(* Copyright (C) 2000, HELM Team.
 * 
 * This file is part of HELM, an Hypertextual, Electronic
 * Library of Mathematics, developed at the Computer Science
 * Department, University of Bologna, Italy.
 * 
 * HELM is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * 
 * HELM is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with HELM; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA  02111-1307, USA.
 * 
 * For details, see the HELM World-Wide-Web page,
 * http://cs.unibo.it/helm/.
 *)

(*  AUTOR: Ferruccio Guidi <fguidi@cs.unibo.it>
 *)

(* time handling  ***********************************************************)

type time = float * float 

let start_time () =
   (Sys.time (), Unix.time ())
   
let stop_time (s0, u0) =
   let s1 = Sys.time () in
   let u1 = Unix.time () in
   Printf.sprintf "%.2fs,%.2fs" (s1 -. s0) (u1 -. u0)

(* operations on lists  *****************************************************)

type 'a comparison = Lt 
                   | Gt
		   | Eq of 'a

let list_join f l1 l2 =
   let rec aux = function
      | [], v
      | v, []                                  -> v 
      | ((h1 :: t1) as v1), ((h2 :: t2) as v2) -> begin
         match f h1 h2 with
	    | Lt   -> h1 :: aux (t1, v2)
	    | Gt   -> h2 :: aux (v1, t2)
            | Eq h -> h  :: aux (t1, t2)
         end
   in aux (l1, l2)

let list_meet f l1 l2 =
   let rec aux = function
      | [], v
      | v, []                                  -> [] 
      | ((h1 :: t1) as v1), ((h2 :: t2) as v2) -> begin
         match f h1 h2 with
	    | Lt   -> aux (t1, v2)
	    | Gt   -> aux (v1, t2)
            | Eq h -> h :: aux (t1, t2)
         end
   in aux (l1, l2)

let rec flat_list out f s = function
   | []        -> ()
   | [a]       -> f a
   | a :: tail -> f a; out s; flat_list out f s tail

let rec add_assoc ap = function
   | []                                  -> [ap]
   | head :: tail when fst head = fst ap -> ap :: tail
   | head :: tail                        -> head :: add_assoc ap tail

(* int of string ************************************************************)

type t = End
       | Space
       | Figure of int
       | Error

let int_of_string s =
   let l = String.length s in
   let get_t i =
      if i = l then End else
      match s.[i] with
         | ' ' | '\t' | '\r' | 'n' -> Space
	 | '0' .. '9'              -> Figure (Char.code s.[i] - Char.code '0')
	 | _                       -> Error
   in
   let rec aux i xv = match get_t i, xv with
      | Error, _ 
      | End, None        -> raise (Failure "int_of_string") 
      | End, Some v      -> v
      | Space, xv        -> aux (succ i) xv
      | Figure f, None   -> aux (succ i) (Some f)
      | Figure f, Some v -> aux (succ i) (Some (10 * v + f))
   in
   aux 0 None