private ISymbolDocumentWriter GetDocumentWriter(string fname)
{
ISymbolDocumentWriter writer = GetCachedDocumentWriter(fname);
if (null != writer) return writer;
writer = _moduleBuilder.DefineDocument(
fname,
Guid.Empty,
Guid.Empty,
SymDocumentType.Text);
_symbolDocWriters.Add(fname, writer);
return writer;
}