DocTocItem *Chm2EngineImpl::GetTocTree()
{
    EbookTocBuilder builder(this);
    doc->ParseToc(&builder);
    if (doc->HasIndex()) {
        // TODO: ToC code doesn't work too well for displaying an index,
        //       so this should really become a tree of its own (which
        //       doesn't rely on entries being in the same order as pages)
        builder.Visit(L"Index", NULL, 1);
        builder.SetIsIndex(true);
        doc->ParseIndex(&builder);
    }
    return builder.GetRoot();
}