/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nsIArray.idl"

/**
 * nsIMutableArray
 * A separate set of methods that will act on the array. Consumers of
 * nsIArray should not QueryInterface to nsIMutableArray unless they
 * own the array.
 *
 * As above, it is legal to add null elements to the array. Note also
 * that null elements can be created as a side effect of
 * insertElementAt(). Conversely, if insertElementAt() is never used,
 * and null elements are never explicitly added to the array, then it
 * is guaranteed that queryElementAt() will never return a null value.
 *
 * Any of these methods may throw NS_ERROR_OUT_OF_MEMORY when the
 * array must grow to complete the call, but the allocation fails.
 */
[scriptable, uuid(af059da0-c85b-40ec-af07-ae4bfdc192cc)]
interface nsIMutableArray : nsIArray
{
    /**
     * appendElement()
     * 
     * Append an element at the end of the array.
     *
     * @param element The element to append.
     * @param weak    Whether or not to store the element using a weak
     *                reference.
     * @throws NS_ERROR_FAILURE when a weak reference is requested,
     *                          but the element does not support
     *                          nsIWeakReference.
     */
    void appendElement(in nsISupports element, in boolean weak);

    /**
     * removeElementAt()
     * 
     * Remove an element at a specific position, moving all elements
     * stored at a higher position down one.
     * To remove a specific element, use indexOf() to find the index
     * first, then call removeElementAt().
     *
     * @param index the position of the item
     *
     */
    void removeElementAt(in unsigned long index);

    /**
     * insertElementAt()
     *
     * Insert an element at the given position, moving the element 
     * currently located in that position, and all elements in higher
     * position, up by one.
     *
     * @param element The element to insert
     * @param index   The position in the array:
     *                If the position is lower than the current length
     *                of the array, the elements at that position and
     *                onwards are bumped one position up.
     *                If the position is equal to the current length
     *                of the array, the new element is appended.
     *                An index lower than 0 or higher than the current
     *                length of the array is invalid and will be ignored.
     *
     * @throws NS_ERROR_FAILURE when a weak reference is requested,
     *                          but the element does not support
     *                          nsIWeakReference.
     */
    void insertElementAt(in nsISupports element, in unsigned long index,
                         in boolean weak);

    /**
     * replaceElementAt()
     *
     * Replace the element at the given position.
     *
     * @param element The new element to insert
     * @param index   The position in the array
     *                If the position is lower than the current length
     *                of the array, an existing element will be replaced.
     *                If the position is equal to the current length
     *                of the array, the new element is appended.
     *                If the position is higher than the current length
     *                of the array, empty elements are appended followed
     *                by the new element at the specified position.
     *                An index lower than 0 is invalid and will be ignored.
     *
     * @param weak    Whether or not to store the new element using a weak
     *                reference.
     *
     * @throws NS_ERROR_FAILURE when a weak reference is requested,
     *                          but the element does not support
     *                          nsIWeakReference.
     */
    void replaceElementAt(in nsISupports element, in unsigned long index,
                          in boolean weak);
    
    
    /**
     * clear()
     *
     * clear the entire array, releasing all stored objects
     */
    void clear();
};
