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|
(** This module defines various utilities to write the interpretation functions
in continuation passing style. *)
open Values
open Contexts
open Errors
(** TODO: change the name *)
type eval_error = EPanic
(** Result of evaluating a statement *)
type statement_eval_res =
| Unit
| Break of int
| Continue of int
| Return
| Panic
| LoopReturn of loop_id
(** We reached a return statement *while inside a loop* *)
| EndEnterLoop of loop_id * typed_value SymbolicValueId.Map.t
(** When we enter a loop, we delegate the end of the function is
synthesized with a call to the loop translation. We use this
evaluation result to transmit the fact that we end evaluation
because we entered a loop.
We provide the list of values for the translated loop function call
(or to be more precise the input values instantiation).
*)
| EndContinue of loop_id * typed_value SymbolicValueId.Map.t
(** For loop translations: we end with a continue (i.e., a recursive call
to the translation for the loop body).
We provide the list of values for the translated loop function call
(or to be more precise the input values instantiation).
*)
[@@deriving show]
(* TODO: remove *)
type eval_result = SymbolicAst.expression
(** Function which takes a context as input, and evaluates to:
- a new context
- a continuation with which to build the execution trace, provided the
trace for the end of the execution.
*)
type cm_fun =
eval_ctx -> eval_ctx * (SymbolicAst.expression -> SymbolicAst.expression)
type st_cm_fun =
eval_ctx ->
(eval_ctx * statement_eval_res)
* (SymbolicAst.expression -> SymbolicAst.expression)
(** Type of a function used when evaluating a statement *)
type stl_cm_fun =
eval_ctx ->
(eval_ctx * statement_eval_res) list
* (SymbolicAst.expression list -> SymbolicAst.expression)
(** Compose continuations that we use to compute execution traces *)
let cc_comp (f : 'b -> 'c) (g : 'a -> 'b) : 'a -> 'c = fun e -> f (g e)
let comp (f : 'b -> 'c) (g : 'x * ('a -> 'b)) : 'x * ('a -> 'c) =
let x, g = g in
(x, cc_comp f g)
let comp2 (f : 'b -> 'c) (g : 'x * 'y * ('a -> 'b)) : 'x * 'y * ('a -> 'c) =
let x, y, g = g in
(x, y, cc_comp f g)
(** [fold] operation for functions which thread a context and return a continuation *)
let fold_left_apply_continuation (f : 'a -> 'c -> 'c * ('e -> 'e))
(inputs : 'a list) (ctx : 'c) : 'c * ('e -> 'e) =
let rec eval_list (inputs : 'a list) : 'c -> 'b =
fun ctx ->
match inputs with
| [] -> (ctx, fun x -> x)
| x :: inputs ->
let ctx, cc = f x ctx in
comp cc (eval_list inputs ctx)
in
eval_list inputs ctx
(** [map] operation for functions which thread a context and return a continuation *)
let map_apply_continuation (f : 'a -> 'c -> 'b * 'c * ('e -> 'e))
(inputs : 'a list) (ctx : 'c) : 'b list * 'c * ('e -> 'e) =
let rec eval_list (inputs : 'a list) (ctx : 'c) : 'b list * 'c * ('e -> 'e) =
match inputs with
| [] -> ([], ctx, fun e -> e)
| x :: inputs ->
let v, ctx, cc1 = f x ctx in
let vl, ctx, cc2 = eval_list inputs ctx in
(v :: vl, ctx, cc_comp cc1 cc2)
in
eval_list inputs ctx
let cc_singleton file line span cf el =
match el with [ e ] -> cf e | _ -> internal_error file line span
(** It happens that we need to concatenate lists of results, for
instance when evaluating the branches of a match. When applying
the continuations to build the symbolic expressions, we need
to decompose the list of expressions we get to give it to the
individual continuations for the branches.
*)
let comp_seqs (file : string) (line : int) (span : Meta.span)
(ls :
('a list * (SymbolicAst.expression list -> SymbolicAst.expression)) list)
: 'a list * (SymbolicAst.expression list -> SymbolicAst.expression list) =
(* Auxiliary function: given a list of expressions el, build the expressions
corresponding to the different branches *)
let rec cc ls el =
match ls with
| [] ->
(* End of the list of branches: there shouldn't be any expression remaining *)
sanity_check file line (el = []) span;
[]
| (resl, cf) :: ls ->
(* Split the list of expressions between:
- the expressions for the current branch
- the expressions for the remaining branches *)
let el0, el = Collections.List.split_at el (List.length resl) in
(* Compute the expression for the current branch *)
let e0 = cf el0 in
(* Compute the expressions for the remaining branches *)
let e = cc ls el in
(* Concatenate *)
e0 :: e
in
(List.flatten (fst (List.split ls)), cc ls)
|
