(*
    ||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 L = List
module U = NUri
module C = Cps
module E = Entity
module G = Options

type csys = {
           uri: E.uri;
   mutable tp : int list;
   mutable t1 : int list;
   mutable tn : (int * int) list;
}

let mark a = E.mark C.err C.start a

(* interface functions ******************************************************)

let init () = {
   uri = U.uri_of_string (G.get_baseuri ());
   tp = []; t1 = []; tn = []
}

let add_nonzero s a = 
   if !G.si && !G.cc then
      let i = abs (mark a) in
      if L.mem i s.tp then () else s.tp <- i :: s.tp
   else ()

let add_zero s a = 
   if !G.si && !G.cc then
      let i = abs (mark a) in
      if L.mem i s.t1 then () else s.t1 <- i :: s.t1
   else ()

let add_equal s xa ia = 
   if !G.si && !G.cc then
      let i = abs (mark xa), abs (mark ia) in
      if L.mem i s.tn then () else s.tn <- i :: s.tn
   else ()