214 lines
8 KiB
OCaml
214 lines
8 KiB
OCaml
(**************************************************************************)
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(* *)
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(* Heptagon *)
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(* *)
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(* Author : Marc Pouzet *)
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(* Organization : Demons, LRI, University of Paris-Sud, Orsay *)
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(* *)
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(**************************************************************************)
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(** This module defines static expressions, used in params and for constants.
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const n: int = 3;
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var x : int^n; var y : int^(n + 2);
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x[n - 1], x[1 + 3],... *)
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open Names
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open Format
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open Types
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open Signature
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open Modules
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open Location
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exception Not_static
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(** Some evaluations are not possible *)
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type eval_error = Division_by_zero
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exception Evaluation_failed of eval_error * location
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(** Some unknown operators could be used preventing the evaluation *)
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type partial_eval_cause = Unknown_op of fun_name | Unknown_param of qualname
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exception Partial_evaluation of partial_eval_cause * location
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let message exn =
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begin match exn with
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| Evaluation_failed (e,loc) ->
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(match e with
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| Division_by_zero ->
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eprintf "%aForbidden division by 0.@."
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print_location loc
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)
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| Partial_evaluation (e,loc) ->
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(match e with
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| Unknown_op op ->
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eprintf "%aUnknown operator %a.@."
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Location.print_location loc
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Global_printer.print_qualname op
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| Unknown_param q ->
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eprintf "%aUninstanciated param %a.@."
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Location.print_location loc
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Global_printer.print_qualname q
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)
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| _ -> raise exn
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end;
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raise Errors.Error
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(** When not [partial],
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@raise Partial_evaluation when the application of the operator can't be evaluated (only Unknown_op).
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Otherwise keep as it is unknown operators. *)
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let apply_op partial loc op se_list =
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match se_list with
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| [{ se_desc = Sint n1 }; { se_desc = Sint n2 }] ->
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(match op with
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| { qual = Pervasives; name = "+" } ->
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Sint (n1 + n2)
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| { qual = Pervasives; name = "-" } ->
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Sint (n1 - n2)
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| { qual = Pervasives; name = "*" } ->
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Sint (n1 * n2)
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| { qual = Pervasives; name = "/" } ->
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if n2 = 0 then raise (Evaluation_failed (Division_by_zero, loc));
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Sint (n1 / n2)
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| { qual = Pervasives; name = "=" } ->
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Sbool (n1 = n2)
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| _ -> assert false (*TODO: add missing operators*)
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)
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| [{ se_desc = Sint n }] ->
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(match op with
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| { qual = Pervasives; name = "~-" } -> Sint (-n)
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| _ -> assert false (*TODO: add missing operators*)
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)
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| _ -> if partial then Sop(op, se_list) (* partial evaluation *)
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else raise (Partial_evaluation (Unknown_op op, loc))
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(** When not [partial],
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@raise Partial_evaluation when a static var cannot be evaluated, a local static parameter for example.
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Otherwise evaluate in a best effort manner. *)
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let rec eval_core partial env se = match se.se_desc with
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| Sint _ | Sfloat _ | Sbool _ | Sconstructor _ | Sfield _ -> se
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| Svar ln ->
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(try (* first try to find in global const env *)
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let cd = find_const ln in
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eval_core partial env cd.c_value
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with Not_found -> (* then try to find in local env *)
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(try
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let se = QualEnv.find ln env in
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(match se.se_desc with
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| Svar ln' when ln'=ln -> (* prevent basic infinite loop *)
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if partial then se else raise Not_found
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| _ -> eval_core partial env se
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)
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with Not_found -> (* Could not evaluate the var *)
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if partial then se
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else raise (Partial_evaluation (Unknown_param ln, se.se_loc))
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)
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)
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| Sop (op, se_list) ->
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let se_list = List.map (eval_core partial env) se_list in
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let se_desc = apply_op partial se.se_loc op se_list in
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{ se with se_desc = se_desc }
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| Sarray se_list ->
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{ se with se_desc = Sarray (List.map (eval_core partial env) se_list) }
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| Sarray_power (se, n) ->
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{ se with se_desc = Sarray_power (eval_core partial env se, eval_core partial env n) }
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| Stuple se_list ->
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{ se with se_desc = Stuple (List.map (eval_core partial env) se_list) }
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| Srecord f_se_list ->
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{ se with se_desc = Srecord
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(List.map (fun (f,se) -> f, eval_core partial env se) f_se_list) }
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(** [simplify env e] returns e simplified with the
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variables values taken from [env] or from the global env with [find_const].
