/*******************************************************************************
* Copyright 2011 See AUTHORS file.
*
* 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
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
* an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
* specific language governing permissions and limitations under the License.
******************************************************************************/
package com.badlogic.gdx.utils;
import com.badlogic.gdx.math.MathUtils;
import java.util.Iterator;
import java.util.NoSuchElementException;
/**
* An unordered map where the keys are ints and values are floats. This implementation is a cuckoo hash map using 3
* hashes, random walking, and a small stash for problematic keys. Null keys are not allowed. No allocation is done
* except when growing the table size. <br>
* <br>
* This map performs very fast get, containsKey, and remove (typically O(1), worst case O(log(n))). Put may be a bit
* slower, depending on hash collisions. Load factors greater than 0.91 greatly increase the chances the map will have
* to rehash to the next higher POT size.
*
* @author Nathan Sweet
*/
public class IntFloatMap {
private static final int PRIME1 = 0xbe1f14b1;
private static final int PRIME2 = 0xb4b82e39;
private static final int PRIME3 = 0xced1c241;
private static final int EMPTY = 0;
public int size;
int[] keyTable;
float[] valueTable;
int capacity, stashSize;
float zeroValue;
boolean hasZeroValue;
private float loadFactor;
private int hashShift, mask, threshold;
private int stashCapacity;
private int pushIterations;
private Entries entries;
private Values values;
private Keys keys;
/**
* Creates a new map with an initial capacity of 32 and a load factor of 0.8. This map will hold 25 items before
* growing the backing table.
*/
public IntFloatMap() {
this(32, 0.8f);
}
/**
* Creates a new map with a load factor of 0.8. This map will hold initialCapacity * 0.8 items before growing the
* backing table.
*/
public IntFloatMap(int initialCapacity) {
this(initialCapacity, 0.8f);
}
/**
* Creates a new map with the specified initial capacity and load factor. This map will hold initialCapacity *
* loadFactor items before growing the backing table.
*/
public IntFloatMap(int initialCapacity, float loadFactor) {
if (initialCapacity < 0)
throw new IllegalArgumentException("initialCapacity must be >= 0: " + initialCapacity);
if (capacity > 1 << 30)
throw new IllegalArgumentException("initialCapacity is too large: " + initialCapacity);
capacity = MathUtils.nextPowerOfTwo(initialCapacity);
if (loadFactor <= 0)
throw new IllegalArgumentException("loadFactor must be > 0: " + loadFactor);
this.loadFactor = loadFactor;
threshold = (int) (capacity * loadFactor);
mask = capacity - 1;
hashShift = 31 - Integer.numberOfTrailingZeros(capacity);
stashCapacity = Math.max(3, (int) Math.ceil(Math.log(capacity)) * 2);
pushIterations = Math.max(Math.min(capacity, 8), (int) Math.sqrt(capacity) / 8);
keyTable = new int[capacity + stashCapacity];
valueTable = new float[keyTable.length];
}
public void put(int key, float value) {
if (key == 0) {
zeroValue = value;
if (!hasZeroValue) {
hasZeroValue = true;
size++;
}
return;
}
int[] keyTable = this.keyTable;
// Check for existing keys.
int index1 = key & mask;
int key1 = keyTable[index1];
if (key == key1) {
valueTable[index1] = value;
return;
}
int index2 = hash2(key);
int key2 = keyTable[index2];
if (key == key2) {
valueTable[index2] = value;
return;
}
int index3 = hash3(key);
int key3 = keyTable[index3];
if (key == key3) {
valueTable[index3] = value;
return;
}
// Update key in the stash.
for (int i = capacity, n = i + stashSize; i < n; i++) {
if (key == keyTable[i]) {
valueTable[i] = value;
return;
}
}
// Check for empty buckets.
if (key1 == EMPTY) {
keyTable[index1] = key;
valueTable[index1] = value;
if (size++ >= threshold)
resize(capacity << 1);
return;
}
if (key2 == EMPTY) {
keyTable[index2] = key;
valueTable[index2] = value;
if (size++ >= threshold)
resize(capacity << 1);
return;
}
if (key3 == EMPTY) {
keyTable[index3] = key;
valueTable[index3] = value;
if (size++ >= threshold)
resize(capacity << 1);
return;
}
push(key, value, index1, key1, index2, key2, index3, key3);
}
public void putAll(IntFloatMap map) {
for (Entry entry : map.entries())
put(entry.key, entry.value);
}
/** Skips checks for existing keys. */
private void putResize(int key, float value) {
if (key == 0) {
zeroValue = value;
hasZeroValue = true;
return;
}
// Check for empty buckets.
