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/*******************************************************************************
* ___ _ ____ ____
* / _ \ _ _ ___ ___| |_| _ \| __ )
* | | | | | | |/ _ \/ __| __| | | | _ \
* | |_| | |_| | __/\__ \ |_| |_| | |_) |
* \__\_\\__,_|\___||___/\__|____/|____/
*
* Copyright (c) 2014-2019 Appsicle
* Copyright (c) 2019-2020 QuestDB
*
* 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 io.questdb.std;
import java.util.Arrays;
public abstract class AbstractLowerCaseAsciiCharSequenceHashSet implements Mutable {
protected static final CharSequence noEntryKey = null;
protected static final int MIN_INITIAL_CAPACITY = 16;
protected final double loadFactor;
protected int mask;
protected int free;
protected int capacity;
// exposed for testing only
protected CharSequence[] keys;
public AbstractLowerCaseAsciiCharSequenceHashSet(int initialCapacity, double loadFactor) {
if (loadFactor <= 0d || loadFactor >= 1d) {
throw new IllegalArgumentException("0 < loadFactor < 1");
}
free = this.capacity = Math.max(initialCapacity, MIN_INITIAL_CAPACITY);
this.loadFactor = loadFactor;
keys = new CharSequence[Numbers.ceilPow2((int) (this.capacity / loadFactor))];
mask = keys.length - 1;
}
@Override
public void clear() {
Arrays.fill(keys, noEntryKey);
free = this.capacity;
}
public boolean excludes(CharSequence key) {
return keyIndex(key) > -1;
}
public boolean excludes(CharSequence key, int lo, int hi) {
return keyIndex(key, lo, hi) > -1;
}
public int keyIndex(CharSequence key) {
int index = Chars.lowerCaseAsciiHashCode(key) & mask;
if (keys[index] == noEntryKey) {
return index;
}
if (Chars.equalsLowerCaseAscii(key, keys[index])) {
return -index - 1;
}
return probe(key, index);
}
public int keyIndex(CharSequence key, int lo, int hi) {
int index = Chars.lowerCaseAsciiHashCode(key, lo, hi) & mask;
if (keys[index] == noEntryKey) {
return index;
}
CharSequence cs = keys[index];
if (Chars.equalsLowerCaseAscii(key, lo, hi, cs, 0, cs.length())) {
return -index - 1;
}
return probe(key, lo, hi, index);
}
public int remove(CharSequence key) {
int index = keyIndex(key);
if (index < 0) {
removeAt(index);
return -index - 1;
}
return -1;
}
public void removeAt(int index) {
if (index < 0) {
int from = -index - 1;
erase(from);
free++;
// after we have freed up a slot
// consider non-empty keys directly below
// they may have been a direct hit but because
// directly hit slot wasn't empty these keys would
// have moved.
//
// After slot if freed these keys require re-hash
from = (from + 1) & mask;
for (
CharSequence key = keys[from];
key != noEntryKey;
from = (from + 1) & mask, key = keys[from]
) {
int idealHit = Chars.lowerCaseAsciiHashCode(key) & mask;
if (idealHit != from) {
int to;
if (keys[idealHit] != noEntryKey) {
to = probe(key, idealHit);
} else {
to = idealHit;
}
if (to > -1) {
move(from, to);
}
}
}
}
}
public int size() {
return capacity - free;
}
/**
* Erases entry in array.
*
* @param index always positive, no arithmetic required.
*/
abstract protected void erase(int index);
abstract protected void move(int from, int to);
private int probe(CharSequence key, int index) {
do {
index = (index + 1) & mask;
if (keys[index] == noEntryKey) {
return index;
}
if (Chars.equalsLowerCaseAscii(key, keys[index])) {
return -index - 1;
}
} while (true);
}
private int probe(CharSequence key, int lo, int hi, int index) {
do {
index = (index + 1) & mask;
if (keys[index] == noEntryKey) {
return index;
}
CharSequence cs = keys[index];
if (Chars.equalsLowerCaseAscii(key, lo, hi, cs, 0, cs.length())) {
return -index - 1;
}
} while (true);
}
}