CristalCaveGem » LustreC

(* Comments in function fold_mutate

 TODO: check if we can generate more cases. The following lines were

	     cylcing and missing to detect that the enumaration was complete,

	     leading to a non terminating process. The current setting is harder

	     but may miss enumerating some cases. To be checked! 

*)

open Lustre_types

open Corelang

open Log

open Format

let random_seed = ref 0

let threshold_delay = 95

let threshold_inc_int = 97

let threshold_dec_int = 97

let threshold_random_int = 96

let threshold_switch_int = 100 (* not implemented yet *)

let threshold_random_float = 100 (* not used yet *)

let threshold_negate_bool_var = 95

let threshold_arith_op = 95

let threshold_rel_op = 95

let threshold_bool_op = 95

let int_consts = ref []

let rename_app id =

  let node = Corelang.node_from_name id in

  let is_imported =

    match node.top_decl_desc with

    | ImportedNode _ -> true

    | _ -> false

  in

  if !Options.no_mutation_suffix || is_imported then

    id

  else

    id ^ "_mutant"

(************************************************************************************)

(*                    Gathering constants in the code                               *)

(************************************************************************************)

module IntSet = Set.Make (struct type t = int let compare = compare end)

module OpCount = Mmap.Make (struct type t = string let compare = compare end)

type records = {

  consts: IntSet.t;

  nb_consts: int;

  nb_boolexpr: int;

  nb_pre: int;

  nb_op: int OpCount.t;

}

let arith_op = ["+" ; "-" ; "*" ; "/"] 

let bool_op = ["&&"; "||"; "xor";  "impl"] 

let rel_op = ["<" ; "<=" ; ">" ; ">=" ; "!=" ; "=" ] 

let ops = arith_op @ bool_op @ rel_op

let all_ops = "not" :: ops

let empty_records = 

  {consts=IntSet.empty; nb_consts=0; nb_boolexpr=0; nb_pre=0; nb_op=OpCount.empty}

let records = ref empty_records

let merge_records records_list = 

  let merge_record r1 r2 =

    {

      consts = IntSet.union r1.consts r2.consts;

      nb_consts = r1.nb_consts + r2.nb_consts;

      nb_boolexpr = r1.nb_boolexpr + r2.nb_boolexpr;

      nb_pre = r1.nb_pre + r2.nb_pre;

      nb_op = OpCount.merge (fun op r1opt r2opt ->

	match r1opt, r2opt with

	| None, _ -> r2opt

	| _, None -> r1opt

	| Some x, Some y -> Some (x+y)

      ) r1.nb_op r2.nb_op 

    }

  in

  List.fold_left merge_record empty_records records_list

let compute_records_const_value c =

  match c with

  | Const_int i -> {empty_records with consts = IntSet.singleton i; nb_consts = 1}

  | _ -> empty_records

let rec compute_records_expr expr =

  let boolexpr = 

    if Types.is_bool_type expr.expr_type then

      {empty_records with nb_boolexpr = 1}

    else

      empty_records

  in

  let subrec = 

    match expr.expr_desc with

    | Expr_const c -> compute_records_const_value c

    | Expr_tuple l -> merge_records (List.map compute_records_expr l)

    | Expr_ite (i,t,e) -> 

      merge_records (List.map compute_records_expr [i;t;e])

    | Expr_arrow (e1, e2) ->       

      merge_records (List.map compute_records_expr [e1;e2])

    | Expr_pre e -> 

      merge_records (

	({empty_records with nb_pre = 1})

	::[compute_records_expr e])

    | Expr_appl (op_id, args, r) -> 

      if List.mem op_id ops then

	merge_records (

	  ({empty_records with nb_op = OpCount.singleton op_id 1})

	  ::[compute_records_expr args])

      else

	compute_records_expr args

    | _ -> empty_records

  in

  merge_records [boolexpr;subrec]

let compute_records_eq eq = compute_records_expr eq.eq_rhs

let compute_records_node nd =

  let eqs, auts = get_node_eqs nd in

  assert (auts=[]); (* Automaton should be expanded by now *)

  merge_records (List.map compute_records_eq eqs)

let compute_records_top_decl td =

  match td.top_decl_desc with

  | Node nd -> compute_records_node nd

  | Const cst -> compute_records_const_value cst.const_value

  | _ -> empty_records

let compute_records prog = 

  merge_records (List.map compute_records_top_decl prog)

