/* -*- mode: objc; coding: utf-8 -*- */
/* Toilet Lisp, a Common Lisp subset for the Étoilé runtime.
 * Copyright (C) 2008  Matthias Andreas Benkard.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or (at
 * your option) any later version.
 *
 * This program 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
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#import <Foundation/NSArray.h>


/* Class: MLKCons

   A cons cell.

   A cons cell (or simply: a cons) is an ordered pair whose first
   element is called the car and whose second element is called the cdr
   of the cons.  Cons cells are mutable by default.

   Note that nil is explicitely allowed as both the car and cdr of a
   cons cell.  In fact, when representing linked lists using cons cells,
   nil in the cdr of the last cons cell is what conventionally marks the
   end of a list.
*/
@interface MLKCons : NSObject <NSCopying>
{
  id _car;
  id _cdr;
}

/*** Section: Creating and Initialising Conses ***/

/* Method: +cons:with:

   Cons two objects together.

   Arguments:

     car - The car of the new cons cell.
     cdr - The cdr of the new cons cell.

   Returns: A newly allocated cons.
*/
+(MLKCons*) cons:(id)car with:(id)cdr;

/* Method: +listWithArray:

   Make a linked list of cons cells out of an array. */
+(MLKCons*) listWithArray:(NSArray *)array;

/* Method: -initWithCar:cdr:

   Initialise a new cons cell with a car and cdr.

   Arguments:

     car - The car of the cons cell.
     cdr - The cdr of the cons cell.

   Returns: The initialised cons cell.
*/
-(MLKCons*) initWithCar:(id)car cdr:(id)cdr;


/*** Section: Accessing Components ***/

/* Method: -car

   The car of the cons cell.

   Returns: An object (may be nil).
*/
-(id) car;

/* Method: -cdr
  
   The cdr of the cons cell.

   Returns: An object (may be nil).
*/
-(id) cdr;

/* Method: -setCar:

   Change the car of the cons cell.

   Arguments:

     value - The new value.
*/
-(void) setCar:(id)value;

/* Method: -setCdr:

   Change the cdr of the cons cell.

   Arguments:

     value - The new value.
*/
-(void) setCdr:(id)value;


/*** Section: Converting to Other Container Types ***/

/* Method: -array

   Return the content of the linked list represented by this cons cell as an array.
*/
-(NSArray *) array;

-(void) appendObject:(id)object;
-(MLKCons *) listByAppendingObject:(id)object;
-(MLKCons *) copyList;
-(int) length;

-(NSString *) bareDescriptionForLisp;  // description without
                                       // parentheses, for internal use
                                       // only
-(NSString *) descriptionForLisp;

-(id) copyWithZone:(NSZone *)zone;
-(BOOL) isEqual:(id)object;
  
-(void) dealloc;
@end