open Types open Values open CfimAst module V = Values type binder = { index : VarId.id; (** Unique variable identifier *) name : string option; (** Possible name *) } [@@deriving show] (** A binder used in an environment, to map a variable to a value *) (** Environment value: mapping from variable to value, abstraction (only used in symbolic mode) or stack frame delimiter. TODO: rename Var (-> Binding?) *) type env_elem = Var of (binder[@opaque]) * typed_value | Abs of abs | Frame [@@deriving show, visitors { name = "iter_env_elem"; variety = "iter"; ancestors = [ "iter_abs" ]; nude = true (* Don't inherit [VisitorsRuntime.iter] *); concrete = true; }, visitors { name = "map_env_elem"; variety = "map"; ancestors = [ "map_abs" ]; nude = true (* Don't inherit [VisitorsRuntime.iter] *); concrete = true; }] type env = env_elem list [@@deriving show, visitors { name = "iter_env"; variety = "iter"; ancestors = [ "iter_env_elem" ]; nude = true (* Don't inherit [VisitorsRuntime.iter] *); concrete = true; }, visitors { name = "map_env"; variety = "map"; ancestors = [ "map_env_elem" ]; nude = true (* Don't inherit [VisitorsRuntime.iter] *); concrete = true; }] type interpreter_mode = ConcreteMode | SymbolicMode [@@deriving show] type config = { mode : interpreter_mode; check_invariants : bool } [@@deriving show] type eval_ctx = { type_context : type_def list; fun_context : fun_def list; type_vars : type_var list; env : env; symbolic_counter : SymbolicValueId.generator; borrow_counter : BorrowId.generator; } [@@deriving show] (** Evaluation context *) let fresh_symbolic_value_id (ctx : eval_ctx) : eval_ctx * SymbolicValueId.id = let id, counter' = SymbolicValueId.fresh ctx.symbolic_counter in ({ ctx with symbolic_counter = counter' }, id) let fresh_borrow_id (ctx : eval_ctx) : eval_ctx * BorrowId.id = let id, counter' = BorrowId.fresh ctx.borrow_counter in ({ ctx with borrow_counter = counter' }, id) let lookup_type_var (ctx : eval_ctx) (vid : TypeVarId.id) : type_var = TypeVarId.nth ctx.type_vars vid let ctx_lookup_binder (ctx : eval_ctx) (vid : VarId.id) : binder = (* TOOD: we might want to stop at the end of the frame *) let rec lookup env = match env with | [] -> raise (Invalid_argument ("Variable not found: " ^ VarId.to_string vid)) | Var (var, _) :: env' -> if var.index = vid then var else lookup env' | (Abs _ | Frame) :: env' -> lookup env' in lookup ctx.env let ctx_lookup_type_def (ctx : eval_ctx) (tid : TypeDefId.id) : type_def = TypeDefId.nth ctx.type_context tid let ctx_lookup_fun_def (ctx : eval_ctx) (fid : FunDefId.id) : fun_def = FunDefId.nth ctx.fun_context fid (** Retrieve a variable's value in an environment *) let env_lookup_var_value (env : env) (vid : VarId.id) : typed_value = (* We take care to stop at the end of current frame: different variables in different frames can have the same id! *) let rec lookup env = match env with | [] -> failwith "Unexpected" | Var (var, v) :: env' -> if var.index = vid then v else lookup env' | Abs _ :: env' -> lookup env' | Frame :: _ -> failwith "End of frame" in lookup env (** Retrieve a variable's value in an evaluation context *) let ctx_lookup_var_value (ctx : eval_ctx) (vid : VarId.id) : typed_value = env_lookup_var_value ctx.env vid (** Update a variable's value in an environment This is a helper function: it can break invariants and doesn't perform any check. *) let env_update_var_value (env : env) (vid : VarId.id) (nv : typed_value) : env = (* We take care to stop at the end of current frame: different variables in different frames can have the same id! *) let rec update env = match env with | [] -> failwith "Unexpected" | Var (var, v) :: env' -> if var.index = vid then Var (var, nv) :: env' else Var (var, v) :: update env' | Abs abs :: env' -> Abs abs :: update env' | Frame :: _ -> failwith "End of frame" in update env let var_to_binder (var : var) : binder = { index = var.index; name = var.name } (** Update a variable's value in an evaluation context. This is a helper function: it can break invariants and doesn't perform any check. *) let ctx_update_var_value (ctx : eval_ctx) (vid : VarId.id) (nv : typed_value) : eval_ctx = { ctx with env = env_update_var_value ctx.env vid nv } (** Push a variable in the context's environment. Checks that the pushed variable and its value have the same type (this is important). *) let ctx_push_var (ctx : eval_ctx) (var : var) (v : typed_value) : eval_ctx = assert (var.var_ty = v.ty); let bv = var_to_binder var in { ctx with env = Var (bv, v) :: ctx.env } (** Push a list of variables. Checks that the pushed variables and their values have the same type (this is important). *) let ctx_push_vars (ctx : eval_ctx) (vars : (var * typed_value) list) : eval_ctx = assert ( List.for_all (fun (var, (value : typed_value)) -> var.var_ty = value.ty) vars); let vars = List.map (fun (var, value) -> Var (var_to_binder var, value)) vars in let vars = List.rev vars in { ctx with env = List.append vars ctx.env } let mk_bottom (ty : ety) : typed_value = { value = Bottom; ty } (** Push an uninitialized variable (which thus maps to [Bottom]) *) let ctx_push_uninitialized_var (ctx : eval_ctx) (var : var) : eval_ctx = ctx_push_var ctx var (mk_bottom var.var_ty) (** Push a list of uninitialized variables (which thus map to [Bottom]) *) let ctx_push_uninitialized_vars (ctx : eval_ctx) (vars : var list) : eval_ctx = let vars = List.map (fun v -> (v, mk_bottom v.var_ty)) vars in ctx_push_vars ctx vars (** Visitor to iterate over the values in the *current* frame *) class ['self] iter_frame = object (self : 'self) inherit [_] V.iter_abs method visit_Var : 'acc -> binder -> typed_value -> unit = fun acc vid v -> self#visit_typed_value acc v method visit_Abs : 'acc -> abs -> unit = fun acc abs -> self#visit_abs acc abs method visit_env_elem : 'acc -> env_elem -> unit = fun acc em -> match em with | Var (vid, v) -> self#visit_Var acc vid v | Abs abs -> self#visit_Abs acc abs | Frame -> failwith "Unreachable" method visit_env : 'acc -> env -> unit = fun acc env -> match env with | [] -> () | Frame :: _ -> (* We stop here *) () | em :: env -> self#visit_env_elem acc em; self#visit_env acc env end (** Visitor to map over the values in the *current* frame *) class ['self] map_frame_concrete = object (self : 'self) inherit [_] V.map_abs method visit_Var : 'acc -> binder -> typed_value -> env_elem = fun acc vid v -> let v = self#visit_typed_value acc v in Var (vid, v) method visit_Abs : 'acc -> abs -> env_elem = fun acc abs -> Abs (self#visit_abs acc abs) method visit_env_elem : 'acc -> env_elem -> env_elem = fun acc em -> match em with | Var (vid, v) -> self#visit_Var acc vid v | Abs abs -> self#visit_Abs acc abs | Frame -> failwith "Unreachable" method visit_env : 'acc -> env -> env = fun acc env -> match env with | [] -> [] | Frame :: env -> (* We stop here *) Frame :: env | em :: env -> let em = self#visit_env_elem acc em in let env = self#visit_env acc env in em :: env end (** Visitor to iterate over the values in a context *) class ['self] iter_eval_ctx = object (self : 'self) inherit [_] iter_env as super method visit_eval_ctx : 'acc -> eval_ctx -> unit = fun acc ctx -> super#visit_env acc ctx.env end (** Visitor to map the values in a context *) class ['self] map_eval_ctx = object (self : 'self) inherit [_] map_env as super method visit_eval_ctx : 'acc -> eval_ctx -> eval_ctx = fun acc ctx -> let env = super#visit_env acc ctx.env in { ctx with env } end