com.mchange.util.impl.IntObjectHash Maven / Gradle / Ivy
/*
* Distributed as part of mchange-commons-java v.0.2.3
*
* Copyright (C) 2012 Machinery For Change, Inc.
*
* Author: Steve Waldman
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License version 2.1, as
* published by the Free Software Foundation.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this software; see the file LICENSE. If not, write to the
* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
* Boston, MA 02111-1307, USA.
*/
package com.mchange.util.impl;
import java.util.NoSuchElementException;
import com.mchange.util.*;
public class IntObjectHash implements IntObjectMap
{
IOHRecord[] records;
int init_capacity;
float load_factor;
int threshold;
int size;
public IntObjectHash(int init_capacity, float load_factor)
{
this.init_capacity = init_capacity;
this.load_factor = load_factor;
this.clear();
}
public IntObjectHash()
{this(101, 0.75f);} //defaults from java.util.Hashtable
public synchronized Object get(int num)
{
int index = getIndex(num);
Object out = null;
if (records[index] != null)
out = records[index].get(num);
return out;
}
public synchronized void put(int num, Object obj)
{
if (obj == null)
throw new NullPointerException("Null values not permitted.");
int index = getIndex(num);
if (records[index] == null)
records[index] = new IOHRecord(index);
boolean replaced = records[index].add(num, obj, true);
if (!replaced) ++size;
if (size > threshold) rehash();
}
public synchronized boolean putNoReplace(int num, Object obj)
{
if (obj == null)
throw new NullPointerException("Null values not permitted.");
int index = getIndex(num);
if (records[index] == null)
records[index] = new IOHRecord(index);
boolean needed_replace = records[index].add(num, obj, false);
if (needed_replace)
{return false;}
else
{
++size;
if (size > threshold) rehash();
return true;
}
}
public int getSize()
{return size;}
public synchronized boolean containsInt(int num)
{
int index = getIndex(num);
return (records[index] != null && records[index].findInt(num) != null);
}
private int getIndex(int num)
{return Math.abs(num % records.length);}
public synchronized Object remove(int num)
{
IOHRecord rec = records[getIndex(num)];
Object out = (rec == null ? null : rec.remove(num));
if (out != null) size--;
return out;
}
public synchronized void clear()
{
this.records = new IOHRecord[init_capacity];
this.threshold = (int) (load_factor * init_capacity);
this.size = 0;
}
public synchronized IntEnumeration ints()
{
return new IntEnumerationHelperBase()
{
int index;
IOHRecElem finger;
{
index = -1;
nextIndex();
}
public boolean hasMoreInts()
{return index < records.length;}
public int nextInt()
{
try
{
int out = finger.num;
findNext();
return out;
}
catch (NullPointerException e)
{throw new NoSuchElementException();}
}
private void findNext()
{
if (finger.next != null) finger = finger.next;
else nextIndex();
}
private void nextIndex()
{
try
{
int len = records.length;
do {++index;}
while (records[index] == null && index <= len);
finger = records[index].next;
}
catch (ArrayIndexOutOfBoundsException e)
{
//just means we're done.
finger = null;
}
}
};
}
//should only be called from a sync'ed method
protected void rehash()
{
IOHRecord[] newRecords = new IOHRecord[records.length * 2];
for (int i = 0; i < records.length; ++i)
{
if (records[i] != null)
{
newRecords[i] = records[i];
newRecords[i * 2] = records[i].split(newRecords.length);
}
}
records = newRecords;
threshold = (int) (load_factor * records.length);
}
}
class IOHRecord extends IOHRecElem
{
IntObjectHash parent;
int size = 0;
IOHRecord(int index)
{super(index, null, null);}
IOHRecElem findInt(int num) //retuns the RecElem previous to the one containing num
{
for (IOHRecElem finger = this; finger.next != null; finger = finger.next)
if (finger.next.num == num) return finger;
return null;
}
boolean add(int num, Object obj, boolean replace) //returns whether or not we would have had to replace
{ //whether we did depends on the value of replace
IOHRecElem prev = findInt(num);
if (prev != null)
{
if (replace)
prev.next = new IOHRecElem(num, obj, prev.next.next);
return true;
}
else
{
this.next = new IOHRecElem(num, obj, this.next);
++size;
return false;
}
}
Object remove(int num)
{
IOHRecElem prev = findInt(num);
if (prev == null) return null;
else
{
Object out = prev.next.obj;
prev.next = prev.next.next;
--size;
if (size == 0)
parent.records[this.num] = null; //kamikaze!!!
return out;
}
}
Object get(int num)
{
IOHRecElem prev = findInt(num);
if (prev != null)
return prev.next.obj;
else return null;
}
IOHRecord split(int new_cap)
{
IOHRecord out = null;
IOHRecElem outFinger = null;
for (IOHRecElem finger = this; finger.next != null; finger = finger.next)
{
if (Math.abs(finger.next.num % new_cap) != this.num)
{
if (out == null)
{
out = new IOHRecord(num * 2);
outFinger = out;
}
outFinger.next = finger.next;
finger.next = finger.next.next;
outFinger = outFinger.next;
outFinger.next = null;
}
}
return out;
}
}
class IOHRecElem
{
int num;
Object obj;
IOHRecElem next;
IOHRecElem(int num, Object obj, IOHRecElem next)
{
this.num = num;
this.obj = obj;
this.next = next;
}
}