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 /**
  18  * A wrapper for an nsISimpleEnumerator instance which implements the
  19  * JavaScript iteration protocol.
  20  */
  21 [scriptable, uuid(4432e8ae-d4d3-42a6-a4d1-829f1c29512b)]
  22 interface nsIJSEnumerator : nsISupports {
  23   [symbol]
  24   nsIJSEnumerator iterator();
  25
  26   [implicit_jscontext]
  27   jsval next();
  28 };
  29
  30 [scriptable, uuid(796f340d-0a2a-490b-9c60-640765e99782)]
  31 interface nsISimpleEnumeratorBase : nsISupports {
  32   /**
  33    * Returns a JavaScript iterator for all remaining entries in the enumerator.
  34    * Each entry is typically queried to the appropriate interface for the
  35    * enumerator.
  36    */
  37   [symbol]
  38   nsIJSEnumerator iterator();
  39
  40   /**
  41    * Returns JavaScript iterator for all remaining entries in the enumerator.
  42    * Each entry is queried only to the supplied interface. If any element
  43    * fails to query to that interface, the error is propagated to the caller.
  44    */
  45   nsIJSEnumerator entries(in nsIIDRef aIface);
  46 };
  47
  48 [scriptable, uuid(D1899240-F9D2-11D2-BDD6-000064657374)]
  49 interface nsISimpleEnumerator : nsISimpleEnumeratorBase {
  50   /**
  51    * Called to determine whether or not the enumerator has
  52    * any elements that can be returned via getNext(). This method
  53    * is generally used to determine whether or not to initiate or
  54    * continue iteration over the enumerator, though it can be
  55    * called without subsequent getNext() calls. Does not affect
  56    * internal state of enumerator.
  57    *
  58    * @see getNext()
  59    * @return true if there are remaining elements in the enumerator.
  60    *         false if there are no more elements in the enumerator.
  61    */
  62   boolean hasMoreElements();
  63
  64   /**
  65    * Called to retrieve the next element in the enumerator. The "next"
  66    * element is the first element upon the first call. Must be
  67    * pre-ceeded by a call to hasMoreElements() which returns PR_TRUE.
  68    * This method is generally called within a loop to iterate over
  69    * the elements in the enumerator.
  70    *
  71    * @see hasMoreElements()
  72    * @throws NS_ERROR_FAILURE if there are no more elements
  73    *                          to enumerate.
  74    * @return the next element in the enumeration.
  75    */
  76   nsISupports getNext();
  77 };