exception IllFormedXml of int;;

(* Utility functions that transform a Pxp attribute into something useful *)

let string_of_attr a =
 let module T = Pxp_types in
  match a with
     T.Value s -> s
   | _ -> raise (IllFormedXml 0)

let get_theory n =
 let module D = Pxp_document in
 let module T = Theory in
  let rec get_theory_elem n =
   let ntype = n # node_type in
   match ntype with
     D.T_element "THEOREM" ->
       let uri = string_of_attr (n # attribute "uri") in
        T.Theorem uri
   | D.T_element "DEFINITION" ->
       let uri = string_of_attr (n # attribute "uri") in
        T.Definition uri
   | D.T_element "AXIOM" ->
      let uri = string_of_attr (n # attribute "uri") in
       T.Axiom uri
   | D.T_element "VARIABLE" ->
      let uri = string_of_attr (n # attribute "uri") in
       T.Variable uri
   | D.T_element "SECTION" ->
      let uri = string_of_attr (n # attribute "uri")
      and subtheory = List.map get_theory_elem (n # sub_nodes) in
       T.Section (uri, subtheory)
   | D.T_element _ | D.T_data | _ ->
      raise (IllFormedXml 1)
  in
   match n # node_type with
      D.T_element "Theory" ->
       let uri = string_of_attr (n # attribute "uri") in
        (uri, List.map get_theory_elem (n # sub_nodes))
    | _ -> raise (IllFormedXml 2)
;;