Core algorithm for building a tree using the zippers

gistfile1.fs

//core algorithm that returns a new zipper with the branch appended
let rec appendToTreeZipper (Loc (t,p) as l) (branch:list<string>) =
    let rightSiblings = match p with
                        | Top(_) -> []
                        | PathNode(_,_,_,rights) -> rights

    let label = match t with
                | Empty -> None
                | TreeNode(lbl,_) -> Some(lbl)

    match label,rightSiblings,branch with
    //empty tree in the zipper, just build a basic tree with zipper with the current branch
    | None,_,_ -> insert_down <| branchToTree branch <| l
    //the current tree label and the head of the branch match -> then go deeper
    | Some(x), _, head::tail when x = head -> appendToTreeZipper <| go_down l <| tail
    //if the label and the head does not match and there is no right simblings then we have to insert node here.
    | _, [] ,_  ->  insert_right <| TreeNode(branch.Head,[Tree.Empty]) <| l
    //Remaining case: try to find a match with the right most simbling.
    | _, _ ,_ -> appendToTreeZipper <| go_right l <| branch