(*****************************************************************)

(*                  Random mutation                              *)

(*****************************************************************)

let check_mut e1 e2 =

  let rec eq e1 e2 =

    match e1.expr_desc, e2.expr_desc with

    | Expr_const c1, Expr_const c2 -> c1 = c2

    | Expr_ident id1, Expr_ident id2 -> id1 = id2

    | Expr_tuple el1, Expr_tuple el2 -> List.length el1 = List.length el2 && List.for_all2 eq el1 el2

    | Expr_ite (i1, t1, e1), Expr_ite (i2, t2, e2) -> eq i1 i2 && eq t1 t2 && eq e1 e2

    | Expr_arrow (x1, y1), Expr_arrow (x2, y2) -> eq x1 x2 && eq y1 y2

    | Expr_pre e1, Expr_pre e2 -> eq e1 e2

    | Expr_appl (id1, e1, _), Expr_appl (id2, e2, _) -> id1 = id2 && eq e1 e2

  | _ -> false

  in

  if not (eq e1 e2) then

    Some (e1, e2)

  else

    None

let mk_cst_expr c = mkexpr Location.dummy_loc (Expr_const c)

let rdm_mutate_int i = 

  if Random.int 100 > threshold_inc_int then

    i+1

  else if Random.int 100 > threshold_dec_int then

    i-1

  else if Random.int 100 > threshold_random_int then

    Random.int 10

  else if Random.int 100 > threshold_switch_int then

    let idx = Random.int (List.length !int_consts) in

    List.nth !int_consts idx

  else

    i

let rdm_mutate_real r =

  if Random.int 100 > threshold_random_float then

    (* interval [0, bound] for random values *)

    let bound = 10 in

    (* max number of digits after comma *)

    let digits = 5 in

    (* number of digits after comma *)

    let shift = Random.int (digits + 1) in

    let eshift = 10. ** (float_of_int shift) in

    let i = Random.int (1 + bound * (int_of_float eshift)) in

    let f = float_of_int i /. eshift in

    (Num.num_of_int i, shift, string_of_float f)

  else 

    r

let rdm_mutate_op op = 

match op with

| "+" | "-" | "*" | "/" when Random.int 100 > threshold_arith_op ->

  let filtered = List.filter (fun x -> x <> op) ["+"; "-"; "*"; "/"] in

  List.nth filtered (Random.int 3)

| "&&" | "||" | "xor" | "impl" when Random.int 100 > threshold_bool_op ->

  let filtered = List.filter (fun x -> x <> op) ["&&"; "||"; "xor"; "impl"] in

  List.nth filtered (Random.int 3)

| "<" | "<=" | ">" | ">=" | "!=" | "=" when Random.int 100 > threshold_rel_op ->

  let filtered = List.filter (fun x -> x <> op) ["<"; "<="; ">"; ">="; "!="; "="] in

  List.nth filtered (Random.int 5)

| _ -> op

let rdm_mutate_var expr =

  if Types.is_bool_type expr.expr_type then

    (* if Random.int 100 > threshold_negate_bool_var then *)

    let new_e = mkpredef_call expr.expr_loc "not" [expr] in

    Some (expr, new_e), new_e

    (* else  *)

