590 lines
17 KiB
Java
590 lines
17 KiB
Java
/*******************************************************************************
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* Copyright 2011 LibGDX.
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* Mario Zechner <badlogicgames@gmail.com>
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* Nathan Sweet <nathan.sweet@gmail.com>
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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 dorkbox.collections;
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import java.util.Iterator;
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import java.util.NoSuchElementException;
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import java.util.Random;
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/** An unordered set where the keys are objects. This implementation uses cuckoo hashing using 3 hashes, random walking, and a
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* small stash for problematic keys. Null keys are not allowed. No allocation is done except when growing the table size. <br>
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* <br>
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* This set performs very fast contains and remove (typically O(1), worst case O(log(n))). Add may be a bit slower, depending on
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* hash collisions. Load factors greater than 0.91 greatly increase the chances the set will have to rehash to the next higher POT
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* size.<br>
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* <br>
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* Iteration can be very slow for a set with a large capacity. {@link #clear(int)} and {@link #shrink(int)} can be used to reduce
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* the capacity. {@link OrderedSet} provides much faster iteration.
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* @author Nathan Sweet */
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@SuppressWarnings({"unchecked", "rawtypes", "NullableProblems", "SuspiciousSystemArraycopy"})
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public class ObjectSet<T> implements Iterable<T> {
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private static final int PRIME1 = 0xbe1f14b1;
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private static final int PRIME2 = 0xb4b82e39;
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private static final int PRIME3 = 0xced1c241;
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public int size;
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T[] keyTable;
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int capacity, stashSize;
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private float loadFactor;
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private int hashShift, mask, threshold;
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private int stashCapacity;
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private int pushIterations;
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private ObjectSetIterator iterator1, iterator2;
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/** Creates a new set with an initial capacity of 51 and a load factor of 0.8. */
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public ObjectSet () {
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this(51, 0.8f);
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}
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/** Creates a new set with a load factor of 0.8.
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* @param initialCapacity If not a power of two, it is increased to the next nearest power of two. */
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public ObjectSet (int initialCapacity) {
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this(initialCapacity, 0.8f);
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}
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/** Creates a new set with the specified initial capacity and load factor. This set will hold initialCapacity items before
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* growing the backing table.
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* @param initialCapacity If not a power of two, it is increased to the next nearest power of two. */
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public ObjectSet (int initialCapacity, float loadFactor) {
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if (initialCapacity < 0) throw new IllegalArgumentException("initialCapacity must be >= 0: " + initialCapacity);
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initialCapacity = MathUtil.nextPowerOfTwo((int)Math.ceil(initialCapacity / loadFactor));
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if (initialCapacity > 1 << 30) throw new IllegalArgumentException("initialCapacity is too large: " + initialCapacity);
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capacity = initialCapacity;
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if (loadFactor <= 0) throw new IllegalArgumentException("loadFactor must be > 0: " + loadFactor);
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this.loadFactor = loadFactor;
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threshold = (int)(capacity * loadFactor);
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mask = capacity - 1;
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hashShift = 31 - Integer.numberOfTrailingZeros(capacity);
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stashCapacity = Math.max(3, (int)Math.ceil(Math.log(capacity)) * 2);
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pushIterations = Math.max(Math.min(capacity, 8), (int)Math.sqrt(capacity) / 8);
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keyTable = (T[])new Object[capacity + stashCapacity];
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}
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/** Creates a new set identical to the specified set. */
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public ObjectSet (ObjectSet set) {
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this((int)Math.floor(set.capacity * set.loadFactor), set.loadFactor);
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stashSize = set.stashSize;
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System.arraycopy(set.keyTable, 0, keyTable, 0, set.keyTable.length);
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size = set.size;
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}
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/** Returns true if the key was not already in the set. If this set already contains the key, the call leaves the set unchanged
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* and returns false. */
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public boolean add (T key) {
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if (key == null) throw new IllegalArgumentException("key cannot be null.");
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T[] keyTable = this.keyTable;
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// Check for existing keys.
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int hashCode = key.hashCode();
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int index1 = hashCode & mask;
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T key1 = keyTable[index1];
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if (key.equals(key1)) return false;
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int index2 = hash2(hashCode);
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T key2 = keyTable[index2];
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if (key.equals(key2)) return false;
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int index3 = hash3(hashCode);
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T key3 = keyTable[index3];
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if (key.equals(key3)) return false;
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// Find key in the stash.
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for (int i = capacity, n = i + stashSize; i < n; i++)
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if (key.equals(keyTable[i])) return false;
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// Check for empty buckets.
