(*
    ||M||  This file is part of HELM, an Hypertextual, Electronic        
    ||A||  Library of Mathematics, developed at the Computer Science     
    ||T||  Department, University of Bologna, Italy.                     
    ||I||                                                                
    ||T||  HELM is free software; you can redistribute it and/or         
    ||A||  modify it under the terms of the GNU General Public License   
    \   /  version 2 or (at your option) any later version.              
     \ /   This software is distributed as is, NO WARRANTY.              
      V_______________________________________________________________ *)

module P = Printf
module F = Format
module C = Cps

type ('a, 'b) item = Term of 'a * 'b
                   | Context of 'a
                   | Warn of string
		   | String of string

type ('a, 'b) specs = {
   pp_term   : 'a -> F.formatter -> 'b -> unit;
   pp_context: F.formatter -> 'a -> unit
}

let level = ref 0

(* Internal functions *******************************************************)

let std = F.std_formatter

let err = F.err_formatter

let init =
   let started = ref false in
   fun () ->
      if !started then () else 
      begin P.printf "\n"; started := true end

let pp_items frm st l items =   
   let pp_item frm = function
      | Term (c, t) -> F.fprintf frm "%a@,%a" st.pp_context c (st.pp_term c) t
      | Context c   -> F.fprintf frm "%a" st.pp_context c
      | Warn s      -> F.fprintf frm "@,%s" s
      | String s    -> F.fprintf frm "%s " s
   in
   let iter map frm l = List.iter (map frm) l in
   if !level >= l then F.fprintf frm "%a" (iter pp_item) items

(* Interface functions ******************************************************)

(*
let warn msg = 
   init (); P.printf " %s\n" msg; flush stdout
*)
let box () = F.fprintf std "@,@[<v 2>%s" "  "; F.pp_print_if_newline std ()

let unbox () = F.fprintf std "@]"

let flush () = F.fprintf std "@]@."

let box_err () = F.fprintf err "@[<v>"

let flush_err () = F.fprintf err "@]@."

let log st l items = pp_items std st l items

let error st items = pp_items err st 0 items

let items1 s = [Warn s]

let ct_items1 s c t =
   [Warn s; Term (c, t)]

let ct_items2 s1 c1 t1 s2 c2 t2 =
   [Warn s1; Term (c1, t1); Warn s2; Term (c2, t2)]

let warn msg = F.fprintf std "@,%s" msg