/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/*
 * The contents of this file are subject to the Netscape Public
 * License Version 1.1 (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/NPL/
 *
 * 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 Mozilla Communicator client code, 
 * released March 31, 1998. 
 *
 * The Initial Developer of the Original Code is Netscape Communications 
 * Corporation.  Portions created by Netscape are
 * Copyright (C) 1998 Netscape Communications Corporation. All
 * Rights Reserved.
 *
 * Contributor(s): 
 *     Samir Gehani <sgehani@netscape.com>
 */

#ifndef _NS_COMPONENTLIST_H_
#define _NS_COMPONENTLIST_H_

#include "XIErrors.h"

class nsComponent;

class nsComponentList
{
public:
    nsComponentList();
    ~nsComponentList();

    /**     
     * GetHead
     *
     * Initializes the next ptr to the second item and 
     * returns the head item.
     *
     * @return mHead    the head of the singly-linked list
     */
    nsComponent *   GetHead();

    /**
     * GetNext
     * 
     * Returns the next available item. GetFirst() has to have 
     * been called prior calling this and after the last time
     * the entire list was iterated over.
     *
     * @return mNext    the next available component
     */
    nsComponent *   GetNext(); 

    /**
     * GetTail
     *
     * Returns the tail item of the list.
     *
     * @return mTail    the tail item of the list
     */
    nsComponent *   GetTail();
    
    /**
     * AddComponent
     *
     * Adds the supplied component to the list's tail.
     *
     * @param aComponent    the component to add
     * @return err          integer err code (zero means OK)
     */
    int             AddComponent(nsComponent *aComponent);

    /**
     * RemoveComponent
     *
     * Searches the list and removes the first component that
     * matches the supplied component.
     *
     * @param aComponent    the component to remove
     * @return err          integer error code (zero means OK)
     */
    int             RemoveComponent(nsComponent *aComponent);

private:
    nsComponent     *mHead; 
    nsComponent     *mTail;
    nsComponent     *mNext;
    int             mLength;
};

#endif /* _NS_COMPONENTLIST_H_ */