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Every operator that can be computed is.
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It can return static_exp with uninstanciated variables.*)
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let simplify env se =
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try eval_core true env se
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with exn -> message exn
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(** [eval env e] does the same as [simplify]
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but if it returns, there are no variables nor op left.
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@raise [Errors.Error] when it cannot fully evaluate. *)
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let eval env se =
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try eval_core false env se
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with exn -> message exn
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(** [int_of_static_exp env e] returns the value of the expression
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[e] in the environment [env], mapping vars to integers.
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@raise [Errors.Error] if it cannot be computed.*)
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let int_of_static_exp env se = match (eval env se).se_desc with
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| Sint i -> i
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| _ -> Misc.internal_error "static int_of_static_exp" 1
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(** [is_true env constr] returns whether the constraint is satisfied
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in the environment (or None if this can be decided)
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and a simplified constraint. *)
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let is_true env =
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function
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| Cequal (e1, e2) when e1 = e2 ->
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Some true, Cequal (simplify env e1, simplify env e2)
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| Cequal (e1, e2) ->
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let e1 = simplify env e1 in
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let e2 = simplify env e2 in
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(match e1.se_desc, e2.se_desc with
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| Sint n1, Sint n2 -> Some (n1 = n2), Cequal (e1, e2)
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| (_, _) -> None, Cequal (e1, e2))
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| Clequal (e1, e2) ->
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let e1 = simplify env e1 in
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let e2 = simplify env e2 in
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(match e1.se_desc, e2.se_desc with
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| Sint n1, Sint n2 -> Some (n1 <= n2), Clequal (e1, e2)
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| _, _ -> None, Clequal (e1, e2))
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| Cfalse -> None, Cfalse
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exception Solve_failed of size_constraint
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(** [solve env constr_list solves a list of constraints. It
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removes equations that can be decided and simplify others.
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If one equation cannot be satisfied, it raises Solve_failed. ]*)
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let rec solve const_env =
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function
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| [] -> []
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| c :: l ->
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let l = solve const_env l in
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let (res, c) = is_true const_env c in
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(match res with
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| None -> c :: l
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| Some v -> if not v then raise (Solve_failed c) else l)
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(** Substitutes variables in the size exp with their value
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in the map (mapping vars to size exps). *)
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let rec static_exp_subst m se =
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match se.se_desc with
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| Svar qn -> (try QualEnv.find qn m with | Not_found -> se)
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| Sop (op, se_list) ->
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{ se with se_desc = Sop (op, List.map (static_exp_subst m) se_list) }
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| Sarray_power (se, n) ->
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{ se with se_desc = Sarray_power (static_exp_subst m se,
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static_exp_subst m n) }
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| Sarray se_list ->
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{ se with se_desc = Sarray (List.map (static_exp_subst m) se_list) }
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| Stuple se_list ->
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{ se with se_desc = Stuple (List.map (static_exp_subst m) se_list) }
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| Srecord f_se_list ->
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{ se with se_desc =
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Srecord (List.map
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(fun (f,se) -> f, static_exp_subst m se) f_se_list) }
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| _ -> se
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(** Substitutes variables in the constraint list with their value
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in the map (mapping vars to size exps). *)
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let instanciate_constr m constr =
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let replace_one m = function
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| Cequal (e1, e2) -> Cequal (static_exp_subst m e1, static_exp_subst m e2)
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| Clequal (e1, e2) -> Clequal (static_exp_subst m e1, static_exp_subst m e2)
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| Cfalse -> Cfalse in
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List.map (replace_one m) constr
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