
* hash functions. This is critical because HashMap uses power-of-two length hash tables, that
* otherwise encounter collisions for hashCodes that do not differ in lower or upper bits.
*/
private static int secondaryHash(int h) {
// Doug Lea's supplemental hash function
h ^= (h >>> 20) ^ (h >>> 12);
return h ^ (h >>> 7) ^ (h >>> 4);
}
/**
* Removes {@code node} from this tree, rearranging the tree's structure as necessary.
*
* @param unlink true to also unlink this node from the iteration linked list.
*/
void removeInternal(Node<K, V> node, boolean unlink) {
if (unlink) {
node.prev.next = node.next;
node.next.prev = node.prev;
node.next = node.prev = null; // Help the GC (for performance)
}
Node<K, V> left = node.left;
Node<K, V> right = node.right;
Node<K, V> originalParent = node.parent;
if (left != null && right != null) {
/*
* To remove a node with both left and right subtrees, move an
* adjacent node from one of those subtrees into this node's place.
*
* Removing the adjacent node may change this node's subtrees. This
* node may no longer have two subtrees once the adjacent node is
* gone!
*/
Node<K, V> adjacent = (left.height > right.height) ? left.last() : right.first();
removeInternal(adjacent, false); // takes care of rebalance and size--
int leftHeight = 0;
left = node.left;
if (left != null) {
leftHeight = left.height;
adjacent.left = left;
left.parent = adjacent;
node.left = null;
}
int rightHeight = 0;
right = node.right;
if (right != null) {
rightHeight = right.height;
adjacent.right = right;
right.parent = adjacent;
node.right = null;
}
adjacent.height = Math.max(leftHeight, rightHeight) + 1;
replaceInParent(node, adjacent);
return;
} else if (left != null) {
replaceInParent(node, left);
node.left = null;
} else if (right != null) {
replaceInParent(node, right);
node.right = null;
} else {
replaceInParent(node, null);
}
rebalance(originalParent, false);
size--;
modCount++;
}
Node<K, V> removeInternalByKey(Object key) {
Node<K, V> node = findByObject(key);
if (node != null) {
removeInternal(node, true);
}
return node;
}
private void replaceInParent(Node<K, V> node, Node<K, V> replacement) {
Node<K, V> parent = node.parent;
node.parent = null;
if (replacement != null) {
replacement.parent = parent;
}
if (parent != null) {
if (parent.left == node) {
parent.left = replacement;
} else {
assert (parent.right == node);
parent.right = replacement;
}
} else {
int index = node.hash & (table.length - 1);
table[index] = replacement;
}
}
/**
* Rebalances the tree by making any AVL rotations necessary between the newly-unbalanced node and
* the tree's root.
*
* @param insert true if the node was unbalanced by an insert; false if it was by a removal.
*/
private void rebalance(Node<K, V> unbalanced, boolean insert) {
for (Node<K, V> node = unbalanced; node != null; node = node.parent) {
Node<K, V> left = node.left;
Node<K, V> right = node.right;
int leftHeight = left != null ? left.height : 0;
int rightHeight = right != null ? right.height : 0;
int delta = leftHeight - rightHeight;
if (delta == -2) {
Node<K, V> rightLeft = right.left;
Node<K, V> rightRight = right.right;
int rightRightHeight = rightRight != null ? rightRight.height : 0;
int rightLeftHeight = rightLeft != null ? rightLeft.height : 0;
int rightDelta = rightLeftHeight - rightRightHeight;
if (rightDelta != -1 && (rightDelta != 0 || insert)) {
assert (rightDelta == 1);
rotateRight(right); // AVL right left
}
rotateLeft(node); // AVL right right
if (insert) {
break; // no further rotations will be necessary
}
} else if (delta == 2) {
Node<K, V> leftLeft = left.left;
Node<K, V> leftRight = left.right;
int leftRightHeight = leftRight != null ? leftRight.height : 0;
int leftLeftHeight = leftLeft != null ? leftLeft.height : 0;
int leftDelta = leftLeftHeight - leftRightHeight;
if (leftDelta != 1 && (leftDelta != 0 || insert)) {
assert (leftDelta == -1);
rotateLeft(left); // AVL left right
}
rotateRight(node); // AVL left left
if (insert) {
break; // no further rotations will be necessary
}
} else if (delta == 0) {
node.height = leftHeight + 1; // leftHeight == rightHeight
if (insert) {
break; // the insert caused balance, so rebalancing is done!
}
} else {
assert (delta == -1 || delta == 1);
node.height = Math.max(leftHeight, rightHeight) + 1;
if (!insert) {
break; // the height hasn't changed, so rebalancing is done!
