org.h2.util.IntIntHashMap Maven / Gradle / Ivy
/*
* Copyright 2004-2014 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (http://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.util;
import org.h2.message.DbException;
/**
* A hash map with int key and int values. There is a restriction: the
* value -1 (NOT_FOUND) cannot be stored in the map. 0 can be stored.
* An empty record has key=0 and value=0.
* A deleted record has key=0 and value=DELETED
*/
public class IntIntHashMap extends HashBase {
/**
* The value indicating that the entry has not been found.
*/
public static final int NOT_FOUND = -1;
private static final int DELETED = 1;
private int[] keys;
private int[] values;
private int zeroValue;
@Override
protected void reset(int newLevel) {
super.reset(newLevel);
keys = new int[len];
values = new int[len];
}
/**
* Store the given key-value pair. The value is overwritten or added.
*
* @param key the key
* @param value the value (-1 is not supported)
*/
public void put(int key, int value) {
if (key == 0) {
zeroKey = true;
zeroValue = value;
return;
}
checkSizePut();
internalPut(key, value);
}
private void internalPut(int key, int value) {
int index = getIndex(key);
int plus = 1;
int deleted = -1;
do {
int k = keys[index];
if (k == 0) {
if (values[index] != DELETED) {
// found an empty record
if (deleted >= 0) {
index = deleted;
deletedCount--;
}
size++;
keys[index] = key;
values[index] = value;
return;
}
// found a deleted record
if (deleted < 0) {
deleted = index;
}
} else if (k == key) {
// update existing
values[index] = value;
return;
}
index = (index + plus++) & mask;
} while (plus <= len);
// no space
DbException.throwInternalError("hashmap is full");
}
/**
* Remove the key-value pair with the given key.
*
* @param key the key
*/
public void remove(int key) {
if (key == 0) {
zeroKey = false;
return;
}
checkSizeRemove();
int index = getIndex(key);
int plus = 1;
do {
int k = keys[index];
if (k == key) {
// found the record
keys[index] = 0;
values[index] = DELETED;
deletedCount++;
size--;
return;
} else if (k == 0 && values[index] == 0) {
// found an empty record
return;
}
index = (index + plus++) & mask;
} while (plus <= len);
// not found
}
@Override
protected void rehash(int newLevel) {
int[] oldKeys = keys;
int[] oldValues = values;
reset(newLevel);
for (int i = 0; i < oldKeys.length; i++) {
int k = oldKeys[i];
if (k != 0) {
// skip the checkSizePut so we don't end up
// accidentally recursing
internalPut(k, oldValues[i]);
}
}
}
/**
* Get the value for the given key. This method returns NOT_FOUND if the
* entry has not been found.
*
* @param key the key
* @return the value or NOT_FOUND
*/
public int get(int key) {
if (key == 0) {
return zeroKey ? zeroValue : NOT_FOUND;
}
int index = getIndex(key);
int plus = 1;
do {
int k = keys[index];
if (k == 0 && values[index] == 0) {
// found an empty record
return NOT_FOUND;
} else if (k == key) {
// found it
return values[index];
}
index = (index + plus++) & mask;
} while (plus <= len);
return NOT_FOUND;
}
}