xpcom/ds/nsISimpleEnumerator.idl

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #include "nsISupports.idl"
   7
   8 /**
   9  * Used to enumerate over elements defined by its implementor.
  10  * Although hasMoreElements() can be called independently of getNext(),
  11  * getNext() must be pre-ceeded by a call to hasMoreElements(). There is
  12  * no way to "reset" an enumerator, once you obtain one.
  13  *
  14  * @version 1.0
  15  */
  16
  17 [scriptable, uuid(D1899240-F9D2-11D2-BDD6-000064657374)]
  18 interface nsISimpleEnumerator : nsISupports {
  19   /**
  20    * Called to determine whether or not the enumerator has
  21    * any elements that can be returned via getNext(). This method
  22    * is generally used to determine whether or not to initiate or
  23    * continue iteration over the enumerator, though it can be
  24    * called without subsequent getNext() calls. Does not affect
  25    * internal state of enumerator.
  26    *
  27    * @see getNext()
  28    * @return true if there are remaining elements in the enumerator.
  29    *         false if there are no more elements in the enumerator.
  30    */
  31   boolean hasMoreElements();
  32
  33   /**
  34    * Called to retrieve the next element in the enumerator. The "next"
  35    * element is the first element upon the first call. Must be
  36    * pre-ceeded by a call to hasMoreElements() which returns PR_TRUE.
  37    * This method is generally called within a loop to iterate over
  38    * the elements in the enumerator.
  39    *
  40    * @see hasMoreElements()
  41    * @throws NS_ERROR_FAILURE if there are no more elements
  42    *                          to enumerate.
  43    * @return the next element in the enumeration.
  44    */
  45   nsISupports getNext();
  46 };