pjs/grendel/calypso/util/HashtableLite.java

341 строка
7.8 KiB
Java
Исходник Обычный вид История

1998-09-09 04:52:38 +04:00
/* -*- Mode: Java; tab-width: 2; indent-tabs-mode: nil -*-
*
* The contents of this file are subject to the Mozilla Public License
* Version 1.0 (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.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS"
* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
* the License for the specific language governing rights and limitations
* under the License.
*
* The Original Code is the Grendel mail/news client.
*
* The Initial Developer of the Original Code is Netscape Communications
* Corporation. Portions created by Netscape are Copyright (C) 1997
* Netscape Communications Corporation. All Rights Reserved.
*/
package calypso.util;
import java.util.*;
class ElementEnumeration
implements Enumeration
{
private int fIndex;
private HashtableLite fTable;
public ElementEnumeration (HashtableLite theTable)
{
fTable = theTable;
}
public boolean hasMoreElements ()
{
if (fIndex < fTable.fCount) return true;
else return false;
}
public Object nextElement ()
{
return fTable.fItems[(fIndex++*2) + 1];
}
}
class KeyEnumeration
implements Enumeration
{
private int fIndex;
private HashtableLite fTable;
KeyEnumeration (HashtableLite theTable)
{
fTable = theTable;
}
public boolean hasMoreElements ()
{
if (fIndex < fTable.fCount) return true;
else return false;
}
public Object nextElement ()
{
return fTable.fItems[fIndex++*2];
}
}
/**
* A utility class to avoid the pain (and memory bloat)
* of making lots of small hashtables. A real HashTable
* isn't created until the number of elements grows past
* a certain number (defined internally to HashtableLite).
*
* It sure would have been nice if Hashtables were an interface.
*
* @author thom 08-19-97 2:06am
*/
public class HashtableLite extends Object
implements java.lang.Cloneable
{
int fCount;
Object fItems[]; // [0] = key, [1] = item, etc
AtomHashtable fRealTable;
private static final int maxItems = 4;
public HashtableLite ()
{
}
public void clear()
{
fCount = 0;
fRealTable = null;
fItems = null;
}
public Object clone()
{
HashtableLite theClone = new HashtableLite();
if (fRealTable != null)
{
theClone.fRealTable = (AtomHashtable) fRealTable.clone();
}
else if (fCount > 0)
{
theClone.fItems = (Object[]) fItems.clone();
theClone.fCount = fCount;
}
return theClone;
}
public boolean contains (Object item)
{
if (fCount > 0)
{
for (int i = 0; i < fCount; ++i )
if (fItems[(i*2) + 1] == item)
return true;
return false;
}
if (fRealTable != null)
return fRealTable.contains (item);
return false;
}
public boolean containsKey (Atom key)
{
if (fCount > 0)
{
for (int i = 0; i < fCount; ++i )
if (fItems[i*2] == key)
return true;
return false;
}
if (fRealTable != null)
return fRealTable.containsKey (key);
return false;
}
public int count ()
{
if (fRealTable != null) return fRealTable.count();
return fCount;
}
public Enumeration elements()
{
if (fCount > 0)
return new ElementEnumeration (this);
if (fRealTable != null)
return fRealTable.elements();
return NullEnumeration.kInstance;
}
public Object[] elementsArray()
{
if (fRealTable != null)
return fRealTable.elementsArray();
Assert.NotYetImplemented("Arg");
return null;
}
public Vector elementsVector ()
{
if (fRealTable != null)
return fRealTable.elementsVector();
Assert.NotYetImplemented("Arg");
return null;
}
/*public void decode (Decoder aDecoder)
{
if (fRealTable != null)
fRealTable.decode(aDecoder);
}
public void describeClassInfo (ClassInfo theInfo)
{
if (fRealTable != null)
fRealTable.describeClassInfo(theInfo);
}
public void encode (Encoder anEncoder)
{
if (fRealTable != null)
fRealTable.encode (anEncoder);
}
public void finishDecoding()
{
if (fRealTable != null)
fRealTable.finishDecoding();
}*/
public Object get (Atom key)
{
if (fCount > 0)
{
for (int i = 0; i < fCount; ++i )
if (fItems[i*2] == key)
return fItems[(i*2) + 1];
return null;
}
else if (fRealTable != null)
return fRealTable.get (key);
return null;
}
public boolean isEmpty ()
{
if (fCount == 0 && fRealTable == null)
return true;
return false;
}
public Object put (Atom key, Object item)
{
if (fRealTable != null)
{
return fRealTable.put (key, item);
}
else
{
if (fItems == null) fItems = new Object[maxItems*2];
// is it already in the table?
for (int i = 0; i < fCount; ++i )
if (fItems[i*2] == key)
{
Object oldItem = fItems[(i*2) + 1];
fItems[(i*2) + 1] = item;
return oldItem;
}
// no, must add new key/item pair
if (fCount == maxItems) // spill over to real hashtable?
{
fRealTable = new AtomHashtable();
for (int i = 0; i < fCount; ++i )
fRealTable.put (fItems[i*2], fItems[(i*2) + 1]);
fItems = null;
fCount = 0;
return fRealTable.put (key, item);
}
// simple case, add the item
fItems[fCount*2] = key;
fItems[(fCount*2) + 1] = item;
++fCount;
}
return null;
}
public Enumeration keys ()
{
if (fRealTable != null)
return fRealTable.keys();
if (fCount > 0) return new KeyEnumeration (this);
return NullEnumeration.kInstance;
}
public Atom[] keysArray()
{
if (fRealTable != null)
return fRealTable.keysArray();
Assert.NotYetImplemented("Arg");
return null;
}
public Vector keysVector()
{
if (fRealTable != null)
return fRealTable.keysVector();
Assert.NotYetImplemented("Arg");
return null;
}
public Object remove (Atom key)
{
if (fRealTable != null)
return fRealTable.remove(key);
if (fCount > 0)
for (int i = 0; i < fCount; ++i )
if (fItems[i*2] == key)
{
Object oldItem = fItems[i*2 + 1];
--fCount;
for (int j = i; j < fCount - 1; ++j)
{
fItems[(j*2) + 1] = fItems[((j+1)*2) + 1];
fItems[ j*2] = fItems[ (j+1)*2];
}
return oldItem;
}
return null;
}
public int size()
{
if (fRealTable != null)
return fRealTable.size();
return fCount;
}
public String toString ()
{
if (fRealTable != null)
return fRealTable.toString();
return "Hi, I'm a hack";
}
}