/** Implementation for NSNull for GNUStep
   Copyright (C) 2000 Free Software Foundation, Inc.

   Written by:  Richard Frith-Macdonald <rfm@gnu.org>
   Date: 2000
   
   This file is part of the GNUstep Base Library.

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public
   License as published by the Free Software Foundation; either
   version 2 of the License, or (at your option) any later version.
   
   This library 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
   Library General Public License for more details.
   
   You should have received a copy of the GNU Library General Public
   License along with this library; if not, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111 USA.

   <title>NSNull class reference</title>
   $Date: 2002/08/20 10:22:04 $ $Revision: 1.5 $
   */
#import <Foundation/NSObject.h>
#import <Foundation/NSNull.h>

/**
 * An object to use as a placeholder - in collections for instance.
 */
@implementation	NSNull

static NSNull	*null = 0;

+ (id) allocWithZone: (NSZone*)z
{
	return null;
}

+ (void) initialize
{
	if (null == 0)
		null = (NSNull*)NSAllocateObject(self, 0, NSDefaultMallocZone());
}

/**
 * Return an object that can be used as a placeholder in a collection.
 * This method always returns the same object.
 */
+ (NSNull*) null
{
  return null;
}

- (id) autorelease
{
  return self;
}

- (id) copyWithZone: (NSZone*)z
{
  return self;
}

- (void) dealloc
{
	return;	// has not really been allocated...
	[super dealloc];	// convince the compiler that this is ok.
}

- (void) encodeWithCoder: (NSCoder*)aCoder
{
}

- (id) initWithCoder: (NSCoder*)aCoder
{
  return self;
}

- (BOOL) isEqual: (id)other
{
  if (other == self)
    return YES;
  else
    return NO;
}

- (void) release
{
}

- (id) retain
{
  return self;
}
@end