}
}
}
}
/** Rotates the subtree so that its root's right child is the new root. */
private void rotateLeft(Node<K, V> root) {
Node<K, V> left = root.left;
Node<K, V> pivot = root.right;
Node<K, V> pivotLeft = pivot.left;
Node<K, V> pivotRight = pivot.right;
// move the pivot's left child to the root's right
root.right = pivotLeft;
if (pivotLeft != null) {
pivotLeft.parent = root;
}
replaceInParent(root, pivot);
// move the root to the pivot's left
pivot.left = root;
root.parent = pivot;
// fix heights
root.height =
Math.max(left != null ? left.height : 0, pivotLeft != null ? pivotLeft.height : 0) + 1;
pivot.height = Math.max(root.height, pivotRight != null ? pivotRight.height : 0) + 1;
}
/** Rotates the subtree so that its root's left child is the new root. */
private void rotateRight(Node<K, V> root) {
Node<K, V> pivot = root.left;
Node<K, V> right = root.right;
Node<K, V> pivotLeft = pivot.left;
Node<K, V> pivotRight = pivot.right;
// move the pivot's right child to the root's left
root.left = pivotRight;
if (pivotRight != null) {
pivotRight.parent = root;
}
replaceInParent(root, pivot);
// move the root to the pivot's right
pivot.right = root;
root.parent = pivot;
// fixup heights
root.height =
Math.max(right != null ? right.height : 0, pivotRight != null ? pivotRight.height : 0) + 1;
pivot.height = Math.max(root.height, pivotLeft != null ? pivotLeft.height : 0) + 1;
}
private EntrySet entrySet;
private KeySet keySet;
@Override
public Set<Entry<K, V>> entrySet() {
EntrySet result = entrySet;
return result != null ? result : (entrySet = new EntrySet());
}
@Override
public Set<K> keySet() {
KeySet result = keySet;
return result != null ? result : (keySet = new KeySet());
}
static final class Node<K, V> implements Entry<K, V> {
Node<K, V> parent;
Node<K, V> left;
Node<K, V> right;
Node<K, V> next;
Node<K, V> prev;
final K key;
final int hash;
V value;
int height;
/** Create the header entry. */
Node() {
key = null;
hash = -1;
next = prev = this;
}
/** Create a regular entry. */
Node(Node<K, V> parent, K key, int hash, Node<K, V> next, Node<K, V> prev) {
this.parent = parent;
this.key = key;
this.hash = hash;
this.height = 1;
this.next = next;
this.prev = prev;
prev.next = this;
next.prev = this;
}
public K getKey() {
return key;
}
public V getValue() {
return value;
}
public V setValue(V value) {
V oldValue = this.value;
this.value = value;
return oldValue;
}
@SuppressWarnings("rawtypes")
@Override
public boolean equals(Object o) {
if (o instanceof Entry) {
Entry other = (Entry) o;
return (key == null ? other.getKey() == null : key.equals(other.getKey()))
&& (value == null ? other.getValue() == null : value.equals(other.getValue()));
}
return false;
}
@Override
public int hashCode() {
return (key == null ? 0 : key.hashCode()) ^ (value == null ? 0 : value.hashCode());
}
@Override
public String toString() {
return key + "=" + value;
}
/** Returns the first node in this subtree. */
public Node<K, V> first() {
Node<K, V> node = this;
Node<K, V> child = node.left;
while (child != null) {
node = child;
child = node.left;
}
return node;
}
/** Returns the last node in this subtree. */
public Node<K, V> last() {
Node<K, V> node = this;
Node<K, V> child = node.right;
while (child != null) {
node = child;
child = node.right;
}
return node;
}
}
private void doubleCapacity() {
table = doubleCapacity(table);
threshold = (table.length / 2) + (table.length / 4); // 3/4 capacity
}
/**
* Returns a new array containing the same nodes as {@code oldTable}, but with twice as many
* trees, each of (approximately) half the previous size.
*/
static <K, V> Node<K, V>[] doubleCapacity(Node<K, V>[] oldTable) {
// TODO: don't do anything if we're already at MAX_CAPACITY
int oldCapacity = oldTable.length;
@SuppressWarnings("unchecked") // Arrays and generics don't get along.
Node<K, V>[] newTable = new Node[oldCapacity * 2];
AvlIterator<K, V> iterator = new AvlIterator<>();
AvlBuilder<K, V> leftBuilder = new AvlBuilder<>();
AvlBuilder<K, V> rightBuilder = new AvlBuilder<>();
// Split each tree into two trees.
for (int i = 0; i < oldCapacity; i++) {
Node<K, V> root = oldTable[i];
if (root == null) {
continue;
}
// Compute the sizes of the left and right trees.
iterator.reset(root);
int leftSize = 0;
int rightSize = 0;
for (Node<K, V> node; (node = iterator.next()) != null; ) {
if ((node.hash & oldCapacity) == 0) {
leftSize++;
} else {
rightSize++;
}
}
// Split the tree into two.
leftBuilder.reset(leftSize);
rightBuilder.reset(rightSize);
iterator.reset(root);
for (Node<K, V> node; (node = iterator.next()) != null; ) {
if ((node.hash & oldCapacity) == 0) {
leftBuilder.add(node);
} else {
rightBuilder.add(node);
}
}
// Populate the enlarged array with these new roots.
newTable[i] = leftSize > 0 ? leftBuilder.root() : null;
newTable[i + oldCapacity] = rightSize > 0 ? rightBuilder.root() : null;
}
return newTable;
}
/**
* Walks an AVL tree in iteration order. Once a node has been returned, its left, right and parent
* links are <strong>no longer used</strong>. For this reason it is safe to transform these links
* as you walk a tree.
