xpcom/ds/nsSupportsArrayEnumerator.cpp

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   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 "nsSupportsArrayEnumerator.h"
   7 #include "nsISupportsArray.h"
   8
   9 nsSupportsArrayEnumerator::nsSupportsArrayEnumerator(nsISupportsArray* array)
  10   : mArray(array)
  11   , mCursor(0)
  12 {
  13   NS_ASSERTION(array, "null array");
  14   NS_ADDREF(mArray);
  15 }
  16
  17 nsSupportsArrayEnumerator::~nsSupportsArrayEnumerator()
  18 {
  19   NS_RELEASE(mArray);
  20 }
  21
  22 NS_IMPL_ISUPPORTS(nsSupportsArrayEnumerator, nsIBidirectionalEnumerator,
  23                   nsIEnumerator)
  24
  25 NS_IMETHODIMP
  26 nsSupportsArrayEnumerator::First()
  27 {
  28   mCursor = 0;
  29   uint32_t cnt;
  30   nsresult rv = mArray->Count(&cnt);
  31   if (NS_FAILED(rv)) {
  32     return rv;
  33   }
  34   int32_t end = (int32_t)cnt;
  35   if (mCursor < end) {
  36     return NS_OK;
  37   } else {
  38     return NS_ERROR_FAILURE;
  39   }
  40 }
  41
  42 NS_IMETHODIMP
  43 nsSupportsArrayEnumerator::Next()
  44 {
  45   uint32_t cnt;
  46   nsresult rv = mArray->Count(&cnt);
  47   if (NS_FAILED(rv)) {
  48     return rv;
  49   }
  50   int32_t end = (int32_t)cnt;
  51   if (mCursor < end) { // don't count upward forever
  52     mCursor++;
  53   }
  54   if (mCursor < end) {
  55     return NS_OK;
  56   } else {
  57     return NS_ERROR_FAILURE;
  58   }
  59 }
  60
  61 NS_IMETHODIMP
  62 nsSupportsArrayEnumerator::CurrentItem(nsISupports** aItem)
  63 {
  64   NS_ASSERTION(aItem, "null out parameter");
  65   uint32_t cnt;
  66   nsresult rv = mArray->Count(&cnt);
  67   if (NS_FAILED(rv)) {
  68     return rv;
  69   }
  70   if (mCursor >= 0 && mCursor < (int32_t)cnt) {
  71     return mArray->GetElementAt(mCursor, aItem);
  72   }
  73   return NS_ERROR_FAILURE;
  74 }
  75
  76 NS_IMETHODIMP
  77 nsSupportsArrayEnumerator::IsDone()
  78 {
  79   uint32_t cnt;
  80   nsresult rv = mArray->Count(&cnt);
  81   if (NS_FAILED(rv)) {
  82     return rv;
  83   }
  84   // XXX This is completely incompatible with the meaning of nsresult.
  85   // NS_ENUMERATOR_FALSE is defined to be 1.  (bug 778111)
  86   return (mCursor >= 0 && mCursor < (int32_t)cnt)
  87     ? (nsresult)NS_ENUMERATOR_FALSE : NS_OK;
  88 }
  89
  90 ////////////////////////////////////////////////////////////////////////////////
  91
  92 NS_IMETHODIMP
  93 nsSupportsArrayEnumerator::Last()
  94 {
  95   uint32_t cnt;
  96   nsresult rv = mArray->Count(&cnt);
  97   if (NS_FAILED(rv)) {
  98     return rv;
  99   }
 100   mCursor = cnt - 1;
 101   return NS_OK;
 102 }
 103
 104 NS_IMETHODIMP
 105 nsSupportsArrayEnumerator::Prev()
 106 {
 107   if (mCursor >= 0) {
 108     --mCursor;
 109   }
 110   if (mCursor >= 0) {
 111     return NS_OK;
 112   } else {
 113     return NS_ERROR_FAILURE;
 114   }
 115 }
 116