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if (key1 == null) {
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keyTable[index1] = key;
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if (size++ >= threshold) resize(capacity << 1);
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return true;
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}
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if (key2 == null) {
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keyTable[index2] = key;
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if (size++ >= threshold) resize(capacity << 1);
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return true;
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}
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if (key3 == null) {
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keyTable[index3] = key;
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if (size++ >= threshold) resize(capacity << 1);
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return true;
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}
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push(key, index1, key1, index2, key2, index3, key3);
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return true;
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}
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public void addAll (Array<? extends T> array) {
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addAll(array.items, 0, array.size);
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}
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public void addAll (Array<? extends T> array, int offset, int length) {
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if (offset + length > array.size)
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throw new IllegalArgumentException("offset + length must be <= size: " + offset + " + " + length + " <= " + array.size);
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addAll((T[])array.items, offset, length);
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}
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public void addAll (T... array) {
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addAll(array, 0, array.length);
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}
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public void addAll (T[] array, int offset, int length) {
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ensureCapacity(length);
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for (int i = offset, n = i + length; i < n; i++)
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add(array[i]);
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}
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public void addAll (ObjectSet<T> set) {
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ensureCapacity(set.size);
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for (T key : set)
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add(key);
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}
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/** Skips checks for existing keys. */
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private void addResize (T key) {
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// Check for empty buckets.
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int hashCode = key.hashCode();
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int index1 = hashCode & mask;
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T key1 = keyTable[index1];
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if (key1 == null) {
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keyTable[index1] = key;
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if (size++ >= threshold) resize(capacity << 1);
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return;
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}
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int index2 = hash2(hashCode);
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T key2 = keyTable[index2];
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if (key2 == null) {
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keyTable[index2] = key;
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if (size++ >= threshold) resize(capacity << 1);
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return;
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}
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int index3 = hash3(hashCode);
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T key3 = keyTable[index3];
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if (key3 == null) {
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keyTable[index3] = key;
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if (size++ >= threshold) resize(capacity << 1);
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return;
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}
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push(key, index1, key1, index2, key2, index3, key3);
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}
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private void push (T insertKey, int index1, T key1, int index2, T key2, int index3, T key3) {
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T[] keyTable = this.keyTable;
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int mask = this.mask;
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// Push keys until an empty bucket is found.
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T evictedKey;
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int i = 0, pushIterations = this.pushIterations;
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do {
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// Replace the key and value for one of the hashes.
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switch (MathUtil.random.nextInt(2)) {
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case 0:
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evictedKey = key1;
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keyTable[index1] = insertKey;
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break;
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case 1:
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evictedKey = key2;
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keyTable[index2] = insertKey;
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break;
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default:
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evictedKey = key3;
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keyTable[index3] = insertKey;
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break;
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}
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// If the evicted key hashes to an empty bucket, put it there and stop.
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int hashCode = evictedKey.hashCode();
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index1 = hashCode & mask;
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key1 = keyTable[index1];
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if (key1 == null) {
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keyTable[index1] = evictedKey;
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if (size++ >= threshold) resize(capacity << 1);
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return;
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}
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index2 = hash2(hashCode);
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key2 = keyTable[index2];
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if (key2 == null) {
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keyTable[index2] = evictedKey;
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if (size++ >= threshold) resize(capacity << 1);
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return;
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}
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index3 = hash3(hashCode);
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key3 = keyTable[index3];
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if (key3 == null) {
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keyTable[index3] = evictedKey;
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if (size++ >= threshold) resize(capacity << 1);
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return;
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}
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if (++i == pushIterations) break;
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insertKey = evictedKey;
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} while (true);
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addStash(evictedKey);
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}
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private void addStash (T key) {
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if (stashSize == stashCapacity) {
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// Too many pushes occurred and the stash is full, increase the table size.
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resize(capacity << 1);
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addResize(key);
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return;
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}
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// Store key in the stash.
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int index = capacity + stashSize;
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keyTable[index] = key;
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stashSize++;
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size++;
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}
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/** Returns true if the key was removed. */
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public boolean remove (T key) {
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int hashCode = key.hashCode();
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int index = hashCode & mask;
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if (key.equals(keyTable[index])) {
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keyTable[index] = null;
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size--;
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return true;
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}
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index = hash2(hashCode);
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if (key.equals(keyTable[index])) {
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keyTable[index] = null;
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size--;
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return true;
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}
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index = hash3(hashCode);
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if (key.equals(keyTable[index])) {
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keyTable[index] = null;
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size--;
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return true;
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}
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return removeStash(key);
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}
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boolean removeStash (T key) {
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T[] keyTable = this.keyTable;
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for (int i = capacity, n = i + stashSize; i < n; i++) {
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if (key.equals(keyTable[i])) {
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removeStashIndex(i);
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size--;
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return true;
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}
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}
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return false;
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}
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void removeStashIndex (int index) {
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// If the removed location was not last, move the last tuple to the removed location.
