/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.lucene.search.grouping;
import java.util.Arrays;
/** A native int set where one value is reserved to mean "EMPTY" */
class SentinelIntSet {
public int[] keys;
public int count;
public final int emptyVal;
public int rehashCount; // the count at which a rehash should be done
public SentinelIntSet(int size, int emptyVal) {
this.emptyVal = emptyVal;
int tsize = Math.max(org.apache.lucene.util.BitUtil.nextHighestPowerOfTwo(size), 1);
rehashCount = tsize - (tsize>>2);
if (size >= rehashCount) { // should be able to hold "size" w/o rehashing
tsize <<= 1;
rehashCount = tsize - (tsize>>2);
}
keys = new int[tsize];
if (emptyVal != 0)
clear();
}
public void clear() {
Arrays.fill(keys, emptyVal);
count = 0;
}
public int hash(int key) {
return key;
}
public int size() { return count; }
/** returns the slot for this key */
public int getSlot(int key) {
assert key != emptyVal;
int h = hash(key);
int s = h & (keys.length-1);
if (keys[s] == key || keys[s]== emptyVal) return s;
int increment = (h>>7)|1;
do {
s = (s + increment) & (keys.length-1);
} while (keys[s] != key && keys[s] != emptyVal);
return s;
}
/** returns the slot for this key, or -slot-1 if not found */
public int find(int key) {
assert key != emptyVal;
int h = hash(key);
int s = h & (keys.length-1);
if (keys[s] == key) return s;
if (keys[s] == emptyVal) return -s-1;
int increment = (h>>7)|1;
for(;;) {
s = (s + increment) & (keys.length-1);
if (keys[s] == key) return s;
if (keys[s] == emptyVal) return -s-1;
}
}
public boolean exists(int key) {
return find(key) >= 0;
}
public int put(int key) {
int s = find(key);
if (s < 0) {
if (count >= rehashCount) {
rehash();
s = getSlot(key);
} else {
s = -s-1;
}
count++;
keys[s] = key;
}
return s;
}
public void rehash() {
int newSize = keys.length << 1;
int[] oldKeys = keys;
keys = new int[newSize];
if (emptyVal != 0) Arrays.fill(keys, emptyVal);
for (int i=0; i<oldKeys.length; i++) {
int key = oldKeys[i];
if (key == emptyVal) continue;
int newSlot = getSlot(key);
keys[newSlot] = key;
}
rehashCount = newSize - (newSize>>2);
}
}