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Shells in OCaml forked from patrick.sirref.org/merry
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960(* We handle _very_ simple arithmetic expressions. Really nothing crazy yet, hopefully enough to handle most [while x < 10 do x = x + 1 done] loops! *)type operator = Add | Sub | Mul | Div | Mod | Lt | Gt | Eq[@@deriving to_yojson]
let exec_op = function | Add -> Int.add | Sub -> Int.sub | Mul -> Int.mul | Div -> Int.div | Mod -> ( mod ) | Lt -> fun a b -> if a < b then 1 else 0 | Gt -> fun a b -> if a > b then 1 else 0 | Eq -> fun a b -> if Int.equal a b then 1 else 0
type expr = | Int of int | Var of string | Binop of operator * expr * expr | Neg of expr | Assign of operator * string * expr | Ternary of (expr * expr * expr)[@@deriving to_yojson]
module Make (S : Types.State) = struct let eval initial_state expr = let lookup state s = match S.lookup state ~param:s with | Some [ Ast.WordLiteral n ] when Option.is_some (int_of_string_opt n) -> int_of_string n | _ -> 0 in let update state s i = match S.update state ~param:s [ Ast.WordLiteral (string_of_int i) ] with | Ok s -> s | Error m -> failwith m in let rec calc state = function | Int i -> (state, i) | Var v -> (state, lookup state v) | Binop (op, e1, e2) -> let state, v1 = calc state e1 in let state, v2 = calc state e2 in (state, exec_op op v1 v2) | Neg n -> let state, v1 = calc state n in (state, Int.neg v1) | Assign (op, var, e) -> let current_v = lookup state var in let state, v1 = calc state e in let nv = exec_op op current_v v1 in (update state var nv, nv) | Ternary (e1, e2, e3) -> let state, v1 = calc state e1 in if Int.equal v1 Int.zero then calc state e3 else calc state e2 in calc initial_state exprend