int index1 = key & mask;
int key1 = keyTable[index1];
if (key1 == EMPTY) {
keyTable[index1] = key;
valueTable[index1] = value;
if (size++ >= threshold)
resize(capacity << 1);
return;
}
int index2 = hash2(key);
int key2 = keyTable[index2];
if (key2 == EMPTY) {
keyTable[index2] = key;
valueTable[index2] = value;
if (size++ >= threshold)
resize(capacity << 1);
return;
}
int index3 = hash3(key);
int key3 = keyTable[index3];
if (key3 == EMPTY) {
keyTable[index3] = key;
valueTable[index3] = value;
if (size++ >= threshold)
resize(capacity << 1);
return;
}
push(key, value, index1, key1, index2, key2, index3, key3);
}
private void push(int insertKey, float insertValue, int index1, int key1, int index2, int key2, int index3, int key3) {
int[] keyTable = this.keyTable;
float[] valueTable = this.valueTable;
int mask = this.mask;
// Push keys until an empty bucket is found.
int evictedKey;
float evictedValue;
int i = 0, pushIterations = this.pushIterations;
do {
// Replace the key and value for one of the hashes.
switch (MathUtils.random(2)) {
case 0:
evictedKey = key1;
evictedValue = valueTable[index1];
keyTable[index1] = insertKey;
valueTable[index1] = insertValue;
break;
case 1:
evictedKey = key2;
evictedValue = valueTable[index2];
keyTable[index2] = insertKey;
valueTable[index2] = insertValue;
break;
default:
evictedKey = key3;
evictedValue = valueTable[index3];
keyTable[index3] = insertKey;
valueTable[index3] = insertValue;
break;
}
// If the evicted key hashes to an empty bucket, put it there and stop.
index1 = evictedKey & mask;
key1 = keyTable[index1];
if (key1 == EMPTY) {
keyTable[index1] = evictedKey;
valueTable[index1] = evictedValue;
if (size++ >= threshold)
resize(capacity << 1);
return;
}
index2 = hash2(evictedKey);
key2 = keyTable[index2];
if (key2 == EMPTY) {
keyTable[index2] = evictedKey;
valueTable[index2] = evictedValue;
if (size++ >= threshold)
resize(capacity << 1);
return;
}
index3 = hash3(evictedKey);
key3 = keyTable[index3];
if (key3 == EMPTY) {
keyTable[index3] = evictedKey;
valueTable[index3] = evictedValue;
if (size++ >= threshold)
resize(capacity << 1);
return;
}
if (++i == pushIterations)
break;
insertKey = evictedKey;
insertValue = evictedValue;
} while (true);
putStash(evictedKey, evictedValue);
}
private void putStash(int key, float value) {
if (stashSize == stashCapacity) {
// Too many pushes occurred and the stash is full, increase the table size.
resize(capacity << 1);
put(key, value);
return;
}
// Store key in the stash.
int index = capacity + stashSize;
keyTable[index] = key;
valueTable[index] = value;
stashSize++;
size++;
}
/**
* @param defaultValue
* Returned if the key was not associated with a value.
*/
public float get(int key, float defaultValue) {
if (key == 0)
return zeroValue;
int index = key & mask;
if (keyTable[index] != key) {
index = hash2(key);
if (keyTable[index] != key) {
index = hash3(key);
if (keyTable[index] != key)
return getStash(key, defaultValue);
}
}
return valueTable[index];
}
private float getStash(int key, float defaultValue) {
int[] keyTable = this.keyTable;
for (int i = capacity, n = i + stashSize; i < n; i++)
if (key == keyTable[i])
return valueTable[i];
return defaultValue;
}
/**
* Returns the key's current value and increments the stored value. If the key is not in the map, defaultValue +
* increment is put into the map.
*/
public float getAndIncrement(int key, float defaultValue, float increment) {
int index = key & mask;
if (key != keyTable[index]) {
index = hash2(key);
if (key != keyTable[index]) {
index = hash3(key);
if (key != keyTable[index])
return getAndIncrementStash(key, defaultValue, increment);
}
}
float value = valueTable[index];
valueTable[index] = value + increment;
return value;
}
private float getAndIncrementStash(int key, float defaultValue, float increment) {
int[] keyTable = this.keyTable;
for (int i = capacity, n = i + stashSize; i < n; i++)
if (key == keyTable[i]) {
float value = valueTable[i];
valueTable[i] = value + increment;
return value;
}
put(key, defaultValue + increment);
return defaultValue;
}
public float remove(int key, float defaultValue) {
if (key == 0) {
if (!hasZeroValue)
return defaultValue;
hasZeroValue = false;
size--;
return zeroValue;
}
int index = key & mask;
if (key == keyTable[index]) {
keyTable[index] = EMPTY;
float oldValue = valueTable[index];
size--;
return oldValue;
}
index = hash2(key);
if (key == keyTable[index]) {
keyTable[index] = EMPTY;
float oldValue = valueTable[index];
size--;
return oldValue;
}
index = hash3(key);
if (key == keyTable[index]) {
keyTable[index] = EMPTY;
float oldValue = valueTable[index];
size--;
return oldValue;
}
return removeStash(key, defaultValue);
}
float removeStash(int key, float defaultValue) {
int[] keyTable = this.keyTable;
for (int i = capacity, n = i + stashSize; i < n; i++) {
if (key == keyTable[i]) {
float oldValue = valueTable[i];
removeStashIndex(i);
size--;
return oldValue;
}
}
return defaultValue;
}
void removeStashIndex(int index) {
// If the removed location was not last, move the last tuple to the removed location.
