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Control statement (interpreter, SM, x86)

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Dmitry Boulytchev 2018-03-11 22:30:01 +03:00
parent 42d94672bc
commit 8758485b80
15 changed files with 132 additions and 55 deletions
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27
src/Language.ml
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@ -110,8 +110,11 @@ module Stmt =
(* read into the variable *) | Read of string
(* write the value of an expression *) | Write of Expr.t
(* assignment *) | Assign of string * Expr.t
(* composition *) | Seq of t * t with show
(* composition *) | Seq of t * t
(* empty statement *) | Skip
(* conditional *) | If of Expr.t * t * t
(* loop *) | While of Expr.t * t with show
(* The type of configuration: a state, an input stream, an output stream *)
type config = Expr.state * int list * int list
@ -123,10 +126,13 @@ module Stmt =
*)
let rec eval ((st, i, o) as conf) stmt =
match stmt with
| Read x -> (match i with z::i' -> (Expr.update x z st, i', o) | _ -> failwith "Unexpected end of input")
| Write e -> (st, i, o @ [Expr.eval st e])
| Assign (x, e) -> (Expr.update x (Expr.eval st e) st, i, o)
| Seq (s1, s2) -> eval (eval conf s1) s2
| Read x -> (match i with z::i' -> (Expr.update x z st, i', o) | _ -> failwith "Unexpected end of input")
| Write e -> (st, i, o @ [Expr.eval st e])
| Assign (x, e) -> (Expr.update x (Expr.eval st e) st, i, o)
| Seq (s1, s2) -> eval (eval conf s1) s2
| Skip -> conf
| If (e, s1, s2) -> eval conf (if Expr.eval st e <> 0 then s1 else s2)
| While (e, s) -> if Expr.eval st e = 0 then conf else eval (eval conf s) stmt
(* Statement parser *)
ostap (
@ -134,9 +140,12 @@ module Stmt =
s:stmt ";" ss:parse {Seq (s, ss)}
| stmt;
stmt:
"read" "(" x:IDENT ")" {Read x}
| "write" "(" e:!(Expr.parse) ")" {Write e}
| x:IDENT ":=" e:!(Expr.parse) {Assign (x, e)}
%"read" "(" x:IDENT ")" {Read x}
| %"write" "(" e:!(Expr.parse) ")" {Write e}
| %"skip" {Skip}
| %"if" e:!(Expr.parse) %"then" s1:parse %"else" s2:parse %"fi" {If (e, s1, s2)}
| %"while" e:!(Expr.parse) %"do" s:parse %"od" {While (e, s)}
| x:IDENT ":=" e:!(Expr.parse) {Assign (x, e)}
)
end