*
* <p><strong>Warning:</strong> this iterator is destructive. It clears the parent node of all
* nodes in the tree. It is an error to make a partial iteration of a tree.
*/
static class AvlIterator<K, V> {
/** This stack is a singly linked list, linked by the 'parent' field. */
private Node<K, V> stackTop;
void reset(Node<K, V> root) {
Node<K, V> stackTop = null;
for (Node<K, V> n = root; n != null; n = n.left) {
n.parent = stackTop;
stackTop = n; // Stack push.
}
this.stackTop = stackTop;
}
public Node<K, V> next() {
Node<K, V> stackTop = this.stackTop;
if (stackTop == null) {
return null;
}
Node<K, V> result = stackTop;
stackTop = result.parent;
result.parent = null;
for (Node<K, V> n = result.right; n != null; n = n.left) {
n.parent = stackTop;
stackTop = n; // Stack push.
}
this.stackTop = stackTop;
return result;
}
}
/**
* Builds AVL trees of a predetermined size by accepting nodes of increasing value. To use:
*
* <ol>
* <li>Call {@link #reset} to initialize the target size <i>size</i>.
* <li>Call {@link #add} <i>size</i> times with increasing values.
* <li>Call {@link #root} to get the root of the balanced tree.
* </ol>
*
* <p>The returned tree will satisfy the AVL constraint: for every node <i>N</i>, the height of
* <i>N.left</i> and <i>N.right</i> is different by at most 1. It accomplishes this by omitting
* deepest-level leaf nodes when building trees whose size isn't a power of 2 minus 1.
*
* <p>Unlike rebuilding a tree from scratch, this approach requires no value comparisons. Using
* this class to create a tree of size <i>S</i> is {@code O(S)}.
*/
static final class AvlBuilder<K, V> {
/** This stack is a singly linked list, linked by the 'parent' field. */
private Node<K, V> stack;
private int leavesToSkip;
private int leavesSkipped;
private int size;
void reset(int targetSize) {
// compute the target tree size. This is a power of 2 minus one, like 15 or 31.
int treeCapacity = Integer.highestOneBit(targetSize) * 2 - 1;
leavesToSkip = treeCapacity - targetSize;
size = 0;
leavesSkipped = 0;
stack = null;
}
void add(Node<K, V> node) {
node.left = node.parent = node.right = null;
node.height = 1;
// Skip a leaf if necessary.
if (leavesToSkip > 0 && (size & 1) == 0) {
size++;
leavesToSkip--;
leavesSkipped++;
}
node.parent = stack;
stack = node; // Stack push.
size++;
// Skip a leaf if necessary.
if (leavesToSkip > 0 && (size & 1) == 0) {
size++;
leavesToSkip--;
leavesSkipped++;
}
/*
* Combine 3 nodes into subtrees whenever the size is one less than a
* multiple of 4. For example we combine the nodes A, B, C into a
* 3-element tree with B as the root.
*
* Combine two subtrees and a spare single value whenever the size is one
* less than a multiple of 8. For example at 8 we may combine subtrees
* (A B C) and (E F G) with D as the root to form ((A B C) D (E F G)).
*
* Just as we combine single nodes when size nears a multiple of 4, and
* 3-element trees when size nears a multiple of 8, we combine subtrees of
* size (N-1) whenever the total size is 2N-1 whenever N is a power of 2.
*/
for (int scale = 4; (size & scale - 1) == scale - 1; scale *= 2) {
if (leavesSkipped == 0) {
// Pop right, center and left, then make center the top of the stack.
Node<K, V> right = stack;
Node<K, V> center = right.parent;
Node<K, V> left = center.parent;
center.parent = left.parent;
stack = center;
// Construct a tree.
center.left = left;
center.right = right;
center.height = right.height + 1;
left.parent = center;
right.parent = center;
} else if (leavesSkipped == 1) {
// Pop right and center, then make center the top of the stack.
Node<K, V> right = stack;
Node<K, V> center = right.parent;
stack = center;
// Construct a tree with no left child.
