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A language for the Internet of Things.
/*
* Copyright (c) 2003-2019, Live Media Pty. Ltd.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification, are permitted
* provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this list of
* conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice, this list of
* conditions and the following disclaimer in the documentation and/or other materials
* provided with the distribution.
* 3. Neither the name of Live Media nor the names of its contributors may be used to endorse
* or promote products derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER
* OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package com.argot.util;
import java.util.Iterator;
public class TwoWayHashMap {
private TwoWayHashItem[] _forwards;
private TwoWayHashItem[] _backwards;
private int _mask;
private int _table_size;
private int _count;
public TwoWayHashMap() {
_table_size = 32;
_forwards = new TwoWayHashItem[_table_size];
_backwards = new TwoWayHashItem[_table_size];
_mask = _table_size - 1;
_count = 0;
}
/*
* int hash(int key)
*
* fast integer hash function taken from
* http://www.concentric.net/~Ttwang/tech/inthash.htm
*/
int inthash(int key) {
key += (key << 12);
key ^= (key >> 22);
key += (key << 4);
key ^= (key >> 9);
key += (key << 10);
key ^= (key >> 2);
key += (key << 7);
key ^= (key >> 12);
return key;
}
public int size() {
return _count;
}
public int findKey(int val) {
TwoWayHashItem item = null;
int hashvalue = inthash(val);
for (item = _backwards[hashvalue & _mask]; item != null; item = item.next_b) {
if ((hashvalue == item.hash_b) && (val == item.val)) {
return item.key;
}
}
return -1;
}
public Object getObjectFromKey(int key) {
TwoWayHashItem item = null;
int hashvalue = inthash(key);
for (item = _forwards[hashvalue & _mask]; item != null; item = item.next_f) {
if ((hashvalue == item.hash_f) && (key == item.key)) {
return item.object;
}
}
return null;
}
public int findValue(int key) {
TwoWayHashItem item = null;
int hashvalue = inthash(key);
for (item = _forwards[hashvalue & _mask]; item != null; item = item.next_f) {
if ((hashvalue == item.hash_f) && (key == item.key)) {
return item.val;
}
}
return -1;
}
public void add(int key, int val, Object object) {
if (object == null)
throw new IllegalArgumentException();
TwoWayHashItem item = null;
int hash = inthash(key);
int index = (hash & _mask);
/* return false if key already there. */
for (item = _forwards[index]; item != null; item = item.next_f) {
if ((hash == item.hash_f) && (key == item.key)) {
throw new IllegalArgumentException();
}
}
TwoWayHashItem new_item = new TwoWayHashItem();
new_item.key = key;
new_item.val = val;
new_item.object = object;
new_item.hash_f = hash;
new_item.next_f = _forwards[index];
_forwards[index] = new_item;
/* now calculate the backwards map. */
hash = inthash(val);
index = (hash & _mask);
new_item.hash_b = hash;
new_item.next_b = _backwards[index];
_backwards[index] = new_item;
/* set current and increment. */
_count++;
}
public void remove(int key) {
TwoWayHashItem ip, item;
int index;
int hashvalue = inthash(key);
for (item = _forwards[hashvalue & _mask]; item != null; item = item.next_f) {
if ((hashvalue == item.hash_f) && (key == item.key)) {
break;
}
}
/* item wasn't found. Return */
if (item == null)
return;
/* remove forward reference. */
index = item.hash_f & _mask;
if (_forwards[index] == item) {
_forwards[index] = item.next_f;
} else {
for (ip = _forwards[index]; ip.next_f != item; ip = ip.next_f)
;
ip.next_f = item.next_f;
}
/* remove backward reference */
index = item.hash_b & _mask;
if (_backwards[index] == item) {
_backwards[index] = item.next_f;
} else {
for (ip = _backwards[index]; ip.next_f != item; ip = ip.next_b)
;
ip.next_b = item.next_b;
}
/* decrement and free item. */
_count--;
}
public Iterator iterator() {
return new TwoWayHashMapIterator(this);
}
public class TwoWayHashMapIterator implements Iterator {
private TwoWayHashMap _map;
private int _index;
private TwoWayHashItem _current;
public TwoWayHashMapIterator(TwoWayHashMap map) {
_map = map;
_index = -1;
_current = null;
}
@Override
public void remove() {
throw new RuntimeException("Not implemented");
}
@Override
public boolean hasNext() {
/* check if we can find the next one quickly */
if (_current != null) {
_current = _current.next_f;
if (_current != null) {
return true;
}
}
/* search through the table for a valid entry */
while (_current == null && _index < (_map._table_size - 1)) {
_index++;
_current = _map._forwards[_index];
}
/* hit the end. No more to get */
if (_current == null) {
return false;
}
return true;
}
@Override
public Integer next() {
return Integer.valueOf(_current.key);
}
}
public class TwoWayHashItem {
public TwoWayHashItem next_b;
public TwoWayHashItem next_f;
public int hash_b;
public int hash_f;
public int val;
public int key;
public Object object;
}
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