X-Git-Url: http://git.nguyen.vg/gitweb/?p=tatoo.git;a=blobdiff_plain;f=src%2Fboolean.ml;fp=src%2Fboolean.ml;h=296f7a66893992089588992d3d9d26181b5ac858;hp=0000000000000000000000000000000000000000;hb=90ce5857f6cad2ebc753fdbc8e37882a1ff47415;hpb=9a127b83fbb1171ebd36e6f42780093412a5e91a

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+(***********************************************************************)
+(*                                                                     *)
+(*                               TAToo                                 *)
+(*                                                                     *)
+(*                     Kim Nguyen, LRI UMR8623                         *)
+(*                   Université Paris-Sud & CNRS                       *)
+(*                                                                     *)
+(*  Copyright 2010-2013 Université Paris-Sud and Centre National de la *)
+(*  Recherche Scientifique. All rights reserved.  This file is         *)
+(*  distributed under the terms of the GNU Lesser General Public       *)
+(*  License, with the special exception on linking described in file   *)
+(*  ../LICENSE.                                                        *)
+(*                                                                     *)
+(***********************************************************************)
+
+INCLUDE "utils.ml"
+
+open Format
+open Misc
+
+(*
+
+(** Implementation of hashconsed Boolean formulae *)
+
+*)
+module type ATOM =
+sig
+  include Hcons.S
+  include Common_sig.Printable with type t := t
+end
+
+type ('formula,'atom) expr =
+  | False
+  | True
+  | Or of 'formula * 'formula
+  | And of 'formula * 'formula
+  | Atom of 'atom * bool
+
+module Make (A: ATOM) =
+struct
+
+
+  type 'hcons node = {
+    pos : ('hcons,A.t) expr;
+    mutable neg : 'hcons;
+  }
+
+  external hash_const_variant : [> ] -> int = "%identity"
+  external vb : bool -> int = "%identity"
+
+  module rec Node : Hcons.S
+    with type data = Data.t = Hcons.Make (Data)
+    and Data : Common_sig.HashedType  with type t = Node.t node =
+  struct
+    type t =  Node.t node
+    let equal x y =
+      match x.pos, y.pos with
+      | a,b when a == b -> true
+      | Or(xf1, xf2), Or(yf1, yf2)
+      | And(xf1, xf2), And(yf1,yf2)  -> xf1 == yf1 && xf2 == yf2
+      | Atom(p1, b1), Atom(p2, b2) -> p1 == p2 && b1 == b2
+      | _ -> false
+
+    let hash f =
+      match f.pos with
+      | False -> 0
+      | True -> 1
+      | Or (f1, f2) ->
+          HASHINT3 (PRIME1, Uid.to_int f1.Node.id, Uid.to_int f2.Node.id)
+      | And (f1, f2) ->
+          HASHINT3(PRIME3, Uid.to_int f1.Node.id, Uid.to_int f2.Node.id)
+      | Atom(p, b) -> HASHINT3(PRIME5, Uid.to_int (A.uid p), int_of_bool b)
+  end
+
+    type t = Node.t
+    let hash x = x.Node.hash
+    let uid x = x.Node.id
+    let equal = Node.equal
+    let expr f = f.Node.node.pos
+
+    let compare f1 f2 = compare f1.Node.id  f2.Node.id
+    let prio f =
+      match expr f with
+      | True | False -> 10
+      | Atom _ -> 8
+      | And _ -> 6
+      | Or _ -> 1
+
+    let rec print ?(parent=false) ppf f =
+      if parent then fprintf ppf "(";
+      let _ = match expr f with
+      | True -> fprintf ppf "%s" Pretty.top
+      | False -> fprintf ppf "%s" Pretty.bottom
+      | And(f1,f2) ->
+          print ~parent:(prio f > prio f1) ppf f1;
+          fprintf ppf " %s "  Pretty.wedge;
+          print ~parent:(prio f > prio f2) ppf f2;
+      | Or(f1,f2) ->
+          (print ppf f1);
+          fprintf ppf " %s " Pretty.vee;
+          (print ppf f2);
+      | Atom(p,b) -> fprintf ppf "%s%a" (if b then "" else Pretty.lnot) A.print p
+  in
+    if parent then fprintf ppf ")"
+
+let print ppf f =  print ~parent:false ppf f
+
+let is_true f = (expr f) == True
+let is_false f = (expr f) == False
+
+let cons pos neg =
+  let nnode = Node.make { pos = neg; neg = Obj.magic 0 } in
+  let pnode = Node.make { pos = pos; neg = nnode } in
+    (Node.node nnode).neg <- pnode; (* works because the neg field isn't taken into
+                                       account for hashing ! *)
+    pnode,nnode
+
+
+let true_,false_ = cons True False
+
+let atom_ p =
+  let a, _ = cons (Atom(p, true)) (Atom(p, false)) in a
+
+let not_ f = f.Node.node.neg
+
+let order f1 f2 = if uid f1 < uid f2 then f2,f1 else f1,f2
+
+let or_ f1 f2 =
+  (* Tautologies: x|x, x|not(x) *)
+
+  if equal f1 f2 then f1
+  else if equal f1 (not_ f2) then true_
+
+  (* simplification *)
+  else if is_true f1 || is_true f2 then true_
+  else if is_false f1 && is_false f2 then false_
+  else if is_false f1 then f2
+  else if is_false f2 then f1
+
+  (* commutativity of | *)
+  else
+    let f1, f2 = order f1 f2 in
+      fst (cons (Or(f1,f2)) (And(not_ f1, not_ f2)))
+
+
+let and_ f1 f2 =
+  not_ (or_ (not_ f1) (not_ f2))
+
+
+let of_bool = function true -> true_ | false -> false_
+
+let fold f phi acc =
+  let rec loop phi acc =
+    match expr phi with
+    | And (phi1, phi2) | Or(phi1, phi2)  ->
+        loop phi2 (loop phi1 (f phi acc))
+    | _ -> f phi acc
+  in
+  loop phi acc
+
+end