center.right = right;
center.height = right.height + 1;
right.parent = center;
leavesSkipped = 0;
} else if (leavesSkipped == 2) {
leavesSkipped = 0;
}
}
}
Node<K, V> root() {
Node<K, V> stackTop = this.stack;
if (stackTop.parent != null) {
throw new IllegalStateException();
}
return stackTop;
}
}
abstract class LinkedTreeMapIterator<T> implements Iterator<T> {
Node<K, V> next = header.next;
Node<K, V> lastReturned = null;
int expectedModCount = modCount;
public final boolean hasNext() {
return next != header;
}
final Node<K, V> nextNode() {
Node<K, V> e = next;
if (e == header) {
throw new NoSuchElementException();
}
if (modCount != expectedModCount) {
throw new ConcurrentModificationException();
}
next = e.next;
return lastReturned = e;
}
public final void remove() {
if (lastReturned == null) {
throw new IllegalStateException();
}
removeInternal(lastReturned, true);
lastReturned = null;
expectedModCount = modCount;
}
}
final class EntrySet extends AbstractSet<Entry<K, V>> {
@Override
public int size() {
return size;
}
@Override
public Iterator<Entry<K, V>> iterator() {
return new LinkedTreeMapIterator<Entry<K, V>>() {
public Entry<K, V> next() {
return nextNode();
}
};
}
@Override
public boolean contains(Object o) {
return o instanceof Entry && findByEntry((Entry<?, ?>) o) != null;
}
@Override
public boolean remove(Object o) {
if (!(o instanceof Entry)) {
return false;
}
Node<K, V> node = findByEntry((Entry<?, ?>) o);
if (node == null) {
return false;
}
removeInternal(node, true);
return true;
}
@Override
public void clear() {
LinkedHashTreeMap.this.clear();
}
}
final class KeySet extends AbstractSet<K> {
@Override
public int size() {
return size;
}
@Override
public Iterator<K> iterator() {
return new LinkedTreeMapIterator<K>() {
public K next() {
return nextNode().key;
}
};
}
@Override
public boolean contains(Object o) {
return containsKey(o);
}
@Override
public boolean remove(Object key) {
return removeInternalByKey(key) != null;
}
@Override
public void clear() {
LinkedHashTreeMap.this.clear();
}
}
/**
* If somebody is unlucky enough to have to serialize one of these, serialize it as a
* LinkedHashMap so that they won't need Gson on the other side to deserialize it. Using
* serialization defeats our DoS defence, so most apps shouldn't use it.
*/
private Object writeReplace() throws ObjectStreamException {
return new LinkedHashMap<>(this);
}
}

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moshi/src/main/java/com/squareup/moshi/LinkedHashTreeMap.kt Normal file
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package com.squareup.moshi
import com.squareup.moshi.LinkedHashTreeMap.Node
import com.squareup.moshi.internal.knownNotNull
import java.io.Serializable
import kotlin.math.max
@Suppress("UNCHECKED_CAST")
private val NATURAL_ORDER = Comparator<Any> { o1, o2 -> (o1 as Comparable<Any>).compareTo(o2) }
/**
* A map of comparable keys to values. Unlike TreeMap, this class uses insertion order for
* iteration order. Comparison order is only used as an optimization for efficient insertion and
* removal.
*
* This implementation was derived from Android 4.1's TreeMap and LinkedHashMap classes.
*/
internal class LinkedHashTreeMap<K, V>
/**
* Create a tree map ordered by [comparator]. This map's keys may only be null if [comparator] permits.
*
* @param comparator the comparator to order elements with, or null to use the natural ordering.
*/
constructor(
comparator: Comparator<Any?>? = null
) : AbstractMutableMap<K, V>(), Serializable {
@Suppress("UNCHECKED_CAST")
private val comparator: Comparator<Any?> = (comparator ?: NATURAL_ORDER) as Comparator<Any?>
private var table: Array<Node<K, V>?> = arrayOfNulls(16) // TODO: sizing/resizing policies
private val header: Node<K, V> = Node()
override var size = 0
private var modCount = 0
private var threshold = table.size / 2 + table.size / 4 // 3/4 capacity
private var entrySet: EntrySet? = null
private var keySet: KeySet? = null
override val keys: MutableSet<K>
get() = keySet ?: KeySet().also { keySet = it }
override fun put(key: K, value: V): V? {
val created = findOrCreate(key)
val result = created.value
created.mutableValue = value
return result
}
override val entries: MutableSet<MutableMap.MutableEntry<K, V>>
get() = entrySet ?: EntrySet().also { entrySet = it }
override fun get(key: K) = findByObject(key)?.value
override fun containsKey(key: K) = findByObject(key) != null
override fun clear() {
table.fill(null)
size = 0
modCount++
// Clear all links to help GC
val header = header
var e = header.next
while (e !== header) {
val next = e!!.next
e.prev = null
e.next = null
e = next
}
header.prev = header
header.next = header.prev
}
override fun remove(key: K) = removeInternalByKey(key)?.value
class Node<K, V> : MutableMap.MutableEntry<K, V?> {
@JvmField
var parent: Node<K, V>? = null
@JvmField
var left: Node<K, V>? = null
@JvmField
var right: Node<K, V>? = null
@JvmField
var next: Node<K, V>?
@JvmField
var prev: Node<K, V>?
private var realKey: K? = null
override val key: K get() = knownNotNull(realKey)
@JvmField
val hash: Int
@JvmField
var mutableValue: V? = null
override val value: V?
