/** Skips checks for existing keys. */
private void addResize(T key) {
// Check for empty buckets.
int hashCode = key.hashCode();
int index1 = hashCode & mask;
T key1 = keyTable[index1];
if (key1 == null) {
keyTable[index1] = key;
if (size++ >= threshold) resize(capacity << 1);
return;
}
int index2 = hash2(hashCode);
T key2 = keyTable[index2];
if (key2 == null) {
keyTable[index2] = key;
if (size++ >= threshold) resize(capacity << 1);
return;
}
int index3 = hash3(hashCode);
T key3 = keyTable[index3];
if (key3 == null) {
keyTable[index3] = key;
if (size++ >= threshold) resize(capacity << 1);
return;
}
push(key, index1, key1, index2, key2, index3, key3);
}
private void push(T insertKey, int index1, T key1, int index2, T key2, int index3, T key3) {
T[] keyTable = this.keyTable;
int mask = this.mask;
// Push keys until an empty bucket is found.
T evictedKey;
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;
keyTable[index1] = insertKey;
break;
case 1:
evictedKey = key2;
keyTable[index2] = insertKey;
break;
default:
evictedKey = key3;
keyTable[index3] = insertKey;
break;
}
// If the evicted key hashes to an empty bucket, put it there and stop.
int hashCode = evictedKey.hashCode();
index1 = hashCode & mask;
key1 = keyTable[index1];
if (key1 == null) {
keyTable[index1] = evictedKey;
if (size++ >= threshold) resize(capacity << 1);
return;
}
index2 = hash2(hashCode);
key2 = keyTable[index2];
if (key2 == null) {
keyTable[index2] = evictedKey;
if (size++ >= threshold) resize(capacity << 1);
return;
}
index3 = hash3(hashCode);
key3 = keyTable[index3];
if (key3 == null) {
keyTable[index3] = evictedKey;
if (size++ >= threshold) resize(capacity << 1);
return;
}
if (++i == pushIterations) break;
insertKey = evictedKey;
} while (true);
addStash(evictedKey);
}
/**
* Clears the map and reduces the size of the backing arrays to be the specified capacity if they
* are larger.
*/
public void clear(int maximumCapacity) {
if (capacity <= maximumCapacity) {
clear();
return;
}
size = 0;
resize(maximumCapacity);
}
/**
* Reduces the size of the backing arrays to be the specified capacity or less. If the capacity is
* already less, nothing is done. If the map contains more items than the specified capacity, the
* next highest power of two capacity is used instead.
*/
public void shrink(int maximumCapacity) {
if (maximumCapacity < 0)
throw new IllegalArgumentException("maximumCapacity must be >= 0: " + maximumCapacity);
if (size > maximumCapacity) maximumCapacity = size;
if (capacity <= maximumCapacity) return;
maximumCapacity = MathUtils.nextPowerOfTwo(maximumCapacity);
resize(maximumCapacity);
}
/** Returns true if the key was not already in the set. */
public boolean add(T key) {
if (key == null) throw new IllegalArgumentException("key cannot be null.");
T[] keyTable = this.keyTable;
// Check for existing keys.
int hashCode = key.hashCode();
int index1 = hashCode & mask;
T key1 = keyTable[index1];
if (key.equals(key1)) return false;
int index2 = hash2(hashCode);
T key2 = keyTable[index2];
if (key.equals(key2)) return false;
int index3 = hash3(hashCode);
T key3 = keyTable[index3];
if (key.equals(key3)) return false;
// Find key in the stash.
for (int i = capacity, n = i + stashSize; i < n; i++) if (key.equals(keyTable[i])) return false;
// Check for empty buckets.
if (key1 == null) {
keyTable[index1] = key;
if (size++ >= threshold) resize(capacity << 1);
return true;
}
if (key2 == null) {
keyTable[index2] = key;
if (size++ >= threshold) resize(capacity << 1);
return true;
}
if (key3 == null) {
keyTable[index3] = key;
if (size++ >= threshold) resize(capacity << 1);
return true;
}
push(key, index1, key1, index2, key2, index3, key3);
return true;
}
private void addStash(T key) {
if (stashSize == stashCapacity) {
// Too many pushes occurred and the stash is full, increase the table size.
resize(capacity << 1);
add(key);
return;
}
// Store key in the stash.
int index = capacity + stashSize;
keyTable[index] = key;
stashSize++;
size++;
}
/**
* 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)));
}