  (*   expr *)

  else

    None, expr

let rdm_mutate_pre orig_expr = 

  let new_e = Expr_pre orig_expr in

  Some (orig_expr, {orig_expr with expr_desc = new_e}), new_e

let rdm_mutate_const_value c =

  match c with

  | Const_int i -> Const_int (rdm_mutate_int i)

  | Const_real (n, i, s) -> let (n', i', s') = rdm_mutate_real (n, i, s) in Const_real (n', i', s')

  | Const_array _

  | Const_string _

  | Const_modeid _

  | Const_struct _

  | Const_tag _ -> c

let rdm_mutate_const c =

  let new_const = rdm_mutate_const_value c.const_value in

  let mut = check_mut (mk_cst_expr c.const_value) (mk_cst_expr new_const) in

  mut, { c with const_value = new_const }

let select_in_list list rdm_mutate_elem = 

  let selected = Random.int (List.length list) in

  let mutation_opt, new_list, _ = 

    List.fold_right

      (fun elem (mutation_opt, res, cpt) -> if cpt = selected then 

	  let mutation, new_elem = rdm_mutate_elem elem in

	  Some mutation, new_elem::res, cpt+1  else mutation_opt, elem::res, cpt+1)

      list 

      (None, [], 0)

  in

  match mutation_opt with

  | Some mut -> mut, new_list

  | _ -> assert false

let rec rdm_mutate_expr expr =

  let mk_e d = { expr with expr_desc = d } in

  match expr.expr_desc with

  | Expr_ident id -> rdm_mutate_var expr

  | Expr_const c -> 

    let new_const = rdm_mutate_const_value c in 

    let mut = check_mut (mk_cst_expr c) (mk_cst_expr new_const) in

    mut, mk_e (Expr_const new_const)

  | Expr_tuple l -> 

    let mut, l' = select_in_list l rdm_mutate_expr in

    mut, mk_e (Expr_tuple l')

  | Expr_ite (i,t,e) -> (

    let mut, l = select_in_list [i; t; e] rdm_mutate_expr in

    match l with

    | [i'; t'; e'] -> mut, mk_e (Expr_ite (i', t', e'))

    | _ -> assert false

  )

  | Expr_arrow (e1, e2) -> (

    let mut, l = select_in_list [e1; e2] rdm_mutate_expr in

    match l with

    | [e1'; e2'] -> mut, mk_e (Expr_arrow (e1', e2'))

    | _ -> assert false

  )

  | Expr_pre e -> 

    let select_pre = Random.bool () in

    if select_pre then

      let mut, new_expr = rdm_mutate_pre expr in

      mut, mk_e new_expr

    else

      let mut, e' = rdm_mutate_expr e in

      mut, mk_e (Expr_pre e')

  | Expr_appl (op_id, args, r) -> 

    let select_op = Random.bool () in

    if select_op then

      let new_op_id = rdm_mutate_op op_id in

      let new_e = mk_e (Expr_appl (new_op_id, args, r)) in

      let mut = check_mut expr new_e in

      mut, new_e

    else

      let mut, new_args = rdm_mutate_expr args in

      mut, mk_e (Expr_appl (op_id, new_args, r))

  (* Other constructs are kept.

  | Expr_fby of expr * expr

  | Expr_array of expr list

  | Expr_access of expr * Dimension.dim_expr

  | Expr_power of expr * Dimension.dim_expr

  | Expr_when of expr * ident * label

  | Expr_merge of ident * (label * expr) list

  | Expr_uclock of expr * int

  | Expr_dclock of expr * int

  | Expr_phclock of expr * rat *)

   | _ -> None, expr

let rdm_mutate_eq eq =

  let mutation, new_rhs = rdm_mutate_expr eq.eq_rhs in

  mutation, { eq with eq_rhs = new_rhs }

let rnd_mutate_stmt stmt =

  match stmt with

  | Eq eq   -> let mut, new_eq = rdm_mutate_eq eq in

		 report ~level:1 

		   (fun fmt -> fprintf fmt "mutation: %a becomes %a@ " 