stashSize--;
int lastIndex = capacity + stashSize;
if (index < lastIndex) {
keyTable[index] = keyTable[lastIndex];
valueTable[index] = valueTable[lastIndex];
}
}
public void clear() {
int[] keyTable = this.keyTable;
for (int i = capacity + stashSize; i-- > 0;)
keyTable[i] = EMPTY;
size = 0;
stashSize = 0;
}
/**
* Returns true if the specified value is in the map. Note this traverses the entire map and compares every value,
* which may be an expensive operation.
*/
public boolean containsValue(float value) {
if (hasZeroValue && zeroValue == value)
return true;
float[] valueTable = this.valueTable;
for (int i = capacity + stashSize; i-- > 0;)
if (valueTable[i] == value)
return true;
return false;
}
/**
* Returns true if the specified value is in the map. Note this traverses the entire map and compares every value,
* which may be an expensive operation.
*/
public boolean containsValue(float value, float epsilon) {
if (hasZeroValue && zeroValue == value)
return true;
float[] valueTable = this.valueTable;
for (int i = capacity + stashSize; i-- > 0;)
if (Math.abs(valueTable[i] - value) <= epsilon)
return true;
return false;
}
public boolean containsKey(int key) {
if (key == 0)
return hasZeroValue;
int index = key & mask;
if (keyTable[index] != key) {
index = hash2(key);
if (keyTable[index] != key) {
index = hash3(key);
if (keyTable[index] != key)
return containsKeyStash(key);
}
}
return true;
}
private boolean containsKeyStash(int key) {
int[] keyTable = this.keyTable;
for (int i = capacity, n = i + stashSize; i < n; i++)
if (key == keyTable[i])
return true;
return false;
}
/**
* Returns the key for the specified value, or null if it is not in the map. Note this traverses the entire map and
* compares every value, which may be an expensive operation.
*/
public int findKey(float value, int notFound) {
if (hasZeroValue && zeroValue == value)
return 0;
float[] valueTable = this.valueTable;
for (int i = capacity + stashSize; i-- > 0;)
if (valueTable[i] == value)
return keyTable[i];
return notFound;
}
/**
* Increases the size of the backing array to acommodate the specified number of additional items. Useful before
* adding many items to avoid multiple backing array resizes.
*/
public void ensureCapacity(int additionalCapacity) {
int sizeNeeded = size + additionalCapacity;
if (sizeNeeded >= threshold)
resize(MathUtils.nextPowerOfTwo((int) (sizeNeeded / loadFactor)));
}
private void resize(int newSize) {
int oldEndIndex = capacity + stashSize;
capacity = newSize;
threshold = (int) (newSize * loadFactor);
mask = newSize - 1;
hashShift = 31 - Integer.numberOfTrailingZeros(newSize);
stashCapacity = Math.max(3, (int) Math.ceil(Math.log(newSize)) * 2);
pushIterations = Math.max(Math.min(newSize, 8), (int) Math.sqrt(newSize) / 8);
int[] oldKeyTable = keyTable;
float[] oldValueTable = valueTable;
keyTable = new int[newSize + stashCapacity];
valueTable = new float[newSize + stashCapacity];
size = hasZeroValue ? 1 : 0;
stashSize = 0;
for (int i = 0; i < oldEndIndex; i++) {
int key = oldKeyTable[i];
if (key != EMPTY)
putResize(key, oldValueTable[i]);
}
}
private int hash2(int h) {
h *= PRIME2;
return (h ^ h >>> hashShift) & mask;
}
private int hash3(int h) {
h *= PRIME3;
return (h ^ h >>> hashShift) & mask;
}
public String toString() {
if (size == 0)
return "{}";
StringBuilder buffer = new StringBuilder(32);
buffer.append('{');
int[] keyTable = this.keyTable;
float[] valueTable = this.valueTable;
int i = keyTable.length;
if (hasZeroValue) {
buffer.append("0=");
buffer.append(zeroValue);
} else {
while (i-- > 0) {
int key = keyTable[i];
if (key == EMPTY)
continue;
buffer.append(key);
buffer.append('=');
buffer.append(valueTable[i]);
break;
}
}
while (i-- > 0) {
int key = keyTable[i];
if (key == EMPTY)
continue;
buffer.append(", ");
buffer.append(key);
buffer.append('=');
buffer.append(valueTable[i]);
}
buffer.append('}');
return buffer.toString();
}
/**
* Returns an iterator for the entries in the map. Remove is supported. Note that the same iterator instance is
* returned each time this method is called. Use the {@link Entries} constructor for nested or multithreaded
* iteration.