get() = mutableValue
@JvmField
var height = 0
/** Create the header entry. */
constructor() {
realKey = null
hash = -1
prev = this
next = prev
}
/** Create a regular entry. */
constructor(parent: Node<K, V>?, key: K, hash: Int, next: Node<K, V>, prev: Node<K, V>) {
this.parent = parent
this.realKey = key
this.hash = hash
height = 1
this.next = next
this.prev = prev
prev.next = this
next.prev = this
}
override fun setValue(newValue: V?): V? {
val oldValue = this.value
this.mutableValue = newValue
return oldValue
}
override fun equals(other: Any?): Boolean {
if (other is Map.Entry<*, *>) {
val (key1, value1) = other
return (
(if (realKey == null) key1 == null else realKey == key1) &&
if (value == null) value1 == null else value == value1
)
}
return false
}
override fun hashCode(): Int {
return (realKey?.hashCode() ?: 0) xor if (value == null) 0 else value.hashCode()
}
override fun toString() = "$key=$value"
/** Returns the first node in this subtree. */
fun first(): Node<K, V> {
var node = this
var child = node.left
while (child != null) {
node = child
child = node.left
}
return node
}
/** Returns the last node in this subtree. */
fun last(): Node<K, V> {
var node = this
var child = node.right
while (child != null) {
node = child
child = node.right
}
return node
}
}
private fun doubleCapacity() {
table = doubleCapacity(table)
threshold = table.size / 2 + table.size / 4 // 3/4 capacity
}
/**
* Returns the node at or adjacent to the given key, creating it if requested.
*
* @throws ClassCastException if `key` and the tree's keys aren't mutually comparable.
*/
private fun findOrCreate(key: K): Node<K, V> {
return knownNotNull(find(key, create = true))
}
/**
* Returns the node at or adjacent to the given key, creating it if requested.
*
* @throws ClassCastException if `key` and the tree's keys aren't mutually comparable.
*/
fun find(key: K, create: Boolean): Node<K, V>? {
val comparator: Comparator<in K?> = comparator
val table = table
val hash = secondaryHash(key.hashCode())
val index = hash and table.size - 1
var nearest = table[index]
var comparison = 0
if (nearest != null) {
// Micro-optimization: avoid polymorphic calls to Comparator.compare().
// Throws a ClassCastException below if there's trouble.
@Suppress("UNCHECKED_CAST")
val comparableKey =
if (comparator === NATURAL_ORDER) key as Comparable<Any?> else null
while (true) {
comparison = comparableKey?.compareTo(knownNotNull(nearest).key) ?: comparator.compare(key, knownNotNull(nearest).key)
// We found the requested key.
if (comparison == 0) {
return nearest
}
// If it exists, the key is in a subtree. Go deeper.
val child = (if (comparison < 0) knownNotNull(nearest).left else knownNotNull(nearest).right) ?: break
nearest = child
}
}
// The key doesn't exist in this tree.
if (!create) {
return null
}
// Create the node and add it to the tree or the table.
val header = header
val created: Node<K, V>
if (nearest == null) {
// Check that the value is comparable if we didn't do any comparisons.
if (comparator === NATURAL_ORDER && key !is Comparable<*>) {
throw ClassCastException("${(key as Any).javaClass.name} is not Comparable")
}
created = Node(null, key, hash, header, knownNotNull(header.prev))
table[index] = created
} else {
created = Node(nearest, key, hash, header, knownNotNull(header.prev))
if (comparison < 0) { // nearest.key is higher
nearest.left = created
} else { // comparison > 0, nearest.key is lower
nearest.right = created
}
rebalance(nearest, true)
}
if (size++ > threshold) {
doubleCapacity()
}
modCount++
return created
}
private fun findByObject(key: Any?): Node<K, V>? {
return try {
@Suppress("UNCHECKED_CAST")
if (key != null) find(key as K, false) else null
} catch (e: ClassCastException) {
null
}
}
/**
* Returns this map's entry that has the same key and value as `entry`, or null if this map
* has no such entry.
*
* This method uses the comparator for key equality rather than `equals`. If this map's
* comparator isn't consistent with equals (such as `String.CASE_INSENSITIVE_ORDER`), then
* `remove()` and `contains()` will violate the collections API.
*/
fun findByEntry(entry: Map.Entry<*, *>): Node<K, V>? {
val mine = findByObject(entry.key)
val valuesEqual = mine != null && equal(mine.value, entry.value)
return if (valuesEqual) mine else null
}
private fun equal(a: Any?, b: Any?): Boolean {
@Suppress("SuspiciousEqualsCombination")
return a === b || a != null && a == b
}
/**
* Applies a supplemental hash function to a given hashCode, which defends against poor quality
* hash functions. This is critical because HashMap uses power-of-two length hash tables, that
* otherwise encounter collisions for hashCodes that do not differ in lower or upper bits.
*/
private fun secondaryHash(seed: Int): Int {
// Doug Lea's supplemental hash function
var h = seed
h = h xor (h ushr 20 xor (h ushr 12))
return h xor (h ushr 7) xor (h ushr 4)
}
/**
* Removes `node` from this tree, rearranging the tree's structure as necessary.
*
* @param unlink true to also unlink this node from the iteration linked list.
*/
fun removeInternal(node: Node<K, V>, unlink: Boolean) {
if (unlink) {
knownNotNull(node.prev).next = node.next
knownNotNull(node.next).prev = node.prev
node.prev = null
node.next = null // Help the GC (for performance)
}
var left = node.left
var right = node.right
val originalParent = node.parent
if (left != null && right != null) {
/*
* To remove a node with both left and right subtrees, move an
* adjacent node from one of those subtrees into this node's place.