		     Printers.pp_node_eq eq

		     Printers.pp_node_eq new_eq);

		 mut, Eq new_eq 

  | Aut aut -> assert false

let rdm_mutate_node nd = 

  let mutation, new_node_stmts =       

    select_in_list 

      nd.node_stmts rnd_mutate_stmt

  in

  mutation, { nd with node_stmts = new_node_stmts }

let rdm_mutate_top_decl td =

  match td.top_decl_desc with

  | Node nd -> 

    let mutation, new_node = rdm_mutate_node nd in 

    mutation, { td with top_decl_desc = Node new_node}

  | Const cst -> 

    let mut, new_cst = rdm_mutate_const cst in

    mut, { td with top_decl_desc = Const new_cst }

  | _ -> None, td

(* Create a single mutant with the provided random seed *)

let rdm_mutate_prog prog = 

  select_in_list prog rdm_mutate_top_decl

let rdm_mutate nb prog = 

  let rec iterate nb res =

    incr random_seed;

    if nb <= 0 then

      res

    else (

      Random.init !random_seed;

      let mutation, new_mutant = rdm_mutate_prog prog in

      match mutation with

	None -> iterate nb res 

      | Some mutation -> ( 

	if List.mem_assoc mutation res then (

	  iterate nb res

	)

	else (

	  report ~level:1 (fun fmt -> fprintf fmt "%i mutants remaining@ " nb); 

	  iterate (nb-1) ((mutation, new_mutant)::res)

	)

      )

    )

  in

  iterate nb []

(*****************************************************************)

(*                  Random mutation                              *)

(*****************************************************************)

type mutant_t =

  | Boolexpr of int

  | Pre of int

  | Op of string * int * string

  | IncrIntCst of int

  | DecrIntCst of int

  | SwitchIntCst of int * int 

(* Denotes the parent node, the equation lhs and the location of the mutation *)

type mutation_loc = ident * ident list * Location.t

let target : mutant_t option ref = ref None

let mutation_info : mutation_loc option ref = ref None

let current_node: ident option ref = ref None 

let current_eq_lhs : ident list option ref = ref None

let current_loc : Location.t option ref = ref None

let set_mutation_loc () =

  target := None;

  match !current_node, !current_eq_lhs, !current_loc with

  | Some n, Some elhs, Some l ->  mutation_info := Some (n, elhs, l)

  | _ -> assert false (* Those global vars should be defined during the

			   visitor pattern execution *)

let print_directive fmt d =

  match d with

  | Pre n -> Format.fprintf fmt "pre %i" n

  | Boolexpr n -> Format.fprintf fmt "boolexpr %i" n

  | Op (o, i, d) -> Format.fprintf fmt "%s %i -> %s" o i d

  | IncrIntCst n ->  Format.fprintf fmt "incr int cst %i" n

  | DecrIntCst n ->  Format.fprintf fmt "decr int cst %i" n

  | SwitchIntCst (n, m) ->  Format.fprintf fmt "switch int cst %i -> %i" n m

let print_directive_json fmt d =

  match d with

  | Pre _ -> Format.fprintf fmt "\"mutation\": \"pre\""

  | Boolexpr _ -> Format.fprintf fmt "\"mutation\": \"not\"" 

  | Op (o, _, d) -> Format.fprintf fmt "\"mutation\": \"op_conv\", \"from\": \"%s\", \"to\": \"%s\"" o d

  | IncrIntCst n ->  Format.fprintf fmt "\"mutation\": \"cst_incr\""

  | DecrIntCst n ->  Format.fprintf fmt "\"mutation\": \"cst_decr\""

  | SwitchIntCst (n, m) ->  Format.fprintf fmt "\"mutation\": \"cst_switch\", \"to_cst\": \"%i\"" m

let print_loc_json fmt (n,eqlhs, l) =

  Format.fprintf fmt "\"node_id\": \"%s\", \"eq_lhs\": [%a], \"loc_line\": \"%i\""

    n

    (Utils.fprintf_list ~sep:", " (fun fmt s -> Format.fprintf fmt "\"%s\"" s)) eqlhs

    (Location.loc_line l)

let fold_mutate_int i = 

  if Random.int 100 > threshold_inc_int then

    i+1

  else if Random.int 100 > threshold_dec_int then

    i-1

  else if Random.int 100 > threshold_random_int then

    Random.int 10

  else if Random.int 100 > threshold_switch_int then

    try

	let idx = Random.int (List.length !int_consts) in

        List.nth !int_consts idx

    with _ -> i

  else

    i

let fold_mutate_float f =

  if Random.int 100 > threshold_random_float then

    Random.float 10.