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stashSize--;
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int lastIndex = capacity + stashSize;
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if (index < lastIndex) {
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keyTable[index] = keyTable[lastIndex];
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keyTable[lastIndex] = null;
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}
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}
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/** Returns true if the set is empty. */
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public boolean isEmpty () {
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return size == 0;
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}
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/** Reduces the size of the backing arrays to be the specified capacity or less. If the capacity is already less, nothing is
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* done. If the set contains more items than the specified capacity, the next highest power of two capacity is used instead. */
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public void shrink (int maximumCapacity) {
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if (maximumCapacity < 0) throw new IllegalArgumentException("maximumCapacity must be >= 0: " + maximumCapacity);
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if (size > maximumCapacity) maximumCapacity = size;
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if (capacity <= maximumCapacity) return;
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maximumCapacity = MathUtil.nextPowerOfTwo(maximumCapacity);
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resize(maximumCapacity);
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}
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/** Clears the set and reduces the size of the backing arrays to be the specified capacity, if they are larger. The reduction
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* is done by allocating new arrays, though for large arrays this can be faster than clearing the existing array. */
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public void clear (int maximumCapacity) {
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if (capacity <= maximumCapacity) {
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clear();
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return;
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}
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size = 0;
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resize(maximumCapacity);
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}
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/** Clears the set, leaving the backing arrays at the current capacity. When the capacity is high and the population is low,
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* iteration can be unnecessarily slow. {@link #clear(int)} can be used to reduce the capacity. */
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public void clear () {
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if (size == 0) return;
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T[] keyTable = this.keyTable;
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for (int i = capacity + stashSize; i-- > 0;)
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keyTable[i] = null;
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size = 0;
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stashSize = 0;
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}
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public boolean contains (T key) {
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int hashCode = key.hashCode();
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int index = hashCode & mask;
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if (!key.equals(keyTable[index])) {
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index = hash2(hashCode);
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if (!key.equals(keyTable[index])) {
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index = hash3(hashCode);
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if (!key.equals(keyTable[index])) return getKeyStash(key) != null;
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}
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}
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return true;
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}
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/** @return May be null. */
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public T get (T key) {
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int hashCode = key.hashCode();
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int index = hashCode & mask;
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T found = keyTable[index];
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if (!key.equals(found)) {
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index = hash2(hashCode);
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found = keyTable[index];
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if (!key.equals(found)) {
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index = hash3(hashCode);
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found = keyTable[index];
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if (!key.equals(found)) return getKeyStash(key);
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}
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}
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return found;
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}
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private T getKeyStash (T key) {
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T[] keyTable = this.keyTable;
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for (int i = capacity, n = i + stashSize; i < n; i++)
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if (key.equals(keyTable[i])) return keyTable[i];
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return null;
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}
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public T first () {
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T[] keyTable = this.keyTable;
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for (int i = 0, n = capacity + stashSize; i < n; i++)
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if (keyTable[i] != null) return keyTable[i];
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throw new IllegalStateException("ObjectSet is empty.");
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}
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/** Increases the size of the backing array to accommodate the specified number of additional items. Useful before adding many
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* items to avoid multiple backing array resizes. */
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public void ensureCapacity (int additionalCapacity) {
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if (additionalCapacity < 0) throw new IllegalArgumentException("additionalCapacity must be >= 0: " + additionalCapacity);
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int sizeNeeded = size + additionalCapacity;
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if (sizeNeeded >= threshold) resize(MathUtil.nextPowerOfTwo((int)Math.ceil(sizeNeeded / loadFactor)));
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}
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private void resize (int newSize) {
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int oldEndIndex = capacity + stashSize;
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capacity = newSize;
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threshold = (int)(newSize * loadFactor);
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mask = newSize - 1;
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hashShift = 31 - Integer.numberOfTrailingZeros(newSize);
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stashCapacity = Math.max(3, (int)Math.ceil(Math.log(newSize)) * 2);
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pushIterations = Math.max(Math.min(newSize, 8), (int)Math.sqrt(newSize) / 8);
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T[] oldKeyTable = keyTable;
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keyTable = (T[])new Object[newSize + stashCapacity];
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int oldSize = size;