*
* Removing the adjacent node may change this node's subtrees. This
* node may no longer have two subtrees once the adjacent node is
* gone!
*/
val adjacent = if (left.height > right.height) left.last() else right.first()
removeInternal(adjacent, false) // takes care of rebalance and size--
var leftHeight = 0
left = node.left
if (left != null) {
leftHeight = left.height
adjacent.left = left
left.parent = adjacent
node.left = null
}
var rightHeight = 0
right = node.right
if (right != null) {
rightHeight = right.height
adjacent.right = right
right.parent = adjacent
node.right = null
}
adjacent.height = max(leftHeight, rightHeight) + 1
replaceInParent(node, adjacent)
return
} else if (left != null) {
replaceInParent(node, left)
node.left = null
} else if (right != null) {
replaceInParent(node, right)
node.right = null
} else {
replaceInParent(node, null)
}
rebalance(originalParent, false)
size--
modCount++
}
fun removeInternalByKey(key: Any?): Node<K, V>? {
val node = findByObject(key)
if (node != null) {
removeInternal(node, true)
}
return node
}
private fun replaceInParent(node: Node<K, V>, replacement: Node<K, V>?) {
val parent = node.parent
node.parent = null
if (replacement != null) {
replacement.parent = parent
}
if (parent != null) {
if (parent.left === node) {
parent.left = replacement
} else {
assert(parent.right === node)
parent.right = replacement
}
} else {
val index = node.hash and table.size - 1
table[index] = replacement
}
}
/**
* Rebalances the tree by making any AVL rotations necessary between the newly-unbalanced node and
* the tree's root.
*
* @param insert true if the node was unbalanced by an insert; false if it was by a removal.
*/
private fun rebalance(unbalanced: Node<K, V>?, insert: Boolean) {
var node = unbalanced
while (node != null) {
val left = node.left
val right = node.right
val leftHeight = left?.height ?: 0
val rightHeight = right?.height ?: 0
val delta = leftHeight - rightHeight
when (delta) {
-2 -> {
val rightLeft = right!!.left
val rightRight = right.right
val rightRightHeight = rightRight?.height ?: 0
val rightLeftHeight = rightLeft?.height ?: 0
val rightDelta = rightLeftHeight - rightRightHeight
if (rightDelta != -1 && (rightDelta != 0 || insert)) {
assert(rightDelta == 1)
rotateRight(right) // AVL right left
}
rotateLeft(node) // AVL right right
if (insert) {
break // no further rotations will be necessary
}
}
2 -> {
val leftLeft = left!!.left
val leftRight = left.right
val leftRightHeight = leftRight?.height ?: 0
val leftLeftHeight = leftLeft?.height ?: 0
val leftDelta = leftLeftHeight - leftRightHeight
if (leftDelta != 1 && (leftDelta != 0 || insert)) {
assert(leftDelta == -1)
rotateLeft(left) // AVL left right
}
rotateRight(node) // AVL left left
if (insert) {
break // no further rotations will be necessary
}
}
0 -> {
node.height = leftHeight + 1 // leftHeight == rightHeight
if (insert) {
break // the insert caused balance, so rebalancing is done!
}
}
else -> {
assert(delta == -1 || delta == 1)
node.height = max(leftHeight, rightHeight) + 1
if (!insert) {
break // the height hasn't changed, so rebalancing is done!
}
}
}
node = node.parent
}
}
/** Rotates the subtree so that its root's right child is the new root. */
private fun rotateLeft(root: Node<K, V>) {
val left = root.left
val pivot = root.right
val pivotLeft = pivot!!.left
val pivotRight = pivot.right
// move the pivot's left child to the root's right
root.right = pivotLeft
if (pivotLeft != null) {
pivotLeft.parent = root
}
replaceInParent(root, pivot)
// move the root to the pivot's left
pivot.left = root
root.parent = pivot
// fix heights
root.height = max(left?.height ?: 0, pivotLeft?.height ?: 0) + 1
pivot.height = max(root.height, pivotRight?.height ?: 0) + 1
}
/** Rotates the subtree so that its root's left child is the new root. */
private fun rotateRight(root: Node<K, V>) {
val pivot = root.left
val right = root.right
val pivotLeft = pivot!!.left
val pivotRight = pivot.right
// move the pivot's right child to the root's left
root.left = pivotRight
if (pivotRight != null) {
pivotRight.parent = root
}
replaceInParent(root, pivot)
// move the root to the pivot's right
pivot.right = root
root.parent = pivot
// fixup heights
root.height = max(right?.height ?: 0, pivotRight?.height ?: 0) + 1
pivot.height = max(root.height, pivotLeft?.height ?: 0) + 1
}
abstract inner class LinkedTreeMapIterator<T> : MutableIterator<T> {
var next = header.next
private var lastReturned: Node<K, V>? = null
private var expectedModCount: Int = modCount
override fun hasNext(): Boolean = next !== header
fun nextNode(): Node<K, V> {
val e = next
if (e === header) {
throw NoSuchElementException()
}
if (modCount != expectedModCount) {
throw ConcurrentModificationException()