  else 

    f

let fold_mutate_op op = 

(* match op with *)

(* | "+" | "-" | "*" | "/" when Random.int 100 > threshold_arith_op -> *)

(*   let filtered = List.filter (fun x -> x <> op) ["+"; "-"; "*"; "/"] in *)

(*   List.nth filtered (Random.int 3) *)

(* | "&&" | "||" | "xor" | "impl" when Random.int 100 > threshold_bool_op -> *)

(*   let filtered = List.filter (fun x -> x <> op) ["&&"; "||"; "xor"; "impl"] in *)

(*   List.nth filtered (Random.int 3) *)

(* | "<" | "<=" | ">" | ">=" | "!=" | "=" when Random.int 100 > threshold_rel_op -> *)

(*   let filtered = List.filter (fun x -> x <> op) ["<"; "<="; ">"; ">="; "!="; "="] in *)

(*   List.nth filtered (Random.int 5) *)

(* | _ -> op *)

  match !target with

  | Some (Op(op_orig, 0, op_new)) when op_orig = op -> (

    set_mutation_loc ();

    op_new

  )

  | Some (Op(op_orig, n, op_new)) when op_orig = op -> (

    target := Some (Op(op_orig, n-1, op_new));

    op

  )

  | _ -> if List.mem op Basic_library.internal_funs then op else rename_app op

let fold_mutate_var expr = 

  (* match (Types.repr expr.expr_type).Types.tdesc with  *)

  (* | Types.Tbool -> *)

  (*     (\* if Random.int 100 > threshold_negate_bool_var then *\) *)

  (*     mkpredef_unary_call Location.dummy_loc "not" expr *)

  (*   (\* else  *\) *)

  (*   (\*   expr *\) *)

  (* | _ -> 

 *)expr

let fold_mutate_boolexpr expr =

  match !target with

  | Some (Boolexpr 0) -> (

     set_mutation_loc ();

    mkpredef_call expr.expr_loc "not" [expr]

  )

  | Some (Boolexpr n) ->

      (target := Some (Boolexpr (n-1)); expr)

  | _ -> expr

let fold_mutate_pre orig_expr e = 

  match !target with

    Some (Pre 0) -> (

      set_mutation_loc ();

      Expr_pre ({orig_expr with expr_desc = Expr_pre e}) 

    )

  | Some (Pre n) -> (

    target := Some (Pre (n-1));

    Expr_pre e

  )

  | _ -> Expr_pre e

let fold_mutate_const_value c = 

match c with

| Const_int i -> (

  match !target with

  | Some (IncrIntCst 0) -> (set_mutation_loc (); Const_int (i+1))

  | Some (DecrIntCst 0) -> (set_mutation_loc (); Const_int (i-1))

  | Some (SwitchIntCst (0, id)) ->

     (set_mutation_loc (); Const_int id) 

  | Some (IncrIntCst n) -> (target := Some (IncrIntCst (n-1)); c)

  | Some (DecrIntCst n) -> (target := Some (DecrIntCst (n-1)); c)

  | Some (SwitchIntCst (n, id)) -> (target := Some (SwitchIntCst (n-1, id)); c)

  | _ -> c)

| _ -> c

(*

  match c with

  | Const_int i -> Const_int (fold_mutate_int i)

  | Const_real s -> Const_real s (* those are string, let's leave them *)

  | Const_float f -> Const_float (fold_mutate_float f)

  | Const_array _

  | Const_tag _ -> c

TODO

				  *)

let fold_mutate_const c =

  { c with const_value = fold_mutate_const_value c.const_value }

let rec fold_mutate_expr expr =

  current_loc := Some expr.expr_loc;

  let new_expr = 

    match expr.expr_desc with

    | Expr_ident id -> fold_mutate_var expr

    | _ -> (

      let new_desc = match expr.expr_desc with

	| Expr_const c -> Expr_const (fold_mutate_const_value c)

	| Expr_tuple l -> Expr_tuple (List.fold_right (fun e res -> (fold_mutate_expr e)::res) l [])

	| Expr_ite (i,t,e) -> Expr_ite (fold_mutate_expr i, fold_mutate_expr t, fold_mutate_expr e)

	| Expr_arrow (e1, e2) -> Expr_arrow (fold_mutate_expr e1, fold_mutate_expr e2)

	| Expr_pre e -> fold_mutate_pre expr (fold_mutate_expr e)

	| Expr_appl (op_id, args, r) -> Expr_appl (fold_mutate_op op_id, fold_mutate_expr args, r)

