/* -*- 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 "nsISupports.idl"

/**
 * Used to enumerate over elements defined by its implementor.
 * Although hasMoreElements() can be called independently of getNext(),
 * getNext() must be pre-ceeded by a call to hasMoreElements(). There is
 * no way to "reset" an enumerator, once you obtain one.
 *
 * @version 1.0
 */

/**
 * A wrapper for an nsISimpleEnumerator instance which implements the
 * JavaScript iteration protocol.
 */
[scriptable, uuid(4432e8ae-d4d3-42a6-a4d1-829f1c29512b)]
interface nsIJSEnumerator : nsISupports {
  [symbol]
  nsIJSEnumerator iterator();

  [implicit_jscontext]
  jsval next();
};

[scriptable, uuid(796f340d-0a2a-490b-9c60-640765e99782)]
interface nsISimpleEnumeratorBase : nsISupports {
  /**
   * Returns a JavaScript iterator for all remaining entries in the enumerator.
   * Each entry is typically queried to the appropriate interface for the
   * enumerator.
   */
  [symbol]
  nsIJSEnumerator iterator();

  /**
   * Returns JavaScript iterator for all remaining entries in the enumerator.
   * Each entry is queried only to the supplied interface. If any element
   * fails to query to that interface, the error is propagated to the caller.
   */
  nsIJSEnumerator entries(in nsIIDRef aIface);
};

[scriptable, uuid(D1899240-F9D2-11D2-BDD6-000064657374)]
interface nsISimpleEnumerator : nsISimpleEnumeratorBase {
  /**
   * Called to determine whether or not the enumerator has
   * any elements that can be returned via getNext(). This method
   * is generally used to determine whether or not to initiate or
   * continue iteration over the enumerator, though it can be
   * called without subsequent getNext() calls. Does not affect
   * internal state of enumerator.
   *
   * @see getNext()
   * @return true if there are remaining elements in the enumerator.
   *         false if there are no more elements in the enumerator.
   */
  boolean hasMoreElements();

  /**
   * Called to retrieve the next element in the enumerator. The "next"
   * element is the first element upon the first call. Must be
   * pre-ceeded by a call to hasMoreElements() which returns PR_TRUE.
   * This method is generally called within a loop to iterate over
   * the elements in the enumerator.
   *
   * @see hasMoreElements()
   * @throws NS_ERROR_FAILURE if there are no more elements
   *                          to enumerate.
   * @return the next element in the enumeration.
   */
  nsISupports getNext();
};