INCLUDE "utils.ml"
INCLUDE "debug.ml"
INCLUDE "trace.ml"


type t

type node = [ `Grammar ] Node.t

type p_type  = [ `Parameter ]
type n_type = [ `NonTerminal ]
type t_type = [ `Terminal ]
type any_type = [ p_type | n_type | t_type ]
type symbol = [ any_type ] Node.t

type p_symbol = p_type Node.t
type n_symbol = n_type Node.t
type t_symbol = t_type Node.t
type tn_symbol = [ n_type | t_type ] Node.t

type partial = Node of tn_symbol * partial array | Leaf of node




external is_nil : t -> t_symbol -> bool = "caml_grammar_is_nil"
external get_tag : t -> t_symbol -> string = "caml_grammar_get_tag"

external get_symbol_at : t -> symbol -> node -> symbol = "caml_grammar_get_symbol_at"
external first_child : t -> symbol -> node -> node = "caml_grammar_first_child"
external next_sibling : t -> symbol -> node -> node = "caml_grammar_next_sibling"


let is_non_terminal (n : [< any_type ] Node.t) =
  let n = Node.to_int n in
  n land 3 == 0

let is_terminal (n : [< any_type ] Node.t) =
  let n = Node.to_int n in
  n land 3 == 1

let is_parameter (n : [< any_type ] Node.t) =
  let n = Node.to_int n in
  n land 3 == 2


external parameter : [< any_type ] Node.t -> p_symbol = "%identity"
external terminal : [< any_type ] Node.t -> t_symbol = "%identity"
external non_terminal : [< any_type ] Node.t -> n_symbol = "%identity"

external get_id1 : t -> n_symbol -> tn_symbol = "caml_grammar_get_id1"
external get_id2 : t -> n_symbol -> tn_symbol = "caml_grammar_get_id2"
external get_param_pos : t -> n_symbol -> int = "caml_grammar_get_param_pos"


let num_params (n : n_symbol) =
  let n = Node.to_int n in
  (n lsr 2) land 0xf

let num_children (n : [< t_type | n_type ] Node.t ) =
  if is_non_terminal n then
    num_params (non_terminal n)
  else
    2


external load : Unix.file_descr -> bool -> t = "caml_grammar_load"

let traversal g =
  let start_symbol = (Node.of_int 0) in
  let dummy_leaf = Leaf (Node.nil) in
  let rec start_loop idx =
    TRACE("grammar", 2, __ "start_loop %a\n%!" Node.print idx);
    if idx >= Node.null then begin
      let symbol = get_symbol_at g start_symbol idx in
      if is_terminal symbol then
	let () = ();TRACE("grammar", 2, __ "Symbol %a is terminal\n%!" Node.print symbol); in
	let ts = terminal symbol in
	if is_nil g ts then (TRACE("grammar", 2, __ "Symbol %a is nil\n%!" Node.print symbol)) else
(*	  let str = get_tag g ts in
	  Printf.printf "<%s>%!" str; *)
	  let fs = first_child g start_symbol idx in
	  start_loop fs;
	  start_loop (next_sibling g start_symbol fs);
(*	  Printf.printf "</%s>%!" str; *)
      else
	let tn = non_terminal symbol in
	let nparam = num_params tn in
	let child = ref (first_child g start_symbol idx) in
	let a_param = Array.init nparam
	  (fun _ -> let c = !child in
		    child := next_sibling g start_symbol c;
		    Leaf c)
	in
	rule_loop tn a_param
    end

  and rule_loop (t : n_symbol) a_param =
    TRACE("grammar", 2, __ "rule_loop %a, (%i) \n%!" Node.print t (Array.length a_param));
    let id1 = get_id1 g t in
    let id2 = get_id2 g t in
    let param_pos = get_param_pos g t in
    let nparam1 = num_children id1 in
    let nparam2 = if is_terminal id2 && is_nil g (terminal id2) then 0 else num_children id2 in
    let a_param1 = Array.create nparam1 dummy_leaf in
    let a_param2 = Array.create nparam2 dummy_leaf in
    let i = param_pos - 2 in
    TRACE("grammar", 2, __ "id1: %i, id2: %i, param_pos: %i, nparam1: %i, nparam2: %i, i: %i\n%!"
      (Node.to_int id1) (Node.to_int id2) param_pos nparam1 nparam2 i);

    TRACE("grammar", 2, __ "blit a(%i) %i b(%i) %i %i\n%!"
      (Array.length a_param) 0 (Array.length a_param1) 0 (i+1));

    Array.blit a_param 0 a_param1 0 (i+1);  (* Pass parameters before id2 *)
    a_param1.(i+1) <- Node(id2, a_param2);  (* id2( ... ) *)

    TRACE("grammar", 2, __ "blit a(%i) %i b(%i) %i %i\n%!"
      (Array.length a_param) (i + nparam2 + 1) (Array.length a_param1) (i+2) (nparam1 - i - 2));
    Array.blit a_param (i + nparam2 + 1) a_param1 (i+2) (nparam1 - i - 2); (* Pass parameters after id2 *)



    TRACE("grammar", 2, __ "blit a(%i) %i b(%i) %i %i\n\n\n%!"
      (Array.length a_param) (i + 1) (Array.length a_param2) 0 (nparam2));
    Array.blit a_param (i + 1) a_param2 0 nparam2; (* parameters below id2 *)
    if is_non_terminal id1 then
      let id1 = non_terminal id1 in
      rule_loop id1 a_param1
    else
      let id1 = terminal id1 in
      terminal_loop id1 a_param1

  and terminal_loop (t : t_symbol) a_param =
    if is_nil g t then () else begin
(*      let str = get_tag g t in *)
(*      Printf.printf "<%s>%!" str; *)
      partial_loop a_param.(0);
      partial_loop a_param.(1)
(*      Printf.printf "</%s>%!" str *)
    end
  and partial_loop = function
    | Leaf id -> start_loop id
    | Node (id, a_param) ->
      if is_terminal id then terminal_loop (terminal id) a_param
      else rule_loop (non_terminal id) a_param
  in

  start_loop (Node.null)
;;



let load filename bp =
  let fd = Unix.openfile filename [ Unix.O_RDONLY ] 0o600 in
  let g =
    try load fd bp with
    | e -> (Unix.close fd; raise e)
  in
  Unix.close fd;
  traversal g;
  g