  (* Other constructs are kept.

  | Expr_fby of expr * expr

  | Expr_array of expr list

  | Expr_access of expr * Dimension.dim_expr

  | Expr_power of expr * Dimension.dim_expr

  | Expr_when of expr * ident * label

  | Expr_merge of ident * (label * expr) list

  | Expr_uclock of expr * int

  | Expr_dclock of expr * int

  | Expr_phclock of expr * rat *)

  | _ -> expr.expr_desc

      in

      { expr with expr_desc = new_desc }

    )

  in

  if Types.is_bool_type expr.expr_type then

    fold_mutate_boolexpr new_expr  

  else

    new_expr

let fold_mutate_eq eq =

  current_eq_lhs := Some eq.eq_lhs;

  { eq with eq_rhs = fold_mutate_expr eq.eq_rhs }

let fold_mutate_stmt stmt =

  match stmt with

  | Eq eq   -> Eq (fold_mutate_eq eq)

  | Aut aut -> assert false

let fold_mutate_node nd =

  current_node := Some nd.node_id;

  { nd with 

    node_stmts = 

      List.fold_right (fun stmt res -> (fold_mutate_stmt stmt)::res) nd.node_stmts [];

    node_id = rename_app nd.node_id

  }

let fold_mutate_top_decl td =

  match td.top_decl_desc with

  | Node nd   -> { td with top_decl_desc = Node  (fold_mutate_node nd)}

  | Const cst -> { td with top_decl_desc = Const (fold_mutate_const cst)}

  | _ -> td

(* Create a single mutant with the provided random seed *)

let fold_mutate_prog prog = 

  List.fold_right (fun e res -> (fold_mutate_top_decl e)::res) prog []

let create_mutant prog directive =  

  target := Some directive; 

  let prog' = fold_mutate_prog prog in

  let mutation_info = match !target , !mutation_info with

    | None, Some mi -> mi

    | _ -> (

      Format.eprintf "Failed when creating mutant for directive %a@.@?" print_directive directive;

      let _ = match !target with Some dir' -> Format.eprintf "New directive %a@.@?" print_directive dir' | _ -> () in

      assert false (* The mutation has not been performed. *)

    )

  in

(*  target := None; (* should happen only if no mutation occured during the

    visit *)*)

  prog', mutation_info

let op_mutation op = 

  let res =

    let rem_op l = List.filter (fun e -> e <> op) l in

  if List.mem op arith_op then rem_op arith_op else 

    if List.mem op bool_op then rem_op bool_op else 

      if List.mem op rel_op then rem_op rel_op else 

	(Format.eprintf "Failing with op %s@." op;

	  assert false

	)

  in

  (* Format.eprintf "Mutation op %s to [%a]@." op (Utils.fprintf_list ~sep:"," Format.pp_print_string) res; *)

  res

let rec remains select list =

  match list with 

    [] -> []

  | hd::tl -> if select hd then tl else remains select tl

let next_change m =

  let res = 

  let rec first_op () = 

    try

      let min_binding = OpCount.min_binding !records.nb_op in

      Op (fst min_binding, 0, List.hd (op_mutation (fst min_binding)))

    with Not_found -> first_boolexpr () 

  and first_boolexpr () =

    if !records.nb_boolexpr > 0 then 

      Boolexpr 0 

    else first_pre ()

  and first_pre () = 

    if !records.nb_pre > 0 then 

      Pre 0 

    else

      first_op ()

  and first_intcst () =

    if IntSet.cardinal !records.consts > 0 then

      IncrIntCst 0

    else

      first_boolexpr ()