*/
public Entries entries() {
if (entries == null)
entries = new Entries(this);
else
entries.reset();
return entries;
}
/**
* Returns an iterator for the values in the map. Remove is supported. Note that the same iterator instance is
* returned each time this method is called. Use the {@link Entries} constructor for nested or multithreaded
* iteration.
*/
public Values values() {
if (values == null)
values = new Values(this);
else
values.reset();
return values;
}
/**
* Returns an iterator for the keys in the map. Remove is supported. Note that the same iterator instance is
* returned each time this method is called. Use the {@link Entries} constructor for nested or multithreaded
* iteration.
*/
public Keys keys() {
if (keys == null)
keys = new Keys(this);
else
keys.reset();
return keys;
}
static public class Entry<K> {
public int key;
public float value;
public String toString() {
return key + "=" + value;
}
}
static private class MapIterator<K> {
static final int INDEX_ILLEGAL = -2;
static final int INDEX_ZERO = -1;
public boolean hasNext;
final IntFloatMap map;
int nextIndex, currentIndex;
public MapIterator(IntFloatMap map) {
this.map = map;
reset();
}
public void reset() {
currentIndex = INDEX_ILLEGAL;
nextIndex = INDEX_ZERO;
if (map.hasZeroValue)
hasNext = true;
else
findNextIndex();
}
void findNextIndex() {
hasNext = false;
int[] keyTable = map.keyTable;
for (int n = map.capacity + map.stashSize; ++nextIndex < n;) {
if (keyTable[nextIndex] != EMPTY) {
hasNext = true;
break;
}
}
}
public void remove() {
if (currentIndex == INDEX_ZERO && map.hasZeroValue) {
map.hasZeroValue = false;
} else if (currentIndex < 0) {
throw new IllegalStateException("next must be called before remove.");
} else if (currentIndex >= map.capacity) {
map.removeStashIndex(currentIndex);
} else {
map.keyTable[currentIndex] = EMPTY;
}
currentIndex = INDEX_ILLEGAL;
map.size--;
}
}
static public class Entries extends MapIterator implements Iterable<Entry>, Iterator<Entry> {
private Entry entry = new Entry();
public Entries(IntFloatMap map) {
super(map);
}
/** Note the same entry instance is returned each time this method is called. */
public Entry next() {
if (!hasNext)
throw new NoSuchElementException();
int[] keyTable = map.keyTable;
if (nextIndex == INDEX_ZERO) {
entry.key = 0;
entry.value = map.zeroValue;
} else {
entry.key = keyTable[nextIndex];
entry.value = map.valueTable[nextIndex];
}
currentIndex = nextIndex;
findNextIndex();
return entry;
}
public boolean hasNext() {
return hasNext;
}
public Iterator<Entry> iterator() {
return this;
}
}
static public class Values extends MapIterator<Object> {
public Values(IntFloatMap map) {
super(map);
}
public boolean hasNext() {
return hasNext;
}
public float next() {
float value;
if (nextIndex == INDEX_ZERO)
value = map.zeroValue;
else
value = map.valueTable[nextIndex];
currentIndex = nextIndex;
findNextIndex();
return value;
}
/** Returns a new array containing the remaining values. */
public FloatArray toArray() {
FloatArray array = new FloatArray(true, map.size);
while (hasNext)
array.add(next());
return array;
}
}
static public class Keys extends MapIterator {
public Keys(IntFloatMap map) {
super(map);
}
public boolean hasNext() {
return hasNext;
}
public int next() {
int key = nextIndex == INDEX_ZERO ? 0 : map.keyTable[nextIndex];
currentIndex = nextIndex;
findNextIndex();
return key;
}
/** Returns a new array containing the remaining keys. */
public IntArray toArray() {
IntArray array = new IntArray(true, map.size);
while (hasNext)
array.add(next());
return array;
}
}
}