ce/eval.ml
2022-01-25 15:28:38 +09:00

76 lines
1.9 KiB
OCaml

open Ast
open Ast.Value
exception No_operation
exception No_such_variable of string
let resolve_type op tp =
let optypes = Binop.get_types op in
let q = Queue.create () in
let rec aux (t1, t2) =
if List.mem (t1, t2) optypes then
t1, t2
else begin
[ Type.supertype t1 |> Option.map (fun t1 -> t1, t2);
Type.supertype t2 |> Option.map (fun t2 -> t1, t2); ]
|> List.filter_map Fun.id
|> List.iter (Fun.flip Queue.push q);
aux @@ Queue.pop q
end
in
aux tp
let rec binop op l r =
let t1 = typeof l and t2 = typeof r in
let t1, t2 = resolve_type op (t1, t2) in
let rec promote_until t x =
if typeof x = t
then x
else promote_until t (promote x)
in
let l = promote_until t1 l
and r = promote_until t2 r in
match Binop.get op (t1, t2) with
| None -> begin
try binop op (promote l) (promote r)
with _ -> raise No_operation
end
| Some f -> f l r
let eval vars ast =
let rec aux = function
| Value v -> v
| Var v -> begin match Hashtbl.find_opt vars v with
| None -> raise @@ No_such_variable v
| Some v -> v
end
| Unary (op, t) ->
let t = aux t in
let op = Unary.get op (Value.typeof t) in
op t
| Binop (l, op, r) ->
let l = aux l and r = aux r in
binop op l r
| Let (var, e) ->
let v = aux e in
Hashtbl.replace vars var v;
v
| Set_binop_pre (op, l) ->
let l =
match aux l with
| Int n -> n
| v -> raise @@ Invalid_type (typeof v)
in
Hashtbl.replace Parser.precedence op l;
Nop
| Get_binop_pre op ->
Int (Hashtbl.find Parser.precedence op)
| Set_binop_aso (op, a) ->
Hashtbl.replace Parser.oper_assoc op @@ Parser.assoc_of_string a;
Nop
| Get_binop_aso op ->
match Hashtbl.find_opt Parser.oper_assoc op with
| None -> String "left"
| Some a -> String (Parser.assoc_to_string a)
in
aux ast