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size = 0;
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stashSize = 0;
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if (oldSize > 0) {
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for (int i = 0; i < oldEndIndex; i++) {
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T key = oldKeyTable[i];
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if (key != null) addResize(key);
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}
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}
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}
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private int hash2 (int h) {
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h *= PRIME2;
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return (h ^ h >>> hashShift) & mask;
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}
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private int hash3 (int h) {
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h *= PRIME3;
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return (h ^ h >>> hashShift) & mask;
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}
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@Override
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public int hashCode () {
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int h = 0;
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for (int i = 0, n = capacity + stashSize; i < n; i++)
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if (keyTable[i] != null) h += keyTable[i].hashCode();
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return h;
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}
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@Override
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public boolean equals (Object obj) {
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if (!(obj instanceof ObjectSet)) return false;
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ObjectSet other = (ObjectSet)obj;
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if (other.size != size) return false;
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T[] keyTable = this.keyTable;
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for (int i = 0, n = capacity + stashSize; i < n; i++)
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if (keyTable[i] != null && !other.contains(keyTable[i])) return false;
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return true;
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}
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@Override
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public String toString () {
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return '{' + toString(", ") + '}';
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}
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public String toString (String separator) {
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if (size == 0) return "";
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StringBuilder buffer = new StringBuilder(32);
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T[] keyTable = this.keyTable;
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int i = keyTable.length;
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while (i-- > 0) {
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T key = keyTable[i];
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if (key == null) continue;
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buffer.append(key);
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break;
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}
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while (i-- > 0) {
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T key = keyTable[i];
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if (key == null) continue;
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buffer.append(separator);
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buffer.append(key);
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}
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return buffer.toString();
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}
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/** Returns an iterator for the keys in the set. Remove is supported. Note that the same iterator instance is returned each
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* time this method is called. Use the {@link ObjectSetIterator} constructor for nested or multithreaded iteration. */
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@Override
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public ObjectSetIterator<T> iterator () {
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if (iterator1 == null) {
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iterator1 = new ObjectSetIterator(this);
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iterator2 = new ObjectSetIterator(this);
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}
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if (!iterator1.valid) {
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iterator1.reset();
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iterator1.valid = true;
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iterator2.valid = false;
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return iterator1;
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}
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iterator2.reset();
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iterator2.valid = true;
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iterator1.valid = false;
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return iterator2;
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}
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static public <T> ObjectSet<T> with (T... array) {
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ObjectSet set = new ObjectSet();
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set.addAll(array);
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return set;
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}
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static public class ObjectSetIterator<K> implements Iterable<K>, Iterator<K> {
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public boolean hasNext;
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final ObjectSet<K> set;
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int nextIndex, currentIndex;
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boolean valid = true;
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public ObjectSetIterator (ObjectSet<K> set) {
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this.set = set;
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reset();
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}
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public void reset () {
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currentIndex = -1;
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nextIndex = -1;
|
|
findNextIndex();
|
|
}
|
|
|
|
private void findNextIndex () {
|
|
hasNext = false;
|
|
K[] keyTable = set.keyTable;
|
|
for (int n = set.capacity + set.stashSize; ++nextIndex < n;) {
|
|
if (keyTable[nextIndex] != null) {
|
|
hasNext = true;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
@Override
|
|
public void remove () {
|
|
if (currentIndex < 0) throw new IllegalStateException("next must be called before remove.");
|
|
if (currentIndex >= set.capacity) {
|
|
set.removeStashIndex(currentIndex);
|
|
nextIndex = currentIndex - 1;
|
|
findNextIndex();
|
|
} else {
|
|
set.keyTable[currentIndex] = null;
|
|
}
|
|
currentIndex = -1;
|
|
set.size--;
|
|
}
|
|
|
|
@Override
|
|
public boolean hasNext () {
|
|
if (!valid) throw new RuntimeException("#iterator() cannot be used nested.");
|
|
return hasNext;
|
|
}
|
|
|
|
@Override
|
|
public K next () {
|
|
if (!hasNext) throw new NoSuchElementException();
|
|
if (!valid) throw new RuntimeException("#iterator() cannot be used nested.");
|
|
K key = set.keyTable[nextIndex];
|
|
currentIndex = nextIndex;
|
|
findNextIndex();
|
|
return key;
|
|
}
|
|
|
|
@Override
|
|
public ObjectSetIterator<K> iterator () {
|
|
return this;
|
|
}
|
|
|
|
/** Adds the remaining values to the array. */
|
|
public Array<K> toArray (Array<K> array) {
|
|
while (hasNext)
|
|
array.add(next());
|
|
return array;
|
|
}
|
|
|
|
/** Returns a new array containing the remaining values. */
|
|
public Array<K> toArray () {
|
|
return toArray(new Array(true, set.size));
|
|
}
|
|
}
|
|
}
|