1 (***********************************************************************)
5 (* Kim Nguyen, LRI UMR8623 *)
6 (* Université Paris-Sud & CNRS *)
8 (* Copyright 2010-2013 Université Paris-Sud and Centre National de la *)
9 (* Recherche Scientifique. All rights reserved. This file is *)
10 (* distributed under the terms of the GNU Lesser General Public *)
11 (* License, with the special exception on linking described in file *)
14 (***********************************************************************)
17 Time-stamp: <Last modified on 2013-03-04 22:52:17 CET by Kim Nguyen>
27 (** Implementation of hashconsed Boolean formulae *)
30 module type PREDICATE =
34 val eval : ctx -> t -> bool
36 include Hcons.Abstract with type t := t
37 include Common_sig.Printable with type t := t
40 type ('formula,'pred) expr =
43 | Or of 'formula * 'formula
44 | And of 'formula * 'formula
47 module Make (P: PREDICATE) =
52 pos : ('hcons,P.t) expr;
56 external hash_const_variant : [> ] -> int = "%identity"
57 external vb : bool -> int = "%identity"
59 module rec Node : Hcons.S
60 with type data = Data.t = Hcons.Make (Data)
61 and Data : Common_sig.HashedType with type t = Node.t node =
65 match x.pos, y.pos with
66 | a,b when a == b -> true
67 | Or(xf1, xf2), Or(yf1, yf2)
68 | And(xf1, xf2), And(yf1,yf2) -> xf1 == yf1 && xf2 == yf2
69 | Atom(p1), Atom(p2) -> p1 == p2
77 HASHINT3 (PRIME1, Uid.to_int f1.Node.id, Uid.to_int f2.Node.id)
79 HASHINT3(PRIME3, Uid.to_int f1.Node.id, Uid.to_int f2.Node.id)
80 | Atom(p) -> HASHINT2(PRIME5, Uid.to_int (P.uid p))
84 let hash x = x.Node.hash
86 let equal = Node.equal
87 let expr f = f.Node.node.pos
89 let compare f1 f2 = compare f1.Node.id f2.Node.id
97 let rec print ?(parent=false) ppf f =
98 if parent then fprintf ppf "(";
99 let _ = match expr f with
100 | True -> fprintf ppf "%s" Pretty.top
101 | False -> fprintf ppf "%s" Pretty.bottom
103 print ~parent:(prio f > prio f1) ppf f1;
104 fprintf ppf " %s " Pretty.wedge;
105 print ~parent:(prio f > prio f2) ppf f2;
108 fprintf ppf " %s " Pretty.vee;
110 | Atom(p) -> fprintf ppf "%a" P.print p
111 (* let _ = flush_str_formatter() in
112 let fmt = str_formatter in
115 | `Left -> Pretty.down_arrow, Pretty.subscript 1
116 | `Right -> Pretty.down_arrow, Pretty.subscript 2
117 | `Epsilon -> Pretty.epsilon, ""
118 | `Up1 -> Pretty.up_arrow, Pretty.subscript 1
119 | `Up2 -> Pretty.up_arrow, Pretty.subscript 2
121 fprintf fmt "%s%s" a_str d_str;
123 let str = flush_str_formatter() in
124 if b then fprintf ppf "%s" str
125 else Pretty.pp_overline ppf str *)
127 if parent then fprintf ppf ")"
129 let print ppf f = print ~parent:false ppf f
131 let is_true f = (expr f) == True
132 let is_false f = (expr f) == False
136 let nnode = Node.make { pos = neg; neg = Obj.magic 0 } in
137 let pnode = Node.make { pos = pos; neg = nnode } in
138 (Node.node nnode).neg <- pnode; (* works because the neg field isn't taken into
139 account for hashing ! *)
143 let true_,false_ = cons True False
145 let atom_ p = fst (cons (Atom(p)) (Atom(P.neg p)))
147 let not_ f = f.Node.node.neg
149 let order f1 f2 = if uid f1 < uid f2 then f2,f1 else f1,f2
152 (* Tautologies: x|x, x|not(x) *)
154 if equal f1 f2 then f1
155 else if equal f1 (not_ f2) then true_
158 else if is_true f1 || is_true f2 then true_
159 else if is_false f1 && is_false f2 then false_
160 else if is_false f1 then f2
161 else if is_false f2 then f1
163 (* commutativity of | *)
165 let f1, f2 = order f1 f2 in
166 fst (cons (Or(f1,f2)) (And(not_ f1, not_ f2)))
170 not_ (or_ (not_ f1) (not_ f2))
173 let of_bool = function true -> true_ | false -> false_
176 match f.Node.node.pos with
179 | Atom p -> P.eval ctx p
180 | And(f1, f2) -> eval ctx f1 && eval ctx f2
181 | Or(f1, f2) -> eval ctx f1 || eval ctx f2