NS_IMETHODIMP
CompositionTransaction::DoTransaction() {
  if (NS_WARN_IF(!mEditorBase)) {
    return NS_ERROR_NOT_INITIALIZED;
  }

  // Fail before making any changes if there's no selection controller
  nsCOMPtr<nsISelectionController> selCon;
  mEditorBase->GetSelectionController(getter_AddRefs(selCon));
  NS_ENSURE_TRUE(selCon, NS_ERROR_NOT_INITIALIZED);

  // Advance caret: This requires the presentation shell to get the selection.
  if (mReplaceLength == 0) {
    ErrorResult rv;
    mTextNode->InsertData(mOffset, mStringToInsert, rv);
    if (NS_WARN_IF(rv.Failed())) {
      return rv.StealNSResult();
    }
    mEditorBase->RangeUpdaterRef().SelAdjInsertText(*mTextNode, mOffset,
                                                    mStringToInsert);
  } else {
    uint32_t replaceableLength = mTextNode->TextLength() - mOffset;
    ErrorResult rv;
    mTextNode->ReplaceData(mOffset, mReplaceLength, mStringToInsert, rv);
    if (NS_WARN_IF(rv.Failed())) {
      return rv.StealNSResult();
    }
    mEditorBase->RangeUpdaterRef().SelAdjDeleteText(mTextNode, mOffset,
                                                    mReplaceLength);
    mEditorBase->RangeUpdaterRef().SelAdjInsertText(*mTextNode, mOffset,
                                                    mStringToInsert);

    // If IME text node is multiple node, ReplaceData doesn't remove all IME
    // text.  So we need remove remained text into other text node.
    if (replaceableLength < mReplaceLength) {
      int32_t remainLength = mReplaceLength - replaceableLength;
      nsCOMPtr<nsINode> node = mTextNode->GetNextSibling();
      while (node && node->IsText() && remainLength > 0) {
        Text* text = static_cast<Text*>(node.get());
        uint32_t textLength = text->TextLength();
        text->DeleteData(0, remainLength, IgnoreErrors());
        mEditorBase->RangeUpdaterRef().SelAdjDeleteText(text, 0, remainLength);
        remainLength -= textLength;
        node = node->GetNextSibling();
      }
    }
  }

  nsresult rv = SetSelectionForRanges();
  NS_ENSURE_SUCCESS(rv, rv);

  return NS_OK;
}