  in

  match m with

  | Boolexpr n -> 

    if n+1 >= !records.nb_boolexpr then 

      first_pre ()

    else

      Boolexpr (n+1)

  | Pre n -> 

    if n+1 >= !records.nb_pre then 

      first_op ()

    else Pre (n+1)

  | Op (orig, id, mut_op) -> (

    match remains (fun x -> x = mut_op) (op_mutation orig) with

    | next_op::_ -> Op (orig, id, next_op)

    | [] -> if id+1 >= OpCount.find orig !records.nb_op then (

      match remains (fun (k1, _) -> k1 = orig) (OpCount.bindings !records.nb_op) with

      | [] -> first_intcst ()

      | hd::_ -> Op (fst hd, 0, List.hd (op_mutation (fst hd)))

    ) else

	Op(orig, id+1, List.hd (op_mutation orig))

  )

  | IncrIntCst n ->

    if n+1 >= IntSet.cardinal !records.consts then

      DecrIntCst 0

    else IncrIntCst (n+1)

  | DecrIntCst n ->

    if n+1 >= IntSet.cardinal !records.consts then

      SwitchIntCst (0, 0)

    else DecrIntCst (n+1)

  | SwitchIntCst (n, m) ->

    if m+1 > -1 + IntSet.cardinal !records.consts then

      SwitchIntCst (n, m+1)

    else if n+1 >= IntSet.cardinal !records.consts then

      SwitchIntCst (n+1, 0)

    else first_boolexpr ()

  in

   (* Format.eprintf "from: %a to: %a@." print_directive m print_directive res;  *)

  res

let fold_mutate nb prog = 

  incr random_seed;

  Random.init !random_seed;

  (* Local references to keep track of generated directives *)

  (* build a set of integer 0, 1, ... n-1 for input n *)

  let cpt_to_intset cpt =

    let arr = Array.init cpt (fun x -> x) in

    Array.fold_right IntSet.add arr IntSet.empty

  in

  let possible_const_id = cpt_to_intset !records.nb_consts in

  (* let possible_boolexpr_id = cpt_to_intset !records.nb_boolexpr in *)

  (* let possible_pre_id = cpt_to_intset !records.nb_pre in *)

  let incremented_const_id = ref IntSet.empty in

  let decremented_const_id = ref IntSet.empty in

  let create_new_incr_decr registered build =

    let possible = IntSet.diff possible_const_id !registered |> IntSet.elements in

    let len = List.length possible in

    if len <= 0 then

      false, build (-1) (* Should not be stored *)

    else

      let picked = List.nth possible (Random.int (List.length possible)) in

      registered := IntSet.add picked !registered;

      true, build picked

  in

  let module DblIntSet = Set.Make (struct type t = int * int let compare = compare end) in

  let switch_const_id = ref DblIntSet.empty in

  let switch_set =

    if IntSet.cardinal !records.consts <= 1 then

      DblIntSet.empty

    else

      (* First element is cst id (the ith cst) while second is the

		       ith element of the set of gathered constants

		       !record.consts *)

      IntSet.fold (fun cst_id set ->

	  IntSet.fold (fun ith_cst set ->

	      DblIntSet.add (cst_id, ith_cst) set

	    ) !records.consts set

        ) possible_const_id DblIntSet.empty 

  in

  let create_new_switch registered build =

    let possible = DblIntSet.diff switch_set !registered |> DblIntSet.elements in

    let len = List.length possible in

    if len <= 0 then

      false, build (-1,-1) (* Should not be stored *)

    else

      let picked = List.nth possible (Random.int (List.length possible)) in

      registered := DblIntSet.add picked !registered;

      true, build picked

  in

  let find_next_new mutants mutant =

    let rec find_next_new init current =

      if init = current || List.mem current mutants then raise Not_found else

	(* TODO: check if we can generate more cases. The following lines were

	   cylcing and missing to detect that the enumaration was complete,

	   leading to a non terminating process. The current setting is harder

	   but may miss enumerating some cases. To be checked! *)