79 lines
2.2 KiB
OCaml
79 lines
2.2 KiB
OCaml
open Printf
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open Eval
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let version = "%%VERSION%%"
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let debug = ref false
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let error_to_string e =
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try raise e with
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| Lex.Invalid_character (col, c) ->
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sprintf "invalid character %c at col %d" c col
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| Lex.Expected (col, c) -> sprintf "expected %c at col %d" c col
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| Parser.Fatal e -> raise e
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| Parser.End_of_tokens -> "expression ended abruptly"
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| Parser.Expected (col, t) -> sprintf "expected %s at col %d" t col
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| Parser.Unexpected_token (col, t) ->
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sprintf "unexpected token \"%s\" at col %d" t col
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| Type.Invalid t -> sprintf "invalid type %s" (Type.to_string t)
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| Eval.Unbound v -> sprintf "unbound value %s" v
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| Eval.No_such_method (m, t) ->
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sprintf "no such method %s matching type %s" m (Type.to_string t)
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| Failure f -> sprintf "error on %s" f
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| Division_by_zero -> "cannot divide by zero"
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| _ -> raise e
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let print_error e =
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printf "error: %s\n" @@ error_to_string e
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let stdlib = [
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"sin"; "cos"; "tan";
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"deg"; "rad";
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"get_op_pre"; "set_op_pre";
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"get_op_assoc"; "set_op_assoc";
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"print"; "println";
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]
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|> List.to_seq
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|> Seq.map (fun v -> v, External v)
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(* global environment *)
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let g =
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let g = Hashtbl.create 100 in
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Hashtbl.add_seq g stdlib;
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g
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(* read-eval-print *)
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let rep () : unit =
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printf "> ";
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let line = read_line () in
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if line = "quit" then raise Exit;
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let ast = line |> Lex.tokenize |> Parser.parse in
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if !debug then Ast.print ast;
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let var, v = Eval.eval_top g ast in
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Hashtbl.replace g "ans" v;
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printf "%s: %s = %s\n"
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var (Type.to_string @@ Value.typeof v) (Value.to_string v)
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exception Reset_line (* used to indicate ^C is pressed *)
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let init_repl () =
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(* treat Ctrl-C as to reset line *)
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let reset_line _ = raise Reset_line in
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Sys.(set_signal sigint (Signal_handle reset_line))
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(* simple REPL with error handling *)
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let rec repl () : unit =
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try rep (); repl () with
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| Exit | End_of_file (* Ctrl-D *) -> ()
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| Noop -> repl ()
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| Reset_line -> printf "\n"; repl ()
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| e -> print_error e; repl ()
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let speclist = [
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"--debug", Arg.Set debug, "print debug infos";
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]
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let () =
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Arg.parse speclist (fun _ -> ()) "";
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init_repl ();
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printf "Configurable Evaluator %s\n" version; (* banner *)
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repl ()
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