}
next = e!!.next
return e.also { lastReturned = it }
}
override fun remove() {
removeInternal(checkNotNull(lastReturned), true)
lastReturned = null
expectedModCount = modCount
}
}
inner class EntrySet : AbstractMutableSet<MutableMap.MutableEntry<K, V>>() {
override val size: Int
get() = this@LinkedHashTreeMap.size
override fun iterator(): MutableIterator<MutableMap.MutableEntry<K, V>> {
return object : LinkedTreeMapIterator<MutableMap.MutableEntry<K, V>>() {
override fun next(): MutableMap.MutableEntry<K, V> {
@Suppress("UNCHECKED_CAST")
return nextNode() as MutableMap.MutableEntry<K, V>
}
}
}
override fun contains(element: MutableMap.MutableEntry<K, V>): Boolean {
return findByEntry(element) != null
}
override fun remove(element: MutableMap.MutableEntry<K, V>): Boolean {
if (element !is Node<*, *>) {
return false
}
val node: Node<K, V> = findByEntry(element) ?: return false
removeInternal(node, true)
return true
}
override fun clear() {
this@LinkedHashTreeMap.clear()
}
override fun add(element: MutableMap.MutableEntry<K, V>): Boolean {
throw NotImplementedError()
}
}
inner class KeySet : AbstractMutableSet<K>() {
override val size: Int
get() = this@LinkedHashTreeMap.size
override fun iterator(): MutableIterator<K> {
return object : LinkedTreeMapIterator<K>() {
override fun next(): K {
return nextNode().key ?: throw NoSuchElementException()
}
}
}
override fun contains(element: K): Boolean {
return containsKey(element)
}
override fun remove(element: K): Boolean {
return removeInternalByKey(element) != null
}
override fun clear() {
this@LinkedHashTreeMap.clear()
}
override fun add(element: K): Boolean {
throw NotImplementedError()
}
}
/**
* If somebody is unlucky enough to have to serialize one of these, serialize it as a
* LinkedHashMap so that they won't need Gson on the other side to deserialize it. Using
* serialization defeats our DoS defence, so most apps shouldn't use it.
*/
private fun writeReplace(): Any = LinkedHashMap(this)
}
/**
* Returns a new array containing the same nodes as `oldTable`, but with twice as many
* trees, each of (approximately) half the previous size.
*/
internal fun <K, V> doubleCapacity(oldTable: Array<Node<K, V>?>): Array<Node<K, V>?> {
// TODO: don't do anything if we're already at MAX_CAPACITY
val oldCapacity = oldTable.size
// Arrays and generics don't get along.
val newTable: Array<Node<K, V>?> = arrayOfNulls<Node<K, V>?>(oldCapacity * 2)
val iterator = AvlIterator<K, V>()
val leftBuilder = AvlBuilder<K, V>()
val rightBuilder = AvlBuilder<K, V>()
// Split each tree into two trees.
for (i in 0 until oldCapacity) {
val root = oldTable[i] ?: continue
// Compute the sizes of the left and right trees.
iterator.reset(root)
var leftSize = 0
var rightSize = 0
run {
var node: Node<K, V>?
while (iterator.next().also { node = it } != null) {
if (knownNotNull(node).hash and oldCapacity == 0) {
leftSize++
} else {
rightSize++
}
}
}
// Split the tree into two.
leftBuilder.reset(leftSize)
rightBuilder.reset(rightSize)
iterator.reset(root)
var node: Node<K, V>?
while (iterator.next().also { node = it } != null) {
if (knownNotNull(node).hash and oldCapacity == 0) {
leftBuilder.add(knownNotNull(node))
} else {
rightBuilder.add(knownNotNull(node))
}
}
// Populate the enlarged array with these new roots.
newTable[i] = if (leftSize > 0) leftBuilder.root() else null
newTable[i + oldCapacity] = if (rightSize > 0) rightBuilder.root() else null
}
return newTable
}
/**
* Walks an AVL tree in iteration order. Once a node has been returned, its left, right and parent
* links are **no longer used**. For this reason it is safe to transform these links
* as you walk a tree.
*
* **Warning:** this iterator is destructive. It clears the parent node of all
* nodes in the tree. It is an error to make a partial iteration of a tree.
*/
internal class AvlIterator<K, V> {
/** This stack is a singly linked list, linked by the 'parent' field. */
private var stackTop: Node<K, V>? = null
fun reset(root: Node<K, V>?) {
var stackTop: Node<K, V>? = null
var n = root
while (n != null) {
n.parent = stackTop
stackTop = n // Stack push.
n = n.left
}
this.stackTop = stackTop
}
operator fun next(): Node<K, V>? {
var stackTop: Node<K, V>? = stackTop ?: return null
val result = stackTop
stackTop = result!!.parent
result.parent = null
var n = result.right
while (n != null) {
n.parent = stackTop
stackTop = n // Stack push.
n = n.left
}
this.stackTop = stackTop
return result
}
}
/**
* Builds AVL trees of a predetermined size by accepting nodes of increasing value. To use:
* 1. Call [reset] to initialize the target size *size*.
* 2. Call [add] *size* times with increasing values.
* 3. Call [root] to get the root of the balanced tree.
