Function count_draft 

pub fn count_draft(
    items: &[Item],
    folders: &FolderIndex,
    roots: &[SmartFolder],
    parent: Option<&str>,
    conditions: &[Value],
) -> usize

How many live items a smart folder with conditions would show inside parent (its ancestors’ conditions apply too), for the dialog’s live count while the rules are edited, as Eagle’s dialog counts them. Empty conditions count nothing, as a group with no children shows nothing.