/// <summary>
/// Fetches the next group of strings.
/// </summary>
public int Next(string[] buffer, int count)
{
// can't use simple interface after calling this method.
m_fetched = -1;
try
{
int fetched = 0;
IntPtr pBuffer = Marshal.AllocCoTaskMem(IntPtr.Size * count);
try
{
int error = m_enumerator.RemoteNext(
count,
pBuffer,
out fetched);
if (error >= 0 && fetched > 0)
{
IntPtr[] pStrings = new IntPtr[m_fetched];
Marshal.Copy(pBuffer, pStrings, 0, fetched);
for (int ii = 0; ii < fetched; ii++)
{
m_buffer[ii] = Marshal.PtrToStringUni(pStrings[ii]);
Marshal.FreeCoTaskMem(pStrings[ii]);
}
}
return(fetched);
}
finally
{
Marshal.FreeCoTaskMem(pBuffer);
}
}
catch (Exception e)
{
// some (incorrect) implementations return E_FAIL at the end of the list.
if (Marshal.GetHRForException(e) == ResultIds.E_FAIL)
{
return(0);
}
throw ComUtils.CreateException(e, "IEnumString.RemoteNext");
}
}
/// <summary>
/// Fetches the next string (returns null if no more data).
/// </summary>
public string Next()
{
// return null if at end of list.
if (m_fetched == -1)
{
return(null);
}
// see if next item is available.
if (m_position < m_fetched)
{
return(m_buffer[m_position++]);
}
m_position = 0;
try
{
// fetch next batch.
m_fetched = 0;
IntPtr pBuffer = Marshal.AllocCoTaskMem(IntPtr.Size * m_buffer.Length);
try
{
int error = m_enumerator.RemoteNext(m_buffer.Length, pBuffer, out m_fetched);
if (error < 0 || m_fetched == 0)
{
return(null);
}
IntPtr[] pStrings = new IntPtr[m_fetched];
Marshal.Copy(pBuffer, pStrings, 0, m_fetched);
for (int ii = 0; ii < m_fetched; ii++)
{
m_buffer[ii] = Marshal.PtrToStringUni(pStrings[ii]);
Marshal.FreeCoTaskMem(pStrings[ii]);
}
}
finally
{
Marshal.FreeCoTaskMem(pBuffer);
}
// check if end of list.
if (m_fetched == 0)
{
m_fetched = -1;
return(null);
}
// return first item.
return(m_buffer[m_position++]);
}
catch (Exception e)
{
if (ComUtils.IsUnknownError(e, ResultIds.E_FAIL))
{
throw ComUtils.CreateException(e, "IEnumString.RemoteNext");
}
// some (incorrect) implementations return E_FAIL at the end of the list.
m_fetched = -1;
return(null);
}
}