*
* The returned tree will satisfy the AVL constraint: for every node *N*, the height of
* *N.left* and *N.right* is different by at most 1. It accomplishes this by omitting
* deepest-level leaf nodes when building trees whose size isn't a power of 2 minus 1.
*
* Unlike rebuilding a tree from scratch, this approach requires no value comparisons. Using
* this class to create a tree of size *S* is `O(S)`.
*/
internal class AvlBuilder<K, V> {
/** This stack is a singly linked list, linked by the 'parent' field. */
private var stack: Node<K, V>? = null
private var leavesToSkip = 0
private var leavesSkipped = 0
private var size = 0
fun reset(targetSize: Int) {
// compute the target tree size. This is a power of 2 minus one, like 15 or 31.
val treeCapacity = Integer.highestOneBit(targetSize) * 2 - 1
leavesToSkip = treeCapacity - targetSize
size = 0
leavesSkipped = 0
stack = null
}
fun add(node: Node<K, V>) {
node.right = null
node.parent = null
node.left = null
node.height = 1
// Skip a leaf if necessary.
if (leavesToSkip > 0 && size and 1 == 0) {
size++
leavesToSkip--
leavesSkipped++
}
node.parent = stack
stack = node // Stack push.
size++
// Skip a leaf if necessary.
if (leavesToSkip > 0 && size and 1 == 0) {
size++
leavesToSkip--
leavesSkipped++
}
/*
* Combine 3 nodes into subtrees whenever the size is one less than a
* multiple of 4. For example, we combine the nodes A, B, C into a
* 3-element tree with B as the root.
*
* Combine two subtrees and a spare single value whenever the size is one
* less than a multiple of 8. For example at 8 we may combine subtrees
* (A B C) and (E F G) with D as the root to form ((A B C) D (E F G)).
*
* Just as we combine single nodes when size nears a multiple of 4, and
* 3-element trees when size nears a multiple of 8, we combine subtrees of
* size (N-1) whenever the total size is 2N-1 whenever N is a power of 2.
*/
var scale = 4
while (size and scale - 1 == scale - 1) {
when (leavesSkipped) {
0 -> {
// Pop right, center and left, then make center the top of the stack.
val right = stack
val center = right!!.parent
val left = center!!.parent
center.parent = left!!.parent
stack = center
// Construct a tree.
center.left = left
center.right = right
center.height = right.height + 1
left.parent = center
right.parent = center
}
1 -> {
// Pop right and center, then make center the top of the stack.
val right = stack
val center = right!!.parent
stack = center!!
// Construct a tree with no left child.
center.right = right
center.height = right.height + 1
right.parent = center
leavesSkipped = 0
}
2 -> {
leavesSkipped = 0
}
}
scale *= 2
}
}
fun root(): Node<K, V> {
val stackTop = stack
check(stackTop!!.parent == null)
return stackTop
}
}

11
moshi/src/test/java/com/squareup/moshi/LinkedHashTreeMapTest.java
View File

@@ -18,14 +18,13 @@ package com.squareup.moshi;
import static com.google.common.truth.Truth.assertThat;
import static org.junit.Assert.fail;
import com.squareup.moshi.LinkedHashTreeMap.AvlBuilder;
import com.squareup.moshi.LinkedHashTreeMap.AvlIterator;
import com.squareup.moshi.LinkedHashTreeMap.Node;
import java.util.Iterator;
import java.util.Map;
import java.util.Random;
import org.junit.Test;
@SuppressWarnings("KotlinInternalInJava")
public final class LinkedHashTreeMapTest {
@Test
public void iterationOrder() {
@@ -228,7 +227,7 @@ public final class LinkedHashTreeMapTest {
Node<String, String>[] oldTable = new Node[1];
oldTable[0] = node(node(node("a"), "b", node("c")), "d", node(node("e"), "f", node("g")));
Node<String, String>[] newTable = LinkedHashTreeMap.doubleCapacity(oldTable);
Node<String, String>[] newTable = LinkedHashTreeMapKt.doubleCapacity(oldTable);
assertTree("(b d f)", newTable[0]); // Even hash codes!
assertTree("(a c (. e g))", newTable[1]); // Odd hash codes!
}
@@ -239,7 +238,7 @@ public final class LinkedHashTreeMapTest {
Node<String, String>[] oldTable = new Node[1];
oldTable[0] = node(node("b"), "d", node("f"));
Node<String, String>[] newTable = LinkedHashTreeMap.doubleCapacity(oldTable);
Node<String, String>[] newTable = LinkedHashTreeMapKt.doubleCapacity(oldTable);
assertTree("(b d f)", newTable[0]); // Even hash codes!
assertThat(newTable[1]).isNull();
@@ -300,9 +299,9 @@ public final class LinkedHashTreeMapTest {
if (root == null) {
return ".";
} else if (root.left == null && root.right == null) {
return String.valueOf(root.key);
return String.valueOf(root.getKey());
} else {
return String.format("(%s %s %s)", toString(root.left), root.key, toString(root.right));
return String.format("(%s %s %s)", toString(root.left), root.getKey(), toString(